More info' for you. Huma is a small German company, in the UK their products are imported by a company called Pocketbond who do not sell directly to the public but who are a trade outlet. Not sure where you are but I'm sure it won't be hard for you to find an importer for Huma products.
The Flettner 282 is product number HM6500
The Focke Achgelis (twin rotor) is 1/72nd & is also a Huma product, Number HM5000.
The U boat 'kite' (drache in German I think) I can't find, I have an idea it may have been a Focke Wulf product, not sure of that though.
I'm going to be away from the forum for a few weeks, home to England on vacation.
So good luck.
Pete