KingAirJockey

My Feedback: (-2)

I hate to do it guys,but does anyone have some close up pics of inner gear door mechanisms on P-51's.I've got a top flite 1/5,and retracts,would like to add sequencing doors as I've already got the correct valve for them on the P-51.

SDCrashmaster

Can't help w/ the gear doors, but that's a great lookin' dog!

Vince

My Feedback: (1)

The inner doors on a P51 are up when the engine is running, and the gear is down. When the engine is shut down the hydraulic pressure bleeds off and the inner gear doors begin to come down. There is a firm in Canada that manufactures a variable air valve that duplicates this operation.

Vince

KingAirJockey

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Thanks

Vince

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The firms name that manufactures the valve is Ultra Precision. The valve is $74.95, but it is an absolute work of art. It is infinatly adjustable. They advertise in most of the model mags.

Vince

KingAirJockey

My Feedback: (-2)

Thanks Vince,I've got a valve already thats very similiar to the one you mention,doors open,gear retracts,door close.And vice versa.What I'm looking for hopefully is someone who has pics of the geometry of the actuators and the hinging they did.

badger41

the Byron used a 90 degree arm mounted on the top of the wing over the inner gear doors hooked to a split rod with clevis' to each door on which is mounted a short control arm very closely mounted next to the door hinge to get the large travel throw .
That 90 was hooked to the slow travel retract servo that is no longer made.
The Platt version uses a rack and pinion to operate two seperate rods going to the doors.

The simplest is to use the Canadian UPS valve and two very small air cylinders that they also sell just for the gear door operation.

By the way Byron went to this valve and cyl mode when Ace could no longer produce the very slow servo 5 to 7 sec travel.
tom

KingAirJockey

My Feedback: (-2)

Thanks,thats pretty much what I was thinking of,but it never hurts to hear other ideas.

Chad Veich

My Feedback: (60)

King Air, here's how it's done on the full size bird. A similar system using air cylinders will work fine on the model. Best of luck, Chad.

http://www.arc2.prohosting.com/AWA/A...doorsfront.jpg

http://www.arc2.prohosting.com/AWA/A...ftgearwell.jpg

http://www.arc2.prohosting.com/AWA/A...inrearview.jpg

http://www.arc2.prohosting.com/AWA/A...s/Mvc-013s.jpg

http://www.arc2.prohosting.com/AWA/A...s/Mvc-023s.jpg

KingAirJockey

My Feedback: (-2)

Thanks Chad,thats exactly what I was picturing in my mind.looks like a simple setup.

Countryboy

My Feedback: (25)

KingAirJockey,

I am also building the 1/5 TopFlight P-51 and I am planning on using mini air rams to actuate the door's. As for actual scale, you will have to deviate/cheat a little due to the design of the center section of the TopFlight wing.

You can see the spacing of the doors on the full scale in the pic links posted. Now I will post a pic of the inner door's installed on the TopFlight wing. As you will see, these door's are being driven by servos.

The pic was sent to me by someone else who was working his way through this. Don't recall who it was so I hope he doesn't mind me posting his pic.

Vince

My Feedback: (1)

The typical way of doing this on large scale WWII warbirds is with small pneumatic cylinders. Both Robart, and Ultra Precision make cylinder for this purpose that are relativly inexpensive.

Vince

P.S. Those pics of the full scale Mustang doors were great.

Chad Veich

My Feedback: (60)

I am near the point of fitting the doors on three Dave Platt Mustang and will be doing it just as Vince suggests. With the Ultra Precision valve and using small cylinders to drive the inner doors this is a relatively simple task nowadays. Especially if you compare it to the mechanical system that Dave shows on his plans, what a mess! Best of luck to all, Chad.

bentwings

Those are some very good pictures of the p-51 door cylinder arrangement. I've used a very similar set up using the small air cylinder made by the valve mfg. The biggest problem is that the cylinder really doesn't have the poop to close the big doors on the Ziroli p-51. If you try to use about the same angles the full size uses you don't really have very much leverage. Ours closes it just fine but the air pressure when the motor is running coming around the open side sort of counter acts it and causes the doors to hang open about 1/4". If you look very closely I think it was #5 picture you will see a latch on the leading edge of the gear door. I think the full size probably has the same problem except the hyd cylinder has a bunch more power for its size. There is a small hyd. cyl on the full size that operates the latch I believe. It probably is a sequencing thing too. I made a cam latch using a very small servo and long arm to simulate this. It is tucked up in the leading edge glove and just clears everything. Unfortunately it takes up another channel and requires some thinking while operating the gear. The doors definitely stay closed however!!! With one exception..... if you use 125 psi air like we do the inner door is history if it is not open when the mains come down!!! And don't retract the gear when the plane is upside down!!!
BTW my son converted my aging Z Corsair with mech doors to air cyl and they work beautifully. Nice and smooth. He used the other version of the Can. valve. These cyl. are now available in some longer lengths too. Still about $22-$25 each. Pretty easy to get $200 in the air system after you get the gear and wheels.
I like that servo on the doors....it looks pretty strong. Be sure it doesn't bind or you will have a big drain on the battery.

more later
bent wings