Hello,
I was wondering how many air brakes does a 747 have?? And how many brakes does a 2 engined aircraft have. Is there any fixed number of airbrakes on a turboprope. I was shocked to know that the An-225 Mirya has 8 air brakes on each wing. Someone also told me that all turboprops weather 2 or 4 engines have 2 airbrakes on each wing.
Kabir
By: Paul Cushion - 22nd January 2001 at 18:24
RE: Barkes!!!
Well Kabir, the ammount/size of airbrakes depend upon the size of the aircraft as much as any thing. The airbrake basically disrupts the airflow over the normally smooth wing which causes drag which slows down the aircraft. I suppose on a 747 wing you need to have a number of airbrakes for practical and operational reasons (i.e: one big airbrake might need a large hydraulic actuator but several would need smaller, less bulky ones) An aircraft is all about balance and using many flap/airbrake combinations on the 747 may be beneficial as opposed just having one or two settings on a smaller aircraft. The turboprop aircraft that you mentioned can slow down by reversing the pitch of the propeller blades to slow down. As a turboprop engine operates at constantly the same speed and that most of the power comes from altering the pitch of the blades, this provides(on the ground!) a very effective brake (rather like reverse thrust). The only time that conventional airbrakes are used on turboprops are in the air when using full reverse pitch would be dangerous. They are of course used on the ground as well but in conjunction with pitch reversal. In case you are wondering also, the full reverse pitch on most types cannot be reversed in the air as a microswitch in the undecarriage bays only completes the reverse pitch circuit when the aircraft is resting firmly on the ground.
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January 22, 2001 at 8:26 am