Operating gear doors

[Peter Jenkins]

Just wondered if anyone knows of a programmable sequencer that can be used to lower and raise u/c doors. I'm thinking of the P51 where the main door open to allow the u/c to extend and then close again. Same thing on retracting the gear. Don't want to get into the complex area if there isn't such a gizmo available off the shelf.

Thanks.

[Ron Gray]

HK do one **LINK**

In fact I think I have some in my accessories drawer, I’ll have a rummage and let you know!

[Peter Jenkins]

Thanks Ron. I'll call you.

[Biggles' Elder Brother - Moderator]

I don't know what transmitter you are using Peter but have you checked the manual to be sure it can't do this? A lot of more recent ones have servo sequencing and slowing available now.

BEB

[Bob Cotsford]

As David says, many transmitters have enough mixers, slows, delays and custom curves available to program something like door sequences. Top hat curves for the inners with a suitable slow setting and the retracts on a slight delay to allow the inner doors to open.

[Peter Jenkins]

Hi BEB and Bob, I've got a JR XG11 Tx that has a lot of features but I don't recall one along these lines. It doesn't mean it won't have that feature just that I have not seen it in the handbook. Looks like I need to contact the guru on RCU on JR programming to see if he can figure out how it could be achieved.

[Former Member]

[This posting has been removed]

[Peter Jenkins]

Thanks Tom. I was going to do that for the tailwheel doors but I think the main doors might need something a bit more positive. I've been following up the link Ron provided and found this one as well. This provides four separate outputs - 2 to the gear and 2 to the gear doors. Sounds like just the thing I need so I ordered one and at £12.55 delivered from Hong Kong doesn't break the bank. It will be some time coming but as I haven't started the build yet that doesn't matter.

[Tim A]

Peter, i have the exact same Turnigy one you link to above for my TN P51 (if I ever get round to finishing it!). Set up on the bench with 3 retracts and 2 door servos it works. Closes inner doors as per the real A/c. Even got it set so one main gear retracts first.

[SR 71]

Iv bought two of them Peter but have not got round to using them yet, but for the money they look good

[Biggles' Elder Brother - Moderator]

Posted by Peter Jenkins on 16/09/2018 23:27:35:

Hi BEB and Bob, I've got a JR XG11 Tx that has a lot of features but I don't recall one along these lines. It doesn't mean it won't have that feature just that I have not seen it in the handbook. Looks like I need to contact the guru on RCU on JR programming to see if he can figure out how it could be achieved.

Hi Peter,

You could save yoursef a few bob, a wait and have one less electronic component to fail! Page 28 of your manual details servo speed control. If your UC is on servos this will do what you want.

1. On UC down: you slow the main gear to ensure the inner doors operate first on opening.

2. On UC up: A nice feature is you can have different speeds in each direction, so for closing you want to do it the other way round. Slow the inner doors and make the UC faster. That way the UC will be tucked away before the inner door gets there. Looks straight forward to do and I don't even use JR!

BEB

Edited By Biggles' Elder Brother - Moderator on 17/09/2018 11:52:42

[Peter Jenkins]

Hi BEB

Thanks for pointing that out. I have used the servo slow function on my Eflite Sea Fury to get the u/c to retract more slowly and at slightly different speeds. I should have known better as by the middle of the war, most aircraft had much higher pressure hydraulic systems and u/cs tended to retract together at the same speed. Indeed, if you watch videos of Mustangs they don't have one leg going up and then the other - that was the preserve of the earlier marks of Spit and Hurri and other such aircraft.

What I really wanted was a sequencer that made sure the door opened first, then the u/c operated, then the door closed. The HK sequencer does this at a reasonable cost. What I have asked of the JR programming guru on RCU is whether the XG Tx series has a similar function. I have yet to get a reply as he usually goes away and tries to see if he can get the software to function in the way in which I'd like. He gave me the way to get crow braking on my aerobatic biplane by swoping over one of the servo connections on one wing and, hey presto, crow braking with all ailerons moving to raise/lower the ailerons on the top/bottom wing respectively. Unfortunately, this reduced the roll rate and as I wanted to slow the aircraft on a vertical down line while doing a full roll, it got rather too close to the ground on occasion. The problem was solved by moving from a 2 blade to a 3 blade prop which gave much better braking on the down line allowing the crow braking to be dispensed with.

BEB - you are right - the JR manual is reasonably easy to follow but is also a bit opaque, as most such books are, when it comes to telling you exactly how to do things.

Many thanks to all who have contributed to pointing me in the right direction and for letting me know that my chosen solution does work fine.