A122

DESIGN: Electrotor-SloMo ~ Rotor (aerodynamic)

Power Requirements of Different Configurations:

Considerations re Interleaving vs. Intermeshing, and also consideration of the Flettner which it is said that it gets 16 lb per horsepower:

	Flettner:	SynchroLite: Intermeshing	Electrotor: 1 rotor only	Electrotor: 1 rotor only	Single: w/ 4 blades
Gross Weight:	2202 lbs	500 lbs	150 lbs	300 lbs	500 lbs
Disk Area (one rotor):	1216 ft²	236 ft²	113	236	236
Total Disk Area:	1292 ft²	272 ft²	113	236	236
Effective Disk Area:	1695 ft²	337 ft²	113	236	236

Blades:	4	4	2	4	4
Radius:	19.675 ft	8.666 ft	6.00 ft	8.666 ft	8.666 ft
Chord:	0.9583 ft	0.4375 ft	0.67 ft	0.4375 ft	0.4375 ft
Aspect Ratio:	20.531	22.087	11.0	19.817	19.817
Twist:	-4º	-7º ⁽¹⁾	-8º ⁽¹⁾	-7º ⁽¹⁾	-7º ⁽¹⁾

Disk Loading:	1.7041	2.4269	1.33	1.2233	2.12
Blade Loading:	29.197	32.351	23.0	32.954	32.954
Rotor Solidity Ratio:	0.0584	0.0750	0.0578	0.0371	0.0642

Stagger:	1.933 ft	2.083 ft	0	0	0
Rotor Speed:	600 rpm	600 rpm	730 rpm ⁽⁵⁾	730 rpm ⁽⁵⁾	730 rpm ⁽⁵⁾

Power Momentum:		24.3 hp	6.0 hp	26.2 hp	26.2 hp
Power Combined:		29.2 hp ⁽³⁾ ⁽⁴⁾	5.1 hp	32.7 hp ⁽³⁾	23.4 hp ⁽³⁾
Guestimate: x 1.2		28.2 hp	7 x 2 = 14.0 hp	30.0 hp ⁽³⁾	30.0 hp ⁽³⁾
		21kW	10.4 kW	22.4kW	22.4 kW

(1) 7º twist used for Access calculations. Actual value will probably be 12º

(3) It appears that the gap factor is not changing for different gaps. It should be higher and thus the horsepower higher. In fact the horsepower should be higher than the Intermeshing.

(4) There is a problem here. This should be less than the intermeshing

(5) This is for hover. Climb and forward flight will be faster.

Power Requirement Comparison - 2-blade vs. 3-blade:

3 bladed rotors are less efficient then 2 bladed rotors, however, more power can be obtained from the motor if it is run faster. This is because higher torque increases engine heat where as higher speed does not.

All specifications are the same except for; the RRPM (tip speed is the same), the number of blades, and the rotor diameter.

Must be change to Electrotor and 300 lb total for the two SloMo rotors. Also a large disk area.

	Electrotor: 2-blades / rotor	Electrotor: 3-blades / rotor
Gross Weight:	500 lbs	500 lbs
Blades:	4	6
Radius:	8.666 ft	8.0 ft
Chord:	0.4375 ft	0.4375 ft
Taper:	0.125"	0.125"
Aspect Ratio:	22.1	20.2
Disk Area (one rotor):	236 ft²	201 ft²
Total Disk Area:	272 ft²	234 ft²
Effective Disk Area:	337 ft²	288 ft²
Twist:	-10º	-9º
Pitch:	9.0º	7.7º
Disk Loading:	1.84	2.13
Blade Loading:	36.8	26.3
Rotor Solidity Ratio:	0.050	0.081
Stagger:	2.083 ft	2.083 ft
Rotor Speed:	606 rpm	657 rpm
Tip Speed:	550 rpm	550 rpm
Power Momentum:	26.1 hp	28.2 hp
Power Combined:	30.5 hp	31.6 hp
Guestimate:	28.3 hp	30 hp
	21.1 kW	22.4 kW

Rotor Induced Vibration:

The use of rotors with 2 blades, a 6.0 ft radius and a speed of 730 RRPM gives an ideal tip speed of 460 fps. This will result in a 2/rev vibration at 12.2 cycles per second. This is near the worst area, therefore perhaps consider 3-blade rotors, but this may not help much. See OTHER: Aerodynamics - Vibration - Rotor Induced - Overview

Last Revised: January 13, 2010