Would ground effect and FOD ingestion be factors at high speeds close to the ground?
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?
ground-effect boeing-757
edited Dec 25 '18 at 21:04
Jimy
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
$endgroup$
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?
ground-effect boeing-757
edited Dec 25 '18 at 21:04
Jimy
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
$endgroup$
2
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
2
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?
ground-effect boeing-757
edited Dec 25 '18 at 21:04
Jimy
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
$endgroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground? Also wouldn't the engines ingest FOD at that power setting that close to the ground on the approach?
ground-effect boeing-757
ground-effect boeing-757
edited Dec 25 '18 at 21:04
Jimy
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
edited Dec 25 '18 at 21:04
Jimy
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
edited Dec 25 '18 at 21:04
Jimy
1,49141227
edited Dec 25 '18 at 21:04
Jimy
1,49141227
edited Dec 25 '18 at 21:04
Jimy
1,49141227
1,49141227
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
asked Dec 25 '18 at 18:16
Rcihard Van SteenbergRcihard Van Steenberg
101
101
2
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
2
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42
add a comment |
2
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
2
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42
2
2
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
2
2
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42
add a comment |
2 Answers
2
active
oldest
votes
$begingroup$
The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
$endgroup$
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?
Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
$endgroup$
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
add a comment |
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2 Answers
2
active
oldest
votes
2 Answers
2
active
oldest
votes
active
oldest
votes
active
oldest
votes
$begingroup$
The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
$endgroup$
add a comment |
$begingroup$
The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
$endgroup$
add a comment |
$begingroup$
The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
$endgroup$
The amount of time a plane in a dive spends close enough to the ground to ingest foreign objects and thereby damage its engines is of order ~fractions of a second.
For a plane that is about to strike a building on the ground, the idea of FOD damage to its engines is not even relevant.
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
edited Dec 27 '18 at 10:57
TomMcW
17.4k965158
17.4k965158
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
answered Dec 25 '18 at 19:32
niels nielsenniels nielsen
2,5041515
2,5041515
add a comment |
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?
Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
$endgroup$
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?
Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
$endgroup$
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
add a comment |
$begingroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?
Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
$endgroup$
How could flight 77 into the pentagon overcome the compression lift of the ground effect at 460 KIAS that close to the ground?
Pitch. If an airplane's nose is low enough, it will descend and eventually collide with the ground.
In the extreme example, with the nose pointed directly down, lift is no longer holding the airplane up at all; the only force keeping the airplane's descent in check is drag. I don't know exactly how fast the plane will end up descending, but it will be pretty dang fast.
But an airplane doesn't need to be pointed straight down to have a violent collision with the ground. A shallower pitch will also work.
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
answered Dec 25 '18 at 18:49
Tanner SwettTanner Swett
2,43311030
2,43311030
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
add a comment |
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
1
1
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
Might want to compare SilkAir Flight 185 (even though that particular case is disputed).
$endgroup$
– a CVn
Dec 25 '18 at 18:57
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
$begingroup$
@aCVn: Not seriously disputed - every one of the investigators involved agreed that it was a case of pilot suicide, with the exception of the NTSC chairman (who then promptly overruled the rest of his team and declared the cause of the crash "undetermined").
$endgroup$
– Sean
Feb 14 at 1:25
add a comment |
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2
$begingroup$
At appears that you're thinking that an airplane traveling fast enough could never crash into the ground ...
$endgroup$
– brhans
Dec 25 '18 at 21:59
2
$begingroup$
If an airplane could not fly close to the ground, it could never land - duh! If you want to fly in ground effect at much more than stall speed, you just need a bit of down elevator. (At least in a single engine prop plane - I can't afford a 757, but I see no reason they'd be fundamentally different.)
$endgroup$
– jamesqf
Dec 26 '18 at 5:42