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## Max. endurance - Turbocharged/supercharged engine

• juansperling
• Topic Author

### juansperling created the topic: Max. endurance - Turbocharged/supercharged engine

I'm working on my KDRs and can't find any information on this topic. I would really appreciate it if someone could help me answer this!

'List/identify aerodynamic and engine considerations which are required to achieve maximum endurance when operating an aircraft with the following type of engine:
(b) turbocharged/supercharged engine.'

• Posts: 1169

### Richard replied the topic: Max. endurance - Turbocharged/supercharged engine

G'day Juan,

Maximum endurance is achieved when flying with minimum power since we are taking fewer "nibbles" out of the fuel per minute with a low power/low RPM setting. With such a low power setting we will be flying quite slowly, theoretically close to or right on the stall. To get maximum energy out of the air to generate the lift we need at such low speeds, we need "thick air" or air of a high density. This occurs at lower altitudes, ideally at sea level. So for maximum endurance we need to fly at low altitude (thick air) and slow with a low power setting and the engine leaned to best economy.

A supercharger/turbocharger comes into its own at higher altitudes by allowing an aircraft to keep rated boost as the aircraft climbs. The problem with higher altitude is, for the same indicated air speed, we will have a higher TAS.

Power determines the TAS, but lift is generated by indicated airspeed. Therefore, to fly at an indicated airspeed just above the stall at 10000ft will require a higher power setting than at sea level because the TAS at 10000ft is much higher. The turbocharger can deliver the power at that altitude but we don't want to be flying for best endurance up there.

So, we need to stay as low as is safe and at best endurance speed. Under these conditions, the turbocharger/supercharger is not adding as much to our performance as we would think. The turbocharger/supercharger really comes into its own when we think about flying at higher altitudes where we benefit from the higher TAS.

Cheers,

Rich

• juansperling
• Topic Author

### juansperling replied the topic: Max. endurance - Turbocharged/supercharged engine

Hi Rich,

Great explanation! Thanks for your help.

Juan