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Dragonmount

Can you gain altitude faster at high altitudes?

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It's been ages since I've flown and I've noticed a consistency with my flying and about 18k it starts getting harder and harder o gain altitude even if it's within your aircrafts current highest altitude, so that's my question, is there a trick to gaining altitude faster?

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It's been ages since I've flown and I've noticed a consistency with my flying and about 18k it starts getting harder and harder o gain altitude even if it's within your aircrafts current highest altitude, so that's my question, is there a trick to gaining altitude faster?

 

Hi Dragonmount,

It depends on the type of a/c you're flying; normally aspirated, turbo charged, turbine or jets. As the a/c climbs the engines and wings will get LESS efficient.

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As you climb in altitude, the air becomes less dense, so there is less lift under the wings and less oxygen for the engines to use in the combustion process.  Turbocharging and supercharging help with combustion at altitude, but even they have limits on how much air pressure they can supply to the engine.  So climb rate is typically fastest at sea level and diminishes as altitude is gained.

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As you climb in altitude, the air becomes less dense, so there is less lift under the wings and less oxygen for the engines to use in the combustion process.  Turbocharging and supercharging help with combustion at altitude, but even they have limits on how much air pressure they can supply to the engine.  So climb rate is typically fastest at sea level and diminishes as altitude is gained.

 

Hi stans, you're basically correct, just let me add a minor correction :)

 

As you climb, the lift over the wings remains unchanged. That doesn't vary. See when you climb at constant INDICATED AIRSPEED; for all aerodynamic purposes, 280 knots at FL380 is the same as 280 knots at sea level. (well, not exactly, compressibility and Mach effects are important at high altitudes, but that's another topic...)

 

The airspeed indicator should be named: dynamic pressure indicator, because that's basically what it's measuring

 

Dragon: As has been well said: Roughly speaking, gas turbine engines and atmospheric piston engines become less efficient at high altitudes. Supercharged piston engines will retain their full power up to a certain altitude (or the power decrease will be less than if they weren't supercharged). This is normal behaviour, as the aircraft climbs, the Specific Excess Power becomes less and less. This makes sense because engines are designed to be most efficient at cruising flight levels. If retaining high vertical speed capability at high altitude was a design requirement, the engines would have to be over-dimensioned and the fuel efficiency would be less.

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You need to use speed of best climb.

It depends on the altitude. You cannot be faster or slower, because your rate of climb would decrease.

 

You should have a table with these speeds inside your Pilot Operating Handbook.

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At 18,000' you have already used up half the atmospheric pressure from 14.7 psi down to around 7.5 psi and it only gets worse from there. As stated above, turbocharging and turbines compensate for this to some degree but only for a while. So if you want to climb faster with altitude you're going to need a rocket.

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