U-2R Dragon Lady 1/105 indoor glider conversion

[ReynoldsSlumber]

This is a downscale of the paper trade Lockheed U-2R Dragon Lady USAF 1/30 plans, by Cor van Haasteren. It was a little too much of a downscale for the fidelity of model I was looking for, as it got pretty finicky with the middle portion of the fuselage, especially the air intakes. I'm realizing that builds will be more enjoyable throughout when the fuselage is at least as big across as my pinky finger! Happy with the results though.

I used 80 lb tag/130 gsm Blick Studio Drawing paper, inkjet printed, with thicker paper for the bulkheads. While the Blick paper's surface texture causes some speckling within printed areas and feathering at their edges (which meant that the white wing panel lines pretty much disappeared), I wanted to give that paper a try because it is thick and therefore stiff compared to other papers of similar weight. Also its off-white color wasn't a problem, as it was entirely printed over. It turned out to be just about the right thickness, the main issue being the wing leading edge didn't quite curl cleanly. Next time I'll have to try ricliete's method of multiple parallel score lines along the leading edge. The trick there is that, since I'm modifying the airfoil, I'm not sure beforehand exactly where the leading edge is going to end up. For other models with stockier wings I'll probably use thinner paper. Also I might try to squeeze in a few wing ribs, for consistency in the modified airfoil shape.

This is my first time using bulkhead formers throughout. I appreciated that they fully constrained the fuselage geometry, and they stiffened the fuselage without too much weight penalty, especially since I'm learning to keep glue application to a minimum. One thing to watch out for on the center body joiner pieces: the part numbers are printed oriented with the tail up, not the nose up (!). For getting the bulkheads into position, I ended up capturing them between two metal tubes and sliding the body segment into place.


Aesthetic modifications:

• 24 lb bond/90 gsm vellum (tracing paper) canopy
• Omitted landing gear and antennas
• Colored in body areas where the altered airfoil exposed unprinted paper
• Extended the engine intake lip to curl around to the inside

Modifications for flight as an indoor paper airplane:

• Changed the wing airfoil to have a zero-thickness aft portion with undercamber, for good small and slow aerodynamics. Moved the spar forward to match, and shortened it to save weight. Modified the wing pods to match the airfoil.
  
• Added a bit of wing dihedral, for roll stability. Though on the real thing the wings did flex upward when it was fully loaded, so it's not really a departure.
• Changed the tail airfoils to have a zero-thickness aft portion, so that they can be bent for trim. Omitted tail spars to save weight. Added glue tabs to the tail surface attachment edges.
• Omitted joiner strips (except for wingtip attachment) to save weight.
• Added a clear plastic finger grip tab to the belly.
• Replaced the tip of the nose with a piece of 2mm thick craft foam rolled up inside the nose cone and sticking out, to absorb impacts with furniture etc.
  
• Added copper wire for nose weight, balanced with test flights at the furthest aft stable center of gravity.
  

[ReynoldsSlumber]

So, how does it fly? On a good throw, like it's on rails. With big, high aspect ratio wings, it was pretty much guaranteed to be a good glider. Given the mid-mounted wings and almost no dihedral, as you can imagine it's barely stable in roll. Not much self-righting going on there. The nice part though is that if you want it to fly along a horizontal arc, you can throw it with some bank, and it'll pretty much hold that bank throughout the flight. In yaw, with the short tail and small stabilizer surfaces relative to the overall size of the plane, if launched askew it'll do a slow side-to side shimmy, or to put it perhaps more accurately a sashay. Meanwhile in pitch it's not too sensitive to elevator, so getting a consistent glide isn't very difficult. The main thing is to throw it straight. Fun to fly! It has a real presence in the air, albatross-like. Gliding speed is around 12 ft/s (3.7 m/s).


Here's the 1/105 U-2R next to the plane it replaced in service, represented by the static 1/120 WB-57F model that I built before. Picture the WB-57 at 14% bigger than seen here for proper proportionality.

[mbauer]

Nice Build, great flight report.

Mike

[Draco]

Where is the "I love it" button?

[CMDRTED]

Looks excellent. Down scaling is always an experimental affair, trying to build the little doodads, deciding whether to leave the part out, redesign it or try to build it as designed.

[ReynoldsSlumber]

Thanks kindly, all!
Mike, you'll appreciate that the real U-2 has gobs of wing incidence, so that was already built into the scale model plans. Trimming the model to glide took just a bit of up elevator.
Draco, to take that literally for a sec, I was bugging Texman to add that exact feature to the site, ha. But thanks!
CMDRTED, indeed, for example I spent a fair bit of effort (and cursing) making the teeny air diverters that go between the air intakes and the body, but since they're in a narrow spot and the whole thing is a dark color, they aren't visually apparent. Could've skipped 'em, no prob. Also a couple of the body segments could be merged in the plans without any loss in model fidelity methinks!

[Mike1158]

Looks amazing, that it flies is a LOT of icing on this particular comestible.

[dhanners]

Nice build! An attractive airframe….