Questions regarding a 757

[kevdog]

What are all you guys talking about. A 757 did not hit the Pentagon. Duh.

 

[mzaharis]

Can't go close to the ground fast because of ground effect......ha, that's a good one. That's a great example of an academic trying to explain reality when they have no experience.

Actually, the academic might agree with you. Ground effect is a circulation-based phenomenon, and lift is circulation * airspeed * density * span, and as you flow lower and faster (increased density and airspeed), circulation decreases. Hence, flying faster at low altitudes should decrease ground effect.

You just need to pick an academic who is familiar with the Kutta-Zhukovsky theorem (which should include any academic who is in aerospace engineering, the only academic discipline which would be able to comment in an informed manner on this issue).

 

[Learsforsale]

Actually, the academic might agree with you. Ground effect is a circulation-based phenomenon, and lift is circulation * airspeed * density * span, and as you flow lower and faster (increased density and airspeed), circulation decreases. Hence, flying faster at low altitudes should decrease ground effect.

You just need to pick an academic who is familiar with the Kutta-Zhukovsky theorem (which should include any academic who is in aerospace engineering, the only academic discipline which would be able to comment in an informed manner on this issue).

I think you beat me to the punch, since induced drag decreases with airspeed... I can assume that it would be approaching zero at 500mph or whatever speed it was going. And since ground effect reduces induced drag.. you see where I am going with this.

 

[Pantherjon]

National Geographic Channel just had on their 'Seconds From Disaster', the episode about the 757 striking the Pentagon..Some things they highlighted in the program:
1)At time of impact the FDR showed the aircraft at 530(they used MPH, so thats what 457KTS?) at an altitude of 10 feet in a slight bank to the left

2)Left engine and left wingtip hit a small concrete 'pad?' almost intataneously as the nose of the craft hitting the building

3) The hole that was punched out on the inside of the building at whats called 'A and E Road' was NOT the nose of the plane, it was from the explosive forces in the building

They showed the video that has been circulating the internet from the security camera..There are some conspiracy thoerists that say it was a missile, well the video is not conclusive either way, but there is signs of dirt being kicked up from something as it strikes the building. I think it is #2 above kicking up the dirt..

Just my thoughts.

 

[Metro752]

shoot, no 757, yet an FDR, wooot

 

[Gorilla]

Let's suppose for a moment it WAS a missile. There are two types, ground based, portable jobs like TOW and Javelin. The destruction at the Pentagon was too great for these, and that rules them out. The other option is a very large cruise type missile. I'm 95% sure long range missiles do NOT attack in this type of very shallow profile. A Tomahawk will nose over at a particular altitude and enter its attack mode at 30 to 45 degrees. This is so garbage like trees and towers will have no ability to deflect it from its course.

I'm not a missile expert, but I can't think of a missile type in our inventory that will do the damage we see, AND fly such a super-shallow profile. That leaves a <gasp> hijacked 757.

The ground effect story is total rubbish. Like gkrangers stated, does that mean any transport at high speed, near wings level, cannot crash because ground effect will be like a big, soft, fluffy pillow, and prevent it from hitting the ground? What a crock.

 

[TrafficInSight]

Stop watching videos you find on the internet.

 

[Fox-Tree]

shoot, no 757, yet an FDR, wooot

details, details - that's not important!! :laugh:

 

[smooshfacekitty]

If Filght 77 never hit the Pentagon, then where exactly is this plane and all it's passengers now? They must be on the 'Lost' island. Conspiracy theorists - what a bunch of morons.

 

[urflyingme?!]

http://www.youtube.com/watch?v=T5XTsQ-9vvo

This is where the 757 went. ANybody who listens to that crap on the internet is ann ass