Setting Up the GP-750 gyro in T-Rex 250 kit

[Mark J]

I have this gyro in a 600n sport and was getting a wag that wouldnt dissapear no matter what gain setting etc, and as a test I put a tie wrap around the gyro to secure it down more solid and it improved it loads, its still got a tiny wiggle, but thats probably down to not clamping it enough, but that might be something to test on your 250's as it seems the pads might be a teeny bit too soft for the gyro so by clampling them down a bit might help get rid of the unwanted wagging etc. from vibration.

Mark.

[kamarasm]

Hi All,

It sounds very good, using travel adjust of gear switch for gyro sensitivity. I have already realized that there are gaps in the gyro sensitivity if I set it with gyro menu as with some value tail is wagging but with that value minus one I had keeping problems.
Otherhand if I use gear switch for gyro what should I use for flight mode? As now I'm using gear switch as idle switch as it is suggested by manual.

Thanks a lot,
Marcell

[Bid Doctor]

Finless,

You are "Da Man!!" I have been fiddling with the Gyro on my 250 for two days and could not get the tail to stop looking like a wiener dog in heat. I set the Gear travel to 35/35 on the Gyro as you suggest and first test flight - totally locked in! Could not get along without your sage advice. Keep it up!

[rotary65]

Anyone else notice that when connecting the battery that the GP750 sometimes powers up and pushes the tail slider all the way out?

Powering off and powering back up resets it and it's good to go. No doubt that the gyro needs to be perfectly still until fully initialized and I'm careful when plugging in the battery, but it still seems to happen very often.

Spooling up when it's like that results in a spinning heli and moving the stick back and forth a few times doesn't help - it send the slider right back out to the end.

I've got a few helis and have never noticed a gyro to be so senesitve on initialization.

Other than that, it works flawlessly.

[Besen]

Try re-binding.

[rotary65]

Thanks Besen - that did it. Now it's initializing properly consistently.

[halley]

Originally Posted by rotary65

Powering off and powering back up resets it and it's good to go. No doubt that the gyro needs to be perfectly still until fully initialized and I'm careful when plugging in the battery, but it still seems to happen very often.

I have found that switching to RATE MODE momentarily works well. In HH mode, any little twitch can make the gyro think a correction is required, and the gyro will give more and more correction in the vain hope that it can undo that little twitch. (You're motionless on the ground, so no amount of correction is going to help.)

I take it further: switch to RATE MODE until my headspeed is up for takeoff. No more twitches, so no more pirouettes.

[rotary65]

Thanks - if it happens again, I'll switch to rate mode and back to see if that helps.

When it powers up normally and I move the heli afterwards (e.g. to put the heli in position for take off), there's no problem. I can just correct with rudder as it spools up and all is well. This is consistent with every other HH gyro I have ever used.

So far, the rebind looks like it did the trick.

[jamhuss]

Deleted.

[oliverdots]

Originally Posted by halley

I have found that switching to RATE MODE momentarily works well. In HH mode, any little twitch can make the gyro think a correction is required, and the gyro will give more and more correction in the vain hope that it can undo that little twitch. (You're motionless on the ground, so no amount of correction is going to help.)

I take it further: switch to RATE MODE until my headspeed is up for takeoff. No more twitches, so no more pirouettes.

I do exactly the same. Learnt that trick when I had the Blade 400. The gyro was notorious for servo creep.

[oliverdots]

I have to say I am totally confused about these settings...all of it, 35% gear travel??. My DX6i has gyro settings of 40% and 60.5%. I understand that 40% for rate and 60.5% for HH. I used the travel adjust on the gyro to stop binding. My tail flys fine with 40mm blades. Do I just continue to fly and not worry or do I really need to get my head around all the settings and working out? I seem to have set mine up quite easily. I'm not showing off, just trying to work out if I am just very lucky, have I done it correctly??

[Deniz]

thank you this is realy helpfull for new comers i own this gyro and it is a real pain in the ass to setup but thx to you i did

[Dilligaf]

Originally Posted by oliverdots

I have to say I am totally confused about these settings...all of it, 35% gear travel??. My DX6i has gyro settings of 40% and 60.5%. I understand that 40% for rate and 60.5% for HH.

Have a look at Finless Bob's videos, OD...
https://www.helifreak.com/showthread.php?t=41692
They explain it all perfectly, even if you do have to watch them a couple of times before it sinks in.

[HugoCraft]

Originally Posted by Finless

The batman blades when they came out for the 450 first were design to help try and remove some of the force of the "Tennis Racket Effect". I plan to use those myself and later add Heim Joints weights.

FYI if you are still using the 2 bearings in each tail grip, you need to get the new single bearings period!

Bob

I got the 250SE super combo and are you talking about the 40 tail blade or the 37 tail blades that came with the kit???? Which should I use? I'm asking because I'm using the KBDD ones and I'm running a true gain of 19.44% and I'm getting a slight about of wag 1/4" left/right every now and then but everybody else is running much higher on the same stock setup. Also I have to tap the rudder every know and then to keep it tail first when doing tail slides straight down. I need to get it on video but mine piro's really really really wicked fast.

Also I changed the BEC voltage to 6v from the default 5.5v and could that be causing a problem?

[CJ19]

Thanks for the set by step, this really helped me understand the GP750 better. However after going through the setup process on my T-Rex 450 again (trying to correct a twitch in the tail). Now all of the sudden after doing the set up. The Gyro will not initialize and I have no response when moving the throttle stick. All the other controls work fine.

Any suggestions?

[Jan Steinar Bjørndahl]

[RCBRHelicopteros]

Thanks for the tutorial!! helped me a lot!!

[DVUSHELI]

I've owned my original 250 since they first came out, and since it's first crash, the tail has always been a hyper active little bastid.

so today, I finally got very tired of the tail wag when flying out've the wind.and started doing some thinking. Well, not really thinking, more of, /i wonder what this will do.
I switched the delay to 500+ class and low n behold, the wag was gone, once the wind died down for a few. Either way, it's better than before.

Can anyone tell me why this feature change may have worked to calm things down, and what does delay do??