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Old Feb 03, 2013, 11:11 PM
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DoubleOne's Avatar
United States, MD, Annapolis
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Build Log
68mm F-35C Project

Hello everyone,

**I have finished building a 37", 1.25 kg F-35C from depron and 3/4 oz fiberglass. I am extremely pleased with the final product, and I am very excited for the maiden.**

Finished and flying great!

F-35C 68mm EDF (2 min 41 sec)



[I'm in the process of designing plans for a larger scale (roughly 39" span) F-35C. I will be using 6mm depron, and I will fiberglass the depron. The plans I am using are modified from au117's F-35 overall layout.

Gear I will be using:

Alloy DPS Series 68mm EDF unit with 3580kv : (235g)
1.7kg (3.78 lb) thrust

E-flite 60 amp ESC (66g)
Turnigy 2200 mah 4s 25-50C battery (238g)
Servos: Undecided, I have several 9g and 15g servos

Ailerons, Elevators, and Rudders. *no longer using retracts, but steerable nose gear*

AUW: Looks to be around 1100-1200 grams (~2.5 lbs)
332 Watts/lb

Please give me any advice, structural..mechanical...anything! I've only dealt with smaller scratch build planes from 10" to 18" wingspans.]
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Last edited by DoubleOne; Feb 24, 2013 at 02:37 PM. Reason: Updating progress/information
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Old Feb 05, 2013, 06:02 AM
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Denver CO
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my advise is always the same.

Keep it light!
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Old Feb 05, 2013, 02:38 PM
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United States, MD, Annapolis
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Should I avoid glassing the depron, and just use carbon fiber supports for strength? I know that would keep the weight down quite a bit, but I'm using an EDF with 1.7kg thrust and I don't want the plane to fall apart in the sky!
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Old Feb 05, 2013, 08:06 PM
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Not around here. we glass everything, and cross our fingers :P
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Old Feb 05, 2013, 10:26 PM
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United States, MD, Annapolis
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Thanks D_FAST,

I did hours of research on glassing and it looks very plausible. I already have polycrylic miniwax, so when I finally get the build closer to completion I'll pick either 1/2 or 3/4 oz per yard FG.
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Old Feb 06, 2013, 02:55 PM
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United States, MD, Annapolis
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Could anyone give me some advice on what kind of airfoil I should go with? I've always gone with a flat wing...but I would like to improve the lift coefficient as well as the strength of the wing.

Obviously I don't want a crazy, high lift airfoil or anything too complex (not trying to reinvent the wheel).

I am leaning towards a clark-y because of the ease in design, but at 11.7% thickness I don't know how it will look on a jet, and how it will perform for an EDF.



Thanks!
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Old Feb 06, 2013, 03:12 PM
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United States, MN, Hermantown
Joined Dec 2008
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Download the free version of profili2, and you can print out any airfoil they have to see how it will look. When you choose a certain airfoil and go to print it, it will ask what size in length (mm) plug the numbers in and your all set to go. It really is very easy.

http://www.profili2.com/

Good luck and have fun!
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Old Feb 06, 2013, 06:33 PM
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Thanks Cooler, that program is pretty sweet!

So, I'm considering the GOE 188 airfoil...flat bottom, max thickness 8.94% at 30% chord and max camber 4.39%.

I've created one wing plan with 5 struts, but I feel like the wing will be too thick for an EDF. I have no idea.

Here is where I'm at:
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Last edited by DoubleOne; Feb 08, 2013 at 11:37 AM.
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Old Feb 06, 2013, 07:03 PM
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Here is the basic layout with the actual thickness shown. Advice/suggestions welcomed!
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Old Feb 07, 2013, 09:40 PM
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Progress! My foam arrived, and I've been busy cutting and gluing.

I've added a couple pics to the first post, but here is my current progress!
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Old Feb 07, 2013, 11:56 PM
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More progress...
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Old Feb 08, 2013, 11:01 AM
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I'm trying to sort out the intake duct...any recommendations?

I like awrightbrother's method,

http://www.rcgroups.com/forums/showt...672388&page=45

However, I'm really trying to minimize weight. Do I need an intake duct with this set up? The area transitioning from the entrance to the EDF will remain almost constant (d = 68mm, A = 3,216 mm^2) with the belly of the plane and the splitter.
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Old Feb 08, 2013, 08:41 PM
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This is what I went with.
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Old Feb 08, 2013, 11:11 PM
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More progress!
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Old Feb 10, 2013, 04:01 PM
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Decided to give up on retracts...but I've built the steerable nose gear and rear landing gear.
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