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Old Jun 07, 2003, 12:17 AM
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DerekB's Avatar
Cape Coral, FL
Joined Nov 2001
1,910 Posts
Not just another fanfold 3D... Twin Mitchell 3D

I just got done drawing up my next fanfold 3D airplane. I always wanted to make a twin and my favorite subject is the B-25 Mitchell bomber. I adapted some 3 view CAD drawings I had into the general format of the Trident (by me) / 3DX (by Tim H.). I gave it a similar wingspan (36"), wing area, wing chord, aileron size, fuselage area (but this includes the engine nacelle area too), rudder size (but this has 2 smaller rudders).

I am thinking about using two generic GWS IPS motors with A gear and 10x4.7 prop (stock Lite Stick stuff) and 2s 1020 Kokam Li-poly battery and 10 amp ESC. This is just a guess, so don't shoot me if it does not work. I never wired up a 2 motor setup, so any advice would be appreciated.

The first photo is a screen shot of my 3 view CAD drawing (that front view is the real thing - the model will not have an inverted gull wing). 2nd photo is all the parts with panel lines (yellow lines - draw those in with sharpie marker). 3rd photo is just the outline of the parts of exactly what to cut out. 4th post is the .dxf file for anyone who is brave enough to try it. Be forewarned that I have not built this yet, so you are on your own. To stiffen the wing and fuselage, I will use my carbon fiber I-beam design (see this thread for discription http://www.rcgroups.com/forums/showt...5&pagenumber=1 ) or can just use carbon tubes. The motor mounts will be 3/16 x 5/16 hardwood (leftover broken Lite Stick fuselage).

I will post more photos and construction details later.

Derek
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Old Jun 07, 2003, 12:19 AM
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Cape Coral, FL
Joined Nov 2001
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Parts with panel lines

This is a screen shot of the CAD file of the parts to cut out. The cyan color is the basic outline and the yellow is the panel lines to draw with sharpie marker.

Derek
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Old Jun 07, 2003, 12:21 AM
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Cape Coral, FL
Joined Nov 2001
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Actual parts

Here are the actual parts to cut out. It's 12:15 a.m. now and if it was not so late, I would run to my office and plot these out and come back home and cut them out. I guess it will have to wait until Saturday

Derek
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Old Jun 07, 2003, 12:28 AM
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Cape Coral, FL
Joined Nov 2001
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dxf file

Here's the .dxf file for those brave enought to try it. I have no idea if this will work. But my gut tells me it could be quite exciting The plans are not complete. There are no notes. The wing span is 36".

The beauty of fanfold foam planes is there is not that much time commitment or money. So just try it.

Notice that the ailerons are split at the engine nacelle. I'm thinking of joining them just like elevator halves by using bamboo skewers and epoxy. I'm not sure how to link the rudders yet

Derek
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Old Jun 07, 2003, 03:20 AM
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Depdog's Avatar
Stockbridge, Georgia, United States
Joined Jan 2003
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Wow, I am not the only one up till the wee hours.


I just saved the file, and will cut it out first of the week, gotta get everything ready for the indoor tomorrow. Just glued the D gearbox back together for the Ultimage Bipe.

I have got to get some brushless motors.

Hmm, what about two IPS Duels on it. About 15 oz of thrust.


Looks great, you and Tim are churning em out faster than we can build and fly them.

Glenn
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Old Jun 07, 2003, 03:46 AM
fix-it-up chappie
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Valley Village, CA
Joined Jan 2002
2,262 Posts
Darn you Derek. I'm working on my first plane which is a modified 3DX. I just reshaped it into a P-51. It looks pretty cool, but I still have to install the radio gear.

On Thursday I was thinking of doing the twin p-51 (I forget the number), but then it occured to me that a P-38 would be just as easy.

So I logon tonight, and what do I see... Derek has built the only other cool allied twin (well not counting the beaufighter). You're stealing my thunder, man. That hurts.

Keep up the good work.
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Old Jun 07, 2003, 10:08 AM
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Cape Coral, FL
Joined Nov 2001
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Glenn,

I thought about two duals. I think that's more than 15 oz thrust though. My Sukalyn weighs 9 oz AUW with that motor and it hovers at 5/8 throttle. The only problem on the B25 is prop size. The nacelles are out just far enought for a 10" propeller. That gives 5/8" clearance to the fuselage. I'd have to stretch the wing out another inch for the 12" prop on the dual. Gee, that took about 15 seconds in the CAD file

Derek
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Old Jun 07, 2003, 10:14 AM
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Cape Coral, FL
Joined Nov 2001
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Updated plans

Here is a better set of plans. I think I got the dual rudder control worked out - at least in theory. This wing is stretched a little to allow clearance for a 12" prop so I can try Twin IPS Dual's with 12x6 prop (yikes, 4 little motors screaming - that should sound cool). A link to the .dxf file is in the next post.

Time to start plotting some plans

Derek
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Old Jun 07, 2003, 10:22 AM
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Cape Coral, FL
Joined Nov 2001
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Final Plans

Here is the link to the plans for the 38" version which will work for up to 12" props.

If you got the older version, disregard that and get this one. I found a few boo foos in the first plan.

And just a reminder. These plans are free but I reserve the rights to the plans. Please do not do anything with these other than build a plane for your own personal enjoyment.

Derek
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Old Jun 07, 2003, 11:16 AM
No cash=time for ideas!
Fall_Ryan's Avatar
Boeing Field, Seattle
Joined Mar 2003
316 Posts
Quote:
Originally posted by tolladay
On Thursday I was thinking of doing the twin p-51 (I forget the number),
What you are looking for is the P/F-82 Twin Mustang.

Anyways... SPIFFIENESS! Although I do belive you are nutter... Dual IPS... NUTTER!
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Old Jun 07, 2003, 01:11 PM
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Stockbridge, Georgia, United States
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Man that looks cool.

Love that profile.

Glenn
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Old Jun 07, 2003, 06:15 PM
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Cape Coral, FL
Joined Nov 2001
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I got mine all cut out. The foam weighs 3.8 oz. I found a few minor errors in the plans. These are minor and I recovered with little effort.

1. The engine nacelle that is part of the wing gets in the way of sliding the wing through the slot in the fuselage. I just cut the front end of the nacelle off on one side, slid the wing in, then I'll glue the little nacelle pieces back on when finished.

2. For the profile engine nacelles, the slot cut for the wing goes too far back. Check this before you cut.

3. The cutout in the rudder where the stabilizer attaches is cut too far back. The front end of the cutout is in the correct place. Check this before you cut.

Take a look at the assembled 3 view plans in the post above to see the correct position of the parts. I'll fix the plans and post new. Other than that mentioned above, I don't see any other problems with the foam parts.

All in all, it went together well. My only concern is the two rudders add extra tail weight. There's plenty of room to move the batteries forward, so balancing should not be a problem.

Next I'll add the carbon fiber reinforcing.

My digital camera is broken and off at Olympus for repairs. It will be another week before I get it back, so no pictures for now. Sorry.

Derek
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Old Jun 08, 2003, 09:58 AM
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Wayne's World - Illinois
Joined May 2002
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I grabbed the 38" ws plans zip and tried to open it in paintshop pro this morning...but it said I didn't have enough memory{nothing else was open and the clipboard was cleared}...got a smaller plan, I'd like to try it.
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Old Jun 08, 2003, 11:58 AM
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d_trafalgar's Avatar
Ontario, Canada
Joined Sep 2001
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DerekB,

Why not use the fuse and Wing nacelle to add some camber to your wing? Then add 2 or 3 more sections along the wing to maintain the shape. Put the motor mount on the nacelle....something like that maybe.......


D
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Old Jun 08, 2003, 02:16 PM
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Cape Coral, FL
Joined Nov 2001
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Quote:
Originally posted by d_trafalgar
DerekB,

Why not use the fuse and Wing nacelle to add some camber to your wing? Then add 2 or 3 more sections along the wing to maintain the shape. Put the motor mount on the nacelle....something like that maybe.......


D
Thanks for the suggestions, but I am using a pure flat plate wing on purpose because that has been very successful on at least three other 3D planes (Gearge Hick's Tribute, my Trident and Tim H. 3DX. Generating lift is not the problem. The flat plate wing actually works very well. And it flies the same upside down as rightside up. By putting camber in a flat plate, you now have an unsymmetrical airfoil. This creates the potatoe chip affect, where the plane wants to stay upside down.

Derek
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