Spartan problem

[Tim Procter]

Had a couple of flights with my T-Rex 500 this afternoon which went well apart from....

I upped the headspeed from 90% in idle 2 to 100%

In turn with the higher headspeed the nose of the heli crept round to the left hence tail was creeping right.

When back in normal mode at a lower headspeed the tail was solid.

I raised the gain limit until the heli had a fast tail shake then reduced the gain until it went, That was fine but the nose still crept left in flight at max revs.

I have closed the gap on the servo arm (Futaba 9257) to the next hole in and reset the gyro end points etc and played around with the gain but it still has this irritating nose to the left.

Tail blades are not too tight or slack and in good order.
Tail drive shaft is straight
All bearings in good order.
Torque tube in good order.
Dampers are good.

I had a tip from Noel Cross once for setting up gyros on the 500 which I never did but have done now.

When setting the servo arm set to 90 degrees then move the arm forward one notch on the splines and start the setup again.

I have done this but run out of daylight now.

Any tips on what might be causing this.

Hence the heli is rock solid at 90% throttle, Just that last 10% makes it do this.

[barney]

Hi Busterboy..with something like this its worth checking the basics out and go from there. The plastic boom clamp is pretty naff on the Rex500 and may be limiting your Gyro gain. give it a good twist tio see if it moves.

If the heli is moved during battery connection and before the Gyro has 'Set' it will possibly Piro slowly.

Not sure what TX your using but normally you have seperate trim setting in each Flight mode. Could you have a inadvertantly added a small amount of trim into Idle 2?

As it's tending to only do it at 100% Throttle something resonating slightly. gyro wires flapping loose..battery leads..all that sort of things

Not sure how you have the DS760 mounted..with/without the metal plate but changing the mount if nothing else obvious comes to mind is worth a try.

If you have a BlueLink cable can you share your settings, servo horn length, Gyro gain level. Slider positions/ etc

That will get you started at least cheers Brian

[rapidgaz]

hi i would check the trim as above

[pieter]

" When setting the servo arm set to 90 degrees then move the arm forward one notch on the splines and start the setup again "

this works for me aswell and seems to fix the bigger part of most gyro problems i have had

but what has the tightness of the tail blades got to do with it my mains are ok but i know for sure my tail blades are rather tight and i also get an annoying drift sometimes

forgive me for not being able to help you but im learning about these things myself

[Tim Procter]

hi i would check the trim as above

Yes I checked for trim this afternoon in all modes, Never have any trim in the rudder and double checked to see if I had caught it by mistake.

Brian.

TX is a JR DSX9 mate.

Have been through the setup 3 times this afternoon ensuring no movement of the heli when dialling in settings.

Dunno if it makes any difference but I am running the Scorpion 1900kv motor on 6s packs, Yes a very high power output but only an 11 tooth pinion fitted to keep headspeed in line.

[Smoothound]

Metal boom clamp hex's?

[rapidgaz]

may be the servo not strong enuf for high head speed look at chinese tail mod on helifreak very interesting

[TimmyB]

Maybe try tinker with the other gyro settings. Changing stop gains has worked for me before. Otherwise maybe a resonant frequency causing the gyro to vibrate?

Just wondering whats the reason for this?....

I had a tip from Noel Cross once for setting up gyros on the 500 which I never did but have done now.

When setting the servo arm set to 90 degrees then move the arm forward one notch on the splines and start the setup again.

[Ade_Law]

i spoke to tim, got some more details, sounds like something is upsetting the gyro, given him a check list of the things to test (mainly tail bearings)...

hopefully he will come back and say xx bearing is shot.

btw... tim, did you say its got a TT? check all the bearings on the shaft and counter shaft too whilst your at it.

Ade

[Tim Procter]

Cheers Ade, Will pop the tail off, It only takes 2 minutes and can slide the TT out and check those bearings too.

Won't hurt to replace the bearings in the back end anyway.

Tis only a small cost compared to a crash.

[Tim Procter]

Update.

All sorted this morning.

Can you believe I fit a new set of tail blades some time back (white ones from a kit) and never gave it a thought as to the size, Just presumed they were the same.

Put some standard black plastics on this morning and all sorted.

Can't believe both these blades are both recommended T-Rex 500 parts suppoesed to be the same size.

[moyesboy]

Interersting. My 500 has the white tail blades in the kit. Tail is really good but the belt is still growing as the heli is new. Ive found they stretch a bit and then stabilise. It was starting to jump teeth at the end of my second pack today.

Maybe the extra blade mass was locking up your grip bearings at the hight speed? how many revs have you got on the head? is it like mad robgts 3000 revs? (manual says keep it below 2400 I think).

My 500 now has a csm720 on a metal plate mount and the tail is really good with the align 520 servo.

[paddle]

hi tim have a look at your tail blade bearings ,it could be that you have a tail bearing locking up or it could be vibration at the higher rpm causing the gyro to drift try another thickness of gyro tape ,had this problem on one of my rex 600 remounted the gyro and the problem went away regards Noel

[Tim Procter]

hi tim have a look at your tail blade bearings ,it could be that you have a tail bearing locking up or it could be vibration at the higher rpm causing the gyro to drift try another thickness of gyro tape ,had this problem on one of my rex 600 remounted the gyro and the problem went away regards Noel

Thanks for the tips Noel.

I did fit new bearings in the tail grips the same time I noticed the factory white blades were much larger than the stock black plastic jobbies (Pictured above)

Fit a new black plastic pair of blades and its solid now with no drifting.

Regards Tim.

[carpman]

Glad u got it sorted will have to rem that 1 for future