Happy Birthday to me = 4 * 40 - RC Groups
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May 29, 2001, 11:22 AM
Registered User

Happy Birthday to me = 4 * 40

A great birthday present, now I'm contemplating the mods to electric. Can those of you who've done it comment on the efficacy of following possible modifications:

1. Built up tail feathers. The balsa in the kit appears to be light. I was considering just boring lightening holes in it. Will built up tail feathers be a significant weight savings?

2. Moving horizontal stab/elevator to the bottom of the fuselage. I've heard this is good for knife-edge. However won't this create a negative incidence on the stab due to the tapering of the bottom of the fuse? What about the ground clearance?

3. Plan calls for 0 side thrust on the motor mount. Should I induce some?

4. How far out on the from the center of the wing to install servos if using seperate aileron servos? Also, if seperate aileron servos are used should the aileron servo cutout guide (where dihedral brace goes) be enlarged in an attempt to save weight?

5. Balsa copy of the lite-ply fuselage. This seems like a no brainer. Do I go for the same thickness balsa as the lite-ply (1/8" sides, 3/16" bottom)? I'd also read someone had done 3/32" balsa with lightening holes reenforced with 1/64" ply. Is this a better solution than just straight balsa?

6. Lightening holes in the ribs. Is it worth the effort?

7. Closed loop controls. How much will this improve performace/save weight?

8. Firewall. Change out to 1/8" birch ply.

Any thing else that I might have missed?

Thanks for any advice on this.

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May 29, 2001, 04:24 PM
Visitor from Reality
Been trying all afternoon to dump a load of suggestions about the 4*40 onto this lot, but it keeps getting spit back - too long maybe.

You're looking at most of the good ideas, the stab lowering involves dropping it down as far as possible parallel to its present angle in the fuselage. Doodle it on the plan, it becomes pretty self-evident. Does need a high tailstrut for grass field ops. Check GWRIGHT postings for more. Bigger H stab helps too, I've found - added 1" to LE.

Rest in short - 2- 3 degree sidethrust, taller UC, closed loop on the rudder. Top hatch for pack access, from 3" aft of firewall to just ahead of canopy. Keep the battery low over the wing. My servos are at the end of the wing centre sheet - no in-wing extensions. 2" higher UC to get more clearance for bigger props, beef up UC mount.

Holes in things only improve morale while building. 1/8" Birch ply firewall - yes.

Search on 4*40 or Four Star 40, much of this is around, or drop me a line on direct for other hints.