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Old Jun 03, 2012, 01:35 PM
TimJC is offline
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United States, OH, South Lebanon
Joined Jul 2005
304 Posts
After seeing my 40 inch wing fly, my dad asked if I could build him something a bit bigger, so it would be easier to see at range. Since he hasn't flown RC, bigger, lighter (wing loading), and slower are all good things.

I took the design from my 40 inch and altered it a bit. Being a bigger plane, finding the CG should be less of an issue, sine there is more room, so I decreased the sweep from 35 to 28 degrees. Using this I scaled it so each of the four wing panels would make the most of a 20"x30" Dollar Tree foam board. The result was a 55 inch wingspan and around 630 square inches of area. In addition to scaling it up, I also tripled the foam spars, boxed in the prop slot, added support wedges to the nose, and enlarged the hatch for a second battery option.

The maiden didn't go well. The plane kept nosing up, and rolling to the left. I tried trimming it, but nothing worked. After a scary landing, I noticed the left control rod broke free from the carbon tube it was glued into, and the left elevon was stuck up. Since the push rods are so long I decided to replace the middle section with carbon tube to eliminate flex. What I should have done is slide the full, uncut, push rod through the carbon tube and CA it somewhere in the middle.

I have that issue sorted, and I will likely remaiden it again tonight with my dad in tow, since it is his plane. For the remaiden, I have added 2oz of nose weight, just to ensure a safe, nose heavy CG, bringing the AUW from 25 to 27oz.

Specs:
- 5 sheets Dollar Tree foamboard
- 55 inch (1397mm) wingspan
- 630 sq in wing area
- 40 amp ESC
- RCTimer BC2836-6 1500KV motor
- APC-E 8x4 prop (23 amps) for low speed and high thrust
+ Will use 7x6 prop later
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Last edited by TimJC; Jun 03, 2012 at 02:03 PM.
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