The design specification changed. Originally, the AMST program was meant to
replace the C-130. However, they realized that neither plane could carry the
new M-1 tank. It was too big. So, how do you get an M-1 tank to the front
lines? THe C-5 could carry it to an airbase, but, it may not be close to the
battlefield.

I'm sure other factors were involved, as well, but they canceled the
competition, with the general feeling that the YC-15 was the better of the
two. They held a new competition for a larger design, based on the YC-14 and
YC-15. Boeing's design was now a trijet, with the third engine mounted like
a 727. And, you know what the Mcdonnel Douglas aircraft looked like.

One concern both the USAF and NASA had about the Boeing design, was, what
if you lost an engine on takeoff or landing? Because it used upper surface
blowing over the wing and flaps for it's short runway performance, it was
felt that a loss of an engine would produce a differential lift that could
become critical. I guess they felt the response time was to short to correct
with any kind of cross flow from the other engine. Once again, this may not
have been the only reason for selecting the C-17, but, it was a concern
expressed to me by a NASA engineer at an SAE symposium.
Ron

wrote in message news:jArAj.1203$z13.457@trnddc06...

On 7-Mar-2008, "Denis F. Blake" wrote:

If I am not mistaken that project led directly to the C17 that we have
now...

Seems to be a bit smaller than the production model.