Definitely having a problem

[al_evans]

I have my 3GX (TRex 250, top-down on gyro tray) adjusted so that it flies fairly decently. But only for 2-4 minutes.

After that, it seems to lose orientation, and takes off in one direction or another -- so far, mostly forward and right. This morning, after flying reasonably well for a little over three minutes, it pitched forward. After I recovered, I had to hold the elevator stick about halfway back until I got it landed.

After I landed, flipped on TH and centered the left stick, it looked like the swashplate was sure enough tilted forward a little. And though the controller seemed to move the swash to compensate when I tilted the heli toward the back, it did not seem to do so if I tilted it forward.

I unplugged the battery, power-cycled the TX, plugged it back in, and everything looked fine again. The TX is a DX8, but it doesn't show any signs of aileron/elevator instability, and it flies my other helis fine.

If anybody has a good idea, I'd like to hear it. At this point, "turn it back to a flybarred heli" is the only thing that's making a lot of sense to me.

--Al Evans

[beenflying]

Didn't you already have a thread about this? What ESC/BEC are you using?

[timmay]

Make sure the swash & wash out arms move freely...no binding.

[al_evans]

Originally Posted by beenflying

Didn't you already have a thread about this? What ESC/BEC are you using?

Is that a problem? I think I've started three threads. I've experienced this situation in three different contexts -- after I first set it up, after rebuilding the head/re-routing the wires, and setting it up once more REALLY carefully, and finally, after sending it off and getting it back with a new board.

The ESC is the standard Align ESC on a TRex 250. There's no indication that anything's drawing much power. Just for fun, I took off the blades, put the transmitter in TH, and zoomed it around like a little kid with a toy airplane for 5 minutes, imitating as much turbulence as I could while wiggling the sticks continuously with my other hand. Total power put back into the battery after this: 31 mAh.

Originally Posted by timmay

Make sure the swash & wash out arms move freely...no binding.

Everything is free and there's no slop.

Although I seem to be the only person with this problem, I'm pretty sure (35 years as a software developer) that it shows a software bug. Maybe something specific to my setup -- 250, 3GX upside down on gyro tray. The thing is, it flies OK at first, then becomes unstable.

I just flew my other (flybarred) 250SE, and it flies like a charm. So I'm pretty sure it's not me or my transmitter.

--Al Evans

[jondabear]

just a point of curiosity.........What is your cyclic comp set to?

[al_evans]

Originally Posted by jondabear

just a point of curiosity.........What is your cyclic comp set to?

50

It seems to be set to 50 in all the example files I have available. The only reference I have says it's for pitch-up tendencies in FFF rolling maneuvers. Here, we're talking about gently swooping around in my back yard trying not to be taken by surprise...

--Al Evans

[jondabear]

Total gains? ail and elev?

[al_evans]

Originally Posted by jondabear

Total gains? ail and elev?

I've attached the current settings.

--Al Evans

[daneger21]

Originally Posted by al_evans

I've attached the current settings.

--Al Evans

maybe try a 60 hiller, 45 bell

where are your POTS on the unit. (all your gains seem really low even compared to the "beginner").


for the attached settings my POTS are around the 10 o'clock position

[al_evans]

Originally Posted by daneger21

maybe try a 60 hiller, 45 bell

where are your POTS on the unit. (all your gains seem really low even compared to the "beginner").


for the attached settings my POTS are around the 10 o'clock position

My POTS are at 12 o'clock. The "total gain compensate" for elev and ail have been adjusted, at least in theory, to take out the adjustments I made to them.

I note that your lock and stop gain adjustments are set way lower than mine, 30-40 as compared to 70. Can I ask what flight characteristics led you to lower them?

--Al Evans

[al_evans]

Last Thursday, I went through the whole setup again. Pulled all the plugs out and reinserted them to make sure everything was well-seated. Re-leveled the swash, checked the pitch, etc. Re-did the 3GX setup, set the params to something that should be mild -- starting with the 250 "easy" setup, lowered the aileron/elevator total gains to 50, upped the Hiller component to 60 and lowered the Bell to 45.

It flew unremarkably for about 45 seconds, then became uncontrollable. I fought it for a while, then hit TH and went into the grass from a couple feet up.

So that's after sending the 3GX in to Assurance RC. They tested it (on a 500) and found no problems, but replaced the board anyway. As far as I can tell, it still just crashes my heli.

As a software developer for over 30 years, I sense a bug. There's something about my setup that's exceeding some implicit expectation and making the thing go wonky. Whether it's something about being upside down and backwards, something about having an orange G10 frame, some kind of vibration that it's just not expecting, I have no idea. All I know is that the heli flies just fine with a flybar, and crashes consistently with the 3GX.

It's annoying that the parts for the FBL head cost substantially more than for the regular head, too -- blade grips 35% more, rotor housing almost 60% more.

I think I'm going to put the FB head back on and wait until there's some indication this problem is fixed. Unless I can talk myself into trying a BeastX.

I'm really disappointed, but I just can't seem to make this thing work.

--Al Evans

[browndog]

Smart man

Originally Posted by al_evans

Last Thursday, I went through the whole setup again. Pulled all the plugs out and reinserted them to make sure everything was well-seated. Re-leveled the swash, checked the pitch, etc. Re-did the 3GX setup, set the params to something that should be mild -- starting with the 250 "easy" setup, lowered the aileron/elevator total gains to 50, upped the Hiller component to 60 and lowered the Bell to 45.

It flew unremarkably for about 45 seconds, then became uncontrollable. I fought it for a while, then hit TH and went into the grass from a couple feet up.

So that's after sending the 3GX in to Assurance RC. They tested it (on a 500) and found no problems, but replaced the board anyway. As far as I can tell, it still just crashes my heli.

As a software developer for over 30 years, I sense a bug. There's something about my setup that's exceeding some implicit expectation and making the thing go wonky. Whether it's something about being upside down and backwards, something about having an orange G10 frame, some kind of vibration that it's just not expecting, I have no idea. All I know is that the heli flies just fine with a flybar, and crashes consistently with the 3GX.

It's annoying that the parts for the FBL head cost substantially more than for the regular head, too -- blade grips 35% more, rotor housing almost 60% more.

I think I'm going to put the FB head back on and wait until there's some indication this problem is fixed. Unless I can talk myself into trying a BeastX.

I'm really disappointed, but I just can't seem to make this thing work.

--Al Evans

[daneger21]

Originally Posted by al_evans

Last Thursday, I went through the whole setup again. Pulled all the plugs out and reinserted them to make sure everything was well-seated. Re-leveled the swash, checked the pitch, etc. Re-did the 3GX setup, set the params to something that should be mild -- starting with the 250 "easy" setup, lowered the aileron/elevator total gains to 50, upped the Hiller component to 60 and lowered the Bell to 45.

It flew unremarkably for about 45 seconds, then became uncontrollable. I fought it for a while, then hit TH and went into the grass from a couple feet up.

So that's after sending the 3GX in to Assurance RC. They tested it (on a 500) and found no problems, but replaced the board anyway. As far as I can tell, it still just crashes my heli.

As a software developer for over 30 years, I sense a bug. There's something about my setup that's exceeding some implicit expectation and making the thing go wonky. Whether it's something about being upside down and backwards, something about having an orange G10 frame, somehow kind of vibration that it's just not expecting, I have no idea. All I know is that the heli flies just fine with a flybar, and crashes consistently with the 3GX.

It's annoying that the parts for the FBL head cost substantially more than for the regular head, too -- blade grips 35% more, rotor housing almost 60% more.

I think I'm going to put the FB head back on and wait until there's some indication this problem is fixed. Unless I can talk myself into trying a BeastX.

I'm really disappointed, but I just can't seem to make this thing work.

--Al Evans

50% gains in the software, then where is it set on the unit?

Maybe you have a bug in the software? I am only seeing a beginner/normal/expert. Sorry had too...


I really do you hope figure it out. I was having a slight tail issue with my 250 3gx, but got it sorted. About 35-50 flights now with no issues...knock on wood

[al_evans]

Originally Posted by daneger21

50% gains in the software, then where is it set on the unit?

Maybe you have a bug in the software? I am only seeing a beginner/normal/expert. Sorry had too...


I really do you hope figure it out. I was having a slight tail issue with my 250 3gx, but got it sorted. About 35-50 flights now with no issues...knock on wood

Pots on the unit are centered. It's kind of irrelevant, though -- I haven't found ANY adjustment in the software or on the unit that causes the kind of radical behavior I'm seeing.

Beginner, easy, whatever.... What it actually seems to have loaded is the "Spanish Inquisition" settings.

I'm glad yours is working great. Mine will be, too, I bet, after I put a flybarred head back on it.

--Al Evans

[Brad_B]

Mine is doing the exact same thing. I have it mounted the same way you do. The unit works flawlessly on my 600N pro. I have the "normal" 250 settings from the software loaded and the pots started at 12. It was too erratic to notice any changes from the pot settings. Ended up crashing. Downloaded a file from another thread containing some settings that worked for others and will test them once I get it repaired.

Several flights were fine. Tail wagged a little but the cyclic was holding fine. Changed tail blades and the tail wag went away and was locked in but then I could hardly hold it in a hover. It kept wanting to take off in random directions. It ended up rolling over from about 30 feet right into the ground. The best way to describe it was like trying to fly a flybarless heli with no cyclic gyro.

It does this ONLY on my 250.

[al_evans]

Originally Posted by al_evans

...Mine will be [working great], too, I bet, after I put a flybarred head back on it.

And I just tested it after putting a flybarred head back on. No other changes (except a setup, obviously). It flies fine, same as it did before the FBL experiment.

--Al Evans

[xzantronos]

Beastx is the way to go as for 2 in one recievers. My beast x survived multiple crashes that were violent after about the 10th the gyro was thrown out of wack on my blade 450x and replaced it with the ar7300bx and its got my heli flying hard 3d with precision, if not look into the mikado Vbar system if you want to spend the money. after all the saying goes you get what you pay for.

[Coolice]

Originally Posted by al_evans

The ESC is the standard Align ESC on a TRex 250. There's no indication that anything's drawing much power. Just for fun, I took off the blades, put the transmitter in TH, and zoomed it around like a little kid with a toy airplane for 5 minutes, imitating as much turbulence as I could while wiggling the sticks continuously with my other hand. Total power put back into the battery after this: 31 mAh.

Hey Buddy.

While this made me chuckle, visualising you running around the back garden model in hand, it's not going to test your ESC's BEC capability at all. Reason being there is no flight loads on the servos from the main blades, so there is no power required to move the blade grips. It is the sheer action of the servos having to hold pitch into the blades and then the FBL unit making it's corrections that is going to pull amps.

Most of what you're describing can be attributed to a poorly rated BEC and from memory the little 250's ESC isn't well known to have a great BEC and the 3GX is a power hungry FBL unit on firmware's above V3.

I've not seen any mention of what firmware you are/were using?

Another possible indication could come from if you are using Spektrum sats on DSM2, as any brownouts will be signalled by their LED's and indeed the 3GX will not initialise on next power up to alert the pilot to a potential problem.

Vibration to can also give you funny symptoms, I'm guessing the model has had the odd knock and so is there any excessive vibration which can be felt (or seen) on the airframe?
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