P-38 Lightning-Roddie style..

balogh wrote:Roddie the plane is very nice.
As for the wing tips I would reinforce them by gluing a flat carbon strip along the "spar" or 2 along the leading and traveling edges both. Flat enough not to bother the aerodynamics, the carbon strip would definitely make the tips stronger and resist snapping.

Thank You for the "tip" Andras!!! I will reattach the wingtips with some sort of thin over-lapping reinforcement material.. possibly "carbon-veil". So far; cyanoacrylate just keeps breaking-off at the joint.

Hobbyshops sell thin glass fibre hinges to be soaked in CA glue. That is also a thin material and provides strong overlap without compromising the airfoil.

Darn it roddie, I spent countless hours on my scale P-38, measuring, doing the math, cutting, trying, moulding, sheeting, constructing and adding all the little bit's and pieces, then went out and flew the thing. Time for procrastinating is over.

Just fly the thing. It's only balsa.

In the best possible spirit.............

Bob

PS - Same for my MG, many agonizing hours spent. Not for looking. When I'm finished I going to drive the crap out of it.

Butt sand the wings where tips break off.

Make new tips.

Attach with epoxy.

Go fly airplane.

... or leave the tips off completely. Some racer Warbirds had clipped wings for greater speed:

KariFS wrote:... or leave the tips off completely. Some racer Warbirds had clipped wings for greater speed:

I was going to suggest that as well. Whatever you do get that thing in the air!!!

Pushy? I'm about ready to climb in that half built MG and head for RI with my flight box and be roddies pit man. Eight pages and still thinking. Enough already! Vintage Triumph on the go. Thumbs up.

Kidding a bit roddie. Different strokes for different folks.

Bob

wonder were all those greenies are coming from.

I'm going to "redo" the lead-outs. I made the terminations at the wingtip; without the wingtip being glued back on. A dumb mistake.

(Sorry for the blurry image.. it's in tune with the night I did the work.    )



There's a risk of the crimp-tubes snagging on the wingtip.. once it's glued back on.

I'm keeping the wingtips on the model. I like the contour.. and also want to keep the span at 26" (1/2" scale)

Good point about the span. If you want to stay traditional, you could use tissue as a reinforcement for the wingtips. If you cover the tip entirely and overlap to the main wing by 1/2” or so, you’ll get a stronger joint and also protection against little dents and dings.

I can't seem to upload any images tonight.. but I removed the bellcrank from the P38.. and cut-off the lead-out cables. I'll be able to utilize those long cables on a single-engine 1/2A model in the future.

I found an unopened package of K & S copper-tube 3/32" x 12"L x 3 pieces.. that I didn't realize I had. I cut a pair of 24" length .015" 7-strand stainless cables.. and "re-did" the connections at the bellcrank.. and will post some photos when the image-server is back on-line. Until then; I need to get those wingtips straightened-out..

These are much better than the first attempt. I also have to remember to "stagger" the outboard terminations when I make them, so they don't get caught on each other. The guide-eyes are about 1.0" apart.

944_Jim wrote:Roddie,

Where did you source the tubing?
$2 for the bundle is too good a deal to pass up. I'm finding it closer to $5 plus S&H...that makes it closer to $5/stick!

That bellcrank end keeper, is it Homebrew or commercial?
It looks like an easier method than bending cleanly, or soldering.
Thanks in advance.

Hi Jim, The K & S 3/32" copper tubing came from a LHS that closed in 2014. A lot of the prices on items were outdated.



The "keepers" on my pushrod (both ends..) are 1/2A spring-style wheel retainers. Cox International had some NOS packages a while back. Sig used to stock them.. but no more. The thing is; you must use 1/16" (.062") music-wire for the pushrod. The "L-bends" really simplify the whole thing.

Ken Cook wrote:            Roddie seeing how you like those so much, I would give them a call. I know they're still made. I looked this up before and they don't list in a search but they did have them  SIG SH121... 1/2A WHEEL RETAINERS 1/16

           Send a inquiry to Becky Van Dee   becky@sigmfg.com with this part listing I posted.

Many thanks Ken! Yes.. I use this simple part for many applications.

When I designed this model, I made its sheet-wing from dis-similar wood-types. The "core" is 1/8" (3mm) basswood.. with 1/8" balsa leading/trailing-edges.. and wingtips, butt-jointed to the basswood.

The balsa pieces were all edge-glued to the basswood with CA.. but as previously mentioned; the "wingtips" have broken-off during handling (more than once..) with discouraging ease. I'd "braced" the tips (top/bottom) with 1/64" plywood strips in anticipation of a problem.. but should have made the tips with their wood-grain running span-wise.. rather than chord-wise.  




So.. I re-glued the joints once-more.. and decided to try an experimental "skin-graft" using strips of "used" laundry fabric-softener (dryer) sheets.. saturated with thin CA glue.



Sanding to a semi-smooth substrate went quick and easy.



I applied vinyl spackling.. and feather-sanded once it had dried.



I won't fuss too much more with imperfections and little surface-dings. The wingtips need to be re-primed/painted, followed by a "misting" of rattle-can clear polyurethane over the entire model.

We're still under 11oz. which isn't too bad for a U-control 1/2A twin.