PDA

View Full Version : Pressurized Cockpit



The_Stealth_Owl
09-28-2009, 02:10 PM
What would happen if you had a pressurized cockpit, witch ment it was sealed (?) and you sat in it underwater or in space?

EoW_WhamO_CO
09-28-2009, 02:15 PM
u'd be in a submarine or space shuttle.

The_Stealth_Owl
09-28-2009, 02:25 PM
Like if you had a P-51 sitting on the moon, you could breave in the cockpit?

general_kalle
09-28-2009, 02:32 PM
Now the P51 is surely a great aircraft but i still think the moon is a bit far fetched http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

EoW_WhamO_CO
09-28-2009, 03:07 PM
no u couldnt breave...nor could you breathe.

Treetop64
09-28-2009, 03:12 PM
Originally posted by The_Stealth_Owl:
Like if you had a P-51 sitting on the moon, you could breave in the cockpit?

You would be dead. First of all the P-51 wasn't designed with a pressurized cockpit, so in that aspect the point is moot.

Obviously, we can use as an expamle any pressurized aircraft, with airliners being the most convenient choice.

The higher a pressurized aircraft flies, the more it must reduce the inside air pressure to maintain a favorable pressure difference between the outside and inside, so if you're inside an airliner traveling at 33,000 feet, the pressurized altitude (density) inside the aircraft is between 7,000 to 8,000 feet. If you were flying that high and tried to maintain sea-level air density inside the aircraft, then in all likelihood the aircraft would suffer catastrophic airframe failure. So, if you had any pressurized aircraft on the moon, well, you could imagine the result, considering there is no air outside to help buffer the airframe stress...

You could theoretically lightly pressurize an airframe on the moon, but to nowhere near the slightest survivable levels.

As for underwater, well lets just say I would not want to be in that situation! Pressurized aircraft are designed to contain a greater pressure inside that what's outside. Underwater, you have much greater forces outside trying to crush the airframe. No good could come out of that!

There's a reason why spacecraft and submarines are built the way they are. http://forums.ubi.com/images/smilies/25.gif

The_Stealth_Owl
09-28-2009, 03:19 PM
So, no plane could be in space?

I know that it couldnt fly.


Theres no noise in space, so if you were in P-51, could you here noise?

I think you are incorect about the P-51 not having a pressurised cockpit.


Also, did it have cockpit heating to keep warm in space?

I have to got to an appointment soon.

Treetop64
09-28-2009, 03:21 PM
Read the whole post, Owl...

The_Stealth_Owl
09-28-2009, 03:26 PM
I also know the engine won't start, becuase theres no Oxygne.



I thought it had a pressurized cockpit?

Treetop64
09-28-2009, 03:29 PM
Originally posted by The_Stealth_Owl:

I think you are incorect about the P-51 not having a pressurised cockpit.



Ever seen video of P-51 pilots flying at high altitudes, wearing oxygen masks? Know why they're wearing those masks?

P-51s weren't pressurized. Why do you think they were?

Bremspropeller
09-28-2009, 04:52 PM
You could theoretically lightly pressurize an airframe on the moon, but to nowhere near the slightest survivable levels.


Looks like you're one of those Apollo-haters http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif

Depends on the plane and how properly sealed it is.


@ Owl:
Building an aircraft that would make you survive SITTING on the moon (no air, no lift, no flight...) ain't a big deal.
Building a pressure-vessel that you could shoot up there in the first place, however, is.

It's all about weight and the stress induced by operating it in differential-pressure (no air outside, but lots of air inside).

In order to save weight (and thrust for launch and thus cost), spacecraft aren't pressurized to normal atmosphere-pressure.
Instead, the use a much lower pressure than on earth, in conjunction with a pure-oxygen atmosphere (not sure about the ISS, thoug...weren't the Russians lobbying against a pore Oxy atmosphere?).
A pure oxygen-atmosphere allows you to operate the spacecraft at lower inthernal pressures, thus there is less differential-pressure and thus less tension on the material.
Less tension is cool, because you can take less material (thickness), or even a generally lighter material.

Now, if you wanna go out for a spacewalk, the pressure inside the suit is VERY low and the astronaut breaths pure oxygen.
The pressure is this low to allow the astronaut to move inside the suit.
If you wanna see why, take a balloon and put some air into it.
The more air there is inside the balloon (=the grater pressure differential), the balloon not only gets bigger and bigger, but also stiffer and stiffer.
So the less pressure inside the suit, the less exhaustive the work for the astronaut in order to just move.
Imagine you're out for a multi-hour spacewalk - the less tired you are from just moving around, the better as you can work more efficiently.

As a fun fact:
Alexei Leonov, the first human to make a spacewalk, almost didn't make it back iside his spacecraft because his suit had infladed too much (sun did heat up the suit and thus the gas inside, leading to an expansion).
He had to manually vent some of his suit-air in oder to get slim enough to fit back in Vozchod's hatch.


I hope this wasn't all too confusing.
But I figured it was nice to know and it surely makes up a nice theme to show off in class http://forums.ubi.com/images/smilies/winky.gif

WTE_Galway
09-28-2009, 04:54 PM
http://i4.photobucket.com/albums/y101/clannagh/space.jpg



On a more serious note - assuming you could strengthen an aircraft cockpit well enough to handle one atmosphere under water or in outer space without imploding or exploding -- you obviously could breathe, but only for a relatively short time.

It would get pretty manky without some way of recycling/replacing the air (like in a Hollywood submarine disaster movie) and you would be gasping for breathe as the CO2 levels rose and eventually pass out and die.

Treetop64
09-28-2009, 05:07 PM
Originally posted by Bremspropeller:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">You could theoretically lightly pressurize an airframe on the moon, but to nowhere near the slightest survivable levels.


Looks like you're one of those Apollo-haters http://forums.ubi.com/groupee_common/emoticons/icon_razz.gif

</div></BLOCKQUOTE>

Um, no. I'm not.
Talking about existing aircraft on the moon here, not purpose-built spacecraft...

Obviously, for Owl's idea to work would require extensive modification of the aircraft, but I think that entirely misses the point of his question.

Bremspropeller
09-28-2009, 05:41 PM
On a more serious note - assuming you could strengthen an aircraft cockpit well enough to handle one atmosphere under water or in outer space without imploding or exploding -- you obviously could breathe, but only for a relatively short time.


Actually, you wouldn't have to - at least for the space-trip.
Normal airliners do have a differential-pressure of 8psi, which is about 0.55 bars.
Breathing pure oxygen, this is actually above the nomral partial-pressure.
And airliner-fuselages are designed for about 60,000-80,000 cycles of depressurisation and repressurisation - all in an aluminium-tube of about 2mm wall-thickness.

The Apollo LM actually had a much thinner skin - only a couple of "layers of tinfoil".
If you dropped a pen or a screwdriver (on the Earth...), it would go right through it's skin.

You see, there isn't much challenge to build a pressure-vessel that can stand a differentual-pressure of one atmosphere - especially if there aren't too many cycles.

The only challenge of getting a P-51 pressurized on the moon youd be properly sealing it's fuselage and cockpit-area.
And that is not too complicated.

deepo_HP
09-28-2009, 06:23 PM
Originally posted by Bremspropeller:
I hope this wasn't all too confusing. just in case we can go into more detail http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif


Originally posted by Bremspropeller:
Now, if you wanna go out for a spacewalk, the pressure inside the suit is VERY low and the astronaut breaths pure oxygen. well, not 'very' low...
since the human body only needs to exchange oxygen and CO2 with the atmosphere, the pressure is the same as partial oxygen-pressure at sea-level:
at average the air-pressure on earth at sealevel is 1014 hPa, where 21% is oxygen. so basically a space-suit needs only a fifth of atmospherical pressure, but pure oxygen, for breathing. for the exhaling of CO2 another 4% is added, as well as some for the vapor. this sums up to 320 hPa suit-pressure, which is about 31% of our earth atmosphere.


Originally posted by Bremspropeller:
In order to save weight (and thrust for launch and thus cost), spacecraft aren't pressurized to normal atmosphere-pressure.
Instead, the use a much lower pressure than on earth, in conjunction with a pure-oxygen atmosphere (not sure about the ISS, thoug...weren't the Russians lobbying against a pore Oxy atmosphere?). that is true for spacecrafts, on the space-station the atmosphere is the same as on earth (since they have a regenerative life-support system).
so the russians had a point to be against a pure oxygen-atmosphere, because otherwise the crew had much of a funny stay up there, being high until they probably intoxicate.

sry, bremspropeller, couldn't resist http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif.
btw, who was this guy, who bailed out in high earth-atmosphere with a defect glove - and then came down alive, but with a giant hand?


added (in regard bremspropeller's last post):
that's right, it is much more problematic to build a submarine than a space-vehicle's hull.
the difference between in- and outside is always (only) 1 bar in space, but 1 bar every 10m in water. the human lungs are already at 30m compressed to their smallest possible size.
it is most fascinating, that spermwhales can dive down to 5.000 ft, more than any military submarine can achieve even with hulls of steel.

wavlength
09-28-2009, 06:41 PM
http://i767.photobucket.com/albums/xx316/wavelength_art/MustangonMoon.jpg

WTE_Galway
09-28-2009, 06:56 PM
Originally posted by deepo_HP:

it is most fascinating, that spermwhales can dive down to 5.000 ft, more than any military submarine can achieve even with hulls of steel.

Well yeah probably true for military subs ... but the Bathyscaphe Trieste reached a depth of 35,800 ft in the Mariana Trench ... no whales down there.

Choctaw111
09-28-2009, 07:01 PM
Originally posted by The_Stealth_Owl:



Theres no noise in space, so if you were in P-51, could you here noise?




Even if you had enough lift in a P51 to get high enough in space where there was no sound, there would also be no air for the engine to run.
Man, where do you come up with such questions?

The_Stealth_Owl
09-28-2009, 07:13 PM
Man, where do you come up with such questions?

I make them up. http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

deepo_HP
09-28-2009, 07:58 PM
Originally posted by WTE_Galway:
Well yeah probably true for military subs ... but the Bathyscaphe Trieste reached a depth of 35,800 ft in the Mariana Trench ... no whales down there. hmm, but then, the bathyscaphe is not even able to move by itself http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif anyway, the comparison was just between the travelling capabilities of a high developed organic life-form and a mecha-steel.

and still, piccard noticed fishy things down there - however they didn't follow him back to the light.

RPMcMurphy
09-28-2009, 08:35 PM
http://i363.photobucket.com/albums/oo71/11072008/MustangonMoon.jpg

Bremspropeller
09-29-2009, 08:14 AM
Thanks for the clarification deepo! http://forums.ubi.com/images/smilies/25.gif

R_Target
09-29-2009, 08:54 AM
Photographic evidence confirms presence of P-51 on the moon.

http://i36.tinypic.com/2l9tyxh.jpg

M_Gunz
09-29-2009, 09:00 AM
Should change Owl to something like Osprey or Pelican since those birds catch fish.

VF-17_Jolly
09-29-2009, 12:16 PM
btw, who was this guy, who bailed out in high earth-atmosphere with a defect glove - and then came down alive, but with a giant hand?


The man is called Joesph Kittinger

Highesst para jump (http://www.youtube.com/watch?v=DNx7OH_QXzc)

Good docu (http://www.youtube.com/watch?v=1VdSeDqU3EY&feature=fvw)

102,000ft

deepo_HP
09-29-2009, 01:15 PM
yesss...

great! thx, jolly