Mini Titan progress - tracking, training gear and tail authority

[Bunter]

Hi folks

After a week away on holiday (yes the missus let me take the heli!) the weather (wind) was kind and I managed to get a couple of packs hovering practice each day. Here is my MT spec.

stock ESC + TT heat sink
stock motor + 13T pinion
Align pro 325 woodies
3 x HS65MG cyclic
Futaba S9650 tail servo
DX7 TX + AR6200 RX
Spartan RC DS760 gyro
Flightpower 2500 Evolite + Revolution 2100

Like others I hadn't been able to get the tracking spot on but today I got round to fitting the metal upper mixer arms. A quick hover in the garden and the tracking was still out :( but I adjusted the long link by a turn and hey presto - spot on tracking!!! :) Hurrah & thank you Freaks.

Next thing was to take it over the park and try take off and landing without the training gear I'd made (see pics). No drama there, in fact it felt easier because it was less prone to bounce.

The wind was pretty strong here today (est. 10-15kts gusting to 20) so hovering was interersting to say the least - I need to factor some wind into my Phoenix set up and practice.

But most surprising was the lack of tail authority. It was the first time I've had confidence to do a complete pirouette and it was pretty slow (about 1 rev per 2-3 seconds). Now I realise that the tail seems to be one area where many factors have an influence and wondered if anyone could help me home in on what is likely to be wrong with mine.

My throttle curve is a flat 95% in normal mode (not moved to idle 1 yet, but that is flat 95% too), with the governor mode switched on in my ESC. (Other ESC settings are no brake, standard timing, standard throttle response.) But I have no idea what my head speed is doing but I would think it isn't the head speed (tail speed).

The gyro setup includes programming it with the mechanical end points of the tail pitch slider. So it knows the extremes that the servo need not move beyond. I have adjusted my TX endpoints to match the mechanical endpoints so that the full TX stick rudder movement matches the mechanical throw possible at the tail pitch slider. As I understand it the TX endpoints could be reduced to reduce piro rate by making the stick extreme movements fall inside the mechanical endpoints if that is desired.

So in summary, I don't think it's the head speed or the endpoint settings in my TX, or the exponential I have in the rudder channel. It could be the stock blades not being very efficient, the stock linkage bending rather than moving the pitch slider. There is no binding, everything mechanically in the tail feels fine (ooerr.)

Any thoughts?

Many thanks in advance.

Cheers

Bill

[ghtracey]

Are you sure that you did your gyro setup correctly? On most gyros the Rudder channel endpoint changes the piro rate of the heli and has absolutely no effect on the servo other than to tell the gyro how fast you want it to piro at full throw. I know you said this yourself, but you also said that you adjusted your Tx endpoints to match the pitch slider's endpoints. Only the gyro needs to know the pitch slider travel to prevent binding. Try setting your Tx endpoints back to 100% maybe, higher yet if its still not fast enough?

Option 2: I may get this wrong and I'm sure I'll be corrected if so. Try using a shorter linkage arm and driving your gyro limit higher. A lot of people recommend (with a 401 anyhow, ymmv) having the gyro limit up near 140% for a faster piro rate.

[Bunter]

Are you sure that you did your gyro setup correctly? On most gyros the Rudder channel endpoint changes the piro rate of the heli and has absolutely no effect on the servo other than to tell the gyro how fast you want it to piro at full throw. I know you said this yourself, but you also said that you adjusted your Tx endpoints to match the pitch slider's endpoints. Only the gyro needs to know the pitch slider travel to prevent binding. Try setting your Tx endpoints back to 100% maybe, higher yet if its still not fast enough?

Option 2: I may get this wrong and I'm sure I'll be corrected if so. Try using a shorter linkage arm and driving your gyro limit higher. A lot of people recommend (with a 401 anyhow, ymmv) having the gyro limit up near 140% for a faster piro rate.

Hi

Thanks for the reply. I'm not 100% sure, as this is my first heli but it seems to make sense. I'll try upping the endpoints and see what happens.

Cheers

Bill

[patrickvdb]

Hello,

I'm no specialist yet but I think you should not have exponential set to the rudder channel when your gyro is in heading hold mode.
That might simply be your problem.
Only use exp on rudder channel when the gyro is in rate mode, which you do not want at this time.

In strong winds I had the problem that my tail started wagging when giving a lot of pitch input, I solved the problem by reducing gain.

[ghtracey]

A lot of people fly with expo on the rudder in HH mode. It doesn't affect your piro rate, it just smooths out the area around center and gives you finer control with larger stick movements.

[Bunter]

Hello,

I'm no specialist yet but I think you should not have exponential set to the rudder channel when your gyro is in heading hold mode.
That might simply be your problem.
Only use exp on rudder channel when the gyro is in rate mode, which you do not want at this time.

In strong winds I had the problem that my tail started wagging when giving a lot of pitch input, I solved the problem by reducing gain.

Thanks I will try that too.

Bill

Edit. Maybe I won't :)

But I am thinking the TX travel limits are the answer. I think I have (or had) an over simplified view of what the gyro does. It is more intelligent that I gave it credit for and knows that if you call for a stick movement of 30% of the available travel (as 100% movement on my TX does with my current endpoints) that equates to a piro rate of 30% of it's 100% rate (whatever that maybe). So with the gyro in HH mode with these low endpoints I'm not making the servo move to it's full limit like I thought I was. In normal mode my way makes sense, so the thing to try would be to leave the endpoints as they are (matched to the mechanical endpoints) and then try a piro in normal mode. Nice and high first mind.

[ghtracey]

On the bench in HH try this, give a very small Rudder command and watch the blades. They will slowly increase in pitch until they reach full throw. The gyro is calulating how many degrees on yaw you have asked for and moving the servo to comply. It does so slowly because you asked for a minor change. Throw the stick farther and you will see the blades change pitch faster, because you asked for a higher yaw rate. The blades keep increasing pitch because the gyro hasn't sensed any change in direction while the total amount of pitch change requested is increasing and its trying to catch up.

[Bunter]

Are you sure that you did your gyro setup correctly? On most gyros the Rudder channel endpoint changes the piro rate of the heli and has absolutely no effect on the servo other than to tell the gyro how fast you want it to piro at full throw. I know you said this yourself, but you also said that you adjusted your Tx endpoints to match the pitch slider's endpoints. Only the gyro needs to know the pitch slider travel to prevent binding. Try setting your Tx endpoints back to 100% maybe, higher yet if its still not fast enough?

Just flown with the rudder TX endpoints set back to 100% and have a pretty fast (too fast for me) piro rate. Thanks for the help.

Cheers

Bill

[ghtracey]

Glad you got it sorted. Now put some expo on the rudder to tame it down and still give you a high piro rate when you want it and your good to go. :)

Happy Flying