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Post Reply Why doesn't airplane come with a parachute?
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Posted 8/5/17

MidoriNoTora wrote:


fredreload wrote:

Hmm, glider does not work at high altitude, how about jet packs? One that shoots out air it could be in any direction and counteract gravity. For the plane of course. Like that re-landing S rocket


You know that you are essentially describing a VTOL at this point?


Right, for safety purposes
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Posted 8/5/17
lol at all the people who think its impossible or just not doable. The truth is human life isn't worth it or else it would be done. You could have a parachute layer easily stretched across the top of the plane with an emergency release mechanism with some slick engineering. While the chances of it increasing survivability aren't that high unless it could slow down the plane significantly, it would be better than nothing.
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Posted 8/5/17

Cavemantero wrote:

lol at all the people who think its impossible or just not doable. The truth is human life isn't worth it or else it would be done. You could have a parachute layer easily stretched across the top of the plane with an emergency release mechanism with some slick engineering. While the chances of it increasing survivability aren't that high unless it could slow down the plane significantly, it would be better than nothing.


In case of emergency, turn off both engines, slow down, lower altitude, then deploy parachutes. We all know flying is the fastest way of traveling. We'll most likely land above water though, so we'll also need some rubber ducks
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Posted 8/5/17

Cavemantero wrote:

While the chances of it increasing survivability aren't that high unless it could slow down the plane significantly, it would be better than nothing.

LMAO so you are saying that the appearance of trying is better than coming up with an actual solution? That makes sense.
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Posted 8/5/17
One key issue that seems to be ignored by some people is that the only thing keeping the plane in the air is the flow of air around the wings caused by the forward momentum. The moment you deploy a parachute to slow the plane you reduce or remove the associated lift and the plane will start to enter free fall.

Therefore you will need a parachute system able to slow the plane's forward momentum and simultaneously take over the entire weight of the aircraft previously held by the lift.

Is it possible? Maybe, depending on the size and design of the plane as well as the layout and materials used in the chute system.

Will it add any degree of safety? Possibly but you are putting all your eggs in one basket - it will be difficult for a large aircraft to regain lift once it loses it so the chute system would be an all-or-nothing gamble.

Is it commercially viable for large aircraft? I doubt it. The size of material required to hold the entire weight of a commercial liner would add a huge weight to the craft and take up significant space. There will be much less space for passengers and a higher amount of fuel or wingspan required to achieve lift. Expect your air fare prices to increase significantly for minimal increase in safety (or possibly even a decrease in safety).
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Posted 8/5/17

fredreload wrote:



Not passengers, the plane


Did you even bother to read the entire article? There is a link, in the final paragraph, to another article discussing the current use of whole plane parachute systems in smaller planes and the current issues that need to be solved to be able to utilize similar systems on larger commercial airliners.
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Posted 8/5/17

MidoriNoTora wrote:

One key issue that seems to be ignored by some people is that the only thing keeping the plane in the air is the flow of air around the wings caused by the forward momentum. The moment you deploy a parachute to slow the plane you reduce or remove the associated lift and the plane will start to enter free fall.

Therefore you will need a parachute system able to slow the plane's forward momentum and simultaneously take over the entire weight of the aircraft previously held by the lift.

Is it possible? Maybe, depending on the size and design of the plane as well as the layout and materials used in the chute system.

Will it add any degree of safety? Possibly but you are putting all your eggs in one basket - it will be difficult for a large aircraft to regain lift once it loses it so the chute system would be an all-or-nothing gamble.

Is it commercially viable for large aircraft? I doubt it. The size of material required to hold the entire weight of a commercial liner would add a huge weight to the craft and take up significant space. There will be much less space for passengers and a higher amount of fuel or wingspan required to achieve lift. Expect your air fare prices to increase significantly for minimal increase in safety (or possibly even a decrease in safety).


It's kind of misleading when you say what's keeping the plane in the air is forward momentum. It's the relative wind that the plane is using to produce lift. Also, you can easily increase your angle of attack and reduce airspeed lower than glide or drift down speed that will increase your descent rate exponentially.

In most scenarios, usually a plane will only lose one engine. Most multi engine airplanes can fly on one engine depending on atmospheric conditions and altitude.
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Posted 8/5/17

riverjustice wrote:


MidoriNoTora wrote:

the only thing keeping the plane in the air is the flow of air around the wings...


It's kind of misleading when you say what's keeping the plane in the air is forward momentum. It's the relative wind that the plane is using to produce lift.


You misread what I wrote. Flow of air around the craft and "relative wind" are effectively the same thing.
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Posted 8/5/17

MidoriNoTora wrote:


riverjustice wrote:


MidoriNoTora wrote:

the only thing keeping the plane in the air is the flow of air around the wings...


It's kind of misleading when you say what's keeping the plane in the air is forward momentum. It's the relative wind that the plane is using to produce lift.


You misread what I wrote. Flow of air around the craft and "relative wind" are effectively the same thing.


Yea I'm just saying the flow of air could've been misinterrupted by actual wind and not relative wind. Because that's a big difference. It's always better to be clear and concise than nebulous when talking about science and especially aerodynamics.
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Posted 8/5/17


The [Boeing] 747's maximum takeoff weight ranges from 735,000 pounds (333,400 kg) for the -100 to 970,000 lb (439,985 kg) for the -8.
wiki


if we model the plane as a rocket of similar weight, and if we assume it has 735,000 lb in weight, you'd need a parachute of about 490m in diameter for the rocket to descend at 20 fps (~6m/s)
source

for comparison, the longest length of a typical American Football Field is only about 110m

this means, if we were to model a typical plane as a rocket, you'd need a parachute the size of about 4 football fields for the plane to land at 20fps (about 6 m/s). this of course, if we model the plane as a rocket of similar weight in free fall.

4 football fields...
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Posted 8/5/17

riverjustice wrote

It's always better to be clear and concise than nebulous when talking about science and especially aerodynamics.


I am guessing that you have little experience in teaching concepts to others. Precision has its place but when you are presenting information to an audience that includes novices it is wise to couch your message in terms that are accessible to all.
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Posted 8/5/17 , edited 8/5/17

namealreadytaken wrote:



The [Boeing] 747's maximum takeoff weight ranges from 735,000 pounds (333,400 kg) for the -100 to 970,000 lb (439,985 kg) for the -8.
wiki


if we model the plane as a rocket of similar weight, and if we assume it has 735,000 lb in weight, you'd need a parachute of about 490m in diameter for the rocket to descend at 20 fps (~6m/s)
source

for comparison, the longest length of a typical American Football Field is only about 110m

this means, if we were to model a typical plane as a rocket, you'd need a parachute the size of about 4 football fields for the plane to land at 20fps (about 6 m/s). this of course, if we model the plane as a rocket of similar weight in free fall.

4 football fields...


Again most airlines are able to fly single engine depending on atmospheric conditions and altitude. In matter of fact, the most practiced emergency procedure is a single engine flameout at takeoff. We don't need parachutes...
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Posted 8/5/17

riverjustice wrote:Again most airlines are able to fly single engine depending on atmospheric conditions and altitude. In matter of fact, the most practiced emergency procedure is a single engine flameout at takeoff. We don't need parachutes...


depending on where the plane is located, a landing is technically possible even without an engine, though the pilot would have to be very experienced to do so. Chesley Sullenberger III is considered a hero for landing the plane in the Hudson river and saving all passengers on board.
http://www.telegraph.co.uk/news/worldnews/northamerica/usa/4250646/New-York-plane-crash-Hero-pilot-did-absolutely-the-right-thing.html
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Posted 8/5/17

MidoriNoTora wrote:


riverjustice wrote

It's always better to be clear and concise than nebulous when talking about science and especially aerodynamics.


I am guessing that you have little experience in teaching concepts to others. Precision has its place but when you are presenting information to an audience that includes novices it is wise to couch your message in terms that are accessible to all.


I guess you will be correct in saying I have little experience in teaching concepts I'm used to talking to people who understand these concepts well.
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Posted 8/5/17

namealreadytaken wrote:


riverjustice wrote:Again most airlines are able to fly single engine depending on atmospheric conditions and altitude. In matter of fact, the most practiced emergency procedure is a single engine flameout at takeoff. We don't need parachutes...


depending on where the plane is located, a landing is technically possible even without an engine, though the pilot would have to be very experienced to do so. Chesley Sullenberger III is considered a hero for landing the plane in the Hudson river and saving all passengers on board.
http://www.telegraph.co.uk/news/worldnews/northamerica/usa/4250646/New-York-plane-crash-Hero-pilot-did-absolutely-the-right-thing.html


Yea the plane functions as a glider when none of the engines are working. I thought this was obvious?
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