CX7 :: [2024-03-13] :: First indoor tests

CX7 means Coaxial Copter, vehicle 7.
WTF is back again! This is a new coax, which is twice as light as CX5 and CX6 due to different motor mounting and few other design decisions. What is special about this coax, is that it runs on batteries from disposed vapes found thrown away in improper places. So, in a sense, it contributes to protecting the environment from lithium pollution.
The first day of testing featured morning and evening tests. The morning tests were with nearly all-default parameters, whereas for the evening tests some PID values were increased based on the morning test results. And... well, this one flies!

[@highvoltage19]

That's really crazy man 😮 keep going 👍

[@HEMANTKUMAR-nq9bx]

Beautiful bro , pls keep updating

[@shogunemperor]

Niiiice!! Looks great!

[@user-od1mg3oi8z]

CX7 is a real beauty🙌

[@ansib1e]

CX7 is amazing! Wishful you one day open source this so I can try to tune one 😆

[@wowthatflies]

I will do at some point. I would prefer not sharing designs with potential severe problems, but postponing all that is probably even worse.

[@ansib1e]

@@wowthatflies I'm a tinkerer myself and love the process of figuring out said problems too 🤣whenever you feel like it, I'd appreciate any files to help me start to try to build my own coax copter!

[@roguso12]

i support you! keep going

[@user-rn6jm5kz1k]

great ❤

[@andrebmx9421]

nice!

[@WillyKling]

Great work, but is a coaxial motor really needed? Are four vanes really needed?

[@wowthatflies]

On this craft, there are two motors and two vanes, not four. From it, you cannot remove anything without losing the ability to control. (I'm not talking here about non-rigid propellers, such as helicopters or recent swashplateless designs such as HALO)
You can build something with one motor and four vanes. In fact, three vanes are enough, but Ardupilot does not support that yet. I have already constructed a reconfigurable craft for improving this part of Ardupilot, which I probably manage to complete this summer. (You can easily configure this in Betaflight and maybe INAV, but they do not currently support proper output control for vanes, so you can tune it to hover nicely, but everything else will be not)

[@WillyKling]

@@wowthatflies You can counteract the motor torque with 2 vanes, you don't need a coaxial motor. Betaflight supports everything you need as a fixed propeller craft with one motor and two vanes is just an airplane without a tail and wings, just ailerons.
What you are trying to do is what 3d airplane flyers do when they stand the plane on its tail in the air. You just need a much lower center of gravity so the software does not have to work so hard to keep it balanced in higher angles of attack. Try the center of gravity of a helicopter.
I have just finished designing a craft on the same principle for sale and expect to get racing speeds in forward flight (Just writing the build manual now). The prototype was easy to fly.
I hope this helps.

[@wowthatflies]

For classic VTOL craft control, you need four degrees of freedom (equivalent to pitch, roll, yaw and thrust).
Every time you have less degrees of freedom, you have to sacrifice something. On a fixed wing, you basically have high speed and don't care about yaw stabilization, you have thrust, pitch and roll, exactly in the way you described. If you want to reduce the number of degrees of freedom on something which can hover, it seems you need to sacrifice a lot. Following what you say, I would imagine something with an extremely low CoG, which can throttle, yaw and pitch, but cannot roll (e.g. to move left, you would have to first turn left then pitch forward). This seems like a natural extension of a fixed wing, with all pros and cons, and maybe this is exactly what you have. Personally, I would not like to fly this, but I see that it can have some use.

[@wowthatflies]

By the way, something like this sounds like a nice-to-have failsafe mode for single-axis copters: in the case some vanes fail during the flight, it may descend and try to keep attitude using remaining degrees of freedom and yawing when necessary. Seems quite complicated and might be tricky when yaw is also by vanes, but could be tested.

[@WillyKling]

@@wowthatflies Yes, it cannot roll, but neither can a helicopter. This can be an advantage as it is inherently stable in hover. The problem I have seen with designs that have a high center of gravity is that they have problems transitioning from hover to forward flight. To hard of a stick input flips it over, because once you get over a certain tilt you lose lift.
Do you need to roll?
This kind of craft is perfect for cameras as you get 360 degree field of veiw with just a tilt servo, as you can rotate the entire craft. So you have a choice between putting it on top, where it has less use, or putting it at the bottom which automatically lowers your center of gravity.
I am not sure what flight characteristics you are going for. Is there anything you can compare it to?

[@Crusinforabruisin]

I have a new design myself I’d like to have someone produce a physical model. Send me your contact information and I’ll send you the files.

[@wowthatflies]

I can be found on Discord as "maximbuzdalov" and on the ArduPilot forum as "MaxBuzz".

[@lead4you]

can barley hear it...

[@wowthatflies]

It is actually quite noisy. I tend to avoid testing it at night...

[@SetUP1]

Опа, опять за старое взялся ))

[@wowthatflies]

Всё новое - хорошо разбитое старое!