# \[Possibly dumb\] question about aircraft ceilings. **URL:** \ **Category:** Factual Questions\ **Created:** [December 20, 2012, 2:53am UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598 "2012-12-20T02:53:19Z")\ **Posts on this page:** 9\ **Page:** 3
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [December 21, 2012, 12:59pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/41 "2012-12-21T12:59:59Z")
The Colgan Dash 8 that crashed in Buffalo also had a pilot who pulled back in response to the stick pusher. Colgan is a subsidiary of Pinnacle. ---
**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:** [December 21, 2012, 1:18pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/42 "2012-12-21T13:18:24Z")
> [@Simple\_Linctus](#): > > It’ll come back down again; |orbital velocity at altitude x| = |escape velocity at altitude x|. Orbital velocity never equals escape velocity. At the surface of the earth, escape velocity is about 25,000 MPH; orbital velocity is about 17,800 MPH. Orbital velocity increases with altitude, but escape velocity decreases with altitude. > [@Mekhazzio](#): > > What stops it from going where noone has gone before is the same old problem all spaceflight has: fuel. Or, more accurately, the efficiency of the conversion from fuel mass to thrust. Efficiency doesn’t matter. If you took all of the chemical energy of the X-15’s fuel load (even condensing the ehxaust steam down to liquid water) and delivered it to the unfueled X-15 as kinetic energy, it would still only hit 11,185 MPH. Not fast enough to achieve orbit, and definitely not fast enough to go to infinity. Or beyond. ---
**Author:** ![Sailboat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sailboat/32/461_2.png) [@Sailboat](https://boards.straightdope.com/u/Sailboat)\ **Post date:** [December 21, 2012, 1:39pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/43 "2012-12-21T13:39:04Z")
> [@Simple\_Linctus](#): > > FYI, the X15 had a reaction control system (and obviously couldn’t be stuck in space as it reached nothing like orbital velocity) > > Which is not to say that any possible thing you did with it would have led to a survivable reentry of course, and at least one dude died after reaching [266 000](https://en.wikipedia.org/wiki/X-15_Flight_3-65-97) feet - which made it a space flight, just by the USAF definition at the time (50 miles) - in one. Good grief! Imagine: [QUOTE=Wikipedia] Adams held the X-15’s controls against the spin, using both the flight controls and the reaction control jets in the nose and wings. He managed to recover from the spin at 118,000 feet and went into an inverted Mach 4.7 dive at an angle between 40 and 45 degrees. In theory, Adams was in a good position to roll upright, pull out of the dive and set up a landing. However, due to high gain in the adaptive control system, the X-15 went into pilot induced oscillation with rapid pitching motion of increasing severity, still in a dive at 160,000 feet per minute. As the X-15 neared 65,000 feet, it was diving at Mach 3.93 and experiencing more than 15g vertically, and 8g laterally. [/QUOTE] ---
**Author:** ![Mekhazzio](https://avatars.discourse-cdn.com/v4/letter/m/b38774/32.png) [@Mekhazzio](https://boards.straightdope.com/u/Mekhazzio)\ **Post date:** [December 21, 2012, 5:07pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/44 "2012-12-21T17:07:01Z")
> [@Machine\_Elf](#): > > Efficiency doesn’t matter. The conversion rate from mass to thrust is what is ultimately the limiting factor in space exploration, because that’s what stops you from just strapping on ever-larger fuel tanks to get you where you want to go. The rate of diminishing return from then having to push that additional mass as well is what really determines your practical velocity limit. (Although, clearly, an X-15 with an awful lot of fuel would start to look less like an X-15 and more like a shuttle :D) ---
**Author:** ![Magiver](https://avatars.discourse-cdn.com/v4/letter/m/4491bb/32.png) [@Magiver](https://boards.straightdope.com/u/Magiver)\ **Post date:** [December 21, 2012, 6:11pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/45 "2012-12-21T18:11:37Z")
> [@Machine\_Elf](#): > > Orbital velocity never equals escape velocity. At the surface of the earth, escape velocity is about 25,000 MPH; orbital velocity is about 17,800 MPH. Orbital velocity increases with altitude, but escape velocity decreases with altitude. > > Efficiency doesn’t matter. If you took all of the chemical energy of the X-15’s fuel load (even condensing the ehxaust steam down to liquid water) and delivered it to the unfueled X-15 as kinetic energy, it would still only hit 11,185 MPH. Not fast enough to achieve orbit, and definitely not fast enough to go to infinity. Or beyond. again, you’re talking about the speed needed to overcome an orbit. I was referring to a straight up trajectory with NO orbit. It doesn’t require any specific speed. It only requires propulsion (and of course fuel). [From Wiki:](http://en.wikipedia.org/wiki/Escape_velocity) A vehicle with a propulsion system can continue to gain energy and travel away from the planet, in any direction, at a speed lower than escape velocity so long as it is under propulsion. ---
**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:** [December 21, 2012, 6:13pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/46 "2012-12-21T18:13:28Z")
> [@Mekhazzio](#): > > The conversion rate from mass to thrust is what is ultimately the limiting factor in space exploration, because that’s what stops you from just strapping on ever-larger fuel tanks to get you where you want to go. The rate of diminishing return from then having to push that additional mass as well is what really determines your practical velocity limit. All true. I just wanted to point out that efficiency didn’t matter in the specific case of the X-15: even with 100% efficient rocket engines and zero aerodynamic drag, the X-15 could not have achieved orbital velocity or escape velocity. ---
**Author:** ![Perderabo](https://avatars.discourse-cdn.com/v4/letter/p/a183cd/32.png) [@Perderabo](https://boards.straightdope.com/u/Perderabo)\ **Post date:** [December 21, 2012, 8:54pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/47 "2012-12-21T20:54:23Z")
> [@Seanette](#): > > Much dumber question than the OP: when I read “ceiling” in connection with aircraft, I thought it meant what the Weather Channel shows Hell, I thought it meant that white thing 8 inches above my head as I walk down the aisle to my seat. :o ---
**Author:** ![Dr.Strangelove](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dr.strangelove/32/6613_2.png) [@Dr.Strangelove](https://boards.straightdope.com/u/Dr.Strangelove)\ **Post date:** [December 21, 2012, 9:29pm UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/48 "2012-12-21T21:29:56Z")
> [@Gray\_Ghost](#): > > The U-2 was reportedly a very unforgiving plane to fly and killed more than a few pilots. Didn’t the Taiwanese Air Force have a very difficult time during their use of the U-2 to overfly the People’s Republic of China, with multiple crashes and deaths? I don’t know, but it wouldn’t surprise me. I do know that just about every aspect of flight was a challenge; landing requires a chase car, and the plane only has center landing gear, so it flops over to one side once it’s moving too slowly (or the pilot makes a tiny mistake). You get a couple of guys hanging off the high wing as a counterweight so someone can install a temporary taxi wheel on the other side. ---
**Author:** ![Tim\_T-Bonham.net](https://avatars.discourse-cdn.com/v4/letter/t/46a35a/32.png) [@Tim\_T-Bonham.net](https://boards.straightdope.com/u/Tim_T-Bonham.net)\ **Post date:** [December 22, 2012, 2:28am UTC](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598/49 "2012-12-22T02:28:01Z")
> [@Gray\_Ghost](#): > > The U-2 was reportedly a very unforgiving plane to fly and killed more than a few pilots. Didn’t the Taiwanese Air Force have a very difficult time during their use of the U-2 to overfly the People’s Republic of China, with multiple crashes and deaths? They had a more difficult time when their pilots were training to learn how to fly the U-2. They lost about twice as many planes in California & Nevada during training than they ever did flying over China. Not surprising, really – with a plane that touchy, the most dangerous time would be when q new pilot is first learning to fly it. [Previous page](https://boards.straightdope.com/t/possibly-dumb-question-about-aircraft-ceilings/644598.md?page=2)