I am interested in building an LSA-legal, Corvair-powered replica of a somewhat unusual warbird (OV-10 Bronco), and in the course of my preliminary design efforts I have run into an issue that it seems should have been answered long ago: what construction methods are best for building the thing? Since it's a replica, one of the major driving factors is that the shape and dimensions will be fixed, and ability to make it look "convincingly" like the real thing is a consideration. But there's little data (that I've found) that lets one directly compare construction methods for the same external shape with the same loads applied on it.
There's a wide variety of possibilities, and what I would LOVE to find is some kind of data that would compare a variety of properly-designed structures to each other... structures with the shape, exterior dimensions, and loading held identical between each one, varying only in construction method. This would allow one to compare relative weights, costs, and building complexities. I've even designed a simplified test structure in CAD for this purpose, but I know the design learning curve is steep and doing this properly means
one has to be well-qualified in EACH method being evaluated (the results are meaningless unless each "sample" is designed to EXACTLY meet
the specified loads only... ANY method can be built "strong enough"
if you just overdo it!)
The lack of this data has been frustrating. Trying to compare wood vs metal vs composite vs X for a structure designed to do the identical job... there's GOT to be some homebuilder someplace who's already considered all these questions and established this data already!! Right?
Hiring a bunch of qualified structural design engineers with vast experience in various construction methods is bound to be both expensive and complicated, unless folks could be found with both the qualifications and personal interest to do this for free. That being said, it might be a worthwhile project, so long as the results were "open sourced" for the benefit of all. Eventually I have to learn some of this in real detail, BUT I think the only way to keep my task within reach is to get this design comparison data to select one desired construction method, before going fully down the path of detailed design. The learning curve is steep and I don't want to climb the same hill ten different ways all at once!
The methods I've thought about so far include:
* Wood - I'm by far most comfortable with this one, though weight may be an issue. For realism the outer surface needs to be solid - thin ply or something else, maybe even a non-structural panel or shell.
* Aluminum - I'd only be interested in pulled rivets, ala Zenith and Sonex. Not much experience with it, but it appears to be easy enough... and it would "look" realistic for an OV-10, a really "dirty" aircraft with many round rivets and such.
* Composites, specifically Fold-A-Plane (like Personal Cruiser) - I really like the concept, and since most surfaces are flat or gently curved except at the corners, should be suitable. I did work for a fiberglass homebuilt manufacturer years ago, and know I do NOT want to deal with composites too much, though the FAP concept appears much less difficult and messy overall.
* Aluminum angle (like Texas Parasol / Chuckbird) - I like the general idea, but am unaware of it being used on other (bigger) designs. Would need outer covering of some sort. the corners on the OV-10 are not sharp angles so would need formers, shells, skin, etc. added to obtain the final shape.
* Aluminum tubing (like Kolb tail boom, Aventura, Sky Ranger) - would require some kind of lightweight structure to give it the proper shape.
* Wood or metal load-bearing structure, covered by an exterior composite frame.
* About steel tubing - Yes, it's the old standby, BUT: I don't weld, don't really WANT to (I worked for homebuilt bipe manuf. until last year, I know a bit about tube structures and what they take to build and I just don't think it's something I'd really enjoy much), and know it would cost a bundle to have someone else do it for me. To me, this is something that's just going to be used for certain sub-assemblies (engine mount & landing gear) unless it's proven it's the only way to achieve the final goal.
Given the type of plane, I think fabric covering is unlikely to look right... although the Loehle 5151s "work" in an aesthetic sense, so maybe it's possible.
As always, cost, ease of construction, general durability / maintainability, crash safety, etc. are always important factors as well. Given that I am seeking to create a 2-seat LSA with a 100 HP pusher and it's a draggy airframe, I suspect weight reduction will rule the day in the end.
Anyway, if anyone has any advice to offer on how to best determine this, I'm all ears! I hope I don't sound too naive... but having been near homebuilts for most my life, and working in the industry long enough to see some of what works and what doesn't, I have come to believe strongly that half the battle is just deciding that you really can do it if you try. So I figured what the heck, a little here and a little there and eventually, you'll get there, even on an ambitious idea like this!