Questions regarding a 757

[matt7723]

Guys,

I've been talking about the Pentagon with some guys on another message board, and they raise some questions which I do not have answers too. Basically, they are saying that it is impossible for a 757 going over 500mph to have been that close to the ground. Yes, they are wackos but without anything from actual 757 pilots they don't believe me. So, for anyone who flies/has flown the 757, is there any truth to their statements?

Thanks,

Matt

 

[gkrangers]

Structural damage?

 

[matt7723]

Structural damage?

Basically, they are saying that ground effect would cause them to be over 60ft off the ground while going over 500mph thus making it impossible a 757 hit the Pentagon....

 

[gkrangers]

So they are saying its impossible for an airplane to hit the ground at a high speed?

 

[big_al]

I never thought I'd say this, but some people give conspiracy theorists a bad name

 

[aussiefly]

hahahah you are so right big al. Cant fly low at high speed due to ground effect??? someone should probably Tell the mil guys then lol

 

[big_al]

I am a proud conspiracy theorist, my problem lies with the idea that these below average extremely low time pilots could have done what they did on 9-11. but talking about a ground effect stopping an airplane from hitting something? yeah umm, no

 

[RipCurl]

OK not to get into a conspiracy argument here, but I'm pretty sure you could teach a monkey to crash an airplane into a wall. Once you're up and cruising, it's all the same man. Pull back, houses get smaller; push forward, houses get bigger. Doesn't matter if you're flying a 150 or a 757.

 

[big_al]

I dont recall the bank angle and angles of attack used but you couldnt teach a monkey, and probably a monkey whos flight instructors said they were far below average pilots

 

[Fugawe]

Guys,

I've been talking about the Pentagon with some guys on another message board, and they raise some questions which I do not have answers too. Basically, they are saying that it is impossible for a 757 going over 500mph to have been that close to the ground. Yes, they are wackos but without anything from actual 757 pilots they don't believe me. So, for anyone who flies/has flown the 757, is there any truth to their statements?

Thanks,

Matt

YGBSM! Sounds like a bunch of monkeys sittin' around debating Socrates.

Placard speeds on the 757 are around 330/.87 I think (been awhile), but the plane will go a helluva lot faster, especially downhill. Mach tuck, flight control anomalies, and finally structural failure will occur -- but point the thing downhill and it'll go supersonic.......won't be pretty, but it will go super.

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. If that 757 was at 500KIAS, he wasn't in the flare and certainly wasn't gonna 'float' above the ground due to effect. At that speed, where do you think the ground effect vortices hit the aircraft?

The media says any jet going fast is going '500MPH' -- they don't have a friggin' clue. This jet could've been doing 300 or 350 and they'd not know the difference. Most have never seen a jet close to the ground doing over 200. Was there a black box or some other data that showed 500?

And.........the Pentagon jet was unlikely to have been cruisin' in at 10'AGL like some imply -- that's ludicrous. It was most likely in a shallow descent, accelerating all the way in. The video would not detect this.

Fugawe

 

[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