I don't know if the same is true for jets or turbine powered aircraft, but for piston powered, normally aspirated engine aircraft, all you have to do is look at the cruise performance charts for your answer.
I am looking at my Cessna 172N POH as an example.
According to the manual, if I select 2300 RPM the engine will produce 60% brake horsepower (BHP) fly at 105 Knots true airspeed (KTAS) & consume 6.7 gallons of fuel per hour (GPH) at a pressure altitude of 2000 ft.
However, the same power setting of 2300 RPM at 12,000 ft pressure altitude will only produce 48% BHP, 101 KTAS, but consume only 5.6 GPH.
So to keep the same true airspeed you would have to increase the power by almost 100 RPM. Your fuel consumption would still be less at 6.0 GPH.
These figures apply provided you properly adjust the fuel mixture, with the change in altitude, & I am only looking at the Standard temperature column. (you only asked about the effect of pressure.
So it seems that with higher altitude the engine will develop less power if you keep the RPM the same, & if you lean your mixture the fuel consumption will drop, but you will also see a drop in your KTAS.
So the aircraft needs more power as it gains altitude to achieve the same KTAS. At a higher altitude the engine needs to turn at a higher RPM to produce the same power in the absence of a turbocharger.
2006-12-22 04:23:28
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answer #1
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answered by No More 7
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The answer is yes it has an effect. A balloon is an air tight container too and when it floats up it expands due to lack of pressure and pops. Your lava lamp would do the same thing if it went high enough. However the glass of the lamp is not very flexible and the square inches of area on it are small so the effect at ground level would be very minimal. A plane is much larger in area so the small amount of pressure change on it is substantial therefore the pressure needs to be regulated. I doubt any air pressure would effect the workings of your lamp
2016-05-23 15:43:26
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answer #2
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answered by Kimberly 4
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Since no one above has bothered to answer your ? (everyone's concerned with engine power available; not power REQUIRED to FLY!), I thought I'd give it a shot here.
I have written and used several spreadsheets which compute airplane performance as a function of true airspeed. They all show a reduction in power required to fly at a particular true airspeed as the density decreases. I know this isn't precisely what you asked, but in each case this density decrease is caused by a pressure decrease, so there is a direct correlation with your ?.
The 'buoyancy' you refer to is actually a reference to the need for an increasing angle of attack at a constant true airspeed as the density decreases, but since the density balances out the angle of attack and the net result is less power (and thrust, BTW) for less density. Just to affirm this, I ran one of these sheets before sending this and for a small airplane the power went from 139 hp at sea level to 99 hp at 25000 ft. This was for 150 KTAS The thrust requirement was 241 lb to 172 lb at altitude.
2006-12-22 09:25:01
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answer #3
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answered by Steve 7
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There is slightly less friction higher up, but there is a much greater loss in engine power in a recip since the air is thinner, and contains less oxygen. The only planes more efficient and high altitude are jets.
2006-12-22 03:52:07
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answer #4
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answered by badabingbob 3
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Air density(high pressure also mean higher density) make lift and drag reduce in the same way, so the plane fly faster and the dynamic pressure it's the same.....so the thrust needed is the same, but power needed is thrust*speed, so the power needed increases
2006-12-23 10:28:43
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answer #5
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answered by sparviero 6
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the engines require a higher power setting to off set the lack of density of the atmosphere at altitue. So they really dont produce more power but its the same as your car in the mountains.
2006-12-22 04:30:48
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answer #6
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answered by permit990 1
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inheretly engine power dicreases at an aproximate 3% per 1000 ft. rate. Therefor flying a 150 HP eaircraft at 7000 ft the HP Available is approx. 129 HP. so such engine requires less fuel to operate not considering the thining of the air and the requireing of less fuel to maintaing air/fuel rate.
2014-05-05 01:59:26
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answer #7
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answered by Josué 1
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