- #1
PhyIsOhSoHard
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Homework Statement
One of your friends is building his own airplane. He has received a quotation for a two-bladed propeller with an efficiency of ##\eta = 80\%## . He asks for your advice on whether it is possible to get a higher efficiency - what is your answer?
- no, the efficiency based on physics not be improved
- use a large diameter propeller
- use a propeller with more blades
- use a higher rotational speed
- use propeller blades with a larger chord
Here is a graph that shows the efficiency of an aircraft but it doesn't go higher than 80% efficiency:
So how is it possible to increase this efficiency by making the diameter larger?
For the record, the speed of advance coefficient (J) is:
##J=\frac{V}{nD}##
Where V is the velocity of the aircraft, D is the diameter and n is the revolutions.