• This site uses cookies. By continuing to use this site, you are agreeing to our use of cookies. Learn more.

FT Racer maiden flights

#1
Hi!
I'm pretty new in the hobby and I just finished the FT racer build (with power pack C provided by FT).
I feel pretty confident flying trainer (sportsman s+), but had a huge difficulties flying racer - during maiden flights it spin and crashed 3 times during turns - and I'm not pretty sure what I was doing wrong.
That's the video of the third crash which was nearly fatal to the plane, but previous 2 flights ended the same way, but with a bit less damage:
I can't reproduce the same behavior in the RealFlight simulator, so I can't understand how and what to fix and a bit afraid that even after rebuilding it plane won't end the same way.
What do you guys think, what am I doing wrong?..
 

d8veh

Well-known member
#2
It looked like it was flying OK. The possibilities I can think of are firstly a brown-out, where the receiver loses power. That can happen when the ESC can't provide enough power for the receiver and all the servos. If you used one of the Flitetest provided ones, that's not likely. Secondly, battery disconnection, however that can happen. Thirdly, transmitter/receiver range. If you've used that gear on a previous plane, that's not so likely. Did you do a range test? Lastly, pilot error. It looked like that at first, but the lack of change as it went further down, says maybe not.

Did it always happen at long range? It could still be a combination of pilot error and the palne's characteristics, especially as you're not used to this type of plane. two things I can suggest if that's the case: firstly, reduce the throws on your elevator and ailerons until you're used to the plane. secondly, don't let it go right onto its wing tip when you turn. Try and keep the wings a bit more level, say 45 deg to horizontal. When you make a normal turn, you tilt the wings a bit, then pull back on the elevator, but if you go right onto the tips then pull the elevator, the plane will just spiral down, though that should be similar on the simulator; however, real models are often harder to fly than the simulator. Do you have exactly the FT Racer on your simulator or is it a similar plane?
 
#3
@d8veh that's interesting, I didn't think about radio problem.
I tried to perform a range test switching Taranis TX to range test mode, but both TX and RX are not new and not previously flown by me.
I'd expect it to be "combination of pilot error and the palne's characteristics" :)
I don't have FT racer in simulator, I tried to use a couple of some similar planes and wasn't able to reproduce the same problem.

That you for tips about flying, I'll try to control turns better next time (as trainer is really forgiving and you can make almost anything with it).
 
Last edited:

Hai-Lee

Old and Bold RC PILOT
#4
Firstly not all crashes are pilot error. Actually most of my crashes were caused by things I did during the build and before the flight.

I agree with the things @d8veh said but I would actually add to the list!

You can get similar behavior if the Rx antenna placements are not good and the Rx antenna is obscured by internal metal objects. In the worst case the Rx will lose all signal and of course a crash is the next thing to occur.

In addition if the ESC is not provided with sufficient cooling airflow then the ESC can overheat quite quickly and if extreme it can shutdown the voltage supply to the Rx and servos. Result yet again is yet again a lose of control and a crash!

We can help you but we would need some more information before we can work out what the problem is or might be. Firstly what radio equipment are you using? What motor/ESC/Battery/propeller are you using. Finally a few pics of the internal layout so we can see the Rx antenna positions as well as the airflow around the ESC etc.

We will wait for your response!

have fun!
 
#5
I'm using the taranis x9d TX and x8r receiver, both are pre-owned.
ESC, motor and props are from https://store.flitetest.com/flite-test-power-pack-c-fixed-wing-large-flt-3003/p674264, ESC located inside the pod, so overheating might be a case as there is almost no air flow inside (photo is not mine, but setup is similar: https://flic.kr/p/fkspYe ). Should it be outside?
I'm not sure I have a photo of the assembled pod, but antennas (x8r has 2) are just lay inside and probably might change position in the flight.
 

DamoRC

Well-known member
Mentor
#6
All of the above are good points / suggestions. Just to get a little more context on your flying experience and style

(1) when flying the sportsman S+ were you using the SAFE technology / auto leveling etc or had you progressed to using no artificial aids?
(2) are you flying it four channel (actively using rudder) or just bank and yank? Just wondering if you are adding to much rudder into the turn which will add to the roll effect of the ailerons.
(3) at the very beginning of the video, when we first see the plane, was it doing the same thing but you managed to recover it?

Most of my FT racer builds have been good fliers, but I have had one that, for no obvious reason apart from a flawed wing build, had a tip stall issue only on one side. So in a high bank turn and pulling on the elevator, it would enter a spiral, or on a tight loop, it would roll out of the loop.

Looks like your flying is pretty good, but we can all dumb-stick it at times.

DamoRC
 
#8
All of the above are good points / suggestions. Just to get a little more context on your flying experience and style

(1) when flying the sportsman S+ were you using the SAFE technology / auto leveling etc or had you progressed to using no artificial aids?
everything is disabled, I'm able to fly/land it and even do some very simple aerobatics.

(2) are you flying it four channel (actively using rudder) or just bank and yank? Just wondering if you are adding to much rudder into the turn which will add to the roll effect of the ailerons.
(3) at the very beginning of the video, when we first see the plane, was it doing the same thing but you managed to recover it?
might be, but not exactly sure. It definitely acted the same way before.
 
Last edited:

DamoRC

Well-known member
Mentor
#9
On the brown out option, does anyone know if the x8r stores a brown out code? (I think some of the spectrum comparable receivers will give you a series of flashes to let you know it experienced an interruption or brown out).

DamoRC
 

d8veh

Well-known member
#10
I can reproduce what happened with your plane in the simulator. it doesn't work with all planes, but it does with ones similar to yours. I take off, gain some height and fly straight and level, then initiate a turn by pushing the right stick to the side until the wing is vertical like yours. The nose then drops and the plane starts to spiral downwards. I then pull on the elevator, but all that does is behave like a rudder because it too is nearly vertical, so the spiral only tightens and the plane goes down exactly like yours. I can't say that this is definitely the cause of your problem, but i think that there's a fair chance it is, especially if your not used to ailerons.

When you initiate a turn with the ailerons, the plane rolls and continues to roll even when you let go of the stick because it has angular momentum. If you want to stop at a 45 deg tilt, you have to knock the stick back in the opposite direction soon after you initiated the turn, then you have to keep nudging the stick back to bring the plane back level, and finally a nudge the other way to make it stay level. You don't have to do any of that with rudder control because the plane is self-levelling, but your new one is definitely not. As long as the plane doesn't go past 45 deg tilt, the elevator will lift the nose when it drops in a turn, after 45 deg, it's effect accelerates downwards along with the plane. In fact if you use the elevator any time you're tilted, it has a component of rudder, so will tighten the turn. If you watch JB's stick movements in this video from 8:55, you'll see that when he turns left, he spends more time pushing the sticks right than left.

To summarise, you move the stick to the left to start a left turn, then more or less immediately, more than that to the right to stop the tilting continuing and to counter the tightening from the elevator you use to hold the nose up. When you've nearly turned enough, push the stick to the right again to level the wings, and finally a short nudge to the right to stop it going past level, so left, right, pause, bigger right reducing, left.

When flying, you don't need to think about what you're doing with the sticks. just watch the plane and don't let it tilt past 45 deg for now, and you'll soon figure out the stick movements without even knowing what you're doing, but bear in mind how it works when you're on the simulator.

 
Last edited:
#11
I can reproduce what happened with your plane in the simulator.
Thank you, that is really helpful!
I'll try to work on in in simulator. Which plane you were using to reproduce it?

And another question which was raised somewhere in topic - should ESC be located outside of the power pod?
 

SlingShot

Maneuvering With Purpose
#12
Wow. I haven't seen that in over 40 years. It looked exactly like what we used to call a "glitch" or a "hit" when somebody had radio interference.

I believe you're on the right track with this brown out/receiver power theory. What are the failsafe settings on the transmitter?

You should definitely make sure that the ESC has good airflow to cool it.
 
Last edited:
#13
Wow. I haven't seen that in over 40 years. It looked exactly like what we used to call a "glitch" or a "hit" when somebody had radio interference.
I believe you're on the right track with this brown out/receiver power theory. What are the failsafe settings on the transmitter?
haven't touched it, so either 'default' or something from the previous owner.
Should it be 'all surfaces in the default' with 50% throttle (just guessing)?
 

Arcfyre

Well-known member
#14
Looks like signal loss or brown out to me. See if you can set fail-safes for your servos to maintain a level glide in the event of signal loss, that is:

Rudder: neutral
Ailerons: neutral
Elevator: 15% up
Throttle: 0%

Hopefully that way if it loses signal again it will just glide until it re-aquires.
 

SlingShot

Maneuvering With Purpose
#16
haven't touched it, so either 'default' or something from the previous owner.
Should it be 'all surfaces in the default' with 50% throttle (just guessing)?
The reason I asked is that you should check it. See if the failsafe control inputs match the plane's behavior when it went in.
 

Merv

Well-known member
#19
It looked exactly like what we used to call a "glitch" or a "hit" when somebody had radio interference.
I agree with @SlingShot, looks like a radio issue to me. I’d look at antenna placement. Batteries, carbon fiber and anything metallic will block radio signals. The other thing to consider, did you bend active element. So I don’t care about the coaxial portion (if any), I only care about the last 25-30 cm of the antenna, the single wire is the active element. If you form a big U with the active element, you will cut your range. Your antenna is built to give the same reception in 360 degrees. With a U shaped active element, you will not have 360 reception, range will be cut on one side. The active element needs to be relatively straight. If you have two antennas, place the active elements 90 degrees to each other.
 
Last edited:

Bricks

Well-known member
#20
Looks to me it was tip stalling when going into a hard bank on that design of a plane you need speed when turning tight or add throttle in the turn. I have a wing that will do the exact same thing every time if I hard bank with out enough speed. Seen this to many times most of the time is not radio problem but flyer problem going to slow in a hard turn.