So what are these wings all about, you might think?
This fabric weighs about 70 grams per square meter, so in total that will be around 1050 grams. It’s quite a challenge to work with this fabric. It’s strong, but at the same time very fragile. Especially because of the forces it has to cope with during the flights, it’s important to sew the seams carefully, and give the wingshape extra strength without making it too heavy. The top part of the kite will be folded around the ribs to create an aerodynamic shape. For extra lift and control I’ll stretch a piece of kitefabric between the legs, as some sort of tailwing.
Below: some pictures of the work so far on adjusting the kiteshape, creating mounting bags for the spars and reducing the weight.
How should this work? My calculations say that with a total weight of 100kg (me 80kg, wingpack 20kg), we would need about 2000W of continuous power. Well-trained arms can output about 5% of that, so we will rely mainly on the outrunner motors for driving the wings. Because human arms and pectoral muscles aren’t very strong, they will mainly function as guides, to control the flapping wing movements in a natural and intuitive way. These calculation are made for an ideal situation. Any inefficiencies aren’t taken into account, this will be found out by trial and error.
Not convinced yet? Check this video below. Before I started building my wings neuromechanics professor Bert Otten helped me out with some of the research. Specially for this project and all interested followers I filmed a conversation with him last summer. (Extra footage here)