tail issues

[funfreex]

Hopefully there is an easy answer to this one.
Problem is during flight the tail lags the input from the Tx. i.e if I give a full input on the rudder it either does not respond at all or it responds slowly and then seems to catch up after a couple of seconds which results in a piro after I have released the rudder stick!!
Have just changed to 2.4gig so I suspect its something in the programing but I cant find it.
Its a 401 gyro.

[funfreex]

I think I may be upsetting the tail servo with too much voltage. Having recently fitted a scorpion 55a esc the output voltage is 5.9v, does this need to be regulated to 4.8v so as not to fry the digital servo?
I am just about to fit a new S9257 and dont want to wreck that also.

[t-rex pedro]

I had a similiar problem but that was with a 9254 tail servo and a 401 on my 600. Turned out to be the servo as a new one cured the problem.

I run the 401/9257 combo on my 450 without the stepdown. No problems so far.

Just a thought but make sure you have the delay pot on the 401 set at 0 and the switch in digital mode - I'm sure you already checked this though.

[funfreex]

Thanks T-rex pedro,
good to hear you have not had probs with your servo at 6v.
The delay pot was the first thing I checked as the symptoms were exactly like it had been adjusted, but it was at 0. I have ordered a step down for the new servo just to be on the safe side.
cheers

[moyesboy]

did you measure the volts outof the ESC BEC Jamie?
Says here the v1 is 5v
And here that the v2 is 5V also.

when I had a HDS577 that was worn out I got slow piro, but not delayed piro...
Anly time I had a probl like you describe is when I'd got some stay loctite made my tail linkage very stiff.

[funfreex]

did you measure the volts outof the ESC BEC Jamie?
Says here the v1 is 5v
And here that the v2 is 5V also.

when I had a HDS577 that was worn out I got slow piro, but not delayed piro...
Anly time I had a probl like you describe is when I'd got some stay loctite made my tail linkage very stiff.

measured voltage at 5.9 which was at the outlet plug from the gyro to the tail servo.
Nothing is binding. The fault does not present itself on the ground even when a bit of load is put on the servo.

[DIJ]

I had exactly the same tail swing issues you describe with a 401/9254 on my 600E and it turned out to be the servo causing the problem.

[David Drew]

Interesting question Jamie

My 450 XL tail kicks out right (nose left) about 15 deg if I give it a burst of throttle, then coorects.

Slight tail wag too.

401 / 3153 combo

Just changed to an Align 35 amp ESC.

Changed to 2.4Ghz

Scorpion 2221-8 motor just fitted, so it could be a combination of those.

Gyro is set to min gain (51% in a Futaba) and control rod is about 6mm from horn centre.

Any advice would be really appreciated

Thanks

David

[funfreex]

Interesting question Jamie

My 450 XL tail kicks out right (nose left) about 15 deg if I give it a burst of throttle, then coorects.

Slight tail wag too.

401 / 3153 combo

Just changed to an Align 35 amp ESC.

Changed to 2.4Ghz

Scorpion 2221-8 motor just fitted, so it could be a combination of those.

Gyro is set to min gain (51% in a Futaba) and control rod is about 6mm from horn centre.

Any advice would be really appreciated

Thanks

David

This problem arose after changing to 2.4gig.
To try and fix the problem I fit a new tail servo-no change. I fit a voltage regulator to the gyro- precausionary more than anything as the output was 5.9v. After speaking to horizon, although unaware of any such issues they suggested taking the dx7 back to place of purchase and have it changed. New set installed Problem disappeared!

[moyesboy]

Wow Jamie thats interesrting. The rudder channel muist have had a lag in the Tx/rx! Neverheard of that. Did you fly anything else with that set such as your glider and notice the rudder lagging?

Dave drew
I think your gyro gain is just way too low.
I set up my first heli just from info on the internet on my own and when I flew it I thought I had a tail wag, so turned the gain down, and down, and down, but the tail was still gong from side to side but also kicking out to the side when collective was applied. Aftera bit I just thought I must be doing the wrong thing and wacked the gain right up to 95% to see what happened. I got a rock steady tail in the hover. But when I disturbed it it wagged furious and fast before it settled. with the gain at about 85% (this was a futaba 7CAP) I got really good tail hold and control and I never looked back. GY401/hds577. It was good until the servo got all worn out and sloppy becuase it had no ball bearing on the output shaft.
anyway my messgae is that the tail moving slowly side to side is not "wag", but probablywander from too little gyro gain. The wag from too much gain is quite furious like a happy dogs tail.

[David Drew]

Cheers Moyesboy.

Off work tomorrow, will give that a go.

I'll let you know how I get on

David

[machasm]

Dave check your head speed as well.
too slow a head speed means that the tail will not have enough authority as well.
I witnessed this this weekend with one of Boggys raptors.
As he put collective in the tail would kick out then as he levelled out it would kick the other way until finally settling down.
After he increased the headspeed through the throttle curve the kicking all but disappeared. Could also be down to too low a gain in the gyro.

[moyesboy]

machism is right.
Increasing the gain is a bit like mechanically adding bigger tail blades or making the tail rotor spin faster. Only what it does is make the tail rotor applymore correcting pitch compared to the tail movement.
At a low head speed the rotor has more pitch and the tail rotor need more pitch to hold it - so in the end the tail rotor just can't cope.

To prove this stretch an outo out as far as it will go and when the rotors are only just holding the heli off the ground then flick the switch so the throttle opens wide. Then watch in amazement as your heli does a neat piroette round the club windsock pole before you manage to regain control of it. Great fun, but not recommended

[David Drew]

I think headspeed is ok, but I'll get someone to tacho it at the w/e. On a Trex450 what should it be. Suspect around 2500 rpm?

But some useful ideas to go at there guys. Thanks, really appreciated.

David

[Tim Procter]

On a Trex450 what should it be. Suspect around 2500 rpm?

Much nearer 3000/3200 David.

Mine were tacho checked at 3150rpm on my previous 450 T-Rex V2