What Gyro?

[Steve]

In my heli flying life to date I've owned 4 gyros - the first three were all CSMs (2 x 560 and 1 x 420), which I thought were pretty good as I didn't know any better. All were/are matched with either a Futaba 9254 (x2) or a Futaba 9253 (x1).

I've now got a Futaba 401/9254 combo as well which performs very well, is easy to set up and has been trouble free.

However, the pirouette rate is much slower with the Futaba than with any of the CSMs - I've found this by swapping the Futaba gyro with a CSM in 2 of my helis now. Also, I like the CSM quick set-up routine, which defines the servo travel limit each way rather than just once.

I know the right/left servo limit option is available in the more expensive Futaba gyros, but is there anything I can do to quicken up the tail response with the 401?

Also, on another gyro thread, does anyone actually use JR gyros and tail servos (I had a 811 tail servo in my very first Scuttle heli - worked well - now owned by a club mate in his raptor 30)? They seem to be advertised all over the place, including eBay, but I've never actually spoken to anyone who owns a JR gyro.

My JR transmitter is the mutts nuts, but are their gyros/servos any good?

[Ade_Law]

If you increase the end points of the rudder servo it will increase the piro rate. Remember they will go to around 140. Go 10% at a time.

811 is not a tail servo. Maybe your thinking of the 810g. These have known reliability issues. the 810g when combined with the 8700g is a reasonably good combo it piros better than the 401 but the ones i have played with have always been a bit soft in the holding department.

for me there are only 2 choices.

401/9254
611/9256

if your doing backwards or lots of piros you want the 611 if not then the 401 is fine. its as simple as that.

Ade

[Steve]

Cheers Ade

I've been coming to the same conclusion myself that the Futaba gyro/servo is the best combination.

But, I don't undertsand the end point thing. If I increase the end points on th Tx, how will that increase the piro speed when the gyro is set to limit the servo travel on the heli. i.e. I could set the end points to 150% (say), but the travel available at the tail pitch slider is constrained by the limit on the gyro.

?????

Oh, and yes, I did mean an 810g - it's been so long since I had it. Doh!

[Disc]

I had the CSM 560 for a long time with a normal servo. I then got a
9254 off ebay and made a diffrence. I then ended up with a 401
and 9254.

What I found was the 401 once setup is good holds my tail spot on.
401's don't require a mass of tinkering to setup and easier to do than
the CSM gyros.

The 560 always had a slight drift always. But I may use it on the Trex
as I need a gyro on it as I robed the 401 for the raptor 60.

[Ade_Law]

HH gyros are clever wee beasties. In the air full right stick doesnt mean full tail pitch. The reason for this is the tail is very powerful on modern helis. It has to be to cope with what we throw at them. Imagine doing a full pitch travelling piroette at high speed. the amount of tail pitch required to pull the tail into wind and countering all the torque is going to be a lot more than it is to hold a high speed piro in the hover in no wind conditions.

the limit adjustment on the gyro is to ensure that the stick input plus anti-torque never over travels the linkage.

The reason you see the servo travel to full pitch on the ground is down to how heading hold works. When you move the stick over a little bit the gyro moves the servo over a little bit. But because the model is on the ground the model doesnt change heading so the gyro tries a bit harder by moving the servo further, this goes on until the it hits the limit of the travel.

so the stick travel isnt directly related to the position of the servo. it merely tells the gyro a rate of rotation. the more you move the stick the faster the gyro lets the model rotate.

So increasing the end points on the tx rudder channel doesnt affect the travel of the servo, it only makes it piro faster.

its not quite that simple as no gyro is 100% heading hold in heading hold mode there is always some rate gyro tendancies in there too.

Ade

[jimbob]

In the final analsys, I have to agree about the amount of travel that the CSM will give you in comparison to the CSM.

I have never been able to get the same crazy piro rate from my 401s that I get with the CSM I have.

The 401 is (IMO) a better gyro, but I wish I could get a faster piro from it. I have set the rudder rates at 140% and still not anywhere near the same speed.

[Fixxxer]

Very interesting reading guys & well put Ade, always wondered exactly how/why they worked how they do.

[Smoothound]

Basically increasing the ATV's tells the gyro to tell the servo to move faster to the travel limit reducing it tells it to travel slower.

[Ade_Law]

sometimes an ultra fast piro rate is a waste. no point having it if you cant control the model whilst its doing it. I wind the piro rate up until i can just about hold it in a stable hover at that piro speed and keep track of it in piro flips.

Ade

[ChrisB]

I would just like to add that i have been a total CSM man until buying a 611,now i am converted..I now also own 2 401`s/9254`s on my other helis and am convinced that Futaba gyros are not only more forgiving and easier to set up,they also totally outperform any CSM gyro in every way..

I have no problem getting a very fast piro rate from my 401`s

[Ade_Law]

jimbob, what model is this one, how long is your servo horn, are you using the full length of the pitch slider and what is the limit value set to.

Ade

[Steve]

Excellently explained Ade.

Cheers.