higher or lower
 

an aeroplane at 20 000 ft will slip through the air faster than one at 5000 ft as the air is less dence, to get the same parasitic drag therefore the same lift. so you go faster with a little more power. this over compensates the engine loosing power at altitude.
true or false?

what i want to know is will a helicopter travel faster and be more economical at a higher altitude or will the lift required out weigh the extra speed?????

Parasite drag reduces with height - bonus.
Engine efficiency increases with height - bonus.
Blade efficiency reduces with height - penalty

Optimum height is variable therefore depending on type of helo but for many it's around 8000DA.

Any advance on the above......

You can run the numbers out: time to climb, ground speed, fuel flow rates etc but we've found the fifty mile rule works pretty well.

If your going less then fifty NM a large climb's not worth it, over 50 it is.

This obviously disregards winds and required climbs.:eek: