Hi all!

Since I started messing around with drones, I was wondering how fixed wing vtols, like the one in the picture below,  can manage to transition from quad to airplane mode with a single radio for both flight modes?

I can imagine having two pilots and two radios, and a transitional period in were the airplane engine goes full throttle until v cruise is reached, and then the quad engines are turned off. Inversily when switching from aircraft mode to quad mode,  the aircraft will go from v cruise to v stall and the aircraft engine will  lower down its rpm while at the same time the quad engines increases its rpm to provide the necessary lift.

I guess you can do that with two radios, two pilots or even one pilot (and two radios) and two flight controllers; one for the aircraft ailerons/engine and another one for the quad motors.

However, if for convenience, you wished to merge everything on a single radio or even a single flight controller? Would it be possible to connect the aircraft and the quad flight controller? Can this be accomplished with Betaflight?

I downloaded a paper of a vtol aircraft in were they use pixhawk. I do not know if pixhawk uses ardupilot software, or if you can do something like that with arduino, or connecting arduino to an fc? Is ardupilot/arduino compatible with betaflight?

I am really curious, because I learned to program in the university, but I never programmed something beyond homework. It will be very cool to learn about those topics, so that perhaps I can recycle some of the past knowledge and have some fun!

I guess you can program a switch to make the aircraft transition from quad to aircraft mode and viceversa. The aircraft will respond to the radio according to the switch position, and activate an aileron or a quad engine.

Probably many vtol aircrafts are fully autonomous during the transition from hover to cruise. They perhaps fly following a waypoint routine to meet the regulations and be able to fly long range, beyond vlos.

Any input will be, as always, greatly appreciated!

Oriol

You might check out this VTOL and channel.
 He has a lot of fixed wing FPV designs flying on his channel.
 
 

Thanks Rob3ddd!

I understand that Pixhawk is a flight controller based on ardupilot software. Pixhawk, or any other ardupilot based system, can allow to connect different ESC that can power a quad or a fixed wing, as such those ESC can serve to power a vtol quadcopter/fixed wing at once. Or even ground vehicles and boats, submarines... I guess almost anything imaginable!

Regarding the flying wing on the video. As the guy on the video says, I do not think it can handle strong wings for taking off and landing, with only two engines and such a high surface against the wind. Probably a flying wing without landing gear, that can take off by hand and land on the grass, can operate better on a windy day.

I was just curious about how to add functions to a quad. Racing quads, whoops or cinewhoops does not require FC with the possibilities, and the weight, of Pixhawk. Ardupilot FCs are probably more intended for industrial use, to fly under the regulations for BVLOS, using waypoints.

Thanks for the inputs again Rob3ddd!

Oriol

it looks pretty stable to me, even on this tiny wing. every surface will struggle with wind, regardless if vertical or horizontale, it might depend on the amount of surface, motor power and surface of the rudders how hard it can fight against wind.



i know this cheapo vtol has two modes.

another kind of vtol https://rotorbuilds.com/build/19224
"parrot swing" calls another example


for vtol, inav might provide better options to settup than betaflight. not sure if the particular link ishelpfull, but you might get good informations on github: https://github.com/iNavFlight/inav/discussions/5607
arduino might provide options too, im bot to familiar both inav pr ardu

There's lightweight FC's available for ardupilot. They call them chibios flight controllers in ardupilot speak.
Holybro kakute h7 mini and Matek 405 are two I use. I have an ardupilot reckon 5" that's no more weighty than a betaflight quad.

I have no experience with VTOL but with regards to Ardupilot just be informed that they do not support F411 and F722 boards due to space/memory limitations. It is not something obvious but I thought its worth mentioning.

Hi hugnosed_bat!

I was thinking more about something that can land with a lot of precision, like a Mavic on a small landing pad.
The idea was more to have fun designing a fixed wing, and trying to figure out a way to program the transition between copter to fixed wing.
In any case, it will be better to start litlle by little and learn to fly with a foam fixed wing first, like those on your links.

I am curious about the possibilities of Ardupilot and INAV, or any other system, capable of programing waypoints.


Hi Evilsteve!

That is so interesting! Are the Kakute and the Matek FCs compatible to Betaflight or you need to configure them with ardupilot?


Hi Kafie!

Do you mean that for using ardupilot, you are forced too use specific FC like those mentioned by Evilsteve above?



Thanks to all for your kind replies!


Oriol

(05-Oct-2021, 12:33 PM)oriol Wrote: Hi Kafie!

Do you mean that for using ardupilot, you are forced too use specific FC like those mentioned by Evilsteve above?

Yes, they have a list: https://ardupilot.org/copter/docs/common...ilots.html

And some of those FC’s have limited support.

Just need to confirm the FC you decide to use is supported by Ardupilot and has the features you require enabled.

Both the matek and holybro are betaflight and ardupilot ready probably inav as well. I've never tried it though so I'm not positive.

I've been considering building a tail landing vtol. No extra motors required and looks crazy wierd to see these in action.

Hi Kafie1980!

I do not know what you mean by saying that Ardupilot FC have limited support?
I understand that for example the Holybro kakute FC on the Ardupilot list, seem to be compatible with both Betaflight and Ardupilot.

Hi EVILsteve!

Sure, it will be crazy fun to build a vtol fixed wing and fly it!
However, I understand that you still need an arduino bigger than usual race quads FC, to be able to manage separetely the Rotor ESC and the aileron servos.

If the airplane lands on the tail, I do not know how to tell, when flying FPV, if the aircraft is flying with the required angle for the wings to generate lift?
Perhaps like in this X-Wing quad, you can set the camera at a fixed angle that you know works with the wing providing lift.

In this aicraft the Melenor v1, they are using Ardupilot software with quad-plane code. I guess this software will solve mucch of the issues involved in transitioning from on mode to the other.

Cheers,

Oriol

Ardupilot’s foot print is huge which is why certain features are disabled or left out for certain FC’s.

https://ardupilot.org/copter/docs/common...d-firmware

So first thing will be understanding all the features you will need for your VTOL and then decide which FC will suite your Ardupilot based build.

Betaflight did similar things for a while with F1/F3 boards where they disabled GPS features just to fit the firmware and keep a reasonable load on the MCU.

I hope this makes sense.

Hi Kafie1980!

If I were to start designing a vtol quadplane. I will probably first learn how to fly, and build perhaps, a fixed wing. Then learn how to fly using waypoints and decide, according to the payload, which FC is the best for the mission.

I am not saying that is a huge undertake that is next to impossible, but it will require an iterative process before getting started with the build itself. In any case, it is fascinating to learn the therotical issues involved in such a project!

Thanks again for your kind replies,

Oriol

Hi!

I have seen in my club a couple of drone companies that come to test their aircrafts. It is surprising that they all fly helis to get the maximum possible payload. Today I asked two pilots of one of those companies, about the feasibility of a VTOL fixed wing versus a heli?
They told me that quadplanes are forced to carry a lot of dead weight to be able to take off vertically, and they can neither hover for long periods nor carry heavy payloads.

Then I asked them about helis versus multicopters? They have told me that helis were much better for heavy payloads.

When I say heavy payloads I mean 25 Kgs, which is the maximum allowed in Spain without being forced to certify the aircraft. Although the larger the prop the more efficient, I did not texpedcted that the difference between a larger drone and a larger heli was that big in terms of flight time, etc.

In any case, the most efficient thing for flying long range and carrying payload is a fixed wing.

I just did a few numbers, to see how big a runway was to be for a fixed wing with a MTOW of 25 Kgs?
If I consider a wing area of 2,5m2, a CL of 1 (just being conservative and thinking about something that would not require flats, like a flying wing), the stall speed I get is 45 kmh. It would be possible to reduce that speed, playing a bit with the aerodynamics and the payload, so that the aircraft can operate from an RC club or an ultralight airfield.

Just sharing some random thoughts, It is cool to sketch things up with numbers.

Good flights everyone!

Oriol

(07-Oct-2021, 07:11 PM)oriol Wrote: Hi!

I have seen in my club a couple of drone ..........

Hi oriol,

did you have any success with your original task?

I did buil some VTOL with the standard betaflight, but it is very tricky to go from hoover to normal flight mode.

Last project was the Lilium with 18 engines.




But it flights like mad max - fast as hell in normal mode.

And soft like a lamb during hovering.

Fly safe
OskarTango