cowled fuse-kits for 1/2A profile scratch-building

Thanks Kari. Years ago I put together a boxed 1/2A C/L profile scratch-build kit as a "Yankee-swap" gift for a club Christmas party. It was a big hit.

I'd need to provide more fabrication to this concept, to make it worth the cost of shipping. A garden-variety profile model fuse-kit doesn't consist of much more than a plank of balsa. A cap-cowl (less fabrication) like the ones I use, can be obtained locally and cheaply by anyone.. therefor the "short-kit" was a dumb idea. If I built the nose; engine/cowl mounts installed to fit a particular/common Cox .049 engine-configuration, cowl-holes all pre-drilled and a hardware package that included a NV-extension.. it might be more attractive.

I figured that omitting wing/tail parts would be cheaper and allow the builder to choose what they wanted. I have boxes full of 1/4" balsa and a few dozen cowls.. so it would only cost "me" the price of a shipping-tube.. and my time to fabricate.

Thanks for commenting. I appreciate it.

KariFS wrote:

OVERLORD wrote:Kari, it says it on the plan: Model Aviation:

http://library.modelaviation.com/ma/1987/2

Lieven

'Scuse me while I slap myself on the back of my head a couple of times and yell stoopid

Didn't realize that was the name of the publication. Thanks. I read the article and one of the kids had actually built a plane with an aerosol cap for a cowl. Kinda like a Corsair but with straight wings.

Ha ha! Thanks guys! Kari.. stop slapping.. I've slapped myself enough for both of us. The "Pattern Plane" plan/pic that you posted, is similar to the idea behind my concept. The rough-dimensions/moments are there to get you in the ballpark. Judicial use of a French-Curve turns square-corners into a stylish flying-machine!

Come "Hell or High Water".. I'm going to apply myself more with modeling this Winter. (it's not Winter yet.. is it? ) I have this fear... I have a ridiculous amount of balsawood. It's not finish-stock.. and it's all 1.75" (44.5mm) in width. I saved it from where I worked a few years ago. Leftover scrap from sign-blanks; a 1.75" thick x 24" wide x 96" long laminated/finish-planed "plank".. (picture a solid-balsa closet door..). The laminations were 6"W. x 36"L. butt-jointed on the long side.. and finger-jointed at the end-grain.

Finger-joint example.. (super-tight/strong)  



Four profiles in the X-shape of a rolling-pin and wooden-spoon were router-cut from the blank to make a "Bakery" sign. I ran the CNC routers. Scrap was discarded.. so I ripped boxes full.. down to gen. hobby sheet-thicknesses (1/8", 3/16" and 1/4") using the panel-saw in the wood-shop. The lengths that I ended up with, vary from 18" to 30". We made 100's of those signs for a major supermarket chain in the Northeast U.S. When I think about the amount of useable scrap-balsa that was thrown away.. it makes me sigh.. because I think about the amount of models that could be built.. the retail-cost of wood today.. and all of us who love to build model airplanes. My fear; is that I know that I'll never come close to using it all in my lifetime. I want to share it somehow.

Grain-pattern and density varies WIDELY.. as there were no structural demands on its intended end-use. Some pieces are very dense/heavy C-grain, where others could be considered contest-grade.

I'd probably pick the heavier 1/4" thick stock for my 1/2A cowled profile-fuse kit. Since it's all 1.75"W.; I'd butt-join two pieces (3.5") and rip-down to 2.5" (cowl-opening ID). The leftover scrap-strip can be used for canopy/turtle-deck/belly profiling. My Grumman F8F-2 fuse started-out pretty much square. The 1/4" hardwood rails top/bottom are vertically-spaced 2.5" apart to fit inside the cowl and accept #2 wood-screws to secure it.




The belly and canopy profiles; I studied drawings of.. and drew-out on scrap-pieces with a French-curve.

prototype with Babe Bee vertical engine..



The nose of the fuse ended-up being designed completely around the Cox Horseshoe backplate and the cowl I planned to use.





Having built it; replicating for that same cowl (I have many..) would be relatively easy.. maybe not quick.. but easy. I have some ideas for the cowl's horizontal-bracing that I want to try. My Bearcat has six-point bracing. I'd like to try a single 2.5" long plastic stick or rod as a "spar-brace" that would locate just behind a 1/32" ply fire-wall skin. I'd have to notch the 3/8" sq. backing hardwood cheek-blocks in their centers for it to pass-through the nose on-center. That would provide four equal radial-points of bracing.

I know that it can be hard to read this stuff and picture it. I often design through writing. It moves an idea/image/calculation from my brain to a hard-copy. Sorry about that.. but many of you will choose to read this far.

Wow.. Finland is roughly at the same latitude as the state of Alaska, here in the US. Thanks for taking the photo! In what town do you live? That's a beautiful area! Of all the places in the world I've wanted to visit; the Scandinavian countries have topped my list since I was a child. I've always wanted to see their fjords/fiords.

I hope your son feels better.. and I hope no one else gets sick. Maybe open the windows for an hour or two.. 7 deg. F would kill most germs that I know of..

Sitting by the warm fireplace, dreaming-up model-airplanes sounds inviting! Put on a pot of coffee.. and I'll be right over!

Absolutely beautiful area! Very picturesque. Thanks for sharing the link!



I like your 4-point cowl-bracing. My Bearcats' cowl is six-point but I only needed a top and a bottom wood-screw to fasten it, due to the ridge inside the cap. You could use two screws (top/bottom) if you install stop-blocks (PVC/PVC-cement?) inside the back of the collar for the horizontal bracing to bear on, eliminating side-movement.

I'd like to test a cowl-mount/bracing with alternate fasteners. Tiny snap-closures (craft-jewelry items) would be cool if they could be mounted securely.. maybe even hook & loop (Velcro) tabs or magnets. It would be nice to be able to easily pull the cowl off after removing the prop.. but there's also the needle-valve to consider. Maybe just an "access-hole" could be drilled in the cowl.. and a needle-adjusting tool inserted to tune the engine.. and then removed once tuned? Something of a cup that would fit over the needle-knob or shaft and be able to rotate it without slipping. This would eliminate the need for a needle-extension.. and the possible "tuning-fork" effect that can cause settings to wander.

I had an idea for the product engine's brass needle that uses a small hex-socket set-screw inside a brass sleeve. Tap the brass-sleeve to accept the set-screw and solder the whole assembly together.



The hex-wrench could be sleeved to form a "cup" for easier locating into the socket.



It's non-destructive to the needle.. and provides a more positive means of adjustment.