fibreglass fuse modifications
01-23-2004, 05:29 AM
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fibreglass fuse modifications
I recently brought a new high performance glider, and it has a fibreglass fuse. I was wondering if it is possible/praticle to use the oringal way of retaining the wing with rubber bands and two dowels through the fuse, rather than the bolted down wing that the kit suggests? My reasoning behind this is that I like the wing to have some give if a tip hits the ground durring a spot landing, rather than having a solid mounted wing. If I can do this will the fibreglass need to be reinforced or will it cope with the loads? I can post some pics if it will help.
01-23-2004, 12:54 PM
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RE: fibreglass fuse modifications
If the fuselage has a hook shape fairing where the leading edge fits into I'm going to suggest that letting the wing move around will cause more damage than it'll prevent in normal flying.
It's common to use nylon bolts for holding wings on such that if the impact is hard enough the bolts are sheared between the wing and fuselage to try and prevent damage. I have a two meter electric glider that uses two 10-32 bolts at the main spar and two 6-32 bolts at the trailing edge. I used two each because the wing is two piece and the bolts hold the halves together as well as to the fuselage. I've had to do some seriously hard pullups in the life of this model and the bolts held fine. So far I'm happy to report that I have not had to test their shearing ability. But others that have tested the tensile strength of nylon bolts would suggest that my 4 bolts is overkill. If you have a one piece wing I would suggest 2x 10-32 at the main spar and a single 6-32 at the trailing edge will be fine.
And then there is the added drag. If it really is a high performance model then using bands and dowels could easily reduce it's performance to mediocre. I suppose you could use buried dowels and centerline rubber bands much like the original Bird of Time and Gentle Lady do but that would require more mods to the fuselage.
In the end you may be best off to do it as designed and sneak up on the flying part. Practice your approaches so that you reduce the need for last minute direction changes that are so large that you risk the tip hitting first. The flaps will also help with reducing the appraoch speed so that the model doesn't have too much energy. In any event most contest models these days are designed to be tough enough to deal with the occasional ground loop on landing.
It's common to use nylon bolts for holding wings on such that if the impact is hard enough the bolts are sheared between the wing and fuselage to try and prevent damage. I have a two meter electric glider that uses two 10-32 bolts at the main spar and two 6-32 bolts at the trailing edge. I used two each because the wing is two piece and the bolts hold the halves together as well as to the fuselage. I've had to do some seriously hard pullups in the life of this model and the bolts held fine. So far I'm happy to report that I have not had to test their shearing ability. But others that have tested the tensile strength of nylon bolts would suggest that my 4 bolts is overkill. If you have a one piece wing I would suggest 2x 10-32 at the main spar and a single 6-32 at the trailing edge will be fine.
And then there is the added drag. If it really is a high performance model then using bands and dowels could easily reduce it's performance to mediocre. I suppose you could use buried dowels and centerline rubber bands much like the original Bird of Time and Gentle Lady do but that would require more mods to the fuselage.
In the end you may be best off to do it as designed and sneak up on the flying part. Practice your approaches so that you reduce the need for last minute direction changes that are so large that you risk the tip hitting first. The flaps will also help with reducing the appraoch speed so that the model doesn't have too much energy. In any event most contest models these days are designed to be tough enough to deal with the occasional ground loop on landing.
01-23-2004, 07:44 PM
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RE: fibreglass fuse modifications
Bigsport
In addition, some drill a small hole down the center of the nylon bolt to aid in the shearing effect. An old trick that had been passed on by Ollie. Ensures the bolt will shear at the plywood brace in the fuselage, with minimal damage to the wing itself.
R/
Gene
In addition, some drill a small hole down the center of the nylon bolt to aid in the shearing effect. An old trick that had been passed on by Ollie. Ensures the bolt will shear at the plywood brace in the fuselage, with minimal damage to the wing itself.
R/
Gene
