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Old Sep 10, 2009, 02:09 AM
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Miraj's Avatar
Brisbane
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1/3 scale retract doors hinge

Working on a 1/3rd scale ash-26 and was interested in info/pictures on how the best way to hinge the retract doors?

Thanks in advance
Steve
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Old Sep 10, 2009, 04:54 AM
3Ding at a field near you!!
Cranny, Vic. Aust
Joined Mar 2008
581 Posts
Hi Steve, Is that one of John Copelands models? Ive got ans ASW 27 he built from ann S2G kit. Its quarter scale though, but if it helps tomorrow I will take a pic or 2 of his instalation and post em for you
Cheers (another) Steve
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Old Sep 10, 2009, 05:29 PM
Are you serious?
Miraj's Avatar
Brisbane
Joined Jun 2005
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Steve
Yes, it is, had sitting around unbuilt for about 2 years. I thought it time to get it flying. John sent me a cd with images on it and they show a hinge system using brass and steel rod, but i saw on rcg sometime ago some guys using tube rubber.
So not sure which way to go?

Steve
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Old Sep 10, 2009, 06:30 PM
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so. cal.
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Pretty sure there is an explanation on the SoaringISSA website in the tech tips area about how to hinge gear doors.
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Old Sep 10, 2009, 06:51 PM
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Australia, VIC, Surrey Hills
Joined Jun 2006
297 Posts
Hi Steve,

there is a pretty tough way of doing it that I used on both my third DG303:

http://www.silentflight.net/index.ph...=114&Itemid=40

Also my cirrus (see image)

the idea came from Chris Williams who covers the technique well on the SSUK site (just ask him in the forum)
http://scalesoaring.co.uk
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Old Sep 10, 2009, 07:15 PM
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Joined Apr 2006
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any drawbacks to silicone hinges? i used this on my 6m schueler and either i was lucky or it is easy. since i dont care that much about inward travel, i used a thick layer. also, it retains the tendency to remain more closed than fully opened which is nice (so long as you cure it wiht doors closed).

here is link to inner tube method.
http://www.scalesoaring.co.uk/GLASS/.../Retracts.html
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Old Sep 11, 2009, 12:59 PM
SoarScale
United States, WI, Wind Lake
Joined Nov 2004
814 Posts
The more friction forces you can eliminate from the doors, the better IMO. I suspect you've heard the odd tail of retracts jamming!!!!

If you have the ability to create an almost friction-free hinge, I'd certainly recommend it. The pictures below show a hinging system I used on my 10.3m Eta. It is a development of the pin and tube type shown in HenryKK's thread.

The small metal hinges are washers. A quarter of the washer is cut away leaving about a 3/4 washer. A hole for the pin is added to one end and the end is filed round. The arc of the washer is about half of the washer and the other 1/4 is bent at 90 degrees. The three bent ends are then captured by the pin and glued to each door. This is an inexpensive method of creating the "door hinge" type of hinge that is generally a two part hinge.

This was simple, worked well and was almost completely friction free. Rubber bands were used to create sufficient forces to close the doors.

Not all the steps are shown here since I didn't take any more photos but I think you get the "picture"!!
FWIW - Tony
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Old Sep 11, 2009, 04:27 PM
yyz
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USA, CA, Paso Robles
Joined Dec 2004
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Aramid

Has anyone gone to the trouble of making their gear doors out of aramid (eg, Kevlar) to toughen them up? Or is there not enough landing and take-off abuse to warrant the extra effort?

Also, has anyone done an internal cg tow hook (attached to the landing gear structure in front of the wheel, etc) ?

MD
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Old Sep 17, 2009, 11:23 AM
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Holland
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I never toughen up the gear doors. When something has to give I rather have the gear doors take the abuse and maybe crack then something else in the construction.

What I do is make a mold of the fuselage outside over the gear door area before I cut the doors out. This way I can make a new door panel later when the need arises. First scratch the gear doors outline on the fuselage, then make the mould (the scratched outline you will find back in the mould for easy reference) and finally cut the doors free.
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Old Sep 17, 2009, 12:40 PM
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New York
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Tony, how do you go about cutting the doors out of the fuse bottom?

TIA,

Steve
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Old Sep 17, 2009, 12:57 PM
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Canada, ON, Toronto
Joined Jan 2004
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Cutting Gear Doors

Steve,

See this recent thread where I asked the same question....it turned out to be very easy to cut out the doors with a razor saw. I just scribed a line where I wanted to cut so that the saw would track until it actually started its own groove.

http://www.rcgroups.com/forums/showthread.php?t=1103007

Dave Smith
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Old Sep 17, 2009, 01:00 PM
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United States, CA, San Mateo
Joined Jun 2000
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Steve,

I use the Dremel Multi-Max. It is easy to use to cut hole in the fiberglass fuse. It cuts about a 1/32" wide gap.

The cutter that came with the kit is meant for wood and soft stuffs. For thin fiberglass, it can cut through with no problem. The negative part is it can't cut round corners.

MOst of the time, I score a thin line on the fuse to mark the door outline, then make a mold of the area. So if I ever loose a door, I have a mold of the area of the door to make a new door.

Brian
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Old Sep 17, 2009, 01:02 PM
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Dorset, Southern England
Joined Dec 2006
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Extremely tough gear doors can be made very easily from two laminations of 1/32" ply. Simply tape them to the fuselage to obtain the desired curve...
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Old Sep 17, 2009, 01:03 PM
yyz
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Great technique. Thanks Harm.


Quote:
Originally Posted by Harm
I never toughen up the gear doors. When something has to give I rather have the gear doors take the abuse and maybe crack then something else in the construction.

What I do is make a mold of the fuselage outside over the gear door area before I cut the doors out. This way I can make a new door panel later when the need arises. First scratch the gear doors outline on the fuselage, then make the mould (the scratched outline you will find back in the mould for easy reference) and finally cut the doors free.
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Old Sep 17, 2009, 01:17 PM
SoarScale
United States, WI, Wind Lake
Joined Nov 2004
814 Posts
Steve, I use nanobots. They wander around my workshop all the time and when I can find them, I give them a task to do. Cutting through a fiberglass fuse is an easy task for them because their hands and feet are constructed as multi-function devices - hair comb, de-licer, butt scratcher, nose hair curler and best of all - four little saws - two outside curved and two inside curved. I program them to follow a particular shape and in the case of the Eta, even the round end to the door. They are very good at it.

I use their front hands to do the major cutting and the back feet to scribe a starting line.

When I can't find them - which is quite often, I use a scribe and razor saw
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