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Old Sep 04, 2010, 03:05 PM
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Derek, Looks like you used blue fan fold. Is that what the plans call for?
I tried the link to Pondmaster's website but did not get through...I got some listing for car insurance and hobby shops, but not his website. ????
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Old Sep 04, 2010, 05:43 PM
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Yeah, i guess has shut down over the years. The 1st post was 2005.

No, the plans call for 6mm and 3mm depron, mostly, so some simple adjustments were made. On the Fuse, it is all 6mm, so the 5mm FFF is so close there is no problem.

On the wing it calls for 6mm ribs and 3mm skins. I skinned it with FFF as well, which really just required enlarging the wing saddle slightly and moving the formers in front of the wing and behind it slightly forward. If you are going to use FFF, build the wing 1st, that way you can get the fuse formers right. You will just have to remember F3 and F5 will need to move out by about 3mm each, and thus F7 enlarged by the same amount front and back.

Alternatively, you could shrink the wing ribs by 2-3mm on all edges, making the wing section almost identical to one done with 3mm sheeting, which actually might be a little easier.
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Old Sep 04, 2010, 05:44 PM
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Oh, and the nacelles are listed to be 3mm, but I used FFF. Of course I had to adjust them slightly as well by enlarging the wing-holes by about 3mm.
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Old Sep 19, 2010, 08:43 PM
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Still here pecking through it. Thinking about full amphibian. I drew this up today; still thinking through it...

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Old Sep 21, 2010, 06:08 AM
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Keep thinking Derek, looking promising
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Old Sep 21, 2010, 07:05 AM
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Here is the mockup. The original plan was to mock in wood and build teh real thing in aluminum at my university's machine shop. Now, i am thinking the whole thing might be done in 1/8" ply, as it really seems plenty strong for modeles. I will have to do lots of testing once I get it in a plane.

Widgeon / Goose Style Landing Gear (0 min 58 sec)
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Old Sep 21, 2010, 01:45 PM
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The looks great Derek. The only thing more it needs is a way to "lock-out" so the "elbow" does not hyper-extend then strip the gears from the servo. This could possibly be achieved with a simple stop-block that the elbow rests on when extended.

The plywood looks great in theory, but what happens when it gets wet??

But I like where you are going with it.... I think it has good potential.
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Old Sep 21, 2010, 01:54 PM
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Looks great! I had the same thoughts about plywood getting wet...

But also by coincidence I am also working on home made retracts. I already modified a servo for continuous rotation in selectable direction. This servo drives a thread end, which has to move the "elbow". Two microswitches bridged by diodes control the limits.

I plan to integrate the whole main gear in the wing! But give me some time to work it out, and for sure I will post if I can show something.
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Old Sep 21, 2010, 02:11 PM
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So you got me thinking....

"Here I am, sitting at work, surrounded by myriad office supplies.... What affordable, ready-made, durable, rust-proof device could I easily modify to make strong retract 'struts'? " (*edit* --- "A-arms")

"BINDER CLIPS!!!"

You could use a hack-saw to cut most of the spring-plate away (weight savings), then use the hinge and clip-handles as your struts. They come in many sizes, from tiny to jumbo. Space them apart enough for a strong parallelogram, and use pliers to re-shape the wire handles to fit your application... hmmmm, food for thought.

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Old Sep 21, 2010, 02:28 PM
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Quote:
Originally Posted by mavlo77 View Post
Looks great! I had the same thoughts about plywood getting wet...

But also by coincidence I am also working on home made retracts. I already modified a servo for continuous rotation in selectable direction. This servo drives a thread end, which has to move the "elbow". Two microswitches bridged by diodes control the limits.

I plan to integrate the whole main gear in the wing! But give me some time to work it out, and for sure I will post if I can show something.
Yeah, my initial plan was to use a jack screw system to operate the system, too. That is sortof what i was planning on the 1st cad filer I drew, since I needed 3" of stroke to operate the gear. But I racked my brain trying to avoid it so it could just use a normal, unmodified servo and a lockout arm, kind of like mechanical retracts. I assumed it would be a lib lighter and more serviceable/reproduceable, but I am not sure yet.

Please if you can post your ideas. I would like to see it in action.



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Originally Posted by warhead_71 View Post
The looks great Derek. The only thing more it needs is a way to "lock-out" so the "elbow" does not hyper-extend then strip the gears from the servo. This could possibly be achieved with a simple stop-block that the elbow rests on when extended.

The plywood looks great in theory, but what happens when it gets wet??

But I like where you are going with it.... I think it has good potential.
I'm not sure how it works wet. The idea i played with was coating it in epoxy, or even a thin fiberglass, hopefully sealing most all of it, at least enough to prevent delaminating.

I didnt go into detail here, but yes, the elbow will be exactly as you describe using a stop-block style lockout. This part will likely be square aluminum tubing. IT may also have a small tension spring out of a ball point pen to keep the arm locked tightly.

I am also trying to hash out a super-mini spring loaded strut to replace the lower elbow arm to improve impact handling, but given the scale this may not be worth while. I have also been looking at your gear design with the ingenious built-in coils for absorbtion to see if that can be integrated, but that really is an entire re-design.

I have a new plan which is also derived from my studies of your design. If the ply doesnt work to make the A arms from bent music wire (which is what it appears you did), like traditional landing gear. The rest can be made out of flat aluminum stock with some manual machining, thus eliminating most of the wood. This is what mockup 2 will be looking like, probably, so we will see hopefully.
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Old Sep 21, 2010, 02:29 PM
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And if you haven't already seen this....

http://www.rcuniverse.com/forum/fb.asp?m=8591318
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Old Sep 21, 2010, 02:30 PM
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Originally Posted by warhead_71 View Post
So you got me thinking....

"Here I am, sitting at work, surrounded by myriad office supplies.... What affordable, ready-made, durable, rust-proof device could I easily modify to make strong retract 'struts'? "

"BINDER CLIPS!!!"

You could use a hack-saw to cut most of the spring-plate away (weight savings), then use the hinge and clip-handles as your struts. They come in many sizes, from tiny to jumbo. Space them apart enough for a strong parallelogram, and use pliers to re-shape the wire handles to fit your application... hmmmm, food for thought.



Very clever! I am sitting here bending A arms right now, and that would probably work great!
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Old Sep 21, 2010, 10:15 PM
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I tried the wire. No luck, it is difficult to manipulate. Needs more thought on my part.

Do you guys think if you layed up the A arms in fiberglass just as my ply ones above they would be strong enough? I have not worked with glass much; not sure of it's strength. I guess you could lay up CF as well...

I may take a trip to the machine shop this week to see what we got as far as milling them down from aluminum as well, I just hoped to find a solution that anyone could duplicate at home.
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Old Sep 21, 2010, 10:23 PM
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Originally Posted by warhead_71 View Post
And if you haven't already seen this....

http://www.rcuniverse.com/forum/fb.asp?m=8591318
Yes! That pneumatic gear is what I modeled mine on, quite literally, but I wanted to avoid pneumatics and keep it electric. Mainly for cost purposes. I replaced the cylinders with a jack screw at first, but I wanted to be even more simple than that and use a servo. If mech retracs can work, maybe this can too, but we'll see.

I am a bit surprised there are not more production amphib units out there.
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Old Sep 22, 2010, 09:06 AM
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Also, see this: retracts on a Grumman F3F/F4F:

http://www.rcgroups.com/forums/showt...264905&page=26

http://www.rcgroups.com/forums/showthread.php?t=1154276

Dig around those threads and you'll find several examples, plus videos.
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