Are high-frequency flapping wings efficient and scalable at high Reynolds numbers? Is high-frequency flapping (similar to how dragonflies fly) an efficient lift production method at high Reynolds numbers?

I have not seen anyone develop wing suits with high frequency flapping, is it efficient only at the insect scale? A few million years ago there used to exist dragonflies with wing spans around 70cm - correlating with the high oxygen content in the atmosphere at that time - so is this possible at larger wingspans too?

I'm thinking of something like the parademons in Justice League:

Some English University researchers studied the tiny helicopter Black Hornet versus Colibri-wings as efficiency. It was shown that rotating wings have LESS LOSS as the flapping ones because the latter must surpass the inertia of the wings at each flap. The insect wings have little weight and so small inertia.  So high-frequency flapping is only for small devices. What is better in the animal wings is the aerodynamic itself> Search "leading-edge vortex" on Google. Why animals have no rotating wings? >there is no rotating device in animals, because they must be fully articulated, by design... Only maple-seeds have a sort of autogyro.


What happens to jettisoned fuel tanks? When an F-15 (or your favorite fighter aircraft) punches it's external tanks...

...to engage in combat, (or when they are empty), what happens to them?

Through my best reasoning skills and Newton's calculations, I have determined that they will fall.

But what happens when they hit the ground? Do they explode? Do they detonate at a certain height? Is this a problem? Are there regulations determining where/when pilots may pickle their tanks? Have there ever been any accidents? (E.g. houses/cows/grandmothers destroyed by falling fuel tanks?)

They are called drop tanks. When a drop tank is jettisoned, very likely it is not retrieved and reused. This is also the case with (sadly, discontinued) Space Shuttle external tank. Those tanks were not reused either. I am not talking about the rocket boosters.

What happens to jettisoned fuel tanks?

It depends on where they land. The tanks jettisoned in Vietnam have been used to make boats (more pictures here).

It is worth noting that these external fuel tanks have disadvantage too:

  A general rule is that only about half the capacity of a streamlined
  drop tank actually goes towards increasing the aircraft's overall
  range, the rest going to overcome the added drag and weight of the
  tank itself.


What could cause lower torque than normal during cruise in a King Air 300? At approx FL200 in our King Air 300 we experience a vibration and notice the torque drop for both engines. The torque stays about 10% lower than normal in cruise. The vibration is intermittent and doesn’t seem to occur in the descent. All other instruments indicate normal readings including oil pressure, temps, and fuel flow. What might be the possible causes?

My guess, and it's just a wild guess, is humidity based ice forming somewhere in the inlet and/or the inlet plenum, more or less similar to carburetor icing.  The symmetrical torque drop is from the flow restriction and the random vibration is when the ice breaks up. I'll guess that you were flying though what appeared to be clear or clearish air with the inlet/plenum anti-ice turned off.

Double simultaneous random mechanical malfunctions are just too microscopic from a probability perspective to be likely at all.  A phenomenon like that, that happens to both engines at the same time,  must be due to an external source related to the atmosphere the aircraft is flying through, unless there is some other system on board that impacts both engines equally if it malfunctions, and that's something you won't generally see design wise.

I would try this question on PPrune Forums.  Somewhere there is a King Air or Twin Otter driver that's had the same experience.


Which agency issues private pilot certificates? With which agency would you apply if you wanted a private pilot certificate? Is it FAA (Federal Aviation Administration), NTSB (National Transportation Safety Board), or ICAO (International Civil Aviation Organization)?

Here in the USA the FAA is the agency that issues all levels of Pilots Certificates. However the certificate is not simply applied for, it requires training and the passage of a written, oral, and practical exam. You can find the current requirements here.

For reference the NTSB investigates accidents (all transportation accidents for that matter)

And ICAO is a UN organization that deals with coordinating aviation related maters all over the globe.


Is it common for jets not to have backup manual control system for emergencies? In July 1989, the United Flight 232 crashed in Sioux City, Iowa, while the pilots were trying to land on the runway without any yoke control. Today, I was reading the PHAK and found this phrase: "In the event of complete (hydraulic or electrical) power unit failure, movement of the control surface can be effected by manually controlling the control tabs" (4-46).

Why didn't the pilots of the United Flight 232 have a backup manual control when their hydraulic system failed? Is it because the aircraft (DC-10) was equipped with three independent hydraulic systems, which were considered to provide adequate redundancy for emergencies? Then, what about other modern passenger jets like Boeing and Airbus models? Do they have a backup manual control system in case of such a hydraulic or electrical control system failure?

On any large jet (the DC-10 was a wide-bodied plane, seating around 300 people), the control surfaces are simply too large to move without hydraulics. Manual control is impossible, and multiple redundant hydraulic systems are provided. This applies to any large plane.

It's considered unlikely that all the hydraulic systems will fail independently. The specific problem on United flight 232 was that the failures weren't independent: all three hydraulic systems were severed by the engine in the tailplane failing and spewing lumps of metal into the narrow conduit that carried the hydraulic lines.


Is it practical to integrate turbofan or ramjet engines into an airliner wing? The de Havilland Comet had turbojet engines integrated into its wings, such that its nacelles were mostly flush with the wings like so:

(wikimedia.org)

I recognize that turbofan engines are significantly larger in diameter than most turbojets, making the Comet's arrangement impractical for most modern airliners, but would it still be possible to integrate the engine nacelle with, say, the bottom of a wing while maintaining good aerodynamic characteristics on the wing? Would ramjet engines, owing to their lower profile, be more practical to integrate into a wing than turbofans?

The first turbofan, the Rolls-Royce Conway, had a bypass ratio of only 0.25 in order have a small enough diameter for placement in wing roots. It was initially planned for the V bombers and planned civilian derivatives of them. So yes, it is practical to place a turbofan engine in the wing, but comes at a cost:

Buried engine placement will shift the optimum to smaller bypass ratios, which reduces fuel efficiency.

Next, now your leading edge is occupied by an intake and cannot use any of the possible leading edge devices to increase lift at low speed for take-off or landing. The same goes for the trailing edge. The consequence is:

Buried engine placement will require a larger wing because the use of high-lift devices is not possible near the engines.

Larger wings weigh more and produce more drag in cruise. The last reason might be the most important: In operation, a podded engine is much easier to service and to repair than a buried one. The lower maintenance cost was the main driver for podded engines in the later members of the first generation of airliners (Boeing 707, DC-8, Convair 880).

Buried engine placement drives maintenance cost up.

There are fewer designs with ramjet engines, many of which never took to the air. Here, placement in the wing plane was mostly chosen to avoid thrust-related pitch moment changes. However, a ramjet is best used at high speed, and then you need to keep wing thickness down in order to reduce wave drag. Therefore, the engine placement cannot really be called buried anymore, but is closer to the buried than the podded variety.

The best example is the Lockheed D-21 drone pictured below (source). Since the aircraft is practically a ramjet with wings, the engine dominates the appearance.

Due to the high thrust needed for supersonic flight, supersonic aircraft keep their engines close to the wing and designs with podded engines like the Convair B-58 or the Myasishchyev M-50 were the exception. Stealth aircraft want to hide the hot exhaust and often use an overwing exhaust location which makes their engine placement also a buried one. You might argue that the engine of the Lockheed RQ-3 pictured below (source) is actually in the fuselage, but being a flying wing it does not have one:

The RQ-3 and similar designs like the Northrop B-2 clearly show that a turbofan engine location inside the wing is very practical indeed.


Why do we have to check that the fuel x feed is properly functioning before departing for an ETOPS flight on the A320? In the A320 family series FCOM under the special operations procedure chapter it is mentioned that we have to check the fuel x feed on ground before departing.

Any specific reason why we only check it before departing for ETOPS flights?

The main reason to check the Fuel-X-FEED on the ground before the flight is to allow the pilots to use the total fuel quantity on both wings in case of a single-engine failure during flying in ETOPS.
(Due to engine-out scenario you may not be able to feed one engine by both fuel tanks without the FUEL-X-FEED Valve)

in addition to this, the Fuel-X-FEED in the A320 MEL is a NO DISPATCH item by means you can't depart without and that reason tracks back to the EASA Requirments listed in AMC-20 AMENDMENT  - 7 (APPENDIX 4 - FLIGHT PREPARATION AND IN-FLIGHT PROCEDURES):

(11)  Fuel  system
(i)    The aeroplane fuel system should provide fuel pressure and flow to the engine(s) in accordance  with  CS  25.951  and  25.955  for  any  fuel  pump  power  supply  failure  condition not shown to be extremely improbable.
(ii)   The fuel necessary to complete the ETOPS mission or during a diversion should be available  to  the  operating  engine(s)  under  any  failure  condition,  other  then  fuel  boost pump failures, not shown to be extremely improbable2 (e.g. crossfeed valve failures, automatic fuel management system failures).


will a Sears-Haack body straighten itself out if "launched" sideways? I'm asking this here not because it's a question about flying a plane but because I read some engineering questions that said to bring aerodynamics questions to aviation.se for the best results.

Will a Sears-Haack body straighten itself out if "launched" sideways? Let's say it's launched from space toward the earth and hits the atmosphere at supersonic speeds. Even if it "hit" air side-on would it straighten itself out? (That is -- one of the pointy-sides now at the front) And if so would it happen in a quick/undramatic way so that the spaceship launching it would have a reasonable chance of hitting an intended destination?

If not, would the addition of fins to one end make it more likely to right itself as it hit the air?

--I guess this question boils down to: "will an object moving at high speed find and stay in its most aerodynamic orientation?" and then: "if not, will a major control surface like fins make it do so?"

will an object moving at high speed find and stay in its most aerodynamic orientation?

No. It will most likely tumble around. With the center of gravity behind its center of pressure, a body of rotation is inherently unstable.

  if not, will a major control surface like fins make it do so?

Yes. That is the reason for those large surfaces at the rear end of airplanes.

This answer is about directional stability over Mach. At supersonic speed directional stability drops with increasing Mach number.

This answer covers a similar topic; now it is about the proper location of fins at supersonic speed.


How do you search for all incidents of a Canadian airline online? Where can I find records of all incidents (per ICAO's definition) for a specific Canadian airline, e.g. WestJet? Typing in 'Westjet' on TSB Canada's site produced only 7 results and none this year: this is wrong because per Google (and Canadian news sources), WestJet has suffered problems with their Boeing 767-300s in 2016.

Avherald has more results, but is difficult to read as it does not enable sorting by date: but what are their sources? And shockingly, Aviation Safety Network neglects WestJet (the second largest airline in Canada)!

Try http://www.tsb.gc.ca/eng/stats/aviation/index-ff.asp on TSB Canada's website. Download the Aviation Occurrence data set and open it in your favourite spreadsheet. It has approximately 60 incidents for WestJet and WestJet Encore.


How does ADS-C and FMS relate to FANS? So - I'm totally confused about FANS and its systems. From what I understand:

FANS 1/A (started in 90s) has some early CPDLC for USA routes (this topic) but what about position reporting? Does it have ADS-C (or other ADS system)? And if it does not, what is used for position reporting to the ATC? Also - is satcom used in the FANS 1/A as a message-transporting service or not? And what is the role of FMS in this system?
FANS 2/B has LINK2000+ CPDLC and ADS-C and uses onboard ATSU to transfer its messages to the ATC. ATSU automatically selects the best form of communication (VHF, Sat, HF...) to transfer the messages. What is the role of FMS in this system? It provides info for ADS-C and provides data to CPDLS or am I wrong?

Thank you. There are so many sources and they differ from each other and I really need to be clear in this.

Regarding the confusion, if this is for your thesis like your previous question, ICAO Doc 10037, which supercedes Doc 9694, should clarify many things. But there could be more applicable references based on your research topic (you can ask your advisor to make recommendations).

Regarding your questions:

Does FANS 1/A have ADS-C?

Only "FANS 1/A ADS-C" does, if "ADS-C" is not in the name, then no. Applicable standard is DO-258A/ED-100A.

If it does not, what is used for position reporting to the ATC?

ACARS is used. ADS-C is mainly about automatic reporting based on fixed intervals, for example. Otherwise the reports are submitted manually – like making a position report via voice, but instead via ACARS (which is supported by FANS 1/A).

Is satcom used in the FANS 1/A as a message-transporting service?

Yes.

FANS 2/B has LINK2000+ CPDLC and ADS-C (...)

Actually, that's FANS C. It includes both CPDLC (LINK2000+ / ATN-B1) and ADS-C. It made its debut recently.

I think you are confusing position reports, with ADS-C. While ADS-C provides position reporting, it is not the only way, as explained earlier.

What is the role of FMS?

There isn't one blanket answer.

An FMS is where all the position sources feed, whether the FMS can distinguish between mandatory reporting points, and whether it allows the position to be overwritten by the crew, it depends on the aircraft and the installed FMS.

For example for the Boeing B737, B777, B757, B767, B717, MD90, MD10, MD11:

  The FMCs on these Boeing aircraft do not distinguish between ATC mandatory waypoints and FMC sequenced waypoints for position reports. However, the FANS 1 of these aircraft will allow the flight crew to overwrite the FMC- determined default "reported waypoint" position and time.

Source: Doc 10037 § C.5 FMS processing of waypoints in position reports


Where can I get IFR charts for throughout the world? (Note this question asks about VFR charts.)

In the U.S, I can get IFR navigation charts from Aeronav or Jeppesen.

Do IFR charts exist worldwide? If so, where can I go for charts of other countries? (A list would be nice since there probably isn't one canonical source?). If not, what are the alternatives?

The primary source for every country would be the countries' Aeronautical Information Publication (AIP). In some cases the AIP is freely accessible, printed copies can be directly obtained from the Civil Aviation Authority (CAA) or commercial companies authorized to distribute these, such as Jeppesen.

In some cases there will be a joint resource for certain areas, e.g.
The IFR charts for European countries can be obtained as digital copies from EAD EUROCONTROL.


After decades of solid research, mostly led by Robert J Englar, why is Circulation Control, the Circulation Control Wing not in use at all? Any research on the CCW by Robert J Englar at Georgia Tech from the 60's into the 2000's.
Many papers have confirmed Englar's work and in many cases, advanced it.
This research has proven extreme lift for slower, safer airliner take-off and landing as well as reduced weight, noise and drag.
https://smartech.gatech.edu/bitstream/handle/1853/14123/naqvi_messam_a_200612_phd.pdf This paper covers much for the practical use of a CCW but also references Englar's basic idea as well as posting several references to Englar's research.  These can also be covered to help answer my question.

Circulation may be controlled via either air blown through spanwise slots or horizontal-axis rotors, alone or in combination.
Experiments on wing systems go back at least as far as 1902 and since then almost every variation imaginable has been tried.
The problems come in the engineering implementation. Where investigations have reached the stage of flight testing, and in many cases sooner than that, the conclusion is always the same. Either you have a system of large air ducts threading through the wing structure and weakening it, or you have a spinning rotor to support along the span of the wing. Either way, the wing must be strengthened and that means more weight. Both approaches require a supplementary power source, more weight again. The mechanical complexity compromises development time, manufacturing and maintenance costs, and reliability. The thing may work, but the downsides of the weight and complexity are greater than the benefits; the technology is not cost-effective.
So I am not sure what evidence base there might be for claims of actual weight reduction.
If you really want super-slow flight technology, get a helicopter with VTOL thrown in for free or, if you are rich and desperate for somewhat higher speeds, a V-22 Osprey.
Who knows, the balance may change as technology advances, stranger things have happened.


What is the relation between airspeed and generated heat at constant drag? I understand higher speed, and higher drag mean higher adiabatic compression leading to heating up the air, and the plane as result. X-15 needed ablative coating to prevent overheating. On reentry of space vehicles heat shielding is the most critical problem. This is perfectly understandable as higher speed with constant or growing air density means higher drag - and this results in higher speed.

I'd like to know how are these values related though.

[for the purpose of this question, let's neglect the issues of engine efficiency. We have a magical rocket engine that weighs nothing and needs no air nor fuel to produce thrust. This is a purely an aerodynamics question.]

At given pressure, drag is directly proportional to lift (both being quadratically proportional to airspeed and linearly to air density). That means higher airspeed allows raising the altitude, lowering air density, and thus lowering drag until lift and gravity even out.

Let's maintain such a flight: We're constantly accelerating (slowly); and climbing, at such a rate, that lift remains constant, and evens out with gravity (minus a minimal delta to retain climb). The increase of lift coming from rising airspeed is being offset by decreasing air density as the craft climbs.

With constant lift, and drag being directly proportional to lift, drag remains constant too.

Maintaining constant drag through climb like that, air density is inversely proportional to square of airspeed.

How would heat creation behave in this situation though?

You express a desire to simplify things by assuming a weightless rocket engine, so I follow with a weightless vehicle which only creates drag to overcome aerodynamic resistance.

This resistance has two parts: One is adiabatic compression when the air ahead of the approaching vehicle is compressed, and the second is friction. Friction shows up in strong shocks and in a layer of high shear stress around the vehicle which is called the boundary layer. Let's also neglect other heat sources like solar radiation which becomes more intense with altitude.

If we look at small changes, the adiabatic temperature rise ∆T due to a deceleration from a speed v to zero is:
$$∆T = \frac{v^2}{2\cdot c_p}$$
where $c_p$ is the specific heat at constant pressure (unit $\frac{J}{kg\cdot K} = \frac{m^2}{s^2\cdot K}$). The amount of heat Q which gets transferred to our vehicle depends on this temperature increase, but also on the air density $\rho$ and the flow speed:
$$Q = v\cdot\rho\cdot c_p\cdot∆T$$
Denser air contains more heat energy, so the proportionality with density should make sense. But why speed? If the hot air is replenished at a faster rate, more heat can be transported to the vehicle's surface per unit of time. Now we have a heat flow which grows with the cube of flow speed, but that is not all. We still need to understand how density will be affected. When air is heated, density drops, but the flow at the forward facing parts of the vehicle is compressed as well, so density goes up in the end:
$$\frac{\rho}{\rho_{\infty}} = \left(1 + \frac{\kappa}{2}\cdot Ma^2\cdot c_p\right)^{\frac{1}{\kappa}}$$
with $\kappa$ as the ratio of the specific heats and $Ma$ the Mach number of the flow. Now things get messy because all parameters will change with temperature, so let me short-cut to NACA report 1381 which covers the re-entry heating of spheres. Here the rate of heat transfer is proportional to the cube of speed, so flying faster at constant dynamic pressure will cause a quadratic rise in the temperature of the surrounding air and a rate of heat transfer rising with the cube of speed due to convection.


How does retracting the gear affect weight and balance? In many of the POHs, in the W&B section it is indicated that there is a moment change due to gear retraction. For example :
Moment change due to gear retraction +780 in-lbs.

Two questions :

If I understand correctly, to simulate a gear retracted scenario I only need to add 780 to the total moment (sum of moment for the empty weight, crew, passengers, baggage etc...) while calculating the W&B. Is that correct?
In the majority of the POHs the C.G. envelope limits are based on gear down (fwd and aft).I saw one aircraft where it states the aft C.G. for both gear down and gear up - does it mean there is a different C.G. envelope for each case?

The aircraft in question is CJ-6A, please note the footnote in the image below

Yes the +780 inlb is the increase in the total moment aft of datum (I'm assuming it's the firewall) due to the center of gravity of the gear strut moving aft when it retracts.  It's like you had a lead weight at your feet and you moved it a foot or two aft.  Some retractable gear airplanes don't account for this but the Nanchang does seem to have a very long nose gear with substantial mass, so it looks like they decided they needed to take its movement into account.

The aircraft's CG envelope is a function of pitch stability at the aft limit and tail authority at the forward limit at various loadings and doesn't change.  You are concerned with the actual CG location relative to the limits and there shouldn't really be two envelopes, just two CG location values for any particular load case, a gear up one and a gear down one, that reflects the 780 in/lb influence of the nose gear's movement on the CJ-6.

Since gear retraction moves the CG aft, your main concern is that the actual CG location respects the potential two worst case conditions; that is, aircraft CG gear up is within the aft limit, and aircraft CG gear down is within the forward limit.

That's how it should work and if there are actually two CG envelopes, it suggests that there are aerodynamic effects of gear extension on pitch stability and/or tail authority that were uncovered in flight testing, and that go beyond just the CG of the nosewheel moving forward.  But in that case you would just expect to see a CG envelope that is more restrictive than it would otherwise be, to cater to the worst case possibilities, not two separate sets of forward and aft limits.


What turn rates are expected by ATC when given expedited turn instructions? One can reasonably expect that for a normal turning instruction (such as a radar vector), ATC will expect you to make a standard rate turn, or perhaps a half rate turn in the high altitude environment.

However, when ATC gives an "expedite turn" on a radar vector or equivalent instruction such as the "Traffic Alert, Turn Left Immediately" used for PRM approach breakouts, what level of performance are they expecting the pilot to demand out of their airplane? A 1.4g (45deg bank) steep turn? A 2g (60deg bank) steep turn? Maximum sustained Gs, even if that means using afterburner in a fast jet?  Get on this heading ASAP even if it means trading a bit of altitude for energy?  Does it depend on whether a light aircraft, a heavy jet, or a fast jet is being vectored around?

The air traffic controller expects you to 1) start your turn immediately and 2) turn as quickly as can safely be done. We do not have all the facts, and do not know exactly what sort of turn you are capable of doing. Using a phrase such as "expedite turn" or "turn immediately" basically means - I've screwed up, you're in danger, watch out and get out of the way. It is then up to you as pilot in command to avoid a collision, by flying your aircraft and knowing its limitations.

When ATC separation has been lost, you should respond promptly to any instructions issued with the purpose of re-establishing separation. We will also, as far as practical, issue traffic information, and expect you to look out the window and take any avoiding action you find appropriate to prevent a collision.

Finally, as a side note, if you have a TCAS, please remember that a TCAS RA takes precedence over any instruction issued by ATC.


Denver International Airport pneumatic tube systems Wikipedia says:

  Denver International Airport uses many pneumatic tube systems, including a 25 cm diameter system for moving aircraft parts to remote concourses, a 10 cm system for United Airlines ticketing, and a robust system in the parking toll collection system with an outlet at every booth.

Note: No citation, and I can't find any reference to it on the web.

Question: If these systems actually exist, what are their total lengthes (eg. 35 km total) and usage rate (eg. 7000 objects per day)?

References appreciated.

According to the Public Relations Department at the Denver International Airport, as of May 24, 2019 there is no such pneumatic tube system at the airport.

  Hello Juan,

  Thank you for contacting Denver International Airport. We have
  evaluated your email. I spoke with airport operations to find out if
  they had any information on using a pneumatic tube system and they
  advised me they do not. We do appreciate your feedback.

  Thank you, kindly, for bringing this matter to our attention.

  Warm Regards,

  Flydenver Team  Meseret


Did the Wright brothers discover the three-axis control system for airplanes/gliders and the adverse yaw? 1) Various sites like this one: Orville and Wilbur Wright, The Inventors of the 3-axis Flight Control System, 9 Months before their powered flight at Kitty Hawk say that the two brothers invented the three-axis control system.

Is it true?

This is what they wrote in the beginning of their British patent: 1904-03-19 – 1904-05-12, Orville and Wilbur Wright, “GB Patent No. 6732, A.D. 1904 – Improvements in Aeronautical Machines”, Date of Application: 19th Mar., 1904, Accepted: 12th May, 1904, 5 pages, the first that was granted to them.

  "Our invention relates to improvements in that class of aeronautical
  machines in which the weight is sustained by the reactions resulting
  when thin surfaces, or wings, are moved horizontally almost edgewise
  through the air at a small angle of incidence, either by the
  application of mechanical power, or by the utilization of the force of
  gravity.

  The objects of our invention are, first, to provide a structure
  combining lightness, strength, convenience of construction, and the
  least possible edge resistance; second, to provide means for
  maintaining or restoring the equilibrium of the apparatus; and third,
  to provide efficient means of guiding the machine in both vertical and horizontal directions."

The expression "three-axis control" does not appear in the patent.

Regarding this patent, more precisely its German version, filed on March 23, 1904, (four days after the British text) the fact that the wing twisting and the vertical rudder had nothing to do with steering the machine was clearly explained by Harry Aubrey Toulmin (the Wright brothers’ patent lawyer) to Carl Pieper (his German correspondent) in a letter dated April 11, 1905. Here is the relevant excerpt of this document:

  “It is evident from the action of the German Patent Office that the
  invention is not yet understood by them. The entire purpose of the
  structure on which the application is based, excepting the front
  rudder, which is for another purpose, is to maintain the body of the
  structure level or parallel with the horizon. It has nothing
  whatever to do with steering, neither has it anything to do with the
  raising and lowering of the plane of flight. The setting of the two
  parallel edges of the supporting planes at different angles is solely
  for the purpose of maintaining the wide body of the machine parallel
  with the horizon. The rear rudder is solely for the purpose of
  overcoming the tendency to turn around a vertical axis which naturally
  results from setting the two edges of the planes at different
  angles. … We shall trust to you to place these matters before the
  German Office in the best way possible and hope that you will be
  successful in obtaining the allowance of the application.”

H. A. Toulmin, “Letter to the Carl Pieper”, Springfield, Ohio, April 11, 1905

The explanation above is puzzling and seems to nullify any kind of pretentious that the Wrights invented the three-axis control system as long as their patent application had “nothing whatever to do with steering”.

2) Regarding the adverse yaw, the description given in the patent and the explanation of Toulmin are quite clear. The Wrights proposed a method for counteracting this unwanted effect but where they the first who noticed it?

The Wright brothers glider as it appeared in the US patent granted on May 22, 1906, which is a bit more detailed than the drawing in the British patent, granted two years before.

The patent lawyer is explaining things quite correctly and this applies to modern aircraft.  The rudder does in fact have nothing to do with steering the airplane.  Its job is to keep the tail lined up behind the nose (or to move the tail out of alignment with the nose if you wish) mainly overcoming adverse yaw caused by warping (or later, ailerons).

The bolded text in the paragraph you quoted describes the wing warping being for roll control, and the rudder for controlling for the adverse yaw that results from the wing warping (same as aileron displacement in modern aircraft), just like any modern aircraft.  He is describing how a modern airplane flies in other words, and this was a pretty radical idea at the time so it didn't make sense to a lot of people.

The Wrights discovered adverse yaw as they were developing their totally new wing warping system concept, as it was abundantly obvious from the way the nose would slew the opposite direction to the wing warp input and a rudder control was the obvious solution.  They didn't get it from anybody else because nobody else had thought of the concept of differential lift to control bank in order to turn.   Lillienthal, from whom the Wrights based a lot of their work in the beginning, used weight shift to control his gliders.

I recall from books I read on the Wrights years ago that they proceeded originally from from Otto Lillienthal's aerodynamic theories, and as they tested their glider machines, they started to discover that Otto had a lot of things wrong, prompting them to build their home made wind tunnel and start development from scratch.

So I would say for (1) yes, they invented the 3 axis control system, that is, all 3 being used together to make coordinated banked turns, because they developed and patented wing warping (ailerons coming later and leading to a long patent legal battle with Glenn Curtiss).  Up until then, and for some time after, developers were controlling turns by skidding using rudders (helped by dihedral effect to achieve banking in some cases) or by weight shift, or in Bleriot's case trying to achive roll control with differential elevator movement like an F-15 to get around the Wrights' wing warp patent (which they defended furiously, leading to the long patent battle with Curtiss, who ironically ended up taking them over in later years and becoming Curtiss-Wright, a running concern to this day).

The proof of this is obvious if you read of the various accounts describing the Flyer's demonstrations through the mid 00s.  The Flyer's contemporaries, such as they were, would slither about the sky, whereas the Flyer flew around making coordinated banked turns like a modern aircraft.  This astounded observers, especially the French when the Wrights demonstrated the Flyer in France.  The French reaction to the Flyer was really something else, one of awe, admiration, and a bit of jealousy, that those two American yahoos brought a flying machine that could literally fly circles around machines like 14-bis.

So for (2) I would say the answer is also yes because they invented differential lift for roll control in order to turn, which quickly indicated the need for a rudder to counteract adverse yaw and which followed on naturally.


Do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers? I gather pilots communicate regularly with air traffic controllers within air traffic controllers' jurisdiction or airspace as they enter the space, during their time in that space and as they leave.  In some or most instances, they will not land in that air space, they are simply passing through and may encounter lots and lots of regional and international air traffic.

They are routinely directed by air traffic controllers to fly at a certain direction, increase or decrease altitude for safety in order to avoid collisions and accidents.  In most instances, auto pilot is engaged and I assume the headphones come off, for flights longer than say 2 hours or even 1 hour.

Speaker phone may be on but pilots can read a book or watch a movie on their laptop or revise their reading on knowledge of their ever changing craft.  At a certain frequency.

I gather lots of communication to planes occurs and listening to all of them can become tedious and may require too much concentration.  In this light, do airline pilots ever risk not hearing communication directed to them specifically, from traffic controllers of space they are flying past on cruise?

Does a light or sound or siren switch on when a message is directed at them and I assume they differentiate communication directed at them by their call sign, e.g., American Airlines Flight 200.

Is there a risk they might not hear it and how is that risk mitigated?

There is a ton of radio communication during the taxi, takeoff and departure phases, and then again during the arrival, landing and taxi phases. Pilots are generally very busy at these times and 100% focused. Airlines have two pilots, and one will be flying while the other works the radios and monitors various instruments.

Cruise is another matter. There generally isn't a lot to do other than keep an eye on the autopilot. The pilots will take turns eating, resting, going to the lav, etc. Radio work usually involves little more than getting handed from one frequency to the next. They may get rerouted due to traffic or weather, but it only takes a few seconds to update the autopilot.

Either way, pilots do occasionally miss radio calls. So does ATC for that matter. It's common enough that nobody gets worried about once or twice, though it's annoying. If it's a real radio problem, there are procedures for both sides to follow to keep everyone safe.

There (usually) isn't any sort of light or tone when someone is calling you. However, the standard format is "called station, calling station, message", so with a little training, your brain can quickly tell whether the message is for you. If so, it "tunes in" and you consciously hear the message; if not, it "tunes out" and the message is just background noise.


Is pumping the control column an acceptable technique during flare? Source: YouTube, higher quality file here.

Example 2: YouTube

Is it normal? Just a different technique? Or do certain situations or aircraft types call for it? The training manuals I've seen advise against excessive changes, or call for constant back pressure, or both.

  Avoid rapid control column movements during the flare (737 FCTM).

But it won't be the first time that a rule has an exception.

An example of minimal changes here: YouTube, albeit a different type, hence the question.

He’s not pumping the yoke per se;  rather the pilot is making a series of quick, precise corrections to the yoke in order to track a precise glideslope to an aimpoint while on short final.  This process can be exacerbated by gusty winds on final, poor throttle control, etc.

Here’s a better example from the cockpit of a C-2 Greyhound CODS aircraft making a Case 1 trap aboard Carl Vinson (CVN-70).  Note the hundreds of minute inputs the pilot makes to the yoke, rudder pedals and throttle on lineup, in close and at the ramp.  He’s applying pitch inputs to correct for deviations from glideslope, throttle inputs to correct for airspeed deviations from Vref+5 kts, aileron and rudder inputs to correct for deviations from lineup on the groove, and rudder inputs to correct for yawing brought on by changes in power.  It looks exhausting.


Are there benefits to opening a flight plan if I'm flying over populated areas? Here in Idaho we have a lot of mountains and desert areas where if I had to make an emergency landing or crashed it may take a very long time to find me. In that case I can see the benefit to opening a flight plan. But in areas where I'm flying over most or all populated areas, someone would see the crash well before they would start looking for me. In that case, are there other reasons to file and open a flight plan?

According to the AIM section 5-1-4, the main reason is search and rescue:

  b. It is strongly recommended that a flight plan (for a VFR flight) be
  filed with an FAA FSS. This will ensure that you receive VFR Search
  and Rescue Protection.

So the question becomes, does search and rescue have value in populated areas? I would say that - excluding large cities - populated areas are actually not very densely populated at all (relatively speaking), and there is a very good chance that no one will see your aircraft come down or even react if they do. You might be flying at night, or no one may be looking in the right direction, or they may assume you're landing at a private strip or doing cropdusting or whatever.

And even when an aircraft is known to be down in a specific area, it's often very hard to find it - especially if you land in trees - so anything you can do to narrow down the search area is important. An AOPA safety video (I forget which one) mentioned an incident where a helicopter went down less than a mile from a runway threshold at a class B airport and it still took 24 hours to locate it (the details may be different, but you get the idea).


How does the Aerobridge dock with an aircraft? What mechanism is employed by the Aerobridges to dock with the aircraft. I am not looking at how the plane docks but how the aerobridge manages to attach itself over the door of the aircraft? Is it some vaccum tech or what? From outside, one can only see the bellows/ flexible diaphragms.

What I am looking for is actually - how two non-conformal surfaces can be "joined" in order to create a sealed "lock" (assuming its closed from all other ends). This came to my mind and now I am trying to understand this as the situation is almost the same.

Well jetways don't exactly 'dock' with an aircraft; there is no hard coupling between the tunnel and the airplane like say that found with a spacecraft docking.  Rather they are just maneuvered up against them with a soft canvas hood which can be actuated around the fuselage allowing protection from the weather for passengers and crew.

The jetway is maneuvered to and away from an aircraft via a small control panel near the hood of the jetway which controls an electrically driven wheeled drive supporting the terminus end of the jetway as well as screw jacks in the support pillars for elevation control.  This allows a user to translate the length of the tunnel or rotate it about its connecting point to the terminal.  The tunnel can do this by means of telescoping sections.  The terminus of the jetway can be swiveled to match the curvature of the fuselage and the tunnel makes contact with the jet at the base of the terminus, usually with a neoprene bumper to prevent damaging the fuselage.  The hood can then be lowered for weather protection.

The jetway will reverse this process after the main cabin door has been closed and secured and before pushback to prevent contact and damage with the aircraft during pushback.


What is that ceiling compartment of a Boeing 737? Does somebody know what that big box in the roof of the 737 cabin is?

It holds a life raft. In case of ditching in the ocean, the raft would be removed from that compartment and tossed into the water, where it would inflate.


What is common number of flight hours a year for an airline pilot? Reading various reports including number of flight hours of the pilots I always wonder how it relates to years of service. In most professions, people work 40 hours a week, which gives around 1900 hours a year (assuming 4-5 weeks vacation as is usual in Europe). But pilots seem to have much fewer flight hours. I even read that in certain military operation the norm was 750 hours in a year. But that was difficult military operation and I haven't seen any number for common airline operations.

So how many flight hours is usual for full-time airline pilot to log in a year? And what does he do in the rest of his duty time? Or does he have less duty time than the usual 40 hours a week?

Flight hours are limited to 30 hours in 7 days, 100 hours in a month and 1000 in a year.  Scheduling rules also say I need at least 1 day off a week, so 6 day trips are the max for me (121 US domestic scheduled).

Let's look at a typical trip, which at my company tended to be a 4 day trip.  You want good productive trips, but you can't always get them.  On a 4 day trip let's say I have 6 hours of flight scheduled each day, or 24 hours scheduled that week.  I am getting paid the better of 24 hours or the actual flight time.  Now let's look at my duty day.  For a 6 hour day with 4 legs it was not unheard of to have a 12 hour duty day.  So now for a 4 day trip, I'm "at work" 48 hours and being paid for half of that.  Now consider that I'm not going home every night and my trip starts at 6 am on Friday and ends at midnight Monday night -- that totals to 90 hours away from home.

How does this compare to a 40 hour work week in an office?  In that case you are on duty 40 hours, getting paid 40 hours (or salary) and if you have a 1 hour commute one way, you are spending 50 hours away from home.

Back to the flight schedule.  A given month will have trips less productive than 24 hours and although you can probably build a 96 hour month if you tried, the average line of flying is typically going to be 75 hours of flying.  You can ballpark that will equate to 150 duty hours and 300 hours away from home for the month.

Extrapolate that to a year, and you have 900 flight hours, 1800 duty hours and 3600 hours away from home.  I would say this represents the average US domestic 121 pilot.  Some do more, some do less, but this is pretty typical.

What do we do with all of that duty time that isn't flying?  Let's see:

Eating
Updating charts
Checking the weather
Checking the paperwork
Coordinating with gate agents, ramp agents, fuel agents to make sure we leave on time
Programming the FMS and getting our IFR clearance
Preflighting the airplane
Postflighting the airplane
Doing the weight and balance
Sleeping

Note, that all of these activities require we are at the airport, in the secure area and we are not being paid.  The pay clock starts (roughly) when the airplane is buttoned up and the parking brake is released and ends when the parking brake is set and main cabin door opened.


Why would an airport be depicted with symbology for runways longer than 8,069 feet even though it is reported on the sectional as 7,200 feet? This airport, KMKO, Muskogee-Davis Regional in Oklahoma southeast of Tulsa is depicted on the sectional chart with symbology normally reserved for airport with a hard surfaced runway longer than 8069 feet, but this one is only reported on the sectional as 7200.

Is this a mistake by the FAA or is there some clear explanation about why this is?

The FAA chart user's guide says:

   Hard-surfaced runways greater than 8069' or some multiple runways less than 8069'

It's the latter case of some multiple runways less than 8069'.

This is also confirmed in the post, "What is significant about the number 8069 ft?"

  Specialists also place these polygons around the runway pattern of aerodromes with multiple runways that are less than 8069 feet, in cases where the multiple runway pattern does not fit into the largest, circular aerodrome symbol.

(FAA FAQ; emphasis mine.)

Most likely MKO doesn't fit in the standard circle  because of 36-18 and/or 4-22 intersecting the circumference.

(Chart Supplement via skyvector.com)


Was the transatlantic crossing for Concorde too short to reach optimal cruising altitude? When listening to Gander/Shannon ATC on shortwave, you could hear Concorde communicate its planned flight levels at longitudes from 20 West till 50 West. What I remember is that it would continue climbing to, say, flight level 570 at 30 West and then descent. So, it seems that it never reached cruising altitude, it would climb until halfway on the Atlantic and then start to descent again.

The simple answer is that the Concorde had no single assigned altitude, it was allowed to climb freely above ~FL450; this is discussed in depth in episode 166 – Flying the Concorde (worth the listen as it answers just about every Concorde question!). As @pilothead alludes to in their answer it climbed as it burned fuel but the aircraft never actually initiated a climb, it simply drifted up as it burned fuel and became lighter.

Also discussed in the episode is the complex approach and departure procedure. Due to the fuel burn schedule the Concorde did not really have the ability to hold for more than a single lap in a holding pattern or do a stepped climb with some route adjustments like many airliners. They had a special departure procedure that was more or less runway to cruise with no interruptions and a similar descent option. So the flight was effectively a climb to cruise block then a glide down right to landing. Depending on the wind and conditions of any given day as well as the load on board, the cruise altitude could vary greatly.


What determines the maximum ground speed of hot air balloons? I am wondering how the ground speed of hot air balloons is controlled. The wind is obviously going to have a large influence upon the ground speed, but apart from wind effects, do hot air balloons have the ability to control their ground speed? If so, how? Is there a maximum limit to the ground speed of a hot air balloon? What factors contribute to this speed limit?

Balloons travel with the wind, so all their motion over ground comes from air movements.

do hot air balloons have the ability to control their ground speed? If so, how?

This was a burning question in the nineteenth century and many attempts were made to influence ground speed, apart from rising into higher altitudes and testing whether the wind direction there is different. Naive people added sails but had to notice that those remained limp and only added weight. Others added paddles or engines (steam, electric and gasoline engines were tried) but success was limited before Zeppelins started to make directed lighter-than-air travel routine.
An interesting variety was tried by the Swedish balloonist Salomon August Andrée who added three long ropes to his balloon, their ends dragging on the ground. This caused drag which slowed the balloon, thus giving it some speed difference versus the wind. Now, with some relative wind, sails could indeed generate a force which could move the balloon sideways. However, when tried in 1897, two of the ropes were lost during launch and the remaining one proved ineffective.

Andrèe's balloon (picture source)

Is there a maximum limit to the ground speed of a hot air balloon?

No, if the balloon rises into the jet stream, it can travel at several hundred miles per hour. There is no speed limit once the balloon is up in the air.
However, filling and launching the balloon requires calm winds; hot air balloons almost never start in winds higher than 10 miler per hour. Landing in higher winds becomes dangerous, so here also a calm wind is preferred.

What factors contribute to this speed limit?

This is not about ground speed limits, but wind speed limits: While there is no fixed limit, higher winds will prevent the envelope to stretch out completely and rise up when being prepared for launch. Instead, the windward side will remain dented. During landing, the gondola will be dragged along on the ground when wind is too high. Both these factors let balloonists prefer calmer wind for take-off and landing. Once the balloon is up in the air, no such limit exists any more.


What considerations should be taken into account for landing on gravel airstrips? For the pilot of a Cessna or Piper 4 seater, what techniques and other considerations should be given before operating on a gravel/dirt airstrip?

Standard soft-field landing and take-off techniques work on dirt, gravel or grass. The differences are more in ground operations, and even then they aren't really big differences: it comes down to being aware of what's around you and what condition the surface is in. That includes taxi and parking areas, not just the runway.

With gravel, the main risk is damage to the aircraft (especially the prop) or nearby people, vehicles or objects caused by gravel being thrown up by the prop. With dirt, you're more likely to have to worry about drag or even getting stuck, especially if the surface is wet.

Some specific considerations for gravel are:

If you're parked on gravel, be careful where the aircraft is pointed when you start up. You don't want to spray some unfortunate person, vehicle or building behind you. Re-position the aircraft before starting up if you have to, and you could also brush gravel away from the prop.
For the same reason, pick your runup spot carefully
Keep back pressure on the controls all the time while taxiing, to keep the prop as far away from the surface as possible. Don't feel you have to taxi in a straight line: taxi wherever the gravel is lightest and the surface is smoothest.
Open the throttle smoothly for takeoff or runups to avoid suddenly throwing up gravel

Dry, well-packed dirt usually isn't much of an issue (apart from visibility), but wet dirt - i.e. mud - is potentially tricky:

If conditions are very dry then you can throw up a lot of dust. That may not be as dangerous as spraying gravel around, but it's still unpleasant for anyone nearby and there is a safety risk if people can't see you or other aircraft/vehicles because of it.
If conditions are wet then there's a risk of getting stuck in mud. Once you're moving, try not to stop unless absolutely necessary. Consider doing a 'rolling runup' if you're confident you can do it safely (practice on tarmac first!).
Calculate your required takeoff roll carefully and know exactly where you have to abort. Mud will create a lot of drag, and you don't want to push your luck on what is most likely a short runway.
If you take off from wet dirt you'll leave ruts behind you. When the dirt dries out those will still be there, and they could be a hazard to other aircraft using the runway (some dirt becomes very hard when it dries). Try to find someone who can smooth them out after you depart.
If you do get mud on your aircraft, clean it off if at all possible before taking off. As well as decreasing performance, it could clog up pitot-static ports or otherwise affect airworthiness.


Why do some fighter jets have double wheels in the front gear whereas some other aircraft have a single wheel? The Typhoon has a single wheel in the front gear, but the Rafale or Gripen have double wheels in the front gear. What is the reason for this difference?

Ther are a lot of reasons for doing one over the other, from design trade offs to steering mechanisms to weight savings vs Service life, runway loading requirements, etc.  In the case of the Rafale-N, the nose landing gear is designed to interface with the catapult shuttle on the ship, so a single nosewheel would not be an option here.


Could the Space Shuttle take off like an airplane? This question got me thinking, would the Space Shuttle have been able to use its main engines to roll up to speed and take off horizontally like an airplane? (I'm not asking about getting to space, just flying around) What would the take off be like? What would forward flight powered by the main engines be like?

Did the space shuttle even carry fuel for the main engines internally? Before posting this question, I tried to find the answer myself, but I've had trouble finding any mention of it, only talk about the external tank. It seems to me you might want to have at least a little, just in case. If it did carry fuel, how long might it be able to fly for that way?

Would there have been anyway to put a usable fuel tank in the cargo bay?

(I realize that this will mostly be speculation, just asking for fun, if that's frowned upon, please let me know)

Despite the scene in Moonraker the Shuttle orbiter carried no fuel for the main engines.

Further, the orbiter sat nose down on its landing gear, lacked the elevator authority to raise the nose off the ground at landing speed, and could not retract its landing gear (it used a straight-fall gravity deployment).  The OMS didn't have enough thrust or delta-V at sea level to accelerate the orbiter from a stop to flight speed, even without the pitch authority issue.


Why does the 757 fuselage bend more on turbulence than those of other airplanes? According to this discussion(2nd)(3rd) and this video there is more fuselage bending in turbulence on the Boeing 757 than on other Jets.

Why does the B757 fuselage bend more on turbulence?
What are the factors related into fuselage bending?
I always thought there is only fuselage bending during take-off and landing on tarmac.

Edit: Picture Zoomed, fuselage shows flexing.

This is really two questions

Why does a fuselage bend?
Why does the 757 fuselage bend more than others

I'll give the simple answers here. You can go into a LOT of detail, but the detailed answers are mainly just bringing more information on design/engineering differences into the simple answers (eg composites bend/break in a different way to aluminium)

Why does a fuselage bend?

Essentially, it's because the lifting force doesn't support the entire fuselage equally. Drag and the aerodynamic forces created by the fuselage itself will also affect things, but it's mainly due to the fact that the lifting force is centred on two points of the fuselage, while the weight is spread along it

The lift is generated, primarily, in two places: the wings and the horizontal stabiliser (some is generated in the body too, but relatively little). Most of that lift is generated at the wings, which are attached in the middle(-ish) of the fuselage. Imagine balancing a ruler (fuselage) on your finger (wings), then stacking coins along the top of the ruler. The heavier the rule, and the more "lift" your finger has to provide, the more the ruler flexes.

Of course, lift isn't constant - turbulence means that over a few second the lift provided by the wings can change quite a lot. Imagine you start bouncing your finger up and down, creating "turbulence": the ruler will flex and unflex as it absorbs that changing force. This is the fuselage flex seen in aircraft.

The fuselage will also bend while landing or taking off, because you're again changing how the weight of the fuselage is supported: the weight is transferred from the wing root/spar to the landing gear. And the final obvious one is that the weight of the aircraft changes during the flight due to fuel burn etc.

Why does the 757 flex more than other airliners?

Well, for one thing I don't see any sources for this other than "I've heard that" (the links you provided are mostly hear-say too), but I have seen it stated as fact. Let's, for the moment, assume it's fact... the theory applies regardless.

The 757 will flex more than some other airliners (although likely less than some others) because of its design, construction and the build materials. The simplest explanation is that it's one of the longest narrow-body airliners.

What does that mean? Well, it means it's one of the longest, thinnest fuselages around. This gives us two causes:

The 757 flexes more than other large airliners because anything bigger than it is a wide-body aircraft, which will resist bending more than a small, narrow bodied thin one
It flexes more than other small airliners because any other narrow body is lighter and shorter than the 757, providing less force on the fuselage and requiring a smaller lifting force.

TL;DR: Flex is caused by lift acting mostly in the middle(ish) of the fuselage, while the weight of the fuselage and other forces on it are spread out along the length.

Overall, then, the 757 is on the boundary between lighter, narrow bodied aircraft and larger, wide bodied ones. Anything smaller than it weighs less so stresses the narrow body less. Anything larger has a bigger, stronger fuselage.


Is an Airbus A319 allowed to fly with a missing flap track fairing? During a recent flight from Copenhagen to Milan in an Airbus A319, one of the flap track fairings were missing from the wing. I saw this during takeoff, and notified a flight attendent as soon as the "seatbelts on" sign was turned off.

She seemed slightly surprised and went to the cockpit (supposedly to tell the pilot). After some minutes she returned and told me that it was fine, the captain had seen it during inspection and it was noted in the log

Is it normal procedure to take off with knowledge of missing flap track fairings? What are the consequences of one missing?

Fully permitted according to this Configuration Deviation List for the A320:

  One fairing may be partly or completely missing.

There are more posts about this occurring. As Noah Krasser points out, it looks fairly dodgy to observant passengers. This is the "Master" list, i.e. the safe and approved baseline. Some airlines may have changes in their own internal documents not to dispatch aircraft in this condition at all.


Which countries (if any) allow beyond-line-of-sight drone use? I was recently thinking about starting up a non-profit that would use large drones (full scale aircraft, not those dinky quadcopters) to deliver humanitarian aid to difficult locations.

It was shot down pretty quickly when I remembered that civilians aren't allowed to fly unmanned systems beyond [the visual] line of sight (BLOS).

So, this led me to my question, are there any countries that allow BLOS use of civilian unmanned aircraft?

The current situation (November 2018) regarding beyond visual line of sight operations (BVLOS) is heterogeneous:

Overall, not allowed in Europe, but there are notable exceptions where BVLOS is explicitly regulated, see below.
Regulated in Canada
Regulated in a few countries in Asia, Africa and Latin America.
Not allowed in the US

US

UAVs fall under Part 107 operations which prevents BVLOS (107.31). Waivers can be requested, but only 27 have been granted to date (enter "107.31" in the search box).

European Union or EASA member states

EASA is the European safety agency. For EASA member states (EU and a few other countries), there are two opposite situations today:

With no surprise North European countries (Iceland, Norway, Sweden), with many isolated locations have allowed BVLOS operations early, including for delivery of goods to consumers, e.g. Aha, an online marketplace, delivers goods using drones in Iceland. Not only this is BVLOS, but it's even automated.

Many countries don't allow it but they are waiting for a EU regulation that would allow them. Actually current opinion of the EASA is it must be allowed (but more for industrial uses than for good delivery to public):

  EASA will develop standard scenarios that will make it simpler to
  obtain authorisations for well‑defined operations (such as, for
  example, linear inspections conducted in BVLOS, or crop spraying).

(Source)

In their declaration EASA mentions linear inspections, which has been actually something done in France since a long time for railways catenaries and electric grid lines.

France has kept with its pioneering role in aviation. BVLOS is regulated since 2012. A company located in Toulouse, another well known place for aviation, paved this road. As I'm not going to do their advertising, I let you read about them online, e.g. last year they were able to have a 50-km civilian flight with a 3G data link.

Switzerland

If you are asking for your home country, Switzerland, which is also an EASA member state:

LOS is required, but waivers are possible, though there are no public criteria provided, so you need to try, when you have defined all the details of your project.

As DeltaLima mentioned (maybe with a good insider knowledge) laws are rapidly evolving in the domain, as does UAV technology.

Around the World

Taken from International Commercial Drone Regulation and Drone Delivery Services by Rand Corporation:

  For countries that have drone regulations, these regulations typically
  incorporate a pilot’s license, registration of the drone, restricted
  zones, and insurance; regulation requirements vary based on such
  parameters as drone mass, population density, altitude, and use cases.

and the list of countries in 2017:

As visible there are legal possibility for BVLOS in many countries and across all continents.

Permission limits

Same document, excerpt for three countries:

For France already mentioned, we see the BVLOS is authorized up to 1 km for 2 kg+ mass, and unlimited below (but constraints like pilot license and registration still apply). Looking at the criteria for a permissive country:

Well, except height and insurance in certain cases, there is no other ones!

Future market

While B2B application have a large market, the B2C market is huge in an era of online sales and home delivery. Amazon is waiting for (experimentation in Japan), as quick food businesses do, for their delivery.


Why did my instructor recommend that I fly a Piper Seminole down to the runway rather than trying to flare it like a Cessna? I have flown as a student the Piper Seminole 3 or 4 times, it was so much fun grabbing a bunch of throttle levers and pushing them all like a real throttle quadrant in a large jet aircraft, but anyway my question is this:

When landing and just nearing the end of final, when I was just about to the chevrons my flight instructors always asked me to fly the plane right down to the runway, which is different from flying 172's where I could flare right at the chevrons and try my best to get a 'greaser' and chirp the tires enabling a nice transition where I momentarily heard the faintest stall horn just before landing, enabling a quick turn off to a taxiway...why did I have to fly the twin right down before cutting throttles?

I'm guessing that is a landing technique that your CFI has developed for handling a Piper Seminole on landing.  Don't worry; everything is fine.

Most likely this is because the PA-44, like it's single engine cousin, the PA-32 and late model Cherokee Arrows rapidly loses energy and sinks quickly once the power is pulled out.  These tend to be the landing characteristics of larger, heavier aircraft.  Cutting the power too early in the approach to roundout could cause this aircraft to slow and drop rapidly leaving a neophyte student with little energy left to flare to a smooth touchdown.  The CFI is trying to make you cognizant of that fact; I'm sure he's endured plenty of firm landings by students with high time in C152s or C172s flying final at 65 KIAS, then chop power over the threshold markings (piano keys) to arrive at a good flare and touchdown; that technique won't work in larger twins and the best way to fly a shallow glide slope is to do so with power, then pull it out just as you begin the flare about 7-10 feet off the runway.  The airplane should then settle into a nice flare 1-2 feet off the runway, quickly exhaust all of its energy and touch down on the mains just as you hear the stall warning tone.

Another factor is the aerodynamic slipstream from the propellers. As wing mounted tractor engines push air over the wings behind the propeller disks, this, in turn is generating additional lift.  During a stabilized approach, this airflow become part of the lift the wing must generate in order to remain on speed at the selected rate of descent.  When the pilot pulls throttles to idle as part of the roundout process, this additional lift is terminated.  Combined with the high drag from the idling low pitch propellers, this causes the airplane to slow down and sink very rapidly; you will feel this in the seat of your pants if you pull the throttles out too early.  If a student pilot remains ignorant of this effect and does not compensate for it, you may be in for a very hard landing or worse.

The Piper aircraft, as you have found out, are designed to put up with a lot of sloppy handling from a new pilot and still shine.  The controls have all the finesse of a Mack truck and they really have to be manhandled to fly them.  IMO it's an attempt by the manufacturer to 'idiot proof' the airplane and make it safe and marketable to a wide range of pilot skill.

All tricycle gear aircraft should be flown to the roundout such that once the flare is established, the airplane should run out of energy and quit flying rapidly.  Strict adherence to a controlled approach speed of 1.3 Vso on final should be used (on small aircraft), but the rate at which the airplane slows and descends when the power is reduced to idle varies between airframes.  Some airplanes do this faster than others; each one has it's own unique handling characteristics and you will have to become familiar with them as you progress through different aircraft.

One note on you flying: for a VFR traffic pattern, aim for the numbers or use an optical glideslope (eg VASI, PAPI, etc), if available, on final until you have become proficient with flying the PA-34.  The 'chevrons' are a blastpad and frangible arrestment for stopping an overrun and are not designed to support an airplane during normal flight operations.  Touchdown too early and end up on the blastpad, it is possible the aircraft could break through and cause damage to the airframe, props or landing gear.  You're also likely to clip other objects like runway threshold lights with that kind of a landing.


How are there some Victor airways that exceed the service area of the VORs they are identified by? As you can see here, V267 has a length of 149nm, is defined by the Craig VOR (CRG) and the Dublin VOR (DBN) and has a MEA of 3000. According to the AIM, the Service volumes of VORs never reach more then 40nm underneath 14,500ft.

Yes, the Craig VOR or rather VORTAC is described to have the Standart High Altitude Service Volume in the A/FD, but at the MEA, which should also guarantee reception of the navaids in use, the range is still only 40nm. A route at that altitude between those two navaids should only be <80nm, so how can it be 149nm?

It says it right there on the page where the service volumes are described in the AIM:

  1-1-8. Navigational Aid (NAVAID) Service Volumes

  c. Standard Service Volume limitations do not apply to published IFR
  routes or procedures.

So V267 has been flown at the MEA by an FAA plane, and it obviously met the signal accuracy requirements to be usable at the distances charted.


What is radar minima? I was studying the Aeronautical Chart User's Guide and I came across the term 'radar minima' several times under the graphics depicting charted airports.

  Blue – Airports with an Instrument Approach Procedure and/or
  RADAR MINIMA published in the high altitude DoD Flight
  Information Publications (FLIPs)

  Green – Airports which have an approved Instrument Approach
  Procedure and/or RADAR MINIMA published in either the
  U.S. Terminal Procedures Publications (TPPs) or the DoD FLIPs

  Brown – Airports without a published Instrument Approach
  Procedure or RADAR MINIMA

Published minimums for an ASR or PAR approach.

An ASR is essentially a non-precision approach with an MDA, while a PAR is a precision approach (found almost exclusively at military fields) with minimums of 200 and 1/2.


When do commercial aircraft tail numbers change? Each (large, commercial and most other) aircraft has a registration number, painted or stickered on its hull: the tail number.

I was under the false impression that tail numbers don't change, and that a number identifies an aircraft until it's decommissioned. That's not true, apparently! This article, for example, explains how new owners may want to change numbers when they buy aircraft.

My question: Under what other circumstances do tail numbers of commercial aircraft typically change? Other than changes-of-ownership?

Notes:

I'm not asking about considerations for changing tail numbers during ownership changes. That's covered.
Of course, someone can arbitrarily change a tail number on a whim, but that's probably very rare; I'm asking about somewhat-common situations in which tail numbers are changed.

Motivation: Want to be able to use tail numbers to distinguish different aircraft, but need more information to qualify that assumption. So, I realize different owners may invalidate the assumption; looking to qualify it further.

I was under the false impression that tail numbers don't change

Tail numbers (AKA registrations) are changeable by definition since each country is allocated codes with different prefixes and formats. If an operator from country X buys an aircraft from an operator in country Y, then the tail number must will most of the time be changed to a valid tail number of country X. Depending on local laws, in some rare cases a tail number of another country will be used, for tax purposes (much more common with sea vessels). This is why some Aeroflot aircraft have VP-B* registrations that belong to Bermuda.

What does not change is the manufacturer serial number (which may be analogues to a road vehicle VIN).

I think the source of the confusion is that the Wikipedia article that you linked to uses "tail number" of civil and military aircraft interchangeably, and that is wrong. Military aircraft's tail numbers do not conform to their countries' ICAO-issued civil registration format, and they may or may not be changed whenever said air force want.

  Already know that different carrier + same tail number may mean different aircraft

This assumption is wrong. Tail numbers are unique. However, they can be re-used over time.

  Under what circumstances do tail numbers of commercial aircraft typically change? That is, other than arbitrary whims (which I assume are rare), when do airlines/aircraft owners go through the number changing procedure?

As mentioned above, the most likely case is when an aircraft is being bought from an operator from another country than the previous operator.

Sometimes the new operator will change the tail number even if the aircraft was bought from an operator in the same country in order to fit the registration scheme that said operator may use (for example, N737* for 737 aircraft, N747* for 747, etc).

Other than the mentioned cases above, it's impossible to answer this question in general terms. Every operator may or may not change tail numbers of aircraft it buys. An operator may even decide to change tail numbers of aircraft it already owns just because.


Why does power help us maintain altitude in slow flight? I was asked this question and didn’t know how to phrase a nice and easy explanation.
What I said is- well because drag is now increasing Un- proportionally to lift, we need something to generate more lift, and since pitching up like we would do in normal speeds isn’t an option because it would just increase drag more, our only way to create more lift is increase thrust- and in so increase that vertical component of thrust that acts as lift and help us maintain altitude.
Am I right in explaining it like that? And is there a nicer and simpler way to explain that?
Something with the 4 forces and thrust-drag and lift-weight couples?
Thanks!

It is not correct to say that power controls altitude. In slow flight, it is taught that power controls altitude and pitch controls speed. Yes, it works, but you have to always keep in mind that a power change will always require a pitch change and a pitch change will require a power change, if you want to maintain the same trimmed speed, altitude and angle of attack.
As you might very well know, in a slow flight, you reduce your power first and start putting down the flaps to sort of keep the aircraft in an approach configuration. Then you pull back on the stick until you are close to the stall speed. Once the speed you want is reached, you add power as required to maintain speed and altitude. If you lose altitude, a little addition of power will arrest it. But trust me, this will also increase the speed by small margin. This might not be registered in the air speed indicator of a smaller aircraft. Similarly, an increase in pitch in attempt to reduce an increasing speed, will change the altitude. So, it is not fixed. Pitch and power are not two separate entities. They always work together. Try flying a high performance aircraft with powerful engines and with a load of inertia and you will see how true my words are.
The reason why more and more power is necessary to successfully accomplish a slow flight is because you are operating below the L/D speed of the aircraft. Once you are below this speed, the increase in induced drag (due to high angle of attack) increases the total drag on the air frame. To overcome this drag you are required to add power or energy. We call this operating behind the power curve or the region of reverse command. Reverse because normally, you need an increase in power to fly at a higher speed. But behind the curve, to fly at a lower speed, you need more and more power.
Look at the graph below, the GD (Green dot) speed is the L/D speed. As you can see, as you go below the L/D there is a steep increase in drag.


What is the reason for these strange radio altimeter calls? I ask as a dilettante, so please feel free to correct or emend this.

I transcribe the radio altimeter enunciations for https://www.youtube.com/watch?v=Vr-0LiQA6wo:

  0m 21s: 400

  0m 23s: 400

  0m 36s: 100 above

  0m 41s: 200

  0m 49s: 100

Are the radio altimeter verbalisations part of the Ground Proximity Warning System?
Why was 400 uttered twice? Isn't the A380 descending?
Same question for 100 at 49 s, compared with 36 s?
What does the above imply?

"Four hundred" was likely annunciated twice due to a bit of a dip in the terrain that would cause it to pass the 400ft level twice. The "hundred above" call-out is for 100 feet above decision height to let the crew know they will need to make their decision soon to either continue or go around. After that, you hear the "two hundred" and "minimum" call-outs right after one another. The "one hundred" call-out afterwards signifies 100 feet above ground level.


What parts of the 787 are produced with 3-D printing (besides air ducts and hinges)? This article from 2013 states that about 30 parts of the Dreamliner are 3-D printed, mostly air ducts and hinges.

I wonder

what other parts are produced by direct manufacturing?
why it was deemed essential to resort to printing them instead of molding/stamping?

Another example of printed parts is electronics covers.

It wasn't necessarily "essential" to use 3D printing, but economical or beneficial versus other choices. For aircraft parts, 3D printing has a few advantages over more traditional methods of manufacturing:

Much less delay for manufacturing. A new part can be designed and
then 3D printed very quickly. Traditional methods need much more time
to create tooling for each new part. If you are delaying a product
worth millions, time is important, and the faster method will have a
big advantage.
There can also be less cost in manufacturing. The cost of initial
tooling for a part only pays off in the long run if many parts are
produced. A 3D printer can potentially make many different parts,
with minimal added expense to make a new design.
The design can also be made more efficient. 3D printing can create
shapes and designs that are not practical with traditional methods.
This can reduce the weight and complexity of parts.


Could the stick position be used as a Angle of Attack indicator? True or False: The stick determines elevator position and elevator position determines angle of attack. When the critical angle of attack is exceeded, the wing stalls. So, given a design with enough elevator authority, if the stick is in your lap, then the wing is stalled. If the stick is, say an inch farther forward, the wing will not be stalled. Let's stipulate no flaps/slats, calm air, normal CG, positive G, and plenty of elevator authority. Maybe use a plane such as the Luscombe 8A for the sake of this discussion. That will keep things straightforward.

I guess the crux of what I'm asking is: why couldn't the stick be used as an angle of attack indicator? Let's assume a pilot is able to very precisely detect the stick position, or that maybe an indicator is installed in the panel which is connected to the bottom of the stick under the cabin floor.

For a given set of configuration parameters, CG, weight, power, G loading, you could theoretically use stick position as an approaching stall indication.  Problem is, the actual location would vary with all those parameters, so if you had a stall indicator device that was measuring and displaying stick position, you would constantly have to vary the calibration with power setting, flap position, G load, all up weight, and center of gravity.

So, take the apparatus you would have developed to go under the floor to measure where the stick is at, and move it out to the wing with a vane that gets blown on in the clean air flow, have THAT drive your indicator, and voila!  No need to adjust for any configuration variables and you know exactly where you stand relative to stall at all times and in all flight regimes.


Is it safe to fly a glider when I can't move the stick fully left and right? This past Saturday, I started training in a Schweizer 2-33A glider.

When I got in the glider for the first time, I found that I couldn't move the control stick fully left and right, because my legs were in the way. I could only move it about halfway. I could move it fully forwards and backwards, though.

Is it safe to fly a glider like this? I asked my instructor about this, and he said it was fine.

Normally, you're not going to use full aileron deflection anyway, unless the glider is on the ground and moving slowly.

On the other hand, if you get into an unusual attitude somehow, then the limited aileron travel could increase the amount of time it takes to recover. But I don't know if that's a realistic concern.

Yes, it is safe.

Well, there is a reason why the stick travels as far as it does. One is the restriction in long-term maximum stick forces of 15 N (see §22.143(b) in the linked PDF), which is easier to fulfil if the stick has more travel. The other is the required roll speed to switch from +45° roll angle to -45° roll angle within 5 seconds for a glider with 15m wing span (see §22.147), which is easier to fulfil if the ailerons have a wider deflection range.

I found myself in the same position on several occasions (after all, I am 6' 6" tall when standing upright - most gliders became only flyable for me after I had fitted a new instrument panel, the 2-33 being a notable exception) and for me it was enough to be able to yank the stick fully to one side when I had lifted my leg off the pedal on that side, so the stick would fit below my knee.

If you want to fly a coordinated turn, the knee on the side where the stick should go will be stretched, in order to push the rudder to full deflection, so then the stick should be able to travel where the knee had been with a centred rudder. This will be the normal case - isolated full aileron without rudder should be the exception.

If you are concerned about unusual attitudes: You will not fly aerobatics, will you? And in order to end a spin, rudder is far more important than aileron, which should be kept centred in a spin.


Malaysia Airlines Flight 370 - Why didn't Malaysian Air Force scramble jets? It seems odd that a large commercial aircraft can deviate radically from its scheduled flight path without the military doing something about the situation. Malaysian military radar tracked the plane for about an hour after said aircraft had dropped off the air traffic controllers radar.

Why were no jets scrambled?

Has Malaysia not heard of "9/11", and how commercial aircraft were used by terrorists?

Which other countries military also pays such little heed "9/11"?

There are multiple reasons for this:

The aircraft stopped communicating after the Kula Lumpur asked the aircraft to contact Ho Chi Minh ACC. The last verbal contact with the aircraft is this:

Lumpur Radar: "Malaysian three seven zero, contact Ho Chi Minh one two zero decimal nine. Good night."
Flight 370: "Good night. Malaysian three seven zero."

The Kula Lumpur Control had no way of knowing whether the aircraft had contacted as instructed (and acknowledged).

According to the Malaysian defence minister, the aircraft was deemed commercial and not hostile.

Even if the aircraft was tracked in radar by the military, that in itself is not sufficient for scrambling jets. Usually, the ATC will inform the authorities about any possible deviation; It is unlikely that the military would have real time details of aircraft routes. Note that it was not possible in this case (the aircraft transponder had gone silent before deviating from path). Also, there can be multiple reasons for loss of communications (usually equipment failure), and one does not immediately conclude that the aircraft has been hijacked.

Scrambling jets is usually the last resort and are sent to shoot the non-responsive aircraft. You don't shoot a civil aircraft with hundreds of passengers just because a microphone stopped working. The ATC must confirm that it had deviated from path and then the aircraft must be deemed a credible threat.

While the procedures for scrambling military aircraft are usually classified, it can be assumed that they are different in case of US (and Europe) and rest of the world. It takes a lot of resources to keep aircraft and pilots ready to intercept aircraft, which not all countries have (or even require most of the time).


What are the eyesight requirements for LPPL/LAPL in the UK? I am a UK resident, and I am interested in learning to fly. Unfortunately my eyesight is not great, and I don't believe I meet the requirements for a PPL.

From my research, it seems the medical requirements of the LPPL and LAPL are a lot lower, and I may qualify for these, but I'm a little unsure of the requirements in terms of eye sight requirements.

I currently wear contact lenses, with corrective strength of -9.5 and -10.

Does anyone know what the requirements are under LPPL/LAPL in order to qualify?

The CAA has a publication called Light aircraft pilot’s licence (LAPL) Medical certificate - A quick guide for Pilots. It says:

  Your GP

  Cannot perform the initial assessment if you have one or more of the pre-existing diagnoses that require additional assessment. See
  below:

  Decreased visual acuity in either eye below 6/9 despite any correction

In other words, if your corrected eyesight is worse than 6/9 (whatever that means) you need to go to an AME for the medical, otherwise the GP can issue it.

Unfortunately the guide is unclear (as far as I can see) on what exactly the AME will do:

  If your GP decides he/she cannot
  issue a LAPL medical certificate
  you will need to see an AME for
  assessment.

I don't know if that means the AME can issue an LAPL medical with limitations, or require you to get a class 2, or something else. Unless someone else can find more information, it may be easiest to call an AME and ask them.


What is the purposes of grid-like pattern route for small aircraft? In these days, I see small aircraft like P68 fly with a very accurate "grid-like" pattern. I'm sorry but I don't know the correct word. Here a couple of examples, grabbed today at the same time:

and

What kind of job they might do with these routes?
I don't think it's about agriculture because the patterns are too long and they fly over cities and sea as well (and I don't think this kind of aircraft is the most suitable for such a task).

I thought about observation of restriction for COVID-19, but I would use helicopters instead of aircraft, and again the patterns are so long for just be sure if anyone goes out for a walk.

Any sort of collecting photographic data? Like Google does for its Maps?

These are most likely photography flights for cartography. Due to the COVID crisis, there are many flights like these lately because it is now easy to obtain permission from Air Traffic Control for these patterns.


How do aviation GPS navigation systems report GPS accuracy? While looking over a tutorial on how to operate the Garmin GNS430, I couldn't find any info on how the device would report a degraded or low accuracy signal. What are the accuracy requirements for aviation GPS navigation systems and how are they required to alert a user in the case of a reduced accuracy situation?

I'm not specifically asking about RAIM here, as I believe that is mostly designed to identify a malfunctioning satellite or compromised signal. An example scenario would be some atmospheric condition that reduces positional accuracy to 1/4 mile or less.

The required GPS accuracy depends mainly on the application. En-route requirements are more lenient than the accuracy requirements for non precision approaches.

The GPS accuracy is the result of inaccuracies in the signal combined with a factor based on the geometry of the satellites. Within the receiver the position error is thus estimated by looking at

The geometry of the satellites contributing to the position fix
The estimated user equivalent ranging error (UERE) caused by various disturbances

From the geometry of the satellites, the (Geometric) Dilution of Precision (DOP) is calculated. This is a number that expresses how the geometry of the satellites used to calculate the position influences the accuracy of the position solution. In an ideal situation, $DOP=1$, any value less than $4$ is considered good.

The DOP can be split up in three components, the horizontal (HDOP), the vertical (VDOP) and the time (TDOP). For horizontal position accuracy HDOP is used.

The second factor in the accuracy estimation is the User Equivalent Ranging Error (UERE). In the illustration above, this is the width of ranging bands.
UERE is composed of various factors:

Ephemeris data - Errors in the transmitted location of the satellite
Satellite clock - Errors in the transmitted clock.
Ionosphere - Errors in pseudorange measurements caused by ionospheric effects
Troposphere - Errors in pseudorange measurements caused by tropospheric effects
Multipath - Errors caused by reflected signals entering the receiver antenna
Receiver- Errors in the receiver's measurement of range caused by various internal factors.

The effect of the ephemeris data error is in the order of 2 meters (standard deviation).

The accuracy of the satellite clock used to be intentionally degraded under the Selective Availability programme. SA was turned of in May 2000, drastically improving the GPS accuracy. Receivers developed before that date are unaware of this change and will estimate a worse accuracy than they actually achieve.
. The residual clock error after SA was turned of is equivalent to about 2.5 meters (standard deviation).

The GPS signal includes parameters for an ionospheric model which can be used to correct ionospheric effects. The residual error cause by signal delay in the ionosphere is in the order of 5 meter (standard deviation).  It is the most significant contribution to the UERE.

Tropospheric effects are much less than the ionospheric effect. The effect is about 0.5 m (standard deviation).

Multipath effects (caused by reflections of signals) are very much depending on the environment. In a city the effects are worse than in the air. For airborne applications multipath can be cause by reflections of the signal from the wings. The effect is very limited. On the airport surface there can be significant effects especially near buildings.

Receiver errors caused by unstable oscillators (thermal noise), quantization and rounding errors, software errors etc. This contribution can be reduced by improving the design of the antenna and receiver; which all comes at cost.
Let's estimate the contributions to UERE about 3 meters.

The UERE is the root mean square of all these contributions.

$$UERE=\sqrt{2^2+2.5^2+5^2+0.5^2+1^2+3^2}\approx6.75meters$$

The 95% accuracy is then estimated by $2\times{UERE}\times{HDOP}$. For a HDOP of $2$, the position would be estimated to be within 27 meters 95% of the time. Typical accuracy is better, because the UERE factors are estimated quite conservatively.

Augmentation systems such as WAAS and GBAS can improve the GPS accuracy by sending correction signals. The GNS 430 (without the 'W') does not use these signals.

If the DOP is greater than $4$, the GNS 430 will display a message "Degraded accuracy". You can find the DOP on the Satellite status page. This page also shows the estimated position error.

Note that all the calculations to estimate the position error assume that GPS is working as it should, i.e. a fault free condition. Faults can occur in the satellites, in the transmission of data to the receiver and in the receiver itself. Fault detection is part of the RAIM function.


Are the same units used for stations and waterlines? I'm trying to decrypt a US aircraft manufacturer's plan. Could W.L. (waterline) and Sta. (station) references use different units?

For example, I have different distances from W.L. 0 to W.L. 200 and from fuselage Sta.3000 to Sta.3200. Are these references always in inches?

Coordinates should always be in the same units. For a US manufacturer, that will be inches. The SI units are generally millimeters. This makes it much easier to locate coordinates, and for calculating things like volumes or distances.


How to convert IAS/CAS to TAS up to Mach 3? Someone had recommended that I use this formula to convert KCAS/KIAS to KTAS:

https://www.experimentalaircraft.info/flight-planning/aircraft-navigation-speed.php

If you scroll down to "True Airspeed, TAS," you will see this formula:

=KIAS*SQRT(SEA LEVEL AIR DENSITY/AIR DENSITY OF DESIRED ALT)

So, enetered into an Excel spreadsheet cell, the formula would look like this:

=100*SQRT(1.225/0.905)

100 is the KIAS, 1.255 is air density at sea level, and 0.905 is air density at 10,000 feet.

This formula gives us 116 knots for KTAS.

This formula works for low airspeeeds, but as airspeeds get higher, the KTAS that is given is not accurate. As I have learned, this formula does not take into account "compressibility," and therefore the KTAS will not be accurate at higher airspeeds.

I am interested in a formula that I can enter into my Excel spreadsheet that will give an accurate KTAS for all airspeeds up to Mach 3, and altitudes up to 100,000 feet.

Is there one particular formula that will work?

For higher airspeeds, TAS is always calculated based on the Mach number:
$$
\mathrm{TAS} = M \cdot a_0 \sqrt{\frac{T}{T_0}}
$$
where $ a_0 $ is the speed of sound at ground level ($ a_0 \approx 661 \, \mathrm{kt} $) and $ T_0 = 288.15 \, \mathrm{K} $ is the temperature at ground level. This formula is just based on the fact that the speed of sound in air is proportional to the square-root of the temperature.

How to calculate the Mach Number

Now, we need to distinguish between subsonic and supersonic flow. The pitot tube will give you the ratio of impact pressure $ q $ and static pressure $ p $. From this ratio, you calculate the the Mach number:

subsonic flow:
$$
M = \sqrt{5 \left( (q/p)^{5/7} - 1 \right)}
$$
supersonic flow:
$$
M \approx 0.8813 \sqrt{\frac{q}{p} \left( 1 - \frac{1}{7 M^2} \right)^{5/2}}
$$
This equation needs to be solved iteratively.

The following plot shows the Mach Number as a function of the $ p / q $ ratio (red for subsonic flow, blue for supersonic flow):

Calculate the True Air Speed

Now that we have the Mach number, we need to calculate the TAS using the formula from above. The last missing piece is the static air temperature $ T $, which can be calculated from the measured total air temperature $ T_\mathrm{tot} $:

$$
T = \frac{T_\mathrm{tot}}{1 + M^2 / 5}
$$

This gives the final answer:

Unfortunately, there is no easy way to calculate this based on KIAS as an input. You will need the ratio $ q / p $ and the temperature $ T_\mathrm{tot} $ as measured by the aircraft.


How high can propeller airplanes fly? Is there a maximum height a propeller airplane could fly?

Some lower bounds for maximum flying altitude:

12,000m (39,370ft): Antonow An-70, produced 1994
12,310m (40,387ft): Lockheed Martin C-130J Super Hercules, delivered in 2012
12,500m (41,010ft): Piaggio P.180 Avanti, production started in 1986
29,523m (96,860ft): NASA Helios HP01, record altitude reached in 2001

Just for comparison: Low earth orbit is about 160,000m.

Upper bounds: I don't know. I guess at some point there is not enough air to get lifted.
And nobody build an airplane with solar cells that flies to space.

I guess important factors for such an upper bound are:

Weight of the airplane,
Size, shape and speed of the propellers
Speed of the propellers

It is a matter of power source (and engine aspiration in case of air breathing engines), wing loading and aerodynamic efficiency. With current technology, the limit is around 100.000 ft (30 km), as proven by Pathfinder and especially Helios. I doubt that much more is possible with really useable aircraft.
Aerodynamics first: The altitude factor of $c_l \cdot Ma^2$ tells you how much lift can be produced at a given flight Mach number, and the wing loading then gives you the minimum density for sustained flight. 0.4 is a good value for subsonic $c_l \cdot Ma^2$, and 30 kg/m$^2$ is a feasible wing loading for flight at 30 km. See this answer for more detail.
If the power source needs ambient air (piston engine), the plane needs triple-stage compressors or turbochargers, which have been tested up to 20 km altitude and should be good for maybe 24 km. They are finicky devices; Boeing Condor rarely flew at its maximum power because the stages of the turbochargers would oscillate in an alternating sequence of surges. One stage would race ahead, causing the other to surge, which made the first surge and free up the other to race ahead, and so on.
Above approximately 24 km, solar-electric propulsion looks like the best option currently. In all cases you can only fly subsonic, so the minimum practical wing loading will limit the maximum altitude. Aircraft like Helios are very delicate already, so they can only be launched in calm weather and are at risk of being blown away by high altitude winds. Payload is minimal, and depending what the aircraft is supposed to do besides flying high will give you a limit on the maximum altitude between 24 and 30 km.
Going to orbit in a propeller driven device is completely illusory. There is not enough matter to push against at higher altitudes, and the theoretical propeller diameter would be measured in Kilometers (or miles, if you prefer that unit). The structural mass would be prohibitive. Also, propeller thrust is inversely proportional to flight speed, and there is no way to accelerate with a propeller to escape velocity. The thrust would be just a rounding error away from zero at 7.9 km/s.
This speed is required to escape earth's gravity by flying fast enough around it so that the centripetal force equals the aircraft's weight and is called orbital velocity. The higher the orbit becomes, the more energy is required to reach it. In order to gain enough energy, a propeller aircraft would accelerate in the atmosphere to a speed quite a bit higher than the desired orbital velocity and then convert that kinetic energy to potential energy to lift its trajectory above at least 100 km, the internationally recognized altitude where spaceflight starts. Note that this phase of the flight requires inverted flight if the acceleration takes some time. The maximum flight Mach number would need to be maybe 12 or even 15 so this maneuver is possible at all.
In short: Going to orbit with a propeller? Forget it!