@@KlingbergWingMkII I wonder if you could spiral wrap the foam sheet first on a mandrel and CA it together at the seams? Then slide the foam tube over a prepreg carbon sleeve and vacuum bag it together with an outer sleeve of Kevlar?
Hey Rol, Once again I really enjoy your content. Having followed your progress for a long time I know exactly which video you are referring to with the spiral wrapped foam core tube. Love your work.
@@KlingbergWingMkII i'd love to, this seems awesome! when you mentioned the seam problem i immediately thought of just wrapping the foam as a long strip and when you showed the tube i knew that's what you did as well, but i watched the video from 5y ago anyways. is the foam available as a long strip on a roll? using something like that and ud carbon tape would make automating production relatively easy. unfortunately the days are so short, between school, job, faith, personal and hobby there is not too much time left. i'm also doing my bachelor professional in EE not ME, although both are very interesting, i'd love to learn every profession. i've been playing with composites, but the home workshop is small, i'm cutting fabric on the floor and I'm only 22, so at the very beginning of having any experience. another solution might be to fill the tubes with 2k PU foam, that's what i've been experimenting with for my rc slope plank design, had 3 fails so far, but now i know, the next might work and you might want to contact Gideon on rc-network, he's been working in composites for a long time and very experienced
Airex foam is availale here: www.r-g.de/en/home.html It comes in sheets which are easy to cut with a razor blade into the desired width. It can be spliced during the wrapping process (using a little CA glue) to make longer pieces of tubing. If you look through my early videos, you will find that I made samples of tubing with foam-in-place urathane foam. Did not work well due to air pokets and it was heavier. All the foam at near the center of the tube is not needed.
When you say "Carbon fiber is heavier than aluminum..." @6:52 I'm not really sure what you mean because, Carbon fiber reinforced composite typically has a density of 1700kg/m^3 vs 2700 kg/m^3 for a typical aluminum alloy
Those are numbers for optimum CF of 70% fiber and 30% epoxy. The average homebuilder can't get anywhere near those numbers with wet layup. All of my components run about 50% to 60% resin and I work hard to hold that down. Plus by the time a designer addresses the buckling issue, the CF will have a higher wall thickness than is needed for basic strength. For an airliner, going with CF is an easy gain. For ultralight aircraft, it is an entirely different game. Actually, for rigid wing hang gliders, wood can be the best answer for many parts. For my current wing tip panels, one has a composite sandwich panel spar and the other is spruce and plywood. The wood spar is about 1/2 pound lighter. So, when I say "heavier" I'm talking about many factors that go beyond basic density. But of course, all of this is not the key point of the video. The concept of sandwich panel tubing is what I'm trying to "sell" to the community. Sorry, if it was confusing for anyone.
This would be a good project for those MPA students in Japan.
Yes, absolutely. Imagine if one could reduce the weight of an HPA by 20%. Big improvement in range!
@@KlingbergWingMkII I wonder if you could spiral wrap the foam sheet first on a mandrel and CA it together at the seams? Then slide the foam tube over a prepreg carbon sleeve and vacuum bag it together with an outer sleeve of Kevlar?
👍
Hey Rol, Once again I really enjoy your content. Having followed your progress for a long time I know exactly which video you are referring to with the spiral wrapped foam core tube. Love your work.
Cool, thanks
How do you manage longer lengths of tubing
Longer tubing+longer fabric+longer oven! Tubing can be spliced (via various methods) to just about any length.
well funny, i live in germany
Are you good with composites? Want to make some tubing?
@@KlingbergWingMkII i'd love to, this seems awesome!
when you mentioned the seam problem i immediately thought of just wrapping the foam as a long strip and when you showed the tube i knew that's what you did as well, but i watched the video from 5y ago anyways.
is the foam available as a long strip on a roll? using something like that and ud carbon tape would make automating production relatively easy.
unfortunately the days are so short, between school, job, faith, personal and hobby there is not too much time left.
i'm also doing my bachelor professional in EE not ME, although both are very interesting, i'd love to learn every profession.
i've been playing with composites, but the home workshop is small, i'm cutting fabric on the floor and I'm only 22, so at the very beginning of having any experience.
another solution might be to fill the tubes with 2k PU foam, that's what i've been experimenting with for my rc slope plank design, had 3 fails so far, but now i know, the next might work
and you might want to contact Gideon on rc-network, he's been working in composites for a long time and very experienced
Airex foam is availale here: www.r-g.de/en/home.html
It comes in sheets which are easy to cut with a razor blade into the desired width. It can be spliced during the wrapping process (using a little CA glue) to make longer pieces of tubing. If you look through my early videos, you will find that I made samples of tubing with foam-in-place urathane foam. Did not work well due to air pokets and it was heavier. All the foam at near the center of the tube is not needed.
When you say "Carbon fiber is heavier than aluminum..." @6:52 I'm not really sure what you mean because, Carbon fiber reinforced composite typically has a density of 1700kg/m^3 vs 2700 kg/m^3 for a typical aluminum alloy
Those are numbers for optimum CF of 70% fiber and 30% epoxy. The average homebuilder can't get anywhere near those numbers with wet layup. All of my components run about 50% to 60% resin and I work hard to hold that down. Plus by the time a designer addresses the buckling issue, the CF will have a higher wall thickness than is needed for basic strength. For an airliner, going with CF is an easy gain. For ultralight aircraft, it is an entirely different game. Actually, for rigid wing hang gliders, wood can be the best answer for many parts. For my current wing tip panels, one has a composite sandwich panel spar and the other is spruce and plywood. The wood spar is about 1/2 pound lighter. So, when I say "heavier" I'm talking about many factors that go beyond basic density. But of course, all of this is not the key point of the video. The concept of sandwich panel tubing is what I'm trying to "sell" to the community. Sorry, if it was confusing for anyone.