Similarity to Current V-22 Design

In general, a good starting point in design is a pre-existing design of the same object, especially when the pre-existing design is a good design. Thus, the present design inherits much of its geometry from the current blades of the V-22.

 
 

Table: Similar geometric parameters for the present design and the current V-22 blades. (Data from Reference [1].)

Geometric Parameter	Symbol	Value
Blade radius, ft	$R$	19
Blade mean chord, ft	$c$	1.71
Thickness-to-chord ratio (inner quarter of blade)	$t/c$	0.28
Thickness-to-chord ratio (second quarter of blade)	$t/c$	0.18
Thickness-to-chord ratio (third quarter of blade)	$t/c$	0.12
Thickness-to-chord ratio (outer quarter of blade)	$t/c$	0.09
Number of blades per rotor	$N_b$	3

Table 1 lists some values that are the same for the current V-22 blades and the present design. There is one difference, though. For simplicity, the chord of the present design is constant, unlike the current V-22 blade. However, the chord length of the present design does equal the mean chord of the current blades.

In addition to blade geometry, the present design inherits the rotor tip speeds for both propeller and helicopter modes. The tip speed is 790 ft/s for helicopter mode, and 662 ft/s in propeller mode.