Re: Sighted a shock wave above airliner wing

Date:         12 Oct 98 00:02:14 
From:         kls@ohare.Chicago.COM (Karl Swartz)
Organization: Chicago Software Works, Menlo Park, California
References:   1 2 3 4
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>> Though I haven't seen one in a while, I can recall on several occasions
>> seeing them above the wing of 727's during cruise. Why this plane and
>> seldom, if ever, on others, I don't know.

>It may have something to do with the 727's relatively high cruising
>speed.  AFAIK, of subsonic passenger aircraft, only the 747 and
>Citation X go (slightly) faster.

The Convair 990A is the fastest subsonic airliner, though I don't know
how it compares to a Citation X.

Boeing's web pages also imply the 707 is faster than the 727, cruising
at 607 mph versus 570-605 mph for the 727.  They don't list speeds for
the newer aircraft, but I thought the 777 was nearly as fast as the 747
and thus might beat the 727.  (According to John Proctor's Convair 880
& 990 book, the 990A has a maximum cruise speed of 621 mph while the
880's top cruise is 610 mph -- so even the 880 beats the 727.)

While it's clear that you were talking about normal cruise speeds, the
DC-8 has gone faster -- it's one of only three airliners to have flown
faster than Mach 1, the other two of course being Concorde and Tu-144,
having done so in a test flight on August 21, 1961.  (Some claim the
China Air 747SP which went into a dive over the Pacific on February 19,
1985 exceeded Mach 1, but the evidence doesn't support that claim.)

It's not likely that many readers will have an opportunity to sight a
shock wave above the wing of an 880 or 990A, or a supersonic DC-8,
though!

--
Karl Swartz	|Home	kls@chicago.com		http://www.chicago.com/~kls/
		|Work	kls@netapp.com		http://www.netapp.com/
"The average dog is a nicer person than the average person."
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