Posts

Winter preparations: Recoil stretch

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This design was just finished, I am still searching for the perfect propellers. The performance is very good already, but the props are not durable enough. The MTM is 150mm, I noticed that quads fly cleaner and with less noise when there is some extra space between the propellers.

Here is my setup
Recoil stretch frame, 2.5mm carbonWeight without Lipo: 80gTake-off weight: 135gAMAX inno 1105 4000 kVEmax Bullet 12A ESCsTattu 4S 450 mAh 75CRuncam Swift micro NTSC, 2.1mmFXT FX806T VTX, 25 mWFrsky R-XSREmax femto (still my favorite FC although I haven't tried many)XT 30AMAX inno 3030 3-blade props











CAD design, manufacturing + test flight of an FPV racing airplane

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I wanted to create a small FPV racing aircraft that has a good performance on small racing tracks with FAI gates. So I created this bimotor airplane. The yaw control makes it very agile. I am using a flight controller with iNAV firmware to stabilize all axes.
The aileron servos are much too slow (0.1s/45°), so it was hard to tune. They will be replaced now with faster ones (0.05s/60°).
Propellers are 4 x4.5 inch, motors are xnova 1407 - 3100kV, Lipo is 1Ah, 4s.
I like the results, and I am looking forward to fly it on race tracks with a lot of gates.
Watch this video to see a timelapse of the design and milling process, followed by some inflight clips:








Side Force Generators (SFGs) in FPV Racing

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Summary: FPV racing multirotors with side force generators (SFGs), will drift less during turns, making them potentially faster on race tracks (watch the video comparison here). But the SFGs need the be carefully placed and dimensioned, so that aerodynamic centre and centre of mass are at the same position. Otherwise it will not work. 
Introduction Recently, I was thinking about how to improve the handling of racing copters. I noticed since quite a long time, that different copters behave quite differently in fast turns: Some drift quite a lot (especially when they carry a larger battery or an action cam), others drift less. I was always preferring copters that drift as little as  possible. That is also why I am trying to reduce the weight of my copters as much as feasible.
The amount of drift depends on the weight of the copter and the lift and drag of the fuselage for sideways air streams (side-slip). The larger the lift and drag, the more side force the fuselage produces at a given…

125mm, 125g mini brushless copter

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Currently, I love to fly with my latest design, called "RECOIL": It is a very small brushless copter (125mm MTM) with a total weight (including 3S 450 mAh lipo) of 125g. It however flies like a large copter and is a lot of fun!

Emax F3 femto
RCX H1105 5000 kV
Racerstar 6A
3x2" props
3S 450 mAh
FX806TC

https://www.youtube.com/watch?v=ctqIlr-9HOk












Some brushed action for the winter

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It has been a while since I posted something here. It is not because my project is dead, it is more because I spent my hobby time with flying and not with making new things. The derbe evo is almost perfect and I am very happy with it, so I don't see the need to design a new frame currently. But I am currently rewriting my flightcontroller code in order to achieve a faster control loop frequency. 1000 Hz should be possible on my 8bit ATXmega32A4. I will achieve this by using integers instead of floating point variables, and by removing every unnecessary line of code.


But recently, I bought an Eachine QX90 (always wanted to adapt my own flight controller for a small brushed copter, but there was not enough time...). And it flies great. I however changed it a bit, here is my setup:
QX90 original FC (stock firmware, see settings in the pictures below)Standard motorsGemfan 65mm propellersCustom frame (weight: 5.5g, see pictures below)Eachine TX01 cam with dipole antennaTurnigy graphene …

Derbe evo available on Shapeways.com

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Hey, I decided to make the derbe evo v2 available on Shapeways.com. So I don't have to send the files manually by e-mail. You can download or order using this URL:
https://www.shapeways.com/shops/shrediquette


Derbe evo - Version 2

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I've been flying the derbe evo for a while now, and it is very agile and fast. I had to reduce the PD parameters by 30%. This is due to the fact that the mass is closer to the centre of the copter, and that reduces the moment of inertia. I was flying a competition with the derbe evo already (Hannover Cebit FPV Cup, here's a video). Unfortunately, the derbe evo crashed very hard during the qualifying (the gates were made out of massive steel, and the video reception was very poor). I think, I was frontally hitting a metal tube, and the 3D printed frame broke (two Cobra motors also have a bent shaft - I had to replace them as I do not manage to remove the shafts).
I implemented some modifications in the new version. The camera angle (wide angle lens) is now 35° (instead of 25°) to allow for higher pitch props. The 3D printed frame is thicker. And the power conncetor is now integrated in the frame. Additionally, I added a small button for the TBS unify pro to change channels comf…