DESIGN: AeroVantage ~ PropRotor - Disk - Rotor 2x4

• I think that a propeller's tip Mach number should be between 0.88 and 0.92. However, I think, that this will be too fast for a PropRotor even though it is only experiencing axial free-air flow.
• Consider the pros and cons of having the wing act as a shroud for a portion of the circumference of the fore and/or aft proprotor when they are acting as rotors. I.e. Reduce the tip loss and recalculation slightly.
• At a gross weight of 1,320 lbs 2 only 8.33 ft dia. and 2 only 6.58 ft dia. PropRotors will give a hovering disk area of 177 ft-sq for a disk loading of 7.4 lb/ft-sq.
• Fore rotor: 8.33 ft dia = 54.5 ft². Gross weight per rotor = (54.5/177) * 1320 = 406 lb.
• Aft rotor: 6.58 ft dia = 34.0 ft². Gross weight per rotor = (34/177) * 1320 = 254 lb.
• The blades must have a very large twist to be optimal for hover (rotor) and cruise (prop). The large twist should not be detrimental since the craft never flies with the rotor's edge on to the free airstream.
• Ground Effect: If one rotor is lower than the rotor it will probably produce more thrust at takeoff, but this extra trust will reduce very quick as the craft starts to rise. This may result in a change in the craft's pitch during the start of takeoff. In addition, if these is the aft rotors then an uplift on the HS may also contribute to a nose down pitch, followed shortly thereafter by the nose up pitch.
• Descent: In descent conditions during which blade-vortex interactions (BVI) can occur, tilt rotor blades can undergo negative tip loading over a substantial region of the rotor disk compared with conventional helicopter blades.

• This is the same PropRotor as on PropRotor - Disk - Propeller
• One objective of the following table is that of balancing the longitudinal moments of the fore and aft rotors. See 1610.html
• From Access Database: