Gotta love that RealAir Duke; I'm starting to dig it more and more. Beautifully made cockpit, and the flight dynamics make flying it quite a dream.
For anyone that's never attempted a landing in this specific product, you must first edit the aircraft.cfg, specifically the contact points.
point.1 =1, -8.04, -5.40, -3.94, 6000, 1, 1.00, 0, 0.30, 2.50, 0.36, 3.1, 3,1, 2, 152, 200
Find the above entry (there are only 3 under "contact_points") and change that comma to a period. Otherwise, when you finally try to land the left main gear bay will open, but no wheel will be present. I belly-landed four or five times before it occurred to me that I might not be just crushing the gear so much as not having a gear there AT ALL. Took me a bit of interweb searching, but I found the culprit.