<p>I have a working theory for why this may be the case; some micro-quad designs support this theory more than others.</p>
<p>Due to Newton's third law, the thrust force created by the propellers also has the effect of trying to lift the propeller up off of the motor in traditional multirotor designs where the propeller is on top of the motor. Aside from ensuring that the propeller can't spin independently of the motor, this is the reason why drones have propeller nuts (<em>or a similar mechanism</em>) to securely hold the propeller to the motor.</p>
<p>Many micro-quad designs, including some of the ones you link to in the OP (<em>e.g. the <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-bnf-hey-tinawhoop-2-3s-86mm" rel="nofollow noreferrer">Diatone BNF TinaWhoop</a> and the <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx" rel="nofollow noreferrer">FullSpeed BNF Cinewhoop</a></em>) instead feature the pusher-prop configuration you mention, with the propeller underneath the motor, and forego the inclusion of propeller nuts or bolts screwed through the propeller into the motor.</p>
<p><a href="https://i.sstatic.net/gr9Xp.jpg" rel="nofollow noreferrer"><img src="https://i.sstatic.net/gr9Xp.jpg" alt="enter image description here" /></a></p>
<p>(<em>FullSpeed BNF Cinewhoop <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx" rel="nofollow noreferrer">cit.</a></em>)</p>
<p>I don't have one of these quads to confirm my observations from looking at the images, but it appears like these designs have the propeller attached to the motor with a simpler mechanism that likely doesn't provide as much strength in the vertical direction. If my hypothesis is correct, this would mean that the propellers could theoretically fly off more easily if the motor wasn't in the way of the path the propeller wants to take during flight.</p>

CC BY-SA 4.0
2020-10-07T02:12:55.367Z
2020-10-07T02:12:55.367Z
ifconfig
<p>Microquads tend to be flown indoors, where the floor is relatively smooth but there are lots of other things to hit. Putting the prop under the frame provides additional protection when the quad flies into an obstruction. The direction of air flowing through a prop would tend to suck objects in from the top and blow then away from the bottom, so more protection is required on the top.</p>
<p>Outdoor quads often have to take off from ground that is covered with grass or other rough objects, and the additional clearance of top-mounted props decreases the chance of getting tangled.</p>
<p><a href="https://drones.stackexchange.com/questions/1137/why-do-most-drones-have-upward-facing-motors?rq=1">This related question</a> shows that there is a small performance improvement to putting the props below the frame, but these quads are not the ultra-small ones with very short flight times and marginal performance, so I think it's mainly for crash protection.</p>

CC BY-SA 4.0
2020-10-07T10:58:11.357Z
2020-10-07T10:58:11.357Z
Robin Bennett
<p>You can make a small quad with relatively large props without the propellers being in the FOV of the camera.</p>
<p>If you look at the quads you've mentioned, if you flip the motors and props over, you'd need to extend the arms or re-design the entire frame to be bigger. Pusher props can be under the quad and squashed together, making the wheelbase smaller.</p>

CC BY-SA 4.0
2021-03-19T15:14:06.977Z
2021-03-19T15:14:06.977Z
Nixfive
<p>Recently, I've seen a rise in popularity of small drones using pusher props. Some of these include the FullSpeed <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx" rel="nofollow noreferrer">TinyPusher</a>, BetaFPV <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/betafpv-bnf-beta95x-v2-2-cinewhoop-choose-your-rx" rel="nofollow noreferrer">Beta95X</a>/<a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/betafpv-bnf-beta85x-v2-2-cinewhoop-choose-your-rx" rel="nofollow noreferrer">Beta85X</a> V2, Diatone <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-pnp-taycan-c25-2-5-cinewhoop" rel="nofollow noreferrer">Taycan</a> and <a href="https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-bnf-hey-tinawhoop-2-3s-86mm" rel="nofollow noreferrer">Tinawhoop</a>, and originally the <a href="https://www.racedayquads.com/products/emax-tinyhawk-frsky-bnf-75mm-indoor-racing-drone?_pos=52&amp;_sid=d931de3c1&amp;_ss=r" rel="nofollow noreferrer">tinyhawk</a>. Why are pusher prop designs for small BNF quads becoming more prominent? I haven't seen any 5-inch BNF quads with pusher props which leads me to wonder, are there advantages to having pusher props on a micro drone that wouldn't benefit larger drones as much?</p>

CC BY-SA 4.0
2020-10-07T00:20:30.410Z
Frankly, I don't know what a pusher prop is...
ifconfig
CC BY-SA 4.0
2020-10-07T00:38:25.243Z
@ifconfig a pusher prop is quadcopter configuration where the propeller is under the motor and arm/support as opposed to a "traditional" configuration where the propeller is above the motor and arm/support. It looks sort of like a regular quad flipped upside down.
Jacob B
CC BY-SA 4.0
2020-10-07T02:13:14.087Z
Gotcha, okay I understand now.
ifconfig
<quadcopters><propellers><design><tinywhoop>
Why are micro pusher-prop quadcopters becoming more popular?
Jacob B
# Why are micro pusher-prop quadcopters becoming more popular?

(Asked by: username_0 on 2020-10-06)

Recently, I've seen a rise in popularity of small drones using pusher props. Some of these include the FullSpeed [TinyPusher](https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx), BetaFPV [Beta95X](https://www.racedayquads.com/collections/pre-built-quads-1/products/betafpv-bnf-beta95x-v2-2-cinewhoop-choose-your-rx)/[Beta85X](https://www.racedayquads.com/collections/pre-built-quads-1/products/betafpv-bnf-beta85x-v2-2-cinewhoop-choose-your-rx) V2, Diatone [Taycan](https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-pnp-taycan-c25-2-5-cinewhoop) and [Tinawhoop](https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-bnf-hey-tinawhoop-2-3s-86mm), and originally the [tinyhawk](https://www.racedayquads.com/products/emax-tinyhawk-frsky-bnf-75mm-indoor-racing-drone?_pos=52&_sid=d931de3c1&_ss=r). Why are pusher prop designs for small BNF quads becoming more prominent? I haven't seen any 5-inch BNF quads with pusher props which leads me to wonder, are there advantages to having pusher props on a micro drone that wouldn't benefit larger drones as much?

**Tags:** quadcopters, propellers, design, tinywhoop
> **Comments:**
> **username_1**: Frankly, I don't know what a pusher prop is...  
> **username_0**: @ifconfig a pusher prop is quadcopter configuration where the propeller is under the motor and arm/support as opposed to a "traditional" configuration where the propeller is above the motor and arm/support. It looks sort of like a regular quad flipped upside down.  
> **username_1**: Gotcha, okay I understand now.  

---

## 3 answers

### Answer by username_1 on 2020-10-07. Score: 4

I have a working theory for why this may be the case; some micro-quad designs support this theory more than others.

Due to Newton's third law, the thrust force created by the propellers also has the effect of trying to lift the propeller up off of the motor in traditional multirotor designs where the propeller is on top of the motor. Aside from ensuring that the propeller can't spin independently of the motor, this is the reason why drones have propeller nuts (*or a similar mechanism*) to securely hold the propeller to the motor.

Many micro-quad designs, including some of the ones you link to in the OP (*e.g. the [Diatone BNF TinaWhoop](https://www.racedayquads.com/collections/pre-built-quads-1/products/diatone-bnf-hey-tinawhoop-2-3s-86mm) and the [FullSpeed BNF Cinewhoop](https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx)*) instead feature the pusher-prop configuration you mention, with the propeller underneath the motor, and forego the inclusion of propeller nuts or bolts screwed through the propeller into the motor.

[![enter image description here](https://i.sstatic.net/gr9Xp.jpg)](https://i.sstatic.net/gr9Xp.jpg)

(*FullSpeed BNF Cinewhoop [cit.](https://www.racedayquads.com/collections/pre-built-quads-1/products/fullspeed-bnf-tinypusher-75mm-cinewhoop-choose-your-rx)*)

I don't have one of these quads to confirm my observations from looking at the images, but it appears like these designs have the propeller attached to the motor with a simpler mechanism that likely doesn't provide as much strength in the vertical direction. If my hypothesis is correct, this would mean that the propellers could theoretically fly off more easily if the motor wasn't in the way of the path the propeller wants to take during flight.


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### Answer by username_2 on 2020-10-07. Score: 3

Microquads tend to be flown indoors, where the floor is relatively smooth but there are lots of other things to hit. Putting the prop under the frame provides additional protection when the quad flies into an obstruction. The direction of air flowing through a prop would tend to suck objects in from the top and blow then away from the bottom, so more protection is required on the top.

Outdoor quads often have to take off from ground that is covered with grass or other rough objects, and the additional clearance of top-mounted props decreases the chance of getting tangled.

[This related question](https://drones.stackexchange.com/questions/1137/why-do-most-drones-have-upward-facing-motors?rq=1) shows that there is a small performance improvement to putting the props below the frame, but these quads are not the ultra-small ones with very short flight times and marginal performance, so I think it's mainly for crash protection.


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### Answer by username_3 on 2021-03-19. Score: 1

You can make a small quad with relatively large props without the propellers being in the FOV of the camera.

If you look at the quads you've mentioned, if you flip the motors and props over, you'd need to extend the arms or re-design the entire frame to be bigger. Pusher props can be under the quad and squashed together, making the wheelbase smaller.


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