I was just wondering if it was possible to mould carbon fiber over a wing template to create the wings of the XL instead of creating an intricate spruce structure. Not that I would replace the current design with it, I always wondered if there was a lighter and stronger alternative as I see a lot of new equipment out there made from thick carbon fiber shells.
The solution to galvanic corrosion in carbon fiber connections is to use titanium or one of its alloys for your hard points. this generally ends up building a NON-reparable part, but if the labor saved pays for the part, I am all for it. Carbon fiber tapes or rods could be laid into the caps of a foam and fiberglass spar giving you the strength without the other.I have assisted in the calculations several times on this, and it generally comes out the same- i.e. when calculations for the spar caps come into play, we can easily plug in and come up with the required carbon rod needs. For example, lets say, we need 4- .125 diam rods for 4 feet, then 3, 2 for another 2 foot, and then 1 for the last. (all starting at the root) All easily calculated. (once you decide which formula is correct) And you know what weight savings you will have for this “spar cap material” which is generally a great savings. So then we need to calculate the spar web and or base these rods attach to. There in lies a major problem, as the rods are so strong for their size, how do we insure the base is strong enough to hold them under extreme load. Soon a simple formula turns into a massive head scratching event. I have no doubts that someday this will be all figured out and have great hopes for that.. And folks like J. Marske and others have gone a long ways, but generally come back to full carbon fiber webs and rod cap supports (i.e. cost) Certainly a catch 22 I once made a rib out of blue builders foam at an airshow. Someone had a booth for hands on demonstration. Nothing to sell, just introducing people to doing something. 3/4 builders foam cut rapidly on a router table with a template. Using Tite bond, you glued a 3/4 " wide rattan edge band from a big spool of the stuff and it was done. I dismissed the idea as not enough rocket science for the jerk that I was ( now a jerk for different reasons, I grew out of that and into something else)I smiled at this Tom, doing demos and lighting the fires is where/how many great new ideas form. I suspect what was being shown was how strong the material can be made quickly. Where the problem starts is how this material reacts under the wing load conditions. Some might call this concern “bond shear” with one area certainly strong enough, with the other area not strong. Just a matter of how to make both a combined “strong” The answer is close…but not sure it is out there for the common builder yet. Please correct me if I am wrong.But I still remember how simple, fast and light it was. I should add inexpensive as well. Tom XL-7Good luck, more importantly, keep it safe
The magic of composites is using the best properties of the best material for the problem at hand. It does not have to be carbon or glass or epoxy to be composite.
Scott If I were to tackle a composite legal eagle fuselage. I would go monocoque.You once made a drawing of a body for the XL. It was green. That would be a great starting point. Then again maybe I will just weld up the steel I have on hand and call it a month.Tom XL-7