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Guest Ted_Thompson

Is higher better?

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This concerns the HU16, but I suppose you can use the DC3 as an example. For long range flights which is better? Flying at 6000' or going to 20,000 ? Terrain not withstanding of course....

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Generally speaking the higher is the better because fuel burn is signficantly lower and airspeed (TAS/GS) higher. The air becomes less dense when you go higher, so less drag the higher you go.Factors to take into consideration:- Winds aloft (strength / direction)- Is the aircraft pressurized, otherwise max 10.000/12.000ft- Ground elevation

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The air is thinner at higher altitudes so you will get lower fuel consumption at higher alt. depending on the winds of course.Dave F.

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Which raises another question for me... Was the Albatross (which is piston powered, if that makes a difference) pressurized? I'm betting not.

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I don't know the Albatros so I can't tell you, but given it's a piston powered aircraft, the ceiling would probably somewhere at 16.000/18.000ft. I think piston powered aircraft can't go higer anyway due to the type of engine (not sure though). The air gets too thin to burn fuel at higher altitudes, the engine simply gets too little air. However if it had an compressor/turbo this would raise the service ceiling.(Don't ask if it had an compressor ;-) )With pressurized I mean the oxygen supply needed for pilots/pax above 12.000/14.000ft. If the aircraft isn't pressurized (most likely) but it still has some kind of oxygen supply (bottles) it can go higher.

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Piston powered aircraft can go very high and, in fact, can do better than many turbo props. They do not need to be pressurized either, except having pressurized mags would certainly help!From Wikipedia:The highest altitude obtained in a piston-driven propeller aeroplane (without a payload) was 17,083 meters (56,047 ft) on October 22, 1938 by Mario Pezzi at Montecelio, Italy in a Caproni 161 driven by a Piaggio XI R.C. engine.The highest altitude for horizontal flight without a payload is 14,301 meters (46,919 ft) set on November 15, 2003 by Bruce Bohannan flying his Bohannon B-1 driven by a Mattituck/Lycoming IO-540 (350 hp) engine over Angleton, Texas.I will add that it was probably a TIO-540, not an IO-540 that acheived that last record, as the "T" stands for turbo, and the "I" stands for fuel injected. I fly behind an O-540, which has a carburetor!Prior to this last one, a Cessna 210 Turbo made it to 43,000' back in the early 1960s and held the record back then.Regards,http://www.dreamfleet2000.com/gfx/images/F...R_FORUM_LOU.jpg

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Max altitude for an HU-16 (aka Albatross) is 21,000' or 21,500' depending on where you look it up.The vintage data I've collected so far (more is coming in the mail) doesn't indicate if it's pressurized or not, but the doc's main focus is external dimensions and control panel arrangement.So the rule of thumb seems to be that the higher altititude is worth the fuel spent on the climb to get there.And am I correct in thinking that the idea is that you get more range at the same speed?

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The HU-16 Albatross is not pressurized. It does have oxygen available for all crew members. In over 800 hours as a crew member from 1959-1962 (Flight Mechanic) including trips from California to Bermuda and California to Porto Rico we never went high enough to use oxygen.Ed Weber

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If the aircraft isn't pressurized (most likely) but it still has some kind of oxygen supply (bottles) it can go higher.While oxygen supplies (bottles) are carried in many aircraft - there is a limit to how well the human body can asorb oxygen at higher altitudes without external pressure to improve the efficiency of the lungs.The WWII movies of B-17 crews on oxygen don't show that the vast majority of the flight was below 10,000 ft (it's still pretty danged cold that high with an open hatch).Pilots flying above FL180 on oxygen can risk Altitude Decompression Sickness - like the bends in divers - if there descent is too fast. The higher they go, the more time their descent must take.Studies today of available information show many aviation pioneers suffered significant permanent brain damage due to lack of oxygen at altitude and too rapid descents when on oxygen.Altitudes/ pressure levels above 5,000 feet cause deterioration in night vision - significant deteroiration at levels above 10,000 ft.In an unpressurized aircraft:Can you fly high without oxygen? Yes up to 14,000 ft in some countries for 1/2 hour or less.Can you fly high with supplemental oxygen? Yes, but again there are issues and consequencesWould you make long distance flights at high altitude to save some fuel? No - if you understand the risks.

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>Pilots flying above FL180 on oxygen can risk Altitude>Decompression Sickness - like the bends in divers - if there>descent is too fast. The higher they go, the more time their>descent must take.>>Studies today of available information show many aviation>pioneers suffered significant permanent brain damage due to>lack of oxygen at altitude and too rapid descents when on>oxygen.Mmm, someone correct me if I'm wrong, but AFAIK decompression sickness can only occur during a decrease in pressure, not an increase. A rapid descent would cause an increase in pressure, and hence no decompression sickness.http://en.wikipedia.org/wiki/Decompression_sicknessIn this article, they say decompression sickness can only be triggered if the aircraft is climbing (or the pressurization system fails, causing a rapid decompression).Marco

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I'm sorry - your right - up / down - whichever :-)Pre-breathing 100% oxygen for 30 minutes before the flight / climb begins is highly recommend for high altitude flights.

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It's also true that smokers and women suffer more from the thinner air (sorry ladies) although like anything it varies from person to person no matter what.(ain't wikipedia grand? :) )

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Do you happen to recall round about what FL you were at for those Cali to X trips?

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You might want to check out "FS Aviator's Propliner Flying in the Classic Era" at Tom Gibson's California Classic Propliner site. It's a thorough treatment of all the issues involved in flight planning, including the factors that went into choosing the proper altitude during different phases of flight. It's a long set of documents, including a tutorial flight, and a somewhat challenging read, but this might be the information you're looking for. http://www.calclassic.com/files/Propliner_Tutorial.zip(He bases his example on a pressurized DC-6, and I don't remember if he takes issues of pressurized vs. non-pressurized aircraft into account or not, but the engine management issues would probably be the same, wouldn't they? On the other hand, pressurized cabins certainly made all the difference in the world to the old airliners in the late 40s - early 50s. In the advertisements they go on and on about being able to "fly above the weather" but in reality the main advantage was being able to go up to higher cruise altitudes to save time, as the tutorial explains.)Happy Independence Day to all!Ed_Garr

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I downloaded it. We'll see what's there! Thanks for the link.

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