Trex 450 - 401 Gyro Problem

[shaun.e]

I have followed Finless Bob's 401 setup video and looked at the advice provided in the sticky on this forum but still seem to have a bit of a problem - in the hover at about 2ft the tail is almost rock solid, perhaps a very slow wag. As I increase throttle to gain height still in the hover as the head starts to speed up the tail wants to kick to the right by about 45 degrees. I have checked and rechecked the mechanics and can't find any problem. Gain is set to 53% and end points to 70%. Setup is 450 V2 SE, FF7 TX, 401 with 9254 (I think) and a Microheli tail case.

Any ideas?

[Made2Fade]

how far out have you got the ball link on the tail servo?

Cheers
Lee

[robgt]

Set a continuous headspeed.
In the throttle curves, if you're flying in normal mode, set point 0 (or low) to 0% (throttle off) and the rest of the points to between 75% and 90% - all the same.

That way, the helicopter should spool up nice and steady, and then remain at a constant headspeed while you fly it - this will give you less issues all-round.

Cheers,
Rob

[shaun.e]

how far out have you got the ball link on the tail servo?

Cheers
Lee

Ball link is on the first hole on the servo

[Aidi]

I have just been having pretty much the same problem on my Blade 400. When climbing out it was squewing out from 45 to 90 degrees everytime. Checked everything over and couldnt find anything obvioiusly wrong.

Got back and found the tail belt to be loose. Tightend it up and re tested, squew has now gone and it climbs straight out.

Might be worth checking the tension on your belt, or even checking the belt/gears for missing teeth etc.

Rgds
Aidi

[shaun.e]

Set a continuous headspeed.
In the throttle curves, if you're flying in normal mode, set point 0 (or low) to 0% (throttle off) and the rest of the points to between 75% and 90% - all the same.

That way, the helicopter should spool up nice and steady, and then remain at a constant headspeed while you fly it - this will give you less issues all-round.

Cheers,
Rob

Whoa - not yet used to all that speed - currently my throttle curve is set at 0,30,65,85,90 and just about happy with tail-in hovering and ready? for some height etc..

[shaun.e]

I have just been having pretty much the same problem on my Blade 400. When climbing out it was squewing out from 45 to 90 degrees everytime. Checked everything over and couldnt find anything obvioiusly wrong.

Got back and found the tail belt to be loose. Tightend it up and re tested, squew has now gone and it climbs straight out.

Might be worth checking the tension on your belt, or even checking the belt/gears for missing teeth etc.

Rgds
Aidi

Thanks Aidi,
New belt fitted and tightened - I do have a problem keeping the belt tight though ??

[shaun.e]

Gents,

Thanks for all the replies . The problem is now solved, I had missed the bit about setting the gyro channel end points to 70%. The heli is now rock solid at low level, with a little wag at higher throttle - gain at 60%, so that will be turned down a little.

Regards

[moyesboy]

A few further points.

If you are trying to fly with a low head speed then the tail is working harder to hold the torque from the blades. The blades are at a higher angle of attack and therefore have more drag. You want more than 2000 rpm and then the 450 flies better. If head speed is too low then the tail might not be able to hold on full tail pitch...
and you will be pulling a lot of current and perhaps getting low flight times. (this was what rob was on about with getting a constant head speed)

The belt grows a bit over the first few flights and needs tightening up - and then stops stretching.

You should change the length of the servo horn until you can set the limit pot on the gyro close to 100%. If you have it turned down to stop the linkage binding then you lose resolution of the tail servo.
(this is a minor issue).

There are a few ways to set the gain on the tx. I have disabled the gyro menu and then the gain is set by the end points of channel 5 via the retracrt switch. I have about 65-70% for the end points.

The end points of the rudder channel don't change how much the servo moves, only the max piroette speed of the heli. The limit pot on the gyro is what sets the end point of the servo travel. At rest in rate mode you will see that the servo stops moving before the tx stick reaches the end of its movement.

People do use 9254's on 450s but they are very big for a 450. Take care not to stall it (overtravel the linkage) or it will pull too much current out of the BEC and then everything will stop working, or it might even break the linkage somehow! more likely you have a 9257 or 9650 there