Start with a 3ft diameter cedar billet and remove everything that doesn't look like a Velomobile.
To answer your question, as pointed out the sharp edges are a liability. Even a 4" radius would help, but there goes your buildability. For examples look to the 1912 Trophenwagen:
Notice the beltline bevel and how it curves down in the top front. Compare with the Airstream Basecamp:
There's also the Stanley Steamer that went 127mph in 1907.
