CFD with FPV racing drones

I am currently checking the feasibility of computational fluid dynamics with racing drones in Autodesk CFD2018.

This is one of my first attempts to simulate a simple copter draft by Heiko Schenk. I am still very new to CFD, so I am looking for feedback too.

I am including the effect of the propeller jet (velocity distribution and swirl) and also the motor housing rotation. The flow velocities of the propellers were calculated in JavaProp (33000 RPM, 360 Watts, 30 m/s, 3 blades, 5 inch diameter).
Watch this video for more information and some results:

Part 2/3: Side force generators - Forces and turning

About a month ago, I was presenting an idea to make drones faster on race tracks: The so called ‘side force generators’ (SFGs) enable racing drones to drift less during turns, making them potentially faster. The placement of the ‘wings’ is very critical and mentioned in more detail in my earlier post on SFGs. Some people tested the SFGs and confirmed the enhanced flight characteristics. Other people didn’t try and didn’t believe that SFGs could help. I must agree that the concept of the SFGs is not so easy to understand. That is why I will explain it in more detail here.

Let’s start with something that everyone knows (figure 1). When you are going through a fast turn with your car, then your car needs to provide two forces to stay on the track (grey line): The ‘thrust’ (green) of your car needs to equal its aerodynamic and friction drag (yellow). When the car turns, then there needs to be a constant force towards the centre of the turn, called ‘centripetal force’ (red). This force is …

Winter preparations: Recoil stretch

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

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:

Part 1/3: Side Force Generators (SFGs) in FPV Racing

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

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

Some brushed action for the winter

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 …