Servers by jDrones

Copter Tailsitters

I’ve been using the Steam version of RF8 and FlightAxis for more than a year, and followed the directions for using the public beta:

This is the command I use to start SITL with FlightAxis:
…/…/Tools/autotest/ -D -G -j4 -f flightaxis:

The URL is for the computer which is running RF8.

BTW, I’m having better luck with your latest bi-wing model. It’s flying well in manual and FBWA, but I’m having trouble with VTOL modes. Looks like it’s just a tuning issue, but I did have to swap the motors from left to right. Also, when the right visual propeller spins it’s actually the left motor that is spinning.

Thanks for testing. It looks like the Pitch P is wrong. Can you get also a Log?
So you don’t need to “prepare” RF8, just running?
It looks like something with python. No experience about but on my Computer.

I will have a look at the left right definitions, again. When editing and modifying left/right things like the wings some other part-definitions change also. When correcting this, another part has again changed.
This editor is somthing I can recommend for masochists. :wink:

It seems control surfaces deflect only a little and with a lot of delay. But I made several flights with control surfaces disabled and the biwing was stable.

It seems that there is a problem with the motor rotation directions; the reaction to differential torque seems to be in the opposite direction that I expect when I disable the control surfaces.

But I am able to get it to hover now with and without control surfaces with parameters similar to the real ones. Without control surfaces, it just goes unstable when I try to yaw, so there is definitely something backwards with respect to torque.

I’ll push the two versions up to the SITL repo for you to look at. I did increase the total mass up to 2.2kg to increase moments of inertia and boosted motor power to 400%
Hover thrust is only 27%, so I should probably reduce the power to 200%

My test variants of the biwing9 design are here, along with the parameters I’m using:

log from a sitl qhover test:

without control surfaces the yaw control of the real model is weak and I got large error, when I made the test I thought also it was not working but it was OK.
I checked the model parameter list and found servo 1 and 2 are disabled.

Thanks for pointing that out. I didn’t have any luck getting flaperons working on the lower wing, but it’s flying pretty well with elevons enabled on both wings now. I updated BiWing9_swapLR JWL-065_AV.RFX and the params in the repo.

Short video of qstabilize, qhover and fbwa:

1 Like

Thanks for the video, I’m happy that it flies.
I can’t test it because I have no luck to run SITL with RF8 on a single PC.
Just for this I don’t like to install other SW as requested in the Wiki to use it on a network.

running sitl on a Windows machine using cygwin or WSL

SITL connect but to something else and I can see an airfield in the desert.
I’ve postet it to the Forum Simulator.

Yes, I defined the rotation direction according @losawing as usual view from front. But in RF8 they see it from back and I didn’t realize that.

Have you assigned the servo also to the lower flapperon as in the pic below.
(Here not the correct servo nrs. yet) In my RF8 upper and lower works simultanyously

@kd0aij @lorbass congratulations, the model fly. The sound is very realistic as we can hear differential thrust working exactly like with my biwing.

Nice to hear. This is called “Reverse engineering” at first the real model and then the Simulation :wink:
May be, for your next Project I’m faster.
It would be intersting to compare the Params Real to SITL in order to know if later the SITL Params could help at the beginnig for a real Model.

I defined 8 servos with mappings to receiver channels 1-8 as in @losawing’s setup:

SERVO1_FUNCTION  77.000000
SERVO2_FUNCTION  78.000000
SERVO3_FUNCTION  77.000000
SERVO4_FUNCTION  78.000000
SERVO5_FUNCTION  33.000000
SERVO6_FUNCTION  34.000000
SERVO7_FUNCTION  35.000000
SERVO8_FUNCTION  36.000000

At one point, I had the flaperon servos assigned to RX channels 3 and 4 instead of 1,2 but the effect is the same as mapping servos 1,3 and 2,4 to left/right elevons as above.

I now run both SITL and RF8 on my Win10 laptop, with SITL running in WSL, and that works well. It’s a quad-core i7 with Nvidia GTX1050 graphics.

There’s definitely something wrong with the motor torque. It looks like the torque control is fighting the ailerons. This is left/right elevon and motors 1/3 while hovering:

So I’ll see if I can reverse all the motors…

Did you swap the prop directions as already realized in Post 124?
As I wrote in my File they where wrong.
How does that look in the real model?

After the reverse engineering, the benchmark…
nice model but 3D printing is a little bit heavy, 50% more weight with same battery.The autopilot is KK2 board. I do not see any transition, the flight looks like q_stabilise mode.

@lorbass I finally got the rotations correct; RFX and params uploaded as BiWing9_swapLR JWL-065 backTorque_AV.RFX here:

video here:

@losawing I guess the BlackFly design’s large fuselage has the advantage of serving as landing gear and, of course a streamlined enclosure for a big payload. Plus it’s amphibious…

I thought first, it’s already your next project which doesn’t fly correct yet.:wink:
And advantage I can see is; It can’t tip over in a windy landing.

Congratulation, a perfect demo flight.
@tridge Unfortunatly can’t reproduce it because SITL and RF8 can’t link.
In the Dev Wiki RF8 ist not explained.
RF9 needs a new InterLink-XD Box and with my experience with RF8 Edit issues I do not trust animore if it will work as described.
And I do not want to install Ubuntu for this one application only.
It is to complicate compared with my FSX from Microsoft which works on 5 PC’s over a simple MS Net.
A simple additional Text-Line in the Application.ini File was enoughe and it works without fighting.

The way the model fly is very close to the real one. That’s impressive.
When flying level, are control surfaces deflected ? Is it complicated to change relative wing pitch and airfoil ?

Elevons are neutral at about 20m/sec 50% throttle and 0 deg pitch


It’s fairly easy to change the airfoil in RealFlight; just have to set the root and tip airfoils for each wing. Incidence should also be straightforward, although I’ve never tried it:

Well, they have made it pretty easy to install Ubuntu on Windows 10:

…and it’s free.

Servers by jDrones