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# 9/11 plane speeds into the WTCs?

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1. (Original post by TheGrinningSkull)
Of course they wouldn't have regard, but how do you control a plane going that fast (Assuming it even is going that fast). It would just break apart.

The engines of the plane wouldn't be able to handle the speed and it'd just start to choke. From the videos I see, then plane doesn't dive down into the WTCs but they crash in at a level altitude and they come in at a level altitude.

Surely the minute they leveled off they would start to slow down after recovering from the velocity dive, which even then, is only 420 knots.

It wouldnt just break apart - it would start to induce stress fractures which might take hours to get to a level of failure, at any road it wouldnt be a matter of seconds like you seem to believe.

As soon as they started to level off they would scrub speed - but you seem to think that the maximum obtainable speed is 420 knots - its not. The maximum reccomended speed is 420 at sea level, but again, the terrorists didnt have much regard for Boeings operating instructions.

It is entirely possible to push the plane beyond what is normally possible because of the large safety margin they have to have for normal flying. Once you dont care about long term reliability and passenger safety even a 747 will do amazing things.
2. (Original post by TheGrinningSkull)
Cruise speeds are at altitudes near 30000 feet.

Air pressure and density at cruising altitude is nearly 3 times smaller than near sea level.

Just take these figures for example:

At altitude 1000 ft air pressure is 97.6kPa
At altitude 30'000 ft, air pressure is 30.1kPa

Here's a link of the table http://www.engineeringtoolbox.com/ai...ume-d_195.html

The engines wouldn't be able to handle the denser air with such speeds near sea level.

Also, we're not talking about a hawker trident, we're talking about a Boeing 767, with a cruising altitude of 533mph anyway. Not at 1000ft either.

I'm not aware of any airliners exceeding 500mph near sea level (without breaking apart as well) so if you have any examples I'd like to see them please.
It's certainly not normal for civil planes to be going that fast that near the ground, usually they're near the ground because they're taking off or landing.

this doesn't mean it's impossible for them to go at that sort of speed though.

Flight 93 was doing >500mph when it crashed - confirmed by the FDR which was recovered.

the plane was pretty much still in one piece and flyable until it hit the deck in that instance.
3. (Original post by Riderz)
It wouldnt just break apart - it would start to induce stress fractures which might take hours to get to a level of failure, at any road it wouldnt be a matter of seconds like you seem to believe.

As soon as they started to level off they would scrub speed - but you seem to think that the maximum obtainable speed is 420 knots - its not. The maximum reccomended speed is 420 at sea level, but again, the terrorists didnt have much regard for Boeings operating instructions.

It is entirely possible to push the plane beyond what is normally possible because of the large safety margin they have to have for normal flying. Once you dont care about long term reliability and passenger safety even a 747 will do amazing things.
You seem to be confusing the numbers.

Vmo is 360 knots.

Vd is 420 knots.

Now please tell me how we can get 504 knots without serious damage?

Going even a percentage above these figures for a short period of time is dangerous, let alone going over these figures by a large percentage for over 2 minutes, at 1000ft or less.

Also, considering the fact that Vd is for emergencies as well, I don’t think we’re looking at the “recommended” value either, it’d have to me the maximum.
4. (Original post by TheGrinningSkull)
The Vd (Velcoity dive, a dive from a height in an emergency) of a 767 is 420 knots. This is the max speed.
Maximum safe speed.

(Original post by TheGrinningSkull)
You seem to be confusing the numbers.

Vmo is 360 knots.

Vd is 420 knots.

Now please tell me how we can get 504 knots without serious damage?
The things crashed. I'd call that serious damage.

If they had landed in one piece you'd almost definitely see some structural fatigue of one degree or another. but if Vmo is x and the plane's wings fall off at x+1 it would be a pretty astonishingly crap design.
5. (Original post by Drewski)
Maximum safe speed.

The things crashed. I'd call that serious damage.

If they had landed in one piece you'd almost definitely see some structural fatigue of one degree or another. but if Vmo is x and the plane's wings fall off at x+1 it would be a pretty astonishingly crap design.
lol haha, I think you may be right, it's annoying when you can't tell what's right and what's wrong with all the disinformation.
6. (Original post by Joinedup)
It's certainly not normal for civil planes to be going that fast that near the ground, usually they're near the ground because they're taking off or landing.

this doesn't mean it's impossible for them to go at that sort of speed though.

Flight 93 was doing >500mph when it crashed - confirmed by the FDR which was recovered.

the plane was pretty much still in one piece and flyable until it hit the deck in that instance.
Hmm, I think you could be right, it's just a lot of disinfo it's hard to tell what's right from what's wrong sometimes, it's frustrating.
7. (Original post by TheGrinningSkull)
You seem to be confusing the numbers.

Vmo is 360 knots.

Vd is 420 knots.

Now please tell me how we can get 504 knots without serious damage?

Going even a percentage above these figures for a short period of time is dangerous, let alone going over these figures by a large percentage for over 2 minutes, at 1000ft or less.

Also, considering the fact that Vd is for emergencies as well, I don’t think we’re looking at the “recommended” value either, it’d have to me the maximum.
Yeh, it's the recommended value in an emergency, for pilots flying the plane safely, not terrorists who don't give a damn about it. Assuming there is a 1.2 factor of safety on this speed (this is a small factor in aerospace engineering) then the maximum speed before the plane falls apart is 580mph..although in reality it won't shatter into a thousand pieces the instant you go above this speed, which is what you seem to be implying.
8. (Original post by TheGrinningSkull)
lol haha, I think you may be right, it's annoying when you can't tell what's right and what's wrong with all the disinformation.
Yeah, a bit. The real problem - especially in these cases - is people who aren't experts in something trying to pass themselves off as such. Someone who doesn't know jot about civil or structural engineering or architecture can't make reasoned decisions about the building's structural integrity. People who aren't au fait with aircraft operations, aeronautical engineering and the like can't really make reasoned decisions about the aircraft and their behaviour.
9. I just want to add that I never doubted that the planes never hit the tower, I was curious about their speeds, that's all.
10. (Original post by Drewski)
Yeah, a bit. The real problem - especially in these cases - is people who aren't experts in something trying to pass themselves off as such. Someone who doesn't know jot about civil or structural engineering or architecture can't make reasoned decisions about the building's structural integrity. People who aren't au fait with aircraft operations, aeronautical engineering and the like can't really make reasoned decisions about the aircraft and their behaviour.
Well, I agree with most of what you say, however, if you imply that we can't make reasoned decisions because we are not experts in the field, then how is anyone going to make reasonable decisions about anything in any other field?

We trust the experts in those fields although I do agree on your point about people trying to make out to be experts when they are not.

I still have issues regarding other parts of the 9/11 "conspiracy" but that has been taken ad nauseum, this was just something I stumbled upon and considered asking here for opinions so thanks for actually sorting that out.
11. (Original post by LeeC)
Yeh, it's the recommended value in an emergency, for pilots flying the plane safely, not terrorists who don't give a damn about it. Assuming there is a 1.2 factor of safety on this speed (this is a small factor in aerospace engineering) then the maximum speed before the plane falls apart is 580mph..although in reality it won't shatter into a thousand pieces the instant you go above this speed, which is what you seem to be implying.
Yea, that's why I asked on here because I had no idea with this route of argument (which looks to be wrong) so I wanted clarification, thanks.

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