Can helis fly in tunnels?
After several beers the other day we were discussing mission impossible, you know the first film. Anyway the bit with the helicopter in the tunnel. After much discussion we decided it would probably not be able to fly because of all the re-circulation of air caused by the tunnels walls which would screw everything up. No discernible technical reasons for this conclusion just beer and waffle. Oh yeah and if it had to lift off in the tunnel we think with the downwash going up the wall and back into the rotors it would probably not have the force to lift off (vortex ring?).
So what do you very clever people think could a helicopter fly in a tunnel?