Gyro question

[mightymouse]

Hey guys was just flying my hurricane 425 yesterday all was well did serveral circets left and right then figure 8s, and some piro's head holding great---then I thought I'd try a punch out not high but just to get a feel how my bird would react. when I did it the gyro let go and did a unwanted piro I thought I was in trouble but I newtralized the collective and it went back to hold , i did a few circets after words with any trouble. I have a futaba 401 (maybe more gain?) any Ideas?

[howardm4]

you could try more gyro gain, more aggressive tail blades, check the servo/linkage for no-binding.

basically, the tail isn't strong enough to counteract the instant torque you threw into the rotorhead.

[Jerrymac]

Another thing might be the head speed. When I put my 425 together I experimented a little head speeds. The manual states a minimum of 2600, or use larger 79mm tail blades. I am using a JR G770 gyro and the tail would swing out about 45 degrees on full collective punch-outs with a head speed of around 2600. I re-geared it for a head speed of 3000 and it holds great on punch-outs now. The tail never moves.

As mentioned, you could increase the gain a little and see if it helps. With mine at 2600, increasing the gain caused the tail to wag, but didn't stop the "swing" on hard collective inputs.

[mightymouse]

Hey Im gonna give those a try my head speed does seem alittle slow, My head holding was perfect until I loaded that torque , there is no binding in the pushrod or servo. thanks guys

[joe1l]

I started off running a 401 on my 425 but my tail would not hold. I first upgraded my tail to Futuba 9254, but it would let loose when ever i would try something other than sport flying my tail would let loose. I upgraded to a quark, and have not looked back. my tail stays perfectly locked at all times. I can do pitch pumps all day and the tail stays locked.

[mightymouse]

Ive increased head speed and its better tail holding that is. But my tail still torks over to left when in popup--gonna try some gain this time and see what happens.

[ukgroucho]

Have you set up the gyro properly?
- Set the limits for throw so that the tail slider has full travel with no binding at either extreme. (LIMIT dial on 401).
- Set the DELAY to 0 (for a digital servo). This should not affect hold much, more likely to affect stops after piros.
- Set the rudder neutral. (Badly documented in the 401 handbook). Basically in RATE mode you want to find how much sub-trim on the rudder is needed to be able to hover without the tail turning. This is 'fine tuning' and should not affect the tail blowing out under high torque. NOTE: REBIND your DX7 to the heli with yhe gyro in HH mode after this step!
- Now sort out the gain. You want the gain set to JUST LESS than the amount needed where the heli wags it's tail a bit in FFF. So fly FFF and if it wags, land and reduce gain a little.

Done all that and it still does not work? You may need to look at the hole that you are using on the rudder servo horn. Ideally the LIMIT should be in the 80 - 120 range on the gyro. If it's low (under 80) then you probably have the tail pushrod connected too far out on the servo horn. Even with a fast servo this can slow down tail response. Reposition to one hole 'in' and reset all the stuff above.