<p>Longer blades are more efficient, but it's only practical to a point. Blades have to withstand high RPM, be balanced, and be light. Also the linear velocity of the tip of the blade increases a ton if u have a long prop. At the same RPM, every rotation the tip travels 2pi*r meters, so more r means more distance in the same time.</p>
<p>This may not seem like an issue, however propellers really don't work very efficiently close to or above the speed of sound. Having the tips go supersonic can lead to compression and other issues. This is why there haven't been any successful supersonic propeller planes. The speed of sound is even lower on mars.</p>
<p>Here is some reading on that if you are interested, that explains it very well:
<a href="https://mars.nasa.gov/mars2020/participate/sounds/" rel="noreferrer">https://mars.nasa.gov/mars2020/participate/sounds/</a>
<a href="https://www.highskyflying.com/can-propeller-planes-go-supersonic/" rel="noreferrer">https://www.highskyflying.com/can-propeller-planes-go-supersonic/</a></p>

CC BY-SA 4.0
2021-11-28T14:36:30.860Z
this is a good answer.  Since it is a close call vote-wise, I will give it a 30 day wait before accepting the highest vote.
John Greene
CC BY-SA 4.0
2022-04-27T10:50:07.660Z
I’m trying to vote on an answer .  Could you Add some links showing how this width of a chord works.
John Greene
CC BY-SA 4.0
2021-11-25T05:24:11.293Z
2021-11-25T05:24:11.293Z
Simon Fox
<p>Increasing blade chord can give more lift, but only up to a point. Helicopter blades are pushing a column of air downwards, accelerating it from stationary to whatever speed is necessary. Each time a blade passes the same point, it gives that part of the column a push downwards. If the air hasn't really slowed down from the previous blade, then the blade adds nothing useful. So there's a limit to how much air each blade can push before it interferes with the next blade - and pushing a fat blade around causes drag and requires power, even if it's not doing anything useful.</p>
<p>For maximum efficiency, you want long, narrow, slow moving blades, so that each one is in 'clean' air.</p>

CC BY-SA 4.0
2022-04-27T10:49:19.107Z
I’m trying to vote on an answer .  Could you Add some links showing how this width of a chord works.
John Greene
CC BY-SA 4.0
2022-04-28T07:54:49.903Z
@JohnGreene - if you want to look into the maths behind rotor performance, this is how it's normally calculated: https://www.spinningwing.com/the-helicopter/momentum-theory/
Robin Bennett
CC BY-SA 4.0
2021-11-22T09:11:51.373Z
2021-11-22T09:11:51.373Z
Robin Bennett
<p>I marveled at the two flight videos today on YouTube by Perseverance helicopter flights during Ingenuity mission.</p>
<p>Got me thinking.</p>
<p>Why aren’t the helicopter blades wider? I would like to think that in order to compensate for Mars’ thinner air.</p>
<p>Doesn’t increasing the area of wing surfaces equal bigger lift?</p>
<p><a href="https://m.youtube.com/watch?time_continue=15&amp;v=40FkAA62uNg" rel="noreferrer">Video 1</a>, <a href="https://m.youtube.com/watch?v=qpqhYEkudvw" rel="noreferrer">Video 2</a></p>

CC BY-SA 4.0
2021-11-20T20:21:28.820Z
Hey, welcome to Drones.SE! Could you please explain what dimension you are referring to when you say "wider"? Do you mean span, chord, camber, or something different?
ifconfig
CC BY-SA 4.0
2021-11-28T14:35:32.387Z
that’s a good question.  i was thinking about the width of the blade.
John Greene
<aerodynamics><helicopters>
Question about Mars Ingenuity helicopter's wide-chord blades
John Greene
# Question about Mars Ingenuity helicopter's wide-chord blades

(Asked by: username_0 on 2021-11-20)

I marveled at the two flight videos today on YouTube by Perseverance helicopter flights during Ingenuity mission.

Got me thinking.

Why aren’t the helicopter blades wider? I would like to think that in order to compensate for Mars’ thinner air.

Doesn’t increasing the area of wing surfaces equal bigger lift?

[Video 1](https://m.youtube.com/watch?time_continue=15&v=40FkAA62uNg), [Video 2](https://m.youtube.com/watch?v=qpqhYEkudvw)

**Tags:** aerodynamics, helicopters
> **Comments:**
> **username_1**: Hey, welcome to Drones.SE! Could you please explain what dimension you are referring to when you say "wider"? Do you mean span, chord, camber, or something different?  
> **username_0**: that’s a good question.  i was thinking about the width of the blade.  

---

## 2 answers

### Answer by username_2 on 2021-11-25. Score: 5 | Accepted answer

Longer blades are more efficient, but it's only practical to a point. Blades have to withstand high RPM, be balanced, and be light. Also the linear velocity of the tip of the blade increases a ton if u have a long prop. At the same RPM, every rotation the tip travels 2pi\*r meters, so more r means more distance in the same time.

This may not seem like an issue, however propellers really don't work very efficiently close to or above the speed of sound. Having the tips go supersonic can lead to compression and other issues. This is why there haven't been any successful supersonic propeller planes. The speed of sound is even lower on mars.

Here is some reading on that if you are interested, that explains it very well:
<https://mars.nasa.gov/mars2020/participate/sounds/>
<https://www.highskyflying.com/can-propeller-planes-go-supersonic/>

> **Comments:**
> **username_0**: this is a good answer.  Since it is a close call vote-wise, I will give it a 30 day wait before accepting the highest vote.  
> **username_0**: I’m trying to vote on an answer .  Could you Add some links showing how this width of a chord works.  

---

### Answer by username_3 on 2021-11-22. Score: 5

Increasing blade chord can give more lift, but only up to a point. Helicopter blades are pushing a column of air downwards, accelerating it from stationary to whatever speed is necessary. Each time a blade passes the same point, it gives that part of the column a push downwards. If the air hasn't really slowed down from the previous blade, then the blade adds nothing useful. So there's a limit to how much air each blade can push before it interferes with the next blade - and pushing a fat blade around causes drag and requires power, even if it's not doing anything useful.

For maximum efficiency, you want long, narrow, slow moving blades, so that each one is in 'clean' air.

> **Comments:**
> **username_0**: I’m trying to vote on an answer .  Could you Add some links showing how this width of a chord works.  
> **username_3**: @JohnGreene - if you want to look into the maths behind rotor performance, this is how it's normally calculated: https://www.spinningwing.com/the-helicopter/momentum-theory/  

---

