Maximum Speed of Airliner At Low Altitude

In article ,
Guy Alcala writes:


Getting back to Pete's point, was the MiG-17's top level speed altitude (usually
given as 13,000 feet) likely because of engine temp limits at lower altitude plus
the use of A/B up higher, or for the reasons you mention in this thread? The other
swept-wing subsonics sans A/B all seem to be fastest on the deck. I wonder if the
F-86D/K/L Sabre's top speed graph was similar to the MiG-17's, owing to the A/B --
Walt? I think the only F-86 graphs I have are for navy Furies and the F-86H.

As it just so happens, I have my F-86D Dash-1 (Flight Handbook) to
hand. And it does have a Vmax curve. In the case of a clean
airplane, 16,000# weight, in AB, the Vmax curve looks something like
this:
Alt Mach Vmph VKTAS
0 0.91 692 601
10,000 0.93 677 588
20,000 0.94 659 572
30,000 0.94 634 550
40,000 0.93 611 530

So, in the Dogship's case, it still holds to the pattern where teh
maximum absolute speed it greates at Sea Level. (Airframe limits are
610 KIAS, no Mach Limit without external tanks.)

I've often wondered about the MiG-17's numbers as well. The guy to
ask, if he's monitoring, is Dave Sutton. It's kinda hard to argue
when he can walk out into the hangar and check. I've suspected that
its some sort of Q limit. My main suspect would be wing flex at high
speeds reducing roll rate, like what happens with a B-47. At those
speeds and altitudes, there's usually not enough temperature rise due
to ram compression for that to be a factor.
I've heard some funny stories about the teh flight limits on Soviet
airplanes. Apparently, the Soviets were very conservative about the
limits they placarded for their export airplanes. (I don't know about
their domestic stuff) This may have been due to an, erm, "mistrust"
in the levels of training received by their clients. I do know that
when the Indian Air FOrce adopted the MiG-21 and Su-7. that they were
very disappointed with the transition training that they received.
But then, at that time, the IAF still had close ties with the RAF, not
only having flown Brit equipment (Vampires, Hunters, and Gnats), but
also having their pilots trained "RAF Style" in India, and arranging
advanced training at the Fighter Leader's School and Empire Test
Pilot's School. The IAF rewrote the handbook for the MiG-21 and Su-7,
and in the process, opened up the flight envelopes a great deal. The
Su-7 was surprising - it turned out to be much faster, adn with much
better PsubS than th handbook limits had indicated. The biggest
problems were that the control system was set up for Soviet Weight
Lifters (I've never heard of anyone over-Ging an Su-7), and it would
run itself out of gas in sight of its own airfield.

--
Pete Stickney
A strong conviction that something must be done is the parent of many
bad measures. -- Daniel Webster