Tail turns while in flight

[briancleator]

Hello again people with the knowledge, yet another question for you all. By now you should be sick of these.

My raptor 30 has been flying great except the odd glitch but this one has me puzzled.
When i take off, the heli starts to pirouette not fast just slow. now i have adjusted the rudder trim to compensate it but when i look at the tail blades they are more angeled than they used to be, should i turn the gain up on the gyro or there is a little switch next to that which just says neutral ????
And when the heli is flying when i power up more it powers the tail up and it starts to pirouette the other way.
If i move the gain on the gyro to - what would this do ? or if i move it to + what would this do. What is the neutrel dial for.

[Steve]

Which gyro have you got?

Which tail servo have you got?

What is the gain currently set to?

[briancleator]

Tail Turns in flight

The gyro is, gws piezo 01 np
The servo is, sanwa srm 102
and gain is on max ??

[Steve]

Sanwa 102 servo is a bottom of the range analogue servo - equivalent to a Futaba 148 - about £6 worth.

Tail servos really need to be high speed and digital. High speed to make fast corrections and digital for their accuracy and holding power. The Sanwa is neither of these.

Does the gyro have a normal/super servo switchable option? It should be set to normal for this servo.

Are you flying in normal or heading hold gyro mode? The tail will drift in heading hold mode if the mechanical linkage is way out. You need to start by getting the linkage exactly the right length by flying it in normal mode and following these steps;

1 set all your sub trims, servo centres and trims on the rudder to zero.
2 adjust the position of the servo output arm on the servo splines so that the angle between the arm and the push rod is exactly 90 degrees with all the trims and sub trims at zero.
3 hover the heli into wind (no wind at all is best for doing this) in normal gyro mode and use the trim to make it hover dead straight with no rudder input.
4 land the model and turn the engine off.
5 inspect the position of the tail pitch slider that gives you steady hoverring, and then reproduce this exact position by returning the trim back to zero and lengthening or shortening the push rod to get your steady hovver tail pitch.

After a 2 or 3 hovvers and minor adjustments, it should be hovvering bang on in normal mode with zero trim and sub trim.

This may well cure the problem, but is at least an absolute first step towards
getting the gyro/servo combination working properly.

Personally, I'd get a Futaba 9254 digi servo on the tail first (about £60ish), but maybe your budget doesn't extend that far, so at least get the system set up accurately mechanically before going into further detail.

PS I'm not familiar with this gyro, so don't know if there are any set-up routines (like with CSM gyros) or dials on it (like Futaba 401 etc) that need to be taken into account, so maybe someone else could comment here as well.

[Ade_Law]

GWS PG-01 is that "loverly" little silver box.

its a rate gyro not heading hold no DS servo support and combined with that servo its amazing it does anything. It is probably in the running for the "cheapest gyro available" awards. As with most things these days you get what you pay for.

That combo will work but will require much fettling of setup and will never hold the tail confidently like a modern gyro with a good servo.

with a 401/9254 which will cost you around 160-170ukp but will hold the tail with a vice like grip.

Ade

[Steve]

Carefull Ade......

Every gyro advert out there tells us that it "holds with a vice-like grip" (as I'm sure the blurb for the GWS one probably says much the same), but we all know that (as you said) you get what you pay for.

So, if a 401/9254 "holds like with a vice-like grip", what's the point in spending £300 (ish) on a 611/9256 combo?

I'm very happy with my 401/9254 setup in one heli, but have found a CSM560/9254 more accurate and precise in another heli.

[Ade_Law]

ok, maybe i should clarify. for most the 401 is excellent.

only time it cops out is in fast backwards or traveling piro moves where it will get soft and whippy.

i personally like the 601 i have a couple and they are great. almost completely trouble free compared to other gyros on the market i hear the 611 is the same beast with a couple of minor improvements.

Ade

[antsis]

If you're on a budget and starting out, the 401/9254 combo is a lot of cash. It would be a better buy for long term. The normal rate gyro is going to make you work harder on the left hand to keep the tail in, but if you are hovering into wind the model should weathercock into it, so any drift would be torque/trim related.

CSM recommend setting 8 degrees of right rudder at centre stick. This is a good place to start the mechanical trim before playing with the gyro gain.

[bandicoot]

when looking at servos online im reading stats like:
Speed (sec): 0.23
Torque (Kg.cm): 1.30
can someone shed some light on what it refers to and whats good (im guessing a high speed high torque is what your after?)

[antsis]

Brian

That speed you indicate is for your standard everyday servo. i.e. 3001, 148 etc.The torque is just the amount of grunt the servo can dish out. 1.3 kg/cm is pretty low, the 3001 pushes 3 kg/cm. For a rudder servo, the ideal speed is in the region of 0.1 secs and faster. I think the 9254 is something like 0.06 secs with approx 3.3kg/cm torque. The idea is for the servo to react to the gyro commands as quick as possible and not struggle to push the blades.

[bandicoot]

thanks...i was looking for a better tail servo for my small electric..looks like the HS-81 fits the bill
Speed (sec): 0.11
Torque (Kg.cm): 2.60

[Ade_Law]

i have found the 81 to be poo for tail rotors. Just couldnt stop it wagging even with a 401.

HS56 works well seems to be more accurate.

or if your wanting to throw money at stuff

Astek 877 or 577
Futaba 9650

Ade

[briancleator]

Tail turns in flight

Cheers for that guys, have just placed an order for the 401 combo.
will it fit to sanwa gear is my concern now as i belive sanwa runs different

[Ade_Law]

modern sanway is the compatible. depends which radio you have.

Ade

[bandicoot]

HS56 works well seems to be more accurate.
Ade

even though it has less touque?