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Old May 13, 2014, 09:32 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
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Forward swept 55mm EDF wing

I'm almost done building this wing, I didn't think to make a thread until now.
It has a KFM-2 airfoil, using strategies learned through flitetest.
I have one question - the spar is at 40% chord, where the kfm-2 should be, but the top surface (intentionally cut oversize) goes to about 50%. Should I cut the top surface back the the spar, or will it work fine at slightly <50%?
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Last edited by boaterguy; May 13, 2014 at 09:38 PM.
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Old May 14, 2014, 05:14 AM
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just build & fly
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Old May 14, 2014, 08:01 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
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The maiden didn't go so well, the CG was way too far back and it would just pitch up as soon as it was launched, the wing may be too big for the weight of the plane.
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Old May 15, 2014, 05:04 AM
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get CG right & try again wing is never to big
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Old May 16, 2014, 04:34 AM
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D_FAST's Avatar
Denver CO
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http://wingcgcalc.bruder.com.br/en_US/

enter your data into this. just use - values in the sweep to get the forward swept wing

fyi

a forward swept wings tip, needs wash in, not wash out
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Last edited by D_FAST; May 16, 2014 at 04:43 AM.
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Old May 16, 2014, 05:58 AM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
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There is not wash in or out as it is foamboard and I wanted to keep it fairly simple.
I had previously calculated the CG, but before redesigning the fuselage I could not get it far enough forward, I just tried it anyways.
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Old May 16, 2014, 06:42 PM
Aka: Tom Jenkins
ApexAero's Avatar
Palm Beach County, Fl.
Joined Aug 2008
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This is coolness at its best to me! Glad to see someone doing a SF EDF!
You'll find it needs a long fulcrum out in front to balance, did you use full elevons or split the control?
The fastest I've ever flown R/C has been on a SF wing! right at 230mph!
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Old May 16, 2014, 07:28 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
2,274 Posts
Well it didn't fly, I tried CG forward, back, right where the calc said, nothing worked.
After enough crashes it was no longer flyable.
Attempt number 2 will have a 28" span, 8" root, 6" tip, 4" sweep from root TE to tip TE.
The 55mm EDF unit is wrecked, something got into the blades, I can't decide between getting a big enough ESC for the 70mm unit I have or getting a new 55mm EDF.
Thoughts?
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Old May 16, 2014, 10:42 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
2,274 Posts
I guess I shouldn't be posting here anymore but since it's already a build thread I'll do it here.
I converted the EDF motor to a pusher config and will run it on 2S either 2650 or 2200mah.
I need to come up with something for the fuselage, any ideas?
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Old May 17, 2014, 05:07 AM
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Not the same as EDF but you can keep it here
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Old May 17, 2014, 02:08 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
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space 1, I'm Ok with it if boaterguy want s to keep it here.

So how about this??
OK, Not the same as scratch, but when I'm ready can I post it here?

I asked this question, with mixed results-- Where would you post this kind of build?
http://www.rcgroups.com/forums/showthread.php?t=2121119


Designed as a pusher, converted with lots of work for edf. Inside needs to be totally gutted, formers for edf, retracts, and flying stab ( bearing plates, shaft, and control horns. I need to cut new wing cores, (need bigger ones to make it a C model) , and will have Y/A spars--removable wings. Some or all of the inside will be glassed, along with entire outside of fuse.

BTW, this is 64" long , WS, will be 46" after new cores. JF90/Het 1200K on 12s...approx weight--11-12lb.

After thought-- pics of how stab shaft , bearings and control horn are set up
Right from the Y/A manual.
http://www.rcgroups.com/forums/showp...3&postcount=58
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Old May 17, 2014, 05:30 PM
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lots people call that Kit bashing I thank here is good
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Old May 17, 2014, 06:56 PM
Do it Right, the first time!
CoolerByTheLake's Avatar
United States, MN, Hermantown
Joined Dec 2008
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My apologies to boaterguy, I got a bit carried away. Hope you get it all figured out..

"Kit bashing " To the extreme.
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Old May 17, 2014, 10:53 PM
Thermite + ice = Big boom.
boaterguy's Avatar
Canada, ON, Ottawa
Joined Apr 2009
2,274 Posts
My cg was too far forward on the last flight and it crashed into the ground. I need to get more hot glue and try to get it up tomorrow (if not, I'll take a pill, that should get it up ).
On a completely unrelated topic, has anyone found a good tutorial for the Taranis?
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Old May 18, 2014, 04:38 AM
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Denver CO
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Quote:
Originally Posted by boaterguy View Post
On a completely unrelated topic, has anyone found a good tutorial for the Taranis?

not sure about a tutorial. But i do know ive stumbled onto a 1500+page thread on here.
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