Since my RV is "done" I've been exploring ideas for another project. Still 3 hours to go before my phase 1 test is up, but thinking about things I want that the RV doesn't quite do. It's aerobatic enough, and fast enough for the tiny amount of cross country I do, but not quite suitable for getting into the back country. Takes off and lands plenty short, but the gear (especially the nose gear) has a reputation of not really being up to regular rough country service.
Something like a Bearhawk Patrol would be pretty much my ideal back country plane, but I'd have to come up with another O-360, and then another hangar to put it in. Stretches the budget beyond what I could justify for toys.
Thinking back about some old threads on a plane that would fit in a 20 foot shipping container it occurred to me: If it fits in a container it would also fit in the hanger next to the RV. Re-read those threads, and while there are single seat designs that could work, there isn't anything two seat. Especially not that meet my back country criteria: Fly two big guys (250 lbs each, or a more reasonably sized passenger and camping gear) into and out of a Utah or Idaho back country strip on a summer afternoon. Being at high altitude those strips tend to be long (3000' or so) but rough. A summer afternoon means high density altitude, so good climb performance needed.
Sketching out various concepts, thinking about Kitfox or Grumman style folding wings, or perhaps sailplane style removable. Put togther a napkin sketch with removable cantilever wings and started studying how such wings attach. Watch some RV-12 wing removal videos as examples, and had the other idea: Just use RV-12 wings. Would be able to get an easy to build kit for wings that are well engineered and already have 600+ examples flying. Takes one big part of design and would move it straight to the "done" column. More expensive than scratch building a custom design, but save tons of time.
The RV-12 is designed to LSA specs, so 1320 lbs with a VNE of 136 KTS. It can carry two 250 lbers but not with full fuel. At 127 ft^2 and 26.75 ft span smaller than what I was sketching, but still shown to have a 45 kt stall speed at that 1320 lbs.
When I started looking at the RV-12 in more detail, I was suprised to find how close it comes to meeting the 20' container criteria. The wings come off for trailering, the overall length is 19'11" (8" too long) stabilator is 8' wide (3" too wide") and the height of the vertical stab is 8'4" (6" too tall). You chould just about put the nose gear up on a ramp and get it in the box. Doesn't have the off road landing gear I want, so not really relevant to my goals, but a worthy contender for someone who wants something that can fit in a smaller hangar/garage type space.
So, take RV-12 wings and put them on top of a simply boxy fuselage. Build the fuse out of either steel tube or riveted aluminum. I have the riveting tools and skills and have always wanted to learn to weld so would be happy going either way. Power with an O-200 or Rotax 912. Fuselage is 44" wide (same as RV-12) so bigger than a 172 or the RV-7 I did my transition training in. Not super comfortable with two big guys but doable.
Put the engine as far back as you can, then put the seats on the CG position so handling doesn't change much solo vs. two up. Make the fuselage tall so I don't have to duck down to look under the wing. Small baggage shelf behind seats. Big tires and shock absorbing landing gear.
Set the horizontal stabilizer span to 7.5' so it fits in the box, then expand the chord till it has the same horizontal tail volume coefficient as the RV-12. Trailing edge of rudder has to sweep forward to fit in the box with the wheels on the ground, set the vertical size much the same way as the horizontal. (I include the part of the vertical inside the fuse as part of this calculation given the flat sides).
With the design criteria and simple shape an obvious name suggests itself: The Box Yours Came In.
TBYCI Three views (red box is interior of 20' container per wikipedia):
TBYCI Modeled in X-plane:
And, TBYCI sharing a hangar with an RV-8A:
This is getting kinda long, so will put performance estimates in another post.
