Jbmitt From United States of America, joined Jan 2002, 549 posts, RR: 2 Posted (12 years 9 months 1 week 2 days 20 hours ago) and read 2610 times:
I just read an article, and it suggested, that of the two planes that crashed into the WTC. That one of them was flying so fast that it was in danger of breaking apart. What sort of speeds, would a plan de-sinegrate at? And any info on specific models?
Arsenal@LHR From United Kingdom, joined Mar 2001, 7792 posts, RR: 20
Reply 1, posted (12 years 9 months 1 week 2 days 15 hours ago) and read 2509 times:
I'm no expert on structural engineering on planes, but exceeding the designated speed would break up any commercial airliner doing excessive speeds. Remember Egyptair flight 990, some people claimed it was flying at 700 mph went it crashed and that the fuselage broke in flight. UA 175 was doing 575 mph at 1000 feet, suprised it didn't break up.
Aerosol From Germany, joined Oct 2000, 559 posts, RR: 0
Reply 5, posted (12 years 9 months 1 week 1 day 15 hours ago) and read 2324 times:
On pprune I read that the Lufthansa bird did not disintegrate, but had severe flap-damage. It was sad that the Lufthansapilot tried to copy a barrel roll which was performed in a test flight of a 707, but exceeded the max. g-force restrictions.
I would really like to see a video of a 707 doing a roll.
Airsicknessbag From Germany, joined Aug 2000, 4723 posts, RR: 33
Reply 6, posted (12 years 9 months 1 week 1 day 15 hours ago) and read 2315 times:
Interesting. This is from the aviation-safety.net´s accident description: "A complete roll was flown, but while attempting a second roll, the plane went out of control in the inverted position. The Boeing became overstressed, disintegrated in flames." I wonder whether it was found out what happened.
NZ767 From New Zealand, joined Nov 2001, 1620 posts, RR: 1
Reply 8, posted (12 years 9 months 1 week 1 day 5 hours ago) and read 2230 times:
That 747 you mentioned had a problem (can't remember what exactly) that caused it to go into that dive, and you're right, it did go supersonic.
As I understand it, the 747 is certified to go supersonic to cover such an eventuality as will be the Sonic Cruiser.
Aircraft landed safely at SFO.
Travatl From United States of America, joined Mar 2001, 2174 posts, RR: 7
Reply 9, posted (12 years 9 months 1 week 10 hours ago) and read 2161 times:
A Northwest Boeing 720 enroute from Miami to Chicago broke up over the Everglades in 1963 while attempting to recover from a turbulence induced dive. The aircraft's IAS exceeded 470 knots whiile in the 95 degree dive.
757man From United Kingdom, joined Feb 2001, 370 posts, RR: 1
Reply 10, posted (12 years 9 months 1 week 10 hours ago) and read 2156 times:
I understand that the near legendary Vickers VC10 broke the sound barrier on more than one occasion - by pure accident. The RR Conways were supposed to be 'twitchy' to control and pilots used to take great care with them. However, some pilots who were new to the type didn't take as much care. None of these a/c were lost, but if you look at the wing design of them, you can probably see why they could go past the sound barrier.
Heavymetal From , joined Dec 1969, posts, RR:
Reply 12, posted (12 years 9 months 1 week 9 hours ago) and read 2133 times:
Now I read it was estimated that UA 175 was doing just over normal cruise speed.....however, if I'm not mistaken, what might be normal at 35,000 feet is in fact much more perilous in the lowest altitudes. Is that not correct?
Fanofjets From United States of America, joined Apr 2000, 2002 posts, RR: 3
Reply 13, posted (12 years 9 months 1 week 9 hours ago) and read 2117 times:
To my knowledge, the only commercial airliner to exceed the sound barrier (except, of course, for the Concorde and Tu-144) was a DC-8-40 during a shallow dive. The flight with the RR Conway powered 'eight occurred in the early 1960s during a test flight; the plane was delivered to Canadian Pacific.
The issue is not so much speed as stress on the airframe encountered when the pilot tried to regain control of the plane. Two incidents come to mind: the China Airlines 747SP-09 and a 727-200 (I believe TWA); both aircraft sustained damage while coming out of a dive. Thankfully, both aircraft landed safely.
Prebennorholm From Denmark, joined Mar 2000, 6517 posts, RR: 54
Reply 17, posted (12 years 9 months 1 week 7 hours ago) and read 2081 times:
All airliners have different speed limits at different altitudes. In any case a hefty safety margin is built into these speed limits so they can handle severe turbulence without structural damage or extreme discomfort for the pax.
The morning of 9/11 must have been rather turbulence free. Therefore even an extreme violation of speed limits would hardly mean structural failure.
Approaching sonic speed is, however, an entirely different type of animal. No airliner - including the Concorde - would survive that in the dense air at low altitude.
If memory treats me well, then the Concorde limit is 340 kts. IAS at low altitude.
Regards, Preben Norholm
Always keep your number of landings equal to your number of take-offs, Preben Norholm