Cruising at 51000 feet
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Cruising at 51000 feet
Caught the tail end of a FlightLine (Discovery Wings) with that bloke with the long hair taking a Gulfstream V up to 51000 feet. 
Interestingly the other pilot had to wear an oxygen mask all the time above something like 41000 feet.
Also in the event of a pressurization failure the thing doves in automatically orchestrated by the electronics.
Not sure I fancy having to wear that mask all the time though
Interestingly the other pilot had to wear an oxygen mask all the time above something like 41000 feet.
Also in the event of a pressurization failure the thing doves in automatically orchestrated by the electronics.
Not sure I fancy having to wear that mask all the time though
Operations above FL410 represent real compromises in safety over efficiency, and those compromises increase with altitude. On the other hand, turbofan aircraft experience little or no fuel savings in these operating environments, so aircraft certified to FL510 will not spend much time at these heights (Concorde excepted!). Cruising at the lower levels, an aircraft certified to be safe at FL510 would be expected to be safer at FL370 than an aircraft certified to FL370, I suppose.
The benefits for business jets operating at these levels mainly reside in direct routing, above the airliner traffic and higher weather.
Rapid decompression is more serious the smaller the aircraft and the higher the altitude. For instance, an 11 square inch hole (3.7 inch diameter) would depressurinse a Lear24 at 50,000' in 10 seconds. The same hole would take several minutes to depresurise a 727 at the same altitude. The time to react in business aircraft is much less than in airliners.
Next to consider is the efficiency of oxygen equipment at high altitude. At 34,000', where ambient pressure is only 188mm, supplemental oxygen delivered at 100% will suply at partial pressure of 101mm. Even on 100% oxygen, passengers will suffer increasingly severe hypoxia above 34,000 feet. Pilots, of course, require pressure breathing equipment much lower than this. At 41,000 feet 100% oxygen will just barely sustain consciousness in a normally healthy non-smoker, assuming the mask in in place and delivering oxygen before the cabin altitude reaches 41,000 feet.
At 51,000 feet ambient pressure is only 81mmHg. At this altitude there is 6mm more partial pressure of Oxygen in the blood than in the lungs so every breath cycle is actually removing Oxygen from the blood. Life expectancy is only about five minutes, with irreversible brain damage taking place in three or less. Physiologists are not sure exactly what happens in an explosive decompression at 51,000 feet because it is too hazardous to test or even to simulate.
Pilots with pressure breathing oxygen equipment have a slim margin for survival after an explosive decompression at 51,000 feet. The 25mHg partial pressure afforded by the pressure system would probably sustain a healthy adult long enough to initiate an emergency decent if the mask was fitted and delivering 100% Oxygen prior to decompression.
{Paraphrased from a Business and Commercial Aviation article "Decompression at 51,000 Feet"/May 1978}
The benefits for business jets operating at these levels mainly reside in direct routing, above the airliner traffic and higher weather.
Rapid decompression is more serious the smaller the aircraft and the higher the altitude. For instance, an 11 square inch hole (3.7 inch diameter) would depressurinse a Lear24 at 50,000' in 10 seconds. The same hole would take several minutes to depresurise a 727 at the same altitude. The time to react in business aircraft is much less than in airliners.
Next to consider is the efficiency of oxygen equipment at high altitude. At 34,000', where ambient pressure is only 188mm, supplemental oxygen delivered at 100% will suply at partial pressure of 101mm. Even on 100% oxygen, passengers will suffer increasingly severe hypoxia above 34,000 feet. Pilots, of course, require pressure breathing equipment much lower than this. At 41,000 feet 100% oxygen will just barely sustain consciousness in a normally healthy non-smoker, assuming the mask in in place and delivering oxygen before the cabin altitude reaches 41,000 feet.
At 51,000 feet ambient pressure is only 81mmHg. At this altitude there is 6mm more partial pressure of Oxygen in the blood than in the lungs so every breath cycle is actually removing Oxygen from the blood. Life expectancy is only about five minutes, with irreversible brain damage taking place in three or less. Physiologists are not sure exactly what happens in an explosive decompression at 51,000 feet because it is too hazardous to test or even to simulate.
Pilots with pressure breathing oxygen equipment have a slim margin for survival after an explosive decompression at 51,000 feet. The 25mHg partial pressure afforded by the pressure system would probably sustain a healthy adult long enough to initiate an emergency decent if the mask was fitted and delivering 100% Oxygen prior to decompression.
{Paraphrased from a Business and Commercial Aviation article "Decompression at 51,000 Feet"/May 1978}
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I used to fly a military aeroplane which would operate above 50 000 ft with ease - I've done 45 deg AOB turns in it watching Phantoms falling out of the sky trying to catch it! We used to have a limit of 45 000 ft using the normal oxygen regulator as even 30mm overpressure was insufficient in the event of rapid decompression above that height if 'aerodynamic suck' reduced the flight deck pressure below the ambient static pressure. To go above 45 000 ft, it was necessary to wear a pressure jerkin and to have an improved regulator which could deliver a 50 mm overpressure. The PJ pushed against the body preventing physiological damage, but those who did the high altitude rapid decompression run in the chamber (25 000 ft to 55 000 ft in 3 seconds?) said it was a pretty unpleasant experience - and if you didn't wear the PJ then you were limited to 40 000 ft as the effect of 50mm without a PJ would be very dangerous!
To be certficiated to cruise at the heights intended, Beoing's Sonic Cruiser is going to need a similar approach to decompression protection as Concorde. Plus, no doubt, little cabin windows as well!!
To be certficiated to cruise at the heights intended, Beoing's Sonic Cruiser is going to need a similar approach to decompression protection as Concorde. Plus, no doubt, little cabin windows as well!!
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I read in a magazine that an explosive decrompression is usually if not always fatal to all on board. This means that the air is expelled from your lungs faster than you can breathe out- effectively causing the lungs to collapse and damage to the chest area. Even with 02 explosive decompression would cause instantaneous incapacititaion. Rapid decompression on the other hand is nowhere near as severe and masks will help. In a Bizjet like a Lear 35 a decompression will most likely be explosive thus leaving the occupants with very little time to act(unlike an airliner which will depressurize much slower)
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To get the required range out of the GV on 6000nm legs you have to spend a good portion of your time in the upper 40's, FL 470-FL490.
The aircraft has an automatic emergency descent mode under certain conditions. If your above 40,000 ft with the autopilot and autothrottles engaged and you get a cabin pressure low alert, the aircraft will turn 90 degrees left of present course, it will descend to 15,000 ft at MMO/VMO and level off and it will then maintain the current heading and a speed of 250 kts. If you have a rapid D you have to get your mask on and you must get the speedbrake out in the GV. The concern I have is that at FL 490 you may not have time to get your mask on, this is why the regs say above 410 one person must wear the mask at all times. The airplane will descend around 7000-9000 ft/min with the speedbrakes out but MUCH slower if you don't. All the occupants are going to be seriously injured if they survive at all. This is not a comforting feeling for me while cruising at high altitudes.
The aircraft has an automatic emergency descent mode under certain conditions. If your above 40,000 ft with the autopilot and autothrottles engaged and you get a cabin pressure low alert, the aircraft will turn 90 degrees left of present course, it will descend to 15,000 ft at MMO/VMO and level off and it will then maintain the current heading and a speed of 250 kts. If you have a rapid D you have to get your mask on and you must get the speedbrake out in the GV. The concern I have is that at FL 490 you may not have time to get your mask on, this is why the regs say above 410 one person must wear the mask at all times. The airplane will descend around 7000-9000 ft/min with the speedbrakes out but MUCH slower if you don't. All the occupants are going to be seriously injured if they survive at all. This is not a comforting feeling for me while cruising at high altitudes.
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BEagle
Ahhhhhhhhhhh as gaunty turns green with envy.
That has to have been the most beautiful aircraft ever built, mind you the Victor and Valiant weren't that ugly either.
It remains an unrealised dream to fly one.
I can see it like it was yesterday when as a youngster in high school who lived near Peery Lakes Stadium in Perth whilst the Commonwealth Games 1962 were on, the Brits sent a Vulcan down here for the opening flypast, and I was witness to the practises and final event which concluded with a max power pull up after passing the saluting base.
The sight of that huge bat powering almost straight up ....was awesome. Went to Pearce AFB later to stand underneath it whilst it had a rest.
I have seen and partaken in many an air display since but have never seen anything to equal it.
Except maybe the RAAF VC10 disappearing around behind the hangars at Biggin as it pulled around for another low run.
Ahhhhhhhhhhh as gaunty turns green with envy.
That has to have been the most beautiful aircraft ever built, mind you the Victor and Valiant weren't that ugly either.
It remains an unrealised dream to fly one.
I can see it like it was yesterday when as a youngster in high school who lived near Peery Lakes Stadium in Perth whilst the Commonwealth Games 1962 were on, the Brits sent a Vulcan down here for the opening flypast, and I was witness to the practises and final event which concluded with a max power pull up after passing the saluting base.
The sight of that huge bat powering almost straight up ....was awesome. Went to Pearce AFB later to stand underneath it whilst it had a rest.
I have seen and partaken in many an air display since but have never seen anything to equal it.
Except maybe the RAAF VC10 disappearing around behind the hangars at Biggin as it pulled around for another low run.
