A NASA-Langley video of free-flight tests of a powered 1/8 scale model of the Bell D-188A VTOL strike fighter (see APR issues V2N3 and V2N4 for a sickeningly large amount of info on this and related designs). For propulsion, compressed air was piped in and ducted to the exhausts; the hose for the air can be seen coming in from above. Of particular interest are the tests showing the aircraft go through transition from hover to forward thrust. This was facilitated by parking the model in the big, controllable low speed wind tunnel. Note that for the model, transition was a *really* slow process. It was to have been faster for the actual aircraft.
[youtube -p7UJEDG4E0]
For those playing along, this is an example of a *good* government program: providing assistance to US industry in developing technologies. NASA (and the NACA before it) differs from the rest of the US Fed Guv in that it winds up actually adding more to the US economy than it sucks out. Perhaps if the Social Security Administration shot senile people into space to test space suits and re-entry shields, or if MediPonziCare used wind tunnels to blow people off of government assistance, or if Fannie Mae and Freddie Mac were strictly limited to dealing with off-world real estate deals, I’d be a bit more positive.
6 Responses to “Bell D-188A wind tunnel test video”
Sorry, the comment form is closed at this time.
Well, that’s another one you can’t embed, but can view via the YouTube direct link.
It’s hard to decide if it or the very similar German VJ-101C was a better design. Ideally you would use the full engine thrust in both VTOL and forward flight, like the Harrier does; and if EWR had ditched the extra lift engines, put the four main engines on the CG, and stuck compressor bleed ducts in the nose and tail for pitch control, you might have had a very good idea indeed.
It would be a ball to see what you could do with that basic idea with four F100 engines in the wingtip pods; you might set the ground on fire during liftoff and landing, but by God could that thing move out once it was in horizontal flight. You could probably shut two of the engines down for cruise flight, and crank all four up for a run over the target at around Mach 3.
By pivoting the wingtip pods up and down during air-to-air combat you could have a roll rate like nothing you’ve ever dreamed of, as will as a power-to-weight ratio that would put even the F-15 to shame – you could probably accelerate to Mach 2 in a vertical climb.
The wind tunnel transition probably had to be slow because the tunnel operator had to adjust the speed of the tunnel air to match what the model would be flying at in free air. Otherwise the model would disappear either into the tunnel or back down the tunnel, or at least as far as the tether permitted…
You should contact the poster of those films.
That would be NASA. I guess they don’t *want* to allow embedding, b ut instead want people to view the YouTube page directly. I gather the difference is that embedded views do not ratchet up the “view counter.”
> the tunnel operator had to adjust the speed of the tunnel air
That would be my guess. A lot of the free-flight tests Way Back When seem to have been really labor intensive, requireing *multiple* pilots (one for roll, another for pitch), working together in some sort of synch.