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Building Tips and technical articles. => Building techniques => Topic started by: Allen Eshleman on May 22, 2019, 08:39:20 PM
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Is it possible to make a stronger profile fuselage by making a several layered one glued together, or by putting 16th inch thick outer layers on a 1/2 inch fuselage. Getting ready to build a Shark 402.
What about using a 5/8th inch board instead of the 1/2 inch one?
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Anything that is made from layers will be stronger and stiffer than a single piece of wood. careful selection of wood can do the same thing. If you are still in the frequent crashing stage, nothing may hold up as indestructible. Look for a heavier, grainier piece of wood for the fuselage. If nothing is to your liking, you can fiberglass the whole thing also with 1/2 or 3/4 ounce glass and thinned epoxy, just don't go over board with the epoxy or forget to sand things along the way. Laminated pieces with thinned epoxy and carbon fiber veil in between works also. Lots of ways have been described in this site. Good time to get familiar with the search function.
Type at you later,
Dan McEntee
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Is it possible to make a stronger profile fuselage by making a several layered one glued together, or by putting 16th inch thick outer layers on a 1/2 inch fuselage. Getting ready to build a Shark 402.
What about using a 5/8th inch board instead of the 1/2 inch one?
Go down to Wallmart and buy 2 target arrows. They are $1.00 each. Using an exacto carving knife, hollow out the top and bottom of the fuselage from the mid point of the wing to the stab and epoxy two of the arrow shafts in the slots (remove the feathers). If you are worried about the weight, don't. Those arrows are probably lighter than the balsa you removed. You now have a bullet proof fuselage in a crash and you have eliminated 90% of the flex, about half of the twist and you have not exceeded the legal width. Now here is the fun part. Put a pin through it about 3" from the tail and you have a BB tube for tail weight.
Ken
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Glue joints will definitely make it flex less. I'm flying a Magician that I drilled a hole diagonally from tail fwd over the wing and inserted a length of K&S aluminum hollow tube. It decreased fuse flex a good bit. The fuse was two lengthwise pieces and built with very light wood so I needed to help prevent flex. I've also done the same using bbq skewers and hard dowels. I've used round tooth picks in horizonal stabs to do the same thing.
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This is something that Tom Farmer showed/told me about probably 18-20 years ago, remove the wood between the wing trailing edge and the L/E of the stab, install diagonal bracing in its place, then install 1/64" plywood down each side from nose to tail after installing the motor mounts using 24 hour epoxy to install the plywood, and you will have a fuse that will not twist/flex at all... It always worked well for me.. y1
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Is it possible to make a stronger profile fuselage by making a several layered one glued together, or by putting 16th inch thick outer layers on a 1/2 inch fuselage. Getting ready to build a Shark 402.
What about using a 5/8th inch board instead of the 1/2 inch one?
The arrow idea is your best bet, I'd say. Use 1/8 sheet sides, glue the arrows along the top and bottom. Put in a row diagonal braces running from above the wing. Cap the top and bottom with 1/8-1/4 in. strips. 1/8 sheet won't need any further reinforcing. 1/16 in is liable to develop hollows if not well supported.
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The arrow idea is your best bet, I'd say. Use 1/8 sheet sides, glue the arrows along the top and bottom. Put in a row diagonal braces running from above the wing. Cap the top and bottom with 1/8-1/4 in. strips. 1/8 sheet won't need any further reinforcing. 1/16 in is liable to develop hollows if not well supported.
I have done it your way too. Yours is better if you don't already have a fuselage. I use those stupid arrows everywhere I can. Cheaper and lighter than a 1/4" hard balsa strip.
Ken
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I built my 402 from the Brodak kit. Wood perfect. No need for extra. 28 oz with LA .25 and stock muffler. You just need to make a 'real' landing gear.
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Truss fuse core and sheet with 1/64" plywood. Pretty light and no flex.
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Truss fuse core and sheet with 1/64" plywood. Pretty light and no flex.
Impossible to fix if the plywood breaks...
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Impossible to fix if the plywood breaks...
If the plywood breaks, what happened to the rest of the plane, motor....
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Allen,
The 1/64 applied to the fuse is extremely stiff and strong. Tom Morris uses this method on the profile Cavalier. I have used this on a Tutor II, just cut some lightening holes (several 2" diameter holes) in the rear. The 1/64" plywood weights about like a medium sheet of 1/16" balsa. If you need to repair glue it back together and use a carbon fiber/epoxy patch over the seam.
Best, DennisT
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Allen, I will reiterate what Dan said in his post. Anytime you laminate sheets/boards together, you will have a much stiffer and stronger profile fuselage. Eric Rule at RSM uses 2 laser cut pieces of 3/16 contest balsa to form the core of the fuselage. Usually the core has voids or cutaways between the wing and stab with geodesic type cross members. Once you glue these two pieces together, you sheet with 1/16 on each side and this gives you a really light and strong fuselage. Tom Morris, as previously mentioned does something similar and sheets the sides with 1/64 plywood. My one and only problem with this is that the cost of 1/64th plywood is ridiculous but still a very good way to sheet the fuselage.
The problem with using a plank of 1/2" thick contest balsa and cutting out a profile is that it has gotten almost impossible to find and if you can, it is usually warped. The supplier I have used in the past has yet to send me a 1/2" x 4" x 36" piece of contest balsa yet that is straight.
I use West Systems epoxy to laminate the pieces with.
Mike
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Impossible to fix if the plywood breaks...
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Tim, why would it break? Oh, nevermind.
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If the plywood breaks, what happened to the rest of the plane, motor....
Nothing good!!!
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My one and only problem with this is that the cost of 1/64th plywood is ridiculous but still a very good way to sheet the fuselage.
A 12 x 48 sheet of 1/64 ply is $20.58 at National Balsa.
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My one and only problem with this is that the cost of 1/64th plywood is ridiculous but still a very good way to sheet the fuselage.
A 12 x 48 sheet of 1/64 ply is $20.58 at National Balsa.
It is a really good way but two target arrow shafts - $2-3.00.
Ken
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My one and only problem with this is that the cost of 1/64th plywood is ridiculous but still a very good way to sheet the fuselage.
A 12 x 48 sheet of 1/64 ply is $20.58 at National Balsa.
I prefer to use a framework of 1/2" balsa, with "RC weight" 3/32" skins. That puts all the strength out where it'll do some good. Be sparing with the glue.
this post (https://stunthanger.com/smf/building-techniques/fancherized-twister-build/msg277642/#msg277642) has a picture of a fuse before laminating on the sides. Ignore the tapered hind end -- that turned out to be too much work and trouble.
(https://stunthanger.com/smf/index.php?action=dlattach;topic=27915.0;attach=112105;image)