Pusha Q

By SlightlyScratchedCorolla on Aug 15, 2020

14  502  7

This 3" frame has been sitting in idle forever because I gutted the Cinequeen for parts. I was hoping I could get my hands on the umma95 kit but it seems to be never in stock in the US. So I'm converting the Cinequeen frame into a bottom mount pusher.

The wide space between the prop guards would allow me to bottom mount the battery, which will stay at the center of the mass while lifting the props away from the ground. This is pretty close to "mid-mount" battery. And if you flip this quad, you bascially get a small top mounted Remix with prop guards, that's where I get the idea of bottom mounting this baby.

I'd love to put on bigger motors but this frame limits me to 9x9 patterns. I chose 1404 over 1206 because of a little more low end torque and props being able to position a little higher (upside down motors).

The build was fairly straight forward. Make sure the motors are spinning in the right direction and install the props like usual (inverted to motors here).

281g take off weight with a 850mah 4s.

Bonus point is usb ports are hella accesible.

Tuning update:

I couldn't get it fly smooth enough for a couple of days, some mid throttle oscillation here and there, turns out a capacitor leg was poorly soldered. Once I cleaned up the joint, it flies good on 1.1 master slider and 1.1 PD balance with rpm filtering. Gyro filters set to 1.1 to 1.2. (Scratch this: this just moves the oscillation to a higher throttle position, thats why I didn't notice when I was flying through some trees on somewhat low speed, a better tune would be all Ps on 1.4 of default, pitch and roll D around 40 D min and 55-60 max, yaw D 15 min 0, around 150 ff, all Is around 100. ESC set to 48khz with rpm filtering)

Final pids here. If you want to try a similar configuration, do not bother with the BF 4.2 default. Start from the parameter in this picture.

Alt Tag

I also zip tied the props guards on each side together to increase the overall rigidity.

After I tuned this quad at this moment I get 7 minutes of smooth cruising flight on an old 4s 850mah pack landing at 3.5v. The flight time is not improving from the regular configuration, the handling is better. Hard ripping a little more than 4 minutes landing at 3.6 to 3.7v on the same pack.

acro and proximity test

earlier flight test

I've flown this thing around everyday since its birth, I'm a terrible freestyle pilot, but it's coming out of dives and rolls with minimum prop wash on my slippery fingers. I originally built this thing just for recycling old gears and experiment, I did not expect to spend this much time on this quad, let alone enjoy its performance so much. I'm not saying the regular configuration is any bad, in fact they are very good, but the two elements: 1) the pusher configuration and 2) the mid mount battery (well it looks like a bottom mount but really is a mid mount cog wise) make the quad pretty in control and stable when you fling it over some trees. The thrust feels "clean" on the stick.

But I have no data to back up any of my claim and they could all be my bias. If you got one of spare whoop frame that can do pusher and mid mount, I encourage you future boys to give it a try.

Photos

Discussion

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QCumberCool   Aug 15, 2020  

does having the motors inverted help performance at all?

SlightlyScratchedCorolla   Aug 15, 2020 
1

I'd need to fly it more to properly answer you. My first impression is its not as steady as the regular configuration (all with prop guards) but faster and punchier, but I have barely tuned this quad so it's not definitive. Also half the reason I did it is that the wide clearance on this frame allows me to bottom mount, and the battery would be at the level of motors/props. You know what people used to say it'll be good to "mid-mount" battery, this is my attempt to put the mass together.

1Smug_Bastard   Aug 21, 2020 

It should (3-7% gain) but the effect is more noticeable with larger propellers.

erikschmidt   Aug 19, 2020  

not sure how it flys, but its super cool . i like the creativity

SlightlyScratchedCorolla   Aug 21, 2020 

https://streamable.com/e76rm1
my most recent test flight dvr. You can tell I'm a limited pilot but the quad has very little prop wash coming out of acro moves.

PidFarmer   Aug 16, 2020  

This is one of my favorite frames.
Just realized I can approximate this with mine with a few software settings since the props are 3D style. I'd be most curious to see how it impacts battery life.

SlightlyScratchedCorolla   Aug 16, 2020 

3D style on this setup would be wild. I'd get rid of the prop guards all together for that lol I guess otherwise the thrust difference when you invert the spinning would be huge.

I've never configured a 3D motor/prop I can't speak for the battery life. But this particular pusher configuration of mine doesn't seem to increase flight time, it just gives a little better handling. I'm using fairly high pitch props though, I'm gonna put on some less aggressive props and see if that increases efficiency.

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