An inspiration to us is the a2 wind tunnel
A2 Wind Tunnel
It's narrow yet full scale cars are tested there
I really wonder how they avoid interference from the closely placed walls. I read somewhere that they adjust the ceiling height or shape to the shape of the object to be tested.
It can run up to 85 mph and is powered by three 72-inch 200HP and one 42-inch diameter 40HP, electric fans.
We aim for higher speeds coming from more propellers and engines.