# If you boosted a business jet to 100,000 feet what happens? Can it come back down intact? **URL:** \ **Category:** Factual Questions\ **Created:** [January 10, 2016, 9:01pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731 "2016-01-10T21:01:30Z")\ **Posts on this page:** 20\ **Page:** 2
**Author:** ![md2000](https://avatars.discourse-cdn.com/v4/letter/m/73ab20/32.png) [@md2000](https://boards.straightdope.com/u/md2000)\ **Post date:** [January 11, 2016, 5:57am UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/21 "2016-01-11T05:57:51Z")
> [@Robot\_Arm](#): > > I remember that one; quite possibly the stupidest movie I have ever seen. Even stupider than what was it, “Airport 75”(?) where a fully pressurized 747 sank into the ocean (without tearing apart or landing, without crumpling once submerged)? Never underestimate the ability of Hollywood to misunderstand how reality works. > [@Robot\_Arm](#): > > Excellent post. > > Suppose you took care of the life support problem, and used a jet with manual controls. What would happen if you tried to take it to 100,000 feet? Obviously the controls would be ineffective and the plane wouldn’t necessarily stay pointed the right way. What happens as it comes back down? The air is going to gradually get thicker until the controls start to work again. Is there any hope of regaining control and stability at that point? > > Part of what got Yeager in the NF-104 was that the elevator was in the full nose-up position when the engine shut down, and without power it stayed there. If you use a jet with manual controls, does it help the situation at all? There was a proposal many years ago, IIRC, to put a small rocket engine into the back end of a 747(?) and use that to boost it to a much higher altitude (60,000 ft? 75,000 ft?) where it would drop a small rocket; much like the underwing launch of the Pegasus - but the extra altitude and thinner air would give it more of a head-start. As others point out, the typical passenger jet is not designed to work above about 50,000ft. The modifications needed would essentially make a new aircraft. Much bigger control surfaces, if not a attitude rocket system for control; possibly to be effective at thinner altitudes, the wing airfoil shape and even wing size might need updating. The current pressurization equipment would be inadequate due to thinner incoming air - would need bigger stronger pups; I don’t know if the current airliner designs tolerate a certain leakage and let the pumps keep up pressure, but if the seals are good, then presumably a short stint in the much tinner air would be doable. Like the 747 example I cite, the problem too is speed. Unless we’re talking Concorde (in which case, build from scratch, use a B2 or something) the airframe and airfoil, nose shape, hull and wing strength, etc. are not designed for supersonic. Depending how you attach the rocket, the attach points have to be able to handle the stress of forcing the aircraft through the air until it gets to the thin air, much as the jet engine pylons do. The iconic SR71 had a number of adaptions for travelling at 3,000mph - to allow the aircraft not to melt from friction, it was mostly corrugated titanium - corrugated to allow for expansion with the friction heat from Mach 5 at 80,000 feet. > [@](#): > > Flying at 80,000 ft (24,000 m) meant that crews could not use standard masks, which could not provide enough oxygen above 43,000 ft (13,000 m). Specialized protective pressurized suits were produced by the David Clark Company for the A-12, YF-12, M-21 and SR-71. Furthermore, an emergency ejection at Mach 3.2 would subject crews to temperatures of about 450 °F (230 °C); thus, during a high altitude ejection scenario, an onboard oxygen supply would keep the suit pressurized during the descent.[66] > > The cockpit could be pressurized to an altitude of 10,000 or 26,000 ft (3,000 or 7,900 m) during flight.[67] The cabin needed a heavy-duty cooling system, for cruising at Mach 3.2 would heat the aircraft’s external surface well beyond 500 °F (260 °C)[68] and the inside of the windshield to 250 °F (120 °C). An air conditioner used a heat exchanger to dump heat from the cockpit into the fuel prior to combustion.[citation needed] The same air conditioning system was also used to keep the front (nose) landing gear bay cool, thereby eliminating the need for the special aluminum-impregnated tires similar to those used on the main landing gear.[69] ---
**Author:** ![Isilder](https://avatars.discourse-cdn.com/v4/letter/i/cc9497/32.png) [@Isilder](https://boards.straightdope.com/u/Isilder)\ **Post date:** [January 11, 2016, 6:13am UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/22 "2016-01-11T06:13:58Z")
All engines on board fail, and the aeroplane goes into emergency mode. Running off battery. Its going to be a real bitch to steer … but hang on, the air is so thin, the control surfaces don’t really work, its impossible, as it descends it runs into uneven atmosphere and strange effects, probably the nose would start to lift, and the back won’t get atmosphere as the nose blasted the air out of the way… So it goes nose up, and backflips… Sooner or later it flops down into the thick air at really high speeds, in a very awkward position, and the wings tear off … ---
**Author:** ![Peter\_Morris](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/peter_morris/32/359_2.png) [@Peter\_Morris](https://boards.straightdope.com/u/Peter_Morris)\ **Post date:** [January 11, 2016, 6:16am UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/23 "2016-01-11T06:16:02Z")
> [@md2000](#): > > Even stupider than what was it, “Airport 75”(?) where a fully pressurized 747 sank into the ocean (without tearing apart or landing, without crumpling once submerged)? Never underestimate the ability of Hollywood to misunderstand how reality works. I looked it up. It was '77. > **[Airport '77 (1977) ⭐ 5.8 | Action, Drama, Thriller](https://www.imdb.com/title/tt0075648/)** > > 1h 54m | PG ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [January 11, 2016, 6:16am UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/24 "2016-01-11T06:16:34Z")
> [@md2000](#): > > Even stupider than what was it, “Airport 75”(?) where a fully pressurized 747 sank into the ocean (without tearing apart or landing, without crumpling once submerged)? Never underestimate the ability of Hollywood to misunderstand how reality works. Yes, stupider than _Airport '77_. > [@](#): > > There was a proposal many years ago, IIRC, to put a small rocket engine into the back end of a 747(?) and use that to boost it to a much higher altitude (60,000 ft? 75,000 ft?) where it would drop a small rocket; much like the underwing launch of the Pegasus - but the extra altitude and thinner air would give it more of a head-start. > > As others point out, the typical passenger jet is not designed to work above about 50,000ft. The modifications needed would essentially make a new aircraft. Much bigger control surfaces, if not a attitude rocket system for control; possibly to be effective at thinner altitudes, the wing airfoil shape and even wing size might need updating. The current pressurization equipment would be inadequate due to thinner incoming air - would need bigger stronger pups; I don’t know if the current airliner designs tolerate a certain leakage and let the pumps keep up pressure, but if the seals are good, then presumably a short stint in the much tinner air would be doable. > > Like the 747 example I cite, the problem too is speed. Unless we’re talking Concorde (in which case, build from scratch, use a B2 or something) the airframe and airfoil, nose shape, hull and wing strength, etc. are not designed for supersonic. Depending how you attach the rocket, the attach points have to be able to handle the stress of forcing the aircraft through the air until it gets to the thin air, much as the jet engine pylons do. > > The iconic SR71 had a number of adaptions for travelling at 3,000mph - to allow the aircraft not to melt from friction, it was mostly corrugated titanium - corrugated to allow for expansion with the friction heat from Mach 5 at 80,000 feet. I know it would take massive modifications to make it work, my question was about what would the failure would be if you didn’t. The initial problem doesn’t say anything about speed. Assume we boost our bizjet to 100,000 but keep it subsonic while doing so; as it fell would it gain enough energy for heating to be a problem? As you descend and the atmosphere gets denser, would you have a chance to regain control or would aerodynamic forces tear the airframe apart first? ---
**Author:** ![MikeS](https://avatars.discourse-cdn.com/v4/letter/m/919ad9/32.png) [@MikeS](https://boards.straightdope.com/u/MikeS)\ **Post date:** [January 11, 2016, 1:24pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/25 "2016-01-11T13:24:19Z")
This whole plan reminds me of the pilots who were flying [Pinnacle Airlines Flight 3701.](https://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701) Even without a rocket booster, it did not end well for them. ---
**Author:** ![scr4](https://avatars.discourse-cdn.com/v4/letter/s/59ef9b/32.png) [@scr4](https://boards.straightdope.com/u/scr4)\ **Post date:** [January 11, 2016, 2:17pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/26 "2016-01-11T14:17:27Z")
Do passenger jets lose cabin pressure as soon as they lose the engines? Can any one engine maintain cabin pressure, or is only one engine connected to the compressor? ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [January 11, 2016, 4:36pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/27 "2016-01-11T16:36:53Z")
I was wondering that. Aircraft-control issues aside, why would you need a special suit to stay alive? ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [January 11, 2016, 5:21pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/28 "2016-01-11T17:21:33Z")
> [@MikeS](#): > > This whole plan reminds me of the pilots who were flying [Pinnacle Airlines Flight 3701.](https://en.wikipedia.org/wiki/Pinnacle_Airlines_Flight_3701) Even without a rocket booster, it did not end well for them. Superficially similar, but that crew never actually lost control of the aircraft. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 11, 2016, 5:30pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/29 "2016-01-11T17:30:23Z")
> [@Elendil\_s\_Heir](#): > > I was wondering that. Aircraft-control issues aside, why would you need a special suit to stay alive? There is an altitude above which breathing even pure oxygen won’t sustain you because it’s just not at high enough pressure. This is [the Armstrong limit,](https://en.wikipedia.org/wiki/Armstrong_limit) and it’s around 62,000 feet. If you’re above this altitude without a pressure suit (to enable you to develop an O2 partial-pressure in your lungs equal to or greater than the ambient pressure at 62,000 feet), you will die. Since engine power is required to maintain cabin pressure, having your business jet rocketed up to 100,000 feet without a pressure suit will be fatal. ---
**Author:** ![Machine\_Elf](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@Machine\_Elf](https://boards.straightdope.com/u/Machine_Elf)\ **Post date:** [January 11, 2016, 5:37pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/30 "2016-01-11T17:37:50Z")
Correction: I misremembered the Armstrong limit, which is the altitude/pressure at which water boils at body temperature. The pressure suit limit is more like 49,000 feet. ---
**Author:** ![Leo\_Bloom](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/leo_bloom/32/10377_2.png) [@Leo\_Bloom](https://boards.straightdope.com/u/Leo_Bloom)\ **Post date:** [January 11, 2016, 6:12pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/31 "2016-01-11T18:12:09Z")
> [@Robot\_Arm](#): > > Superficially similar, but that crew never actually lost control of the aircraft. Debatable. Not to get too zen-swordsman-ish, but the chucklehead dudes would appear to have lost control early on. ---
**Author:** ![iljitsch](https://avatars.discourse-cdn.com/v4/letter/i/77aa72/32.png) [@iljitsch](https://boards.straightdope.com/u/iljitsch)\ **Post date:** [January 11, 2016, 6:54pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/32 "2016-01-11T18:54:16Z")
[Apparently](http://www.engineeringtoolbox.com/standard-atmosphere-d_604.html), going up 15 km will reduce the air pressure by about a factor 10. So at 30 km it’s about 1% of sea level pressure and about 10% of what a business jet is designed for. Not sure if that means you wouldn’t be able to point the plane forward. If that becomes a problem, then you’l end up in a spin and the question will be if you can get out of it when you descend into thicker air. That thicker air won’t hit you like brick wall, though, it gets thicker very gradually. But before that the engines will very likely stop because they can’t get enough air in, which means the cabin pressure will bleed away and everyone will soon be unconscious and probably dead. The problem is not so much the boiling of bodily fluids, but that the partial pressure of even pure oxygen isn’t enough to have your red blood cells absorb enough of it. This effect kicks in at around 15 km. I don’t think regular airliners have facilities to keep the cabin pressure up when power fails, but because business jets fly a bit higher, maybe they do. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [January 11, 2016, 8:48pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/33 "2016-01-11T20:48:28Z")
> [@Machine\_Elf](#): > > …Since engine power is required to maintain cabin pressure, having your business jet rocketed up to 100,000 feet without a pressure suit will be fatal. Wow - thanks. I assumed modern jet aircraft cockpits and passenger cabins are absolutely airtight and will hold in breathable air indefinitely. (Of course, I suppose it might get stale after awhile, or you might use up the breathable air and die of C02 poisoning). I had no idea engine power was, in fact, necessary to maintain cabin pressure. Fascinating! Ignorance fought. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [January 11, 2016, 9:00pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/34 "2016-01-11T21:00:20Z")
> [@Machine\_Elf](#): > > Since engine power is required to maintain cabin pressure, having your business jet rocketed up to 100,000 feet without a pressure suit will be fatal. Are you sure that’s true though? I know under normal circumstances, air is constantly being pushed out the outflow vent (leaving disgusting cigarette tar stains on the side of the plane during the smoking era) but if cabin pressure starts to drop, the vent should close right? I imagine even with the vent closed the plane isn’t completely airtight, but it should hold for a while. Perhaps long enough to plummet from 100,000 feet to below the pressure suit altitude? ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [January 11, 2016, 9:18pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/35 "2016-01-11T21:18:01Z")
Just a note: FAA requires pressurization or oxygen at 12,000 feet. Unless your bizjet is made of plastic (and re-inforced with lots of titanium for the stresses of rocket flight), it is going to be out of air long before it drops 88,000 feet. And, as noted, your blood will ‘boil’ without serious pressurization. And airplanes (which use ram air for pressurization) cannot pressurize without lots of air. The X-15 had bottled gas for pressure and forced oxygen for breathing. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [January 11, 2016, 9:25pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/36 "2016-01-11T21:25:10Z")
Airplanes don’t work much above 50,000 feet - Virgin Galactic’s White Knight launch plane drops the rocket-powered space plane at 50,000. An airplane’s wing produces lift only when lots of air molecules are flowing over it. Around FL500, the molecules get few and far between. What is so hard to imagine about this? ---
**Author:** ![Ranger\_Jeff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ranger_jeff/32/2065_2.png) [@Ranger\_Jeff](https://boards.straightdope.com/u/Ranger_Jeff)\ **Post date:** [January 11, 2016, 9:37pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/37 "2016-01-11T21:37:26Z")
Yep, I was going to mention Yeager’s NF-104 flight also. ---
**Author:** ![Robot\_Arm](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/robot_arm/32/18280_2.png) [@Robot\_Arm](https://boards.straightdope.com/u/Robot_Arm)\ **Post date:** [January 11, 2016, 9:40pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/38 "2016-01-11T21:40:06Z")
> [@Leo\_Bloom](#): > > Debatable. Not to get too zen-swordsman-ish, but the chucklehead dudes would appear to have lost control early on. Not in the sense that’s relevant to this thread. Those two pilots tried to climb to the maximum their jet was capable of. While doing so, they exceeded other limits and damaged the engines. They still should have been within gliding range of an airport, but after diving to restart the engines and denying the severity of the problem to ATC they crashed a couple miles short of a runway. Stupid, yes, but they never lost stability or steering control of the airplane. ---
**Author:** ![GreasyJack](https://avatars.discourse-cdn.com/v4/letter/g/df705f/32.png) [@GreasyJack](https://boards.straightdope.com/u/GreasyJack)\ **Post date:** [January 11, 2016, 10:35pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/39 "2016-01-11T22:35:28Z")
> [@usedtobe](#): > > Just a note: > > FAA requires pressurization or oxygen at 12,000 feet. > > Unless your bizjet is made of plastic (and re-inforced with lots of titanium for the stresses of rocket flight), it is going to be out of air long before it drops 88,000 feet. > > And, as noted, your blood will ‘boil’ without serious pressurization. And airplanes (which use ram air for pressurization) cannot pressurize without lots of air. > > The X-15 had bottled gas for pressure and forced oxygen for breathing. My understanding is that cabin pressurization takes huge amounts of air not because the airplanes are super-leaky, but because the passengers would make the cabin completely disgusting if the air wasn’t constantly exchanging. The outflow vent closes immediately if the pressure drops because otherwise an unexpected engine shutdown would result in dangerously rapid decompression. Considering that our hypothetical plane is going to drop the first 50,000 feet _fast_, it should be down to an altitude where the pilots can breathe only using an oxygen mask pretty darn quickly. Even if the plane is a little leaky when the vents are buttoned-up, it seems like it should be able to hold some pressure for the few minutes it takes to get there. ---
**Author:** ![usedtobe](https://avatars.discourse-cdn.com/v4/letter/u/ec9cab/32.png) [@usedtobe](https://boards.straightdope.com/u/usedtobe)\ **Post date:** [January 11, 2016, 10:43pm UTC](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731/40 "2016-01-11T22:43:45Z")
Pinnacle Airlines Flight 3701 This was simply tragic. But it has nothing to do with the thin air above FL500 - the plane had a max operational altitude of FL410, and the airline had developed a secret “club” of pilots who had sneaked a plane to that level. They did not run out of enough air to produce lift and operate control surfaces - they just exceeded the operational limits of the engines and failed to re-start the engines after they quit. There was no indication that the cabin pressure was lost nor did the wing stall. Both of which would have happened (real quickly) had they rocketed to 100,000’ MSL [Previous page](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731.md?page=1) [Next page](https://boards.straightdope.com/t/if-you-boosted-a-business-jet-to-100-000-feet-what-happens-can-it-come-back-down-intact/742731.md?page=3)