Can Ardupilot be modified to control a Stopped-Rotor Configuration with 8kw motors?

Large (300 lb) Stopped Rotor fixed wing VTOL. Configuration is similar to a quad copter for takeoff. Tail mounted tilt-rotors operate together in vertical orientation; thrusters are mounted on the tips of the horizontal stabilizers. Main Wingtip mounted large diameter rotors are configured as rotor blades. After VTOL takeoff Tail rotors tilt to horizontal to generate forward velocity. When stall speed is exceeded, wingtip mounted rotors are stopped and repositioned to an extended “V-wing” configuration and act as ailerons in cruise flight. My question is; can Ardupilot be modified to signal the wingtip motors to stop and then signal the wingtip motors to reposition the rotor blades?

Can you post a diagram of the setup?

It sounds like it would be hard due to two step transition.

You could consider drehmFlight as it has significantly smaller code base that will be easier to get into.

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I’m not sure what you mean by “setup”, but I’ve attached a simple block diagram of the control elements, and a depiction of the configuration changes from VTOL to Cruise with a description of the processes. The purpose of the vehicle is to show that a properly designed Stopped-Rotor aircraft can achieve both efficient VTOL and efficient cruise. The CFD analyses indicate that this design can be efficient in VTOL and still attain an L/D of 18 in cruise, which is pretty darn good for a VTOL machine. It’s efficient because the elements that produce VTOL thrust actually contribute to cruise efficiency. I haven’t seen any other design that has this capability. My design uses single motors for each empennage mounted cruise thruster (a ducted fan to reduce acoustics signature), and dual motors for each rotor mechanism. In a simpler version, a single motor rotor can work depending on the size/weight of the vehicle (but two motors provide a fail-safe mechanism), and the ducted fans tilt in unison with only a single tilt motor, although that would reduce yaw control in hover.
I would build it with a single motor rotor and a single motor tilt only for a proof of concept prototype; the “concept” being that a “Stopped Rotor” design provides the most optimum long-range, VTOL capable aircraft.
FYI, I’ve attached an illustration of the fixed-wing and rotor-wing configurations, and a a simplified block diagram of the control elements.
Thanks for your interest,

AV-1 Block Diagram.pdf (226.3 KB)


Hello, this is a fascinating and novel concept for a VTOL aircraft. I suggest gaining a robust understanding of the arduplane VTOL/quadplane control logic to determine which features of your design may or may not be feasible given control limitations.

Regarding your approach to aircraft development, I might also suggest starting with a lighter (<50lb) scale design to minimize regulatory hurdles and perform design maturation and risk reduction. A scale aircraft may sacrifice some of the novel control concepts (such as the wingtip blade trim) for more traditional surfaces, however, it will give the opportunity to have a buildup approach and finally answer if ardupilot is a good long term solution

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Thanks for you comments! I have designed a <55lb size, which utilizes the single -otor rotor controller version, but, as you correctly indicated, the blade trim will be sporty at the smaller scale. In the larger design the blade trim tab actuator servo is mounted inside the trim tab. But at the smaller scale, the trim tab is pretty small and the servo would need to be also. Although if I look hard enough I can probably find one that’s small enough, otherwise I just modify the design a bit. For a proof of concept vehicle that would be just fine.
The larger question though is, if I modify Ardupilot to control a ‘street legal’ <55lb machine with smaller say 1.5 kw motors, will the same software be able to control a much larger 300lb machine with, say 8 kw motors?
I guess I’ll find out, and I suppose that’s why they call it flight TEST!

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As long as it isn’t intended to carry humans it will be fine.

Unfortunately Ardupilot is pretty much unverifiable under DO-178 due to the nature of open source software.

One thing that worries me a bit is maintaining good roll control during rotor stopping procedure.

PS I think it should be viable with a large Lua script to manage everything.

This isn’t the first stoprotor that ArduPilot has controlled. This one runs ArduPilot:
I suspect you could do most of the control with lua scripts and treat it as a tilt quadplane.
First step will be to create a good simulation model to help develop the control approach. Do you have a simulator already?

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I haven’t worked with software verification since the MX missile program back in the early '80s (I was an infant then), but the planned 300 lb size is ‘not intended for human consumption’. However, growing it to a PAV size is definitely in the cards, so SW verification is definitely necessary. Although, other than a reference to DO-178, it is still somewhat undefined in FAA regs.
I’m not a programmer, haven’t even played one on TV, am not conversant in LUA, and have only studied PYTHON briefly. So I suppose I could learn LUA too. Developing the control laws and then programming them is definitely the long pole in this tent, which is why I’m looking for advice from those who are much more knowledgeable than I.

Glad to hear that the Australian stopped rotor used Arduino. That means that Arduino can bring the rotor to a controlled stop at a precise azimuth. I haven’t developed a simulator yet - currently looking at creating one with X-Plane.
Thanks for your interest… keep in touch.

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BTW, I haven’t located the patent, and couldn’t tell from the photo of the Aussie stopped-rotor how it managed the “backward blade” problem, but if you’re interested, take a look at one developed at the US Naval Research Center … US8070090B2 Tayman. Very clever method of rapidly rotating the ‘baclward’ blade so it’s forward facing. It still uses a symmetrical airfoil, so cruise efficiency is somewhat diminished, but it’s a pretty spiffy design.

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