V-tail assistance

[Obsidian Triniti]

Hello,
I have a rather strange request…I know V-tails aren’t popular these days but I decided to build one just for S&G’s. I like flying quads but I love building them. I’m using Betaflight and can’t seem to get this one right (pictures attached). I’ve tried the 3 configurations, including the default BF one first. The problem is with the rear props; I can’t seem to get this bird off the ground.

Would anyone have any advice as to how to configure this one? Any advice about motor order, configuration, etc. would be greatly appreciated. I’ve heard that I need to mess with the mixing, but not sure how to do that in BF. Help!

 

[Fast and Curious]

I apologise if this is all too basic and things you have tried already.
If you spin up the props and pitch forward does it move correctly? Is the top/higher side of the propeller moving forwards? In the receiver tab on Betaflight, with the quad disarmed and props off to be safe, increase the throttle stick to full and you should see the bar for throttle go nearly all the way from 1000-2000. With props off connect to Betaflight, plug in a battery, go to motors tab and power up one motor at a time to full, they should all do the same. If you put it in angle mode and slowly increase the throttle to around 80% what happens?

 

[Obsidian Triniti]

No apology needed, I appreciate you reaching out. I will try this - using the radio to see what happens while in BF. What I do see is that when im trying to take off, it flips backwards, as if the front is lifting but the rear is not. I’ve had the 3 configs and the props in the back right side up, on according to the diagram, but same thing.

I will try what you’re recommending and see is the ESC is the issue. Thanks!

 

[Obsidian Triniti]

No apology needed, I appreciate you reaching out. I will try this - using the radio to see what happens while in BF. What I do see is that when im trying to take off, it flips backwards, as if the front is lifting but the rear is not. I’ve had the 3 configs and the props in the back right side up, on according to the diagram, but same thing.

I will try what you’re recommending and see is the ESC is the issue. Thanks!

OK, I've tried that and all seems to be working ok. (thanks for the systematic way of diagnosing this, you have taught me lots so far!).

So the inputs from the radio work fine, bars are in the appropriate range. When I have it connected to BF and use the radio, everything seems to work fine in angle and acro mode. Seems the bird is responding appropriately. Off of BF and on the ground, I have all props right side up, even though the rear motors are on upside down - this is correct, right?

BTW, I am attaching some BF screen shots, not sure if this helps, but . . . Also, I'm using an HGLRC Zeus F760 STACK 30X30 3-6S | F722 Flight Controller | 60A BL32 4in1 ESC (just in case). And a CLI dump (I think) if that helps.

I'm thinking of flashing the FC just in case I clicked something somewhere that I shouldn't, but for the most part, I'm running BF defaults.

Thanks for your assistance in helping me diagnose this one. You're the best!

 

[Kilrah]

I have all props right side up, even though the rear motors are on upside down - this is correct, right?

It is, but your motors might be turning in the wrong direction?

 

[Fast and Curious]

It is, but your motors might be turning in the wrong direction?

Yes,
The props are mounted for this orientation


(props out)
which is correct for image 3 and 4 but not 6 (props in).
So if the higher, slightly curved back, smoother side is forwards it is correct. But yes it is something that is easy to get wrong on a half standard half pusher v-tail quad.

 

[Obsidian Triniti]

Yes,
The props are mounted for this orientation


(props out)
which is correct for image 3 and 4 but not 6 (props in).
So if the higher, slightly curved back, smoother side is forwards it is correct. But yes it is something that is easy to get wrong on a half standard half pusher v-tail quad.

Hmmm . . . so if I used the orientation and motor ordering in image 4, it should work, correct? Currently I have it with the BF orientation, with the props on correctly, but it still flips. I did notice something . . . it is like the rear props fight each other. If I arm it while holding it, once the props spin, it starts to jump in the back. That is the rear becomes unstable like it is being pushed from each side.

Of course, I thought, OK, the props aren't balanced. Yeah, that wasn't it. Anyhow, I'm going to try this 4th image with the different motor ordering and if that doesn't work, I'm scrapping her. I don't know what else to do. She was fun to create, though!

Thanks for all of your help, and I will let you know if this last thing does the trick.

 

[Fast and Curious]

Double check that motor 1-2-3-4 match up on the quad and in Betaflight. Sometimes quads behave weirdly when the props are spinning but it doesn't have enough throttle to fly.

 

[Obsidian Triniti]

Will do, thanks again!

 

[Obsidian Triniti]

Well, sad to say that I believe I have tried everything to get her off the ground, but it didn’t work. I do appreciate everyone chiming in. It could very well be the design of that particular bird. Technically it should have worked so I have to blame the design.

I do have one more question, completely unrelated: does anyone use TBS Crossfire and the Tango 2 remote? I recently set up one and can’t believe the range! The only thing I can’t get to work is the ESC tone when the bird loses connection with the remote. Is that strictly a DJI air unit thing? I am running the air unit as the vtx with the crossfire nano as the rx.