Thanks Christian and Rolf!
I have a digital level showing up tomorrow and an IBeam level a few days later.
I’m curious if anyone here used the 5° inward tilt for their Fighter? We’ll most often fly in the 6000-9000 foot MSL range. Often in windy conditions.
Thanks!
someone has flutter problems, I’m having it.
Hi Rocio,
welcome to the forum and to the VTOL area.
A more detailed description (fluttering while hovering or in airplane mode ?) and especially a link to a logfile would be essential for help.
Rolf
Hello, I’m asking someone to give me a hand, I can’t find a way for the plane to keep my height and constant throttle in auto modes. I notice that it lowers height and raises the accelerator then raises and lowers it and so on all the time. I also notice that it is not stable in flight. In FBWA mode, this does not happen to me, once the little in my cruising speed that is 19m/s works fine.
Flight lod attached.
https://drive.google.com/drive/folders/1pfBiyVzaiOflpB2_rAFXBoWUrn7lIrQr?usp=sharing
Cheers
Alfredo
Hi Alfredo,
the oscillatory change of potential energy (flight altitude) with kinetic energy (flight speed) with low frequency and very low damping is called Phugoid in aviation.
Your logfile is a good example:
In man-carrying aviation it is known as a consequence of incorrect trim of the elevator in level flight. My experience with my model airplanes is that it is no different than the big ones and the elevator trim is not in actual center position:
Rolf
Hello,
We have replaced the mfe motor and esc with
Tmotor V505 260kv and 60A flame esc
But with same parameters fighter is not flying stable.
Facing lots of twitching movement.
Did you redo the PID tuning after changing hardware?
The oscillations look like a tuning issue after you are above 1 m (away from turbulence created by the wings and props close to ground). Also check that all motors are aligned and level or slightly inward (5 degrees) and all hardware is fastened securely.
Let us know if that resolves the issue.
-Christian
Thanks, @Christian_H
The issue is Resolved. I think the power of the motor I was using was too much. I replaced the motor with the mad motor. now it is flying stably.
In the last few days, the weather conditions finally suited me to continue on the QFE Fighter. I have installed the latest beta ( 4.4.0beta2 ) firmware and the Quicktune lua script. I was not satisfied with the QPID settings and hoped that Quicktune would do the work for me.
The plane was on the ground longer, so I tried QStabilize and Qhover first and then qloiter with recalibrated kompass. To be safe, I then hovered low over the grain to start Quicktune there. The roll axis worked well, but when the D values were ramped up, the aircraft rocked so much that I had to abort:
Logfile: MagentaCLOUD
Parameters: MagentaCLOUD
With reduced D, however, resonant oscillations of the wings then occurred during the transitions in a certain speed range. With reduced P and D again it almost came to a crash when I let the plane hover backwards and it swung up terribly.
Logfile: MagentaCLOUD
Parameters: MagentaCLOUD
The fixed-wing flight itself is not a problem. Everything went well. The airspeed sensors are not yet calibrated. The airspeed is about 10%-15% higher according to log evaluation. I don’t like the torsional vibrations of the wings due to the heavy quad motor mounts. I plan to redo the entire QPID settings from scratch.
Rolf
Hi Rolf,
Thanks for sharing this.
Prior to purchasing my Fighter, I was given the impression that these were pretty straightforward to setup. Including that the stock settings were good enough. I have my airframe built, but still need to wire everything. But this is making me nervous about the setup and testing process. Has anyone here had an easy go at getting their Fighter up and running?
Hi @Clowd
don’t be discouraged. I think most people have managed to get their fighter to hover without any problems. When I ordered mine 2 years ago, the MFE quad engines were suddenly not available in Europe due to the Covid-19 pandemic regulations . I therefore relied on the T-motors including the ESCs from T-Motor. As you can see in the film, they already hover at 30%, have a different control behaviour and I think my difficulties are not typical for the Fighter with MFE motors.
Rolf
Thanks @Rolf, I appreciate the encouragement!
I have T-motor ESCs and motors as well. It may have been one of your posts higher up that I saw when looking for alternatives due to stock issues I had last year.
My pusher motor and ESC are:
My lift motors are (with MFE ESCs):
Yes, the 5 motors are the same. At least I’m satisfied with the propulsion motor for now.
About 18 m/s with 7 amps. Prop is a Biela 18x7 , ESC the Flycolor X-Cross HV 80 Amp.
I will still eliminate the hover issues. Unfortunately, in the last weeks we had again either too much wind or rain or I had no time to set the QPID values from scratch.
Rolf
I just set the Q-A-RAT-PIT values again today by hand conventionally, and it looks much better:
Improvements still needs to be done so that the motors rock less during backtransition.
Rolf
Dear Rolf,
Thanks for updating your progresss with Fighter VTOL. Please keep posting - I am followimg with real interest.
Piers
Hi @Rolf ,
Thank you for sharing your data. Just simple questions:
I am still testing some APC propellers, and try to get the optimum cruising speed, to achieve better efficiency.
Thank you
@piersac
Hi Piers, for sure I will report further.
Hi Tony @ton999 ,
AUW (total weight) is 9,8 kg
The forward propulsion is provided by T-Motor AT4120 kv250 ,Biela 16x8 and ESC: Flycolor X-Cross HV 80A 5-12S BLHeli32 ESC.
The airspeed sensor displayed in the OSD still needs to be recalibrated. According to the logfile the actual airspeed is even 10% higher than displayed. TRIM_ARSPD_CM was 1650. But the activated airspeed sensor still measures too low. I will need a few more flights to adjust parameters, e.g. the TECS values as well.
Rolf
I was to suggest maybe even trying a 14" or 16" pitch. Consider that you’re propping for cruise, which presumably is only about 50% throttle setting. You may have a 4-5 second full throttle burst to transition for FW mode. You might even be able to reduce your cruise throttle setting below 45% or lower and potentially increase your flight time without much stress on the motor or battery.
I converted an RVJet and used the stock 35xx-910kv motor and had an APC 13x8E. It comfortably cruised at about 42-44 mph at 45%-50% throttle. As a fixed wing, one wouldn’t probably put anything bigger than an 11x7 prop on 4S.
Food for thought.
Hi @Rolf
Tks for your info.
Your AUW seems so light, are you using 22 Ah or 16 Ah battery? My Fighter AUW is 11 kg using 25 Ah Lion and about 500 gr Camera, with 300 gr Landing gear. I am testing 16x12 and 16x14 Apc props. I have not finished yet with the result, but I believe that these two propellers are very efficient.
