samparfitt

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7.5" air cylinders (can put collar on it to reduce throw):
Darrell has them (I believe they are UP's)
http://www.sierraprecision.com/prod17.html

DENTO

Thanks Sam did send an order into him a week ago have not herd back,As I need them rather urgent thought I would try somewhere else,Maybe he is away flying somewhere and has not been into the office,I still may here from him, Hope so.
REGARDS
JOHN

samparfitt

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John,
He's pretty busy working long hours on completing orders.
I find it best to call him.

ram3500-RCU

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I can only imagine how busy he is. He is pretty good about answering emails as well. At least from my experience.

Mustangman40

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Hey Gary,
here are the pics of the starterwe talked about last night, she works like charmand it was cheap to do...

Jimbo

ram3500-RCU

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Thanks Jimbo. Nice idea. Might have to make a trip to Harbor Freight.

ram3500-RCU

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Bit of an update.

After flying Zombie this summer, we have some findings regarding the new electric gear.

As you know, we installed Down & Locked conversions to the mains, their, sequencer, and servos on the gear doors. The tail wheel has been left air, as originally built.

The mains have worked well. They are dependable and consistent in stagger and speed. It is nice to be able to run them up and down in flight without worry of expending air and loosing control of them. Nice for making those down-and-dirty passes.

The gear doors (inner on the P-47) have been another matter. A mysterious and perplexing problem they have been. We originally had Spectrum 821s on them. Both servos burnt up while open. Too small right? We installed Hitec 5645s. Both of these also burnt up while open. Bigger servos right? We installed JR 8411s. Surely they would be able to operate those little doors. They both burnt up while open. Six servos fried while in flight. Now we are using a 2c lipo on the gear, so we thought maybe the 7.4 volts was cooking the servos, although the servo on the air valve for the tail wheel was unaffected. Brian wired the servos to a regulator for the power, and just took the signal from the sequencer. Now they only get 5.1 volts. We flew her again today, and once again, the inner gear doors did NOT close. This in spit of the working flawlessly when cycled on the ground. I landed, and we tested them again, and this time, with the lower voltage, they did not burn up, but they could not pull the doors shut in the air.

Our conclusion is, as hard as it is for us to believe, these servos just cant pull the doors shut against the wind resistance. The higher voltage cooked them because they were stalled the whole flight.

We are going to remove the servos, and install air cylinders, plugged into the tail wheel system. This should fix the problem. The D&L sequencer will still be operating them, and the gear will be unaffected.

On the Two Corsairs we are working on, air will be used on gear doors, even if the gear in converted to electric.

Here are some pictures of her from a couple outings. The last picture is of our AMA president Bob Brown with Zombie in the background, and one of our CARF corsairs in the foreground.

ram3500-RCU

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Some more pictures

ram3500-RCU

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Here is a good source for these, and other sizes. Very fast shipping and reasonable pricing.

www.shulmanaviation.com/index.php

DENTO

Thanks Gary
Shall put that info to good use.
REGARDS
JOHN

ram3500-RCU

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Brian has finished modifying the inner door operation on our Meister. She now has air cylinders on the inner doors. Here is a video of them and a picture of the install. The whole assembly comes out cylinder and all with the removal of the screw you see.

www.youtube.com/watch?v=ZU1PR1r4ci8

The electric gear can be cycled with a battery directly connected to it. We use a 4.8V so it runs slow. This way it is easy to stop in time, as no end point protection is in place this way. That come from the control box in the fuselage.

ram3500-RCU

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Cycling the gear prior to start up. The inner doors would work perfectly on the ground, but not in the air.

ram3500-RCU

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Zombie at the Cleveland RC club Military Fly In.

www.youtube.com/watch?v=jqBiP0qMjJA

ram3500-RCU

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Landing Zombie at the Cleveland RC club's summer war bird event. At 0ver 950' long, this grass strip is great for the giant scale birds. Hope to see a nice turn out next year.

www.youtube.com/watch?v=hD6ebGHHbwc

ram3500-RCU

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Some pictures from our trip to Monster Planes in Lakeland Florida.

Still could not get those inner doors closed, even with the air cylinders. Definitely a mechanical disadvantage in the airstream. This will be corrected over the winter. I would like to fly her at Top Gun in 2012.

dvs1

Gary, your problem is a perplexing one. I cannot understand why the inner doors are not shutting. There shouldn't be that much wind resistance even at 100 mph. I mean it's not like a flap or control surface like a barn door hanging in the wind, the surface area is so small facing forward that they should move relatively easily. Very strange that both multiple servos and air cylinders will not operate them. I have never had a problem on my 1/5 mustang with scale doors and they are fairly heavy composite construction running of single air cylinders. Not sure if it is an option for you but would it be possible to run a worm gear drive actuator to your gear doors? Best of luck, it's always the little things that give me so many problems as well.

Curt

ram3500-RCU

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Yes, this has been very perplexing. After everything we have tried, we are convinced that, as unlikely as it may seem, it is in fact air that is keeping them open. In static, they work perfectly. We can cycle them all day on the ground, and they will close every time, on time. And it was the same case when driven with servos, perfect on the ground, no go in the air, only with the servos, they just sat there and cooked. At least the air doesn't care if moves or not.

Looking at them from head on, they resemble little flat bottom wings (the air foil pulling/lifting them open), and we now feel this is not being overcome with the way we have the cylinders attached. We are going to redo this to give the cylinders more mechanical advantage. I would never have thought this was the case, but we have no other reason we can logically turn to.

dvs1

So are you going to relocate the arm outward on the gear door slightly or completely redesign the mechanics of it? I looked at your picture again and did notice your linkage is very close to the hinge line. I looked at mine and it is a little further out, plus my mustang door is curved towards the gear so with your theory mine actually would close easier than it would open. What your saying does make sense, it just blows me away that something so small causes so much drag.

ram3500-RCU

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You are so right. We kept doubting that this could be the problem. It just could not be possible in our minds. When you try to pry the door open against the air pressure, it does not seem possible. But it apparently is the case.

Not sure what Brian will do, but we took a look at how Wayne Fussel had his rigged, and they closed fine. He had the cylinder working 90deg from ours and used a bell crank to transfer the pressure. Looked like a lot more torque was brought to bear that way. He also had the scale-like inner skins on the doors.

This is the way Dino did it on his P-47. Wayne's was very similar.

DENTO

G-DAY Gary
Had the same problem with a S/M Viper Jet ,It had small air cylinders on the doors put larger Robarts on and fixed the problem they are like a little bulldog,s ,Pulling power .
REGARDS
JOHN

ram3500-RCU

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We have some very beefy Shulman Aviation cylinders which are supposed to be more powerful than the Robarts, and still no joy. Keep in mind that we also tried JR 8411 servos with 6V of power, and they still would not close. I think it is more a geometry issue. Not enough leverage.

scale only 4 me

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Gary,
Just another thought,,
Seams to me maybe the angle of your linkage is pulling down to much towards the hinge line, not rotating around the hingle line enough,, an easy test would be to just add about 1/4 or so to the existing control horn on the door,, maybe just that little added leverage and angle would be enough. would that still clear the wheel?

good luck

CGAV8R

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I would think an easy way to test if it were air pressure keeping the doors open would be to fly straight up to a stall. At stall there would be no airspeed keeping the doors open. If they close, then it may very well be the airflow keeping them open.
Just a thought, Aaron D.

dvs1

Gary, an even better way of doing it with the horizontal setup and bellcrank is to use a bell crank that is longer on the cylinder end and shorter on the door rod end. About a 2/1 ratio would work great. That way you will instantly double your torque right at the bellcrank. Also if you could move your attaching point on the door even 1/4 inch that would probably help tremendously as well.

ram3500-RCU

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The problem we run into with this is the clearance for the tire. I think we will need to redesign the whole linkage.