Futaba 401 gyro

[Dardoug]

Can anybody advise me on what rates the limit and delay should be set at for my trex 450? It holds in headlock for a short while while hovering then in starts to drift away any clues?

[tourerjim]

What TX & heli have you.

[bolders]

Limit should be adjusted so the tail slider is just up aginst the end stop without causing the servo to bind. Delay setting depends on the servo. I think I set 0 delay when using my 401 with a DS520 om my 450.

Is this a new gyro or has it just recently started misbehaving. Im wondering if there is a possibility you have got a fake unit - did this come from ebay or somewhere else.

[Steve]

If you're using a Futaba tail servo then the delay should be set to zero from memory, but it's been a long time since I played with a 401. The travel limits on nearly all gyros including the 401 should be as close to 100% as you can get it really. My method is to set it to 100% and then make travel adjustments physically by moving ball links in or out on the servo arm or other similar to get maximum slider travel without binding. Use the limits for fine tuning only around the 100 mark.

Just to add - the 401 is quite an old gyro by modern standards. It's very capable for sure but I wouldn't expect it to hold as well as some more expensive and modern alternatives.

[Dardoug]

[PHP][/PHP]

What TX & heli have you.

It's a dx6i and a trex 450 which bought second hand?

[Steve]

The delay pot is used to compensate for differing types of tail servo and has nothing to do with the transmitter or heli. It's a throw back from years ago when there were only a few dedicated tail servos on the market, and many people actually used 'normal' servos in the heli tail. That's how old the 401 is. If you have a dedicated tail servo, then the delay pot goes to zero. If it's a 'normal' slow servo then you have to increase it. If you have any type of modern tail servo then zero it is. Don't use a JR tail servo with the 401 - it will most likely fry the servo.

[Dardoug]

It's a futaba 9650 digital servo? Would the ds switch on the gyro make a big difference of it was off and would it have damaged the servo in any way?

[Steve]

Won't have damaged the servo. Just won't get the best performance out of it. The digital switch should be on.

Your tail servo is a reasonable speed servo, but it isn't a dedicated tail servo. It's more like a mini fast cyclic servo looking at the specs. I think you'd be ok with the delay set at zero. Experiment and see what happens. If I remember rightly, the delay pot actually makes very little difference in flight performance.

[Steve]

Have a read of the document attached to the first post on this thread. It was written years ago (and recently updated), and a lot of the setup procedures were based on and wholly relevant to the 401 gyro. Read the stuff about setting the neutral point.

http://www.rcheliaddict.co.uk/beginn...explained.html

[GIR8]

The delay pot is used to compensate for differing types of tail servo and has nothing to do with the transmitter or heli. It's a throw back from years ago when there were only a few dedicated tail servos on the market, and many people actually used 'normal' servos in the heli tail. That's how old the 401 is. If you have a dedicated tail servo, then the delay pot goes to zero. If it's a 'normal' slow servo then you have to increase it. If you have any type of modern tail servo then zero it is. Don't use a JR tail servo with the 401 - it will most likely fry the servo.

I use a JR servo with a 401 on my 450 and it's fine has been for years.

Btw you should set the delay to zero and have digital mode on.

I still trim my gyro's properly as I feel it's needed with these types of gyro's if you don't you will still get drift from my experience this has always been the case.

[bolders]

I use a JR servo with a 401 on my 450 and it's fine has been for years.

Btw you should set the delay to zero and have digital mode on.

I still trim my gyro's properly as I feel it's needed with these types of gyro's if you don't you will still get drift from my experience this has always been the case.

I always used to set my tail with slider centred so you have equal travel in both directions with no drift.

Also to OP, setting the ball distance on the tail servo to about 7.5mm on the 450 should get you at around 100 on the limit pot whilst getting full travel on the tail slider

[GIR8]

I trim the tail mechanically so it counteracts the the torque when in normal mode as I feel this works best especially with older gyro's like the 401. I don't think it's required with the likes of the 601 onwards and probably not the same with the other more up to date gyro's but until I discover different I'll keep doing it this way.

Sometimes normal gyro mode is nice to use but most of the time it's spent in heading hold which will obviously compensate for this trim anyway.

[cjcj1949]

If you want to use rate or normal mode then you will have to trim the heli in that mode. In Hold mode with a 401 the setting is not critical as the gyro sorts it out. The trim setting is memorised by the servo and usually works within 2 or three clicks of centre. I rarely fly in rate mode and just use it to reset the tail servo before takeoff so that no nasty rotation happens as the heli takes off.

The drift will not be affected by the settings you mention. I doubt it is drift. It is probably that your centre yaw stick position is too far out. Try it with no trim on rudder. Also do not move the heli after switch on. The red led should come on and stay on. ou can reset the zero position by switching between rate and hold three times. This may be necessary if there really is drift due to your temperature compensation not working correctly.

[Steve]

I use a JR servo with a 401 on my 450 and it's fine has been for years.

I'm surprised at this, but if you say it's so then so be it. I know several years ago, there many reports of JR8700G servos going bang with Futaba gyros - something to do with incompatible pulse widths or something. There was a lower spec JR tail servo 890G or so which I think worked ok (I think I had one actually for a while), but it wasn't really suitable for 50 size helis and above - more suited to the olden days of 30 size before 450 electrics came along.

[electricsceadu]

the 401 doesn't like the 8700
but the 8900 will work fine with the 401
my vario r22 has a 401 with the 8900 fitted