Second WTC Plane Travelling Faster

AP ^ | Saturday February 23 9:13 AM ET

[sixmil]

Second WTC Plane Travelling Faster

NEW YORK (AP) - Researchers believe the second hijacked plane to hit the World Trade Center tower was traveling about 100 mph faster than the first, according to a published report.

Investigators are focusing on the speed of the two planes as they seek to explain what caused the south tower to collapse first, even though it was hit later, The New York Times reported Saturday.

Researchers have closely studied videos, sound recordings and radar to estimate how fast the two jetliners were moving. Studies show that both planes were traveling well over the federal limits for altitudes below 10,000 feet, The Times said.

The second plane was flying so fast that it was in danger of breaking up in the air as it approached the south tower, Boeing spokeswoman Liz Verdier told the Times.

``These guys exceeded even the emergency dive speed,'' Verdier said. ``It's off the chart.''

Two studies have analyzed the speed of the planes, one by the Federal Aviation Administration (news - web sites) in consultation with the National Transportation Safety Board (news - web sites) and the other by Eduardo Kausel, a professor of civil and environmental engineering at Massachusetts Institute of Technology (news - web sites).

Both found that United Airlines Flight 175, which hit the south tower at 9:02 a.m., was traveling significantly faster than American Airlines Flight 11, which hit the north tower at approximately 8:46 a.m.

The government's calculations put the speed of the first plane at 494 mph, and the second at 586 mph. The MIT analysis determined the first plane was traveling 429 mph, and the second 537 mph, The Times said.

The south tower collapsed 56 minutes after the crash. The north tower stood for 102 minutes.

Structural engineers have not determined to what extent the speed of the planes affected how long the buildings stood. They are studying many factors, including the point at which each tower was hit.

The south tower was hit between the 78th and 84th floors, while the north tower was struck between the 94th and 99th floors, meaning more weight bore down on the damaged floors in the south tower, The Times said.

[sheik yerbouty]

586mph=871fps; about the speed of a 45ACP round at the muzzle.

[El Gato]

I wonder how fast the notional 707 in the design requirements for the building was supposed to have been flying? I'll bet not anywhere near this fast, as they would not have been thinking about someone deliberately ramming the building at speed, but more like a plane off course upon landing or takeoff, when they would be going about 1/2 to 1/3 as fast. Since the energy involved in the collision is proportional to the square of the speed, and also to the mass/weight of the aircraft, one would think these strikes exceeded the design standard by a factor of 5 to 10, maybe more. The wonder is not that the buildings fell, but rather that they stood long enough for tens of thousands of people to get out before they fell.

[Straight Vermonter]

Regading why the second tower fell first, there was some talk on FR months ago about how the tower design engineers never anticipated simultaneous fires. The fire control system in the first tower was able to, at least partially, contain the fires for a time. When the second plane hit and the sprinkler system came on there was too little water in either tower to make any difference.

[ErnBatavia]

eerie...saved this one:

http://www.freerepublic.com/focus/fr/520265/posts

[Northern Yankee]

Ping!

Absolutely... regardless of which plane was traveling faster, the water was just not there for the second tower to keep the steal from melting quicker.

[Tijeras_Slim]

The second plane also hit lower, which may have contributed, since there was a greater number of floors above pushing down on the structural steel.

[ml/nj]

I wonder how fast the notional 707 in the design requirements for the building was supposed to have been flying?

There is a 250 kts (288 mph) speed limit for planes flying below 10,000 feet. (Source: FARs § 91.117) Unless designers were expecting really illegal operation, they probably used 300 mph.

ML/NJ

[E Rocc]

The second plane also hit lower, which may have contributed, since there was a greater number of floors above pushing down on the structural steel

That would so clearly have been the deciding factor that I'm wondering why they are even bothering about speed.

-Eric

[txhurl]

That's right. Write those jerks a speeding ticket, too.

Actually, not a bad idea. Could be auctioned off..

[Vinomori]

cAN WE FINE THEIR FAMILIES OR ESTATES FOR THEIR HAVING EXCEEDING fEDERAL REGULATIONS FOR SPEED?

[VOA]

bump

[Harrison Bergeron]

"The south tower was hit between the 78th and 84th floors, while the north tower was struck between the 94th and 99th floors, meaning more weight bore down on the damaged floors in the south tower...

No matter how fast the planes were travelling, both buildings withstood the impacts. The weight of the structure above the melting steel on the damaged floors determined the timing of the pancaking collapse.

WTC Collapse Engineering Report (PDF Powerpoint Presentation)

[Young Rhino]

At this point, I'm more concerned with the assorted projectiles that enter bin Laden and his buddies - preferably slow and excruciatingly painful.

[Excuse_My_Bellicosity]

By doing some quick hand calculations: a plane moving at 586 MPH has 5.5 times the kinetic energy of a plane moving at 250 MPH even though the speed of the faster plane is about 2.3 times the speed of the slower plane. (Kinetic Energy = 1/2 * Mass * Velocity^2)

[n.y.muggs]

Studies show that both planes were traveling well over federal limits for altitudes below 10,000 ft.

Amazing observation, I wonder if anyone actually thought that these terrorist cowards cared about federal speed limits below 10,000 ft. For that matter I'm sure the speed limit is even lower in the city..

Were these studies even needed. A speeding jumbo jet, full of highly flammable fuel crashed into a very tall structure. The structure collaspes. Killing 1000's of innocent victims.

No need to waste taxpayer money on dueling studies.

[Tymesup]

There was a thread within the last month (probably week) about a couple of individuals who had been doing some plumbing/sprinkler work in the WTC the week before 9/11. Let me know if you need it; a quick search didn't turn up anything.

[Amore]

The second plane also hit lower, which may have contributed, since there
was a greater number of floors above pushing down on the structural steel

That would so clearly have been the deciding factor that I'm wondering why they are even bothering about speed.

Well, I'm not an engineer, but that's certainly my take on it.

[LJLucido]

Studies show that both planes were traveling well over the federal limits for altitudes below 10,000 feet, The Times said.

That settles it. We'll have to lower the speed limit for airliners travelling below 10,000 feet over populated areas.

[zeaal]

... I'm wondering why they are even bothering about speed.

Cause people that know the math formula to do that kind of calculation like to do it to make those of us that don't "got math?" wish we would have listened during our high school math classes.

hehee