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OTHER: Aerodynamics - Blade Profile - VR-8 & VR-8b

Overview:

Centers, forces, moments, vectors, etc. related to the VR8 & VR-8b airfoil.

For information related to the specific blade for the Unicopter see: UniCopter ~ Rotor - Blade - VR-modified

Drawing:

All below that is in light grey is from VR-7 and is wrong

Characteristics:

Thickness	t/c	= 0.08
Leading Edge Circle	r/c	= 0.0113
Center at	x/c	= 0.01055
Center at	y/c	= 0.004
Trailing Edge Tab	from x/c	= 0.96
Trailing Edge Tab	to x/c	= 1.01
T.E. Tab Thickness	t/c	= 0.005

Airfoils with Different Tab Settings and Angles of Attack:

Airfoil integral coefficients: Cl (lift), Cd (drag) and Cm (aerodynamic moment in respect to 1/4 of the chord). It's important to note that Cd is theoretically null in a 2-D non-viscous subsonic flow; hence this number is a measure of the numeric errors in the code and in the choice of the points.

The Cm is considered positive when pulling up.

The following calculations are from the freeware program NVFoil.

ά		[alpha] The angle of attack is the angle between the airfoil chord and the velocity vector.
c_l		Coefficient of lift; two-dimensional
c_d		Coefficient of drag; two-dimensional
c_m0		Coefficient of moment; two-dimensional. (pitching-moment coefficient) @ 25% of chord
x_cp		Location on X-axis of center of pressure as a percentage of chord from leading edge.
Airfoil & Tab	ά		c_l	c_d	c_l^3/2/c_d	c_m0	x_cp
VR-8	0		0.299	0.0001		-0.047	41
	1		0.415	-0.001		-0.049	37
	2		0.54	-0.002		-0.05	34
	4		0.782	-0.002		-0.053	32
	6		1.024	0		-0.056	31
	8		1.264	0.005		-0.059	30
	10		1.504	0.013		-0.062	29.5
	12		1.741	0.023		-0.064	29.3
VR-8b - 0	0		0.176	0.002		-0.02	37
	1		0.228	0		-0.021	32
	2		0.402	-0.002		-0.02	30
	4		0.628	-0.003		-0.019	28
	6		0.854	-0.001		-0.019	27
	8		1.079	0.002		-0.019	27
	10		1.303	0.009		-0.019	26.5
	12		1.526	0.017		-0.019	26.5
VR-8b - 2	0		0.111	0.003		-0.007	32
	1		0.225	0		-0.007	28
	2		0.339	-0.002		-0.006	27
	4		0.565	-0.003		-0.006	26
	6		0.791	-0.002		-0.006	25.5
	8		1.017	0.001		-0.006	25.5
	10		1.242	0.007		-0.006	26
	12		1.465	0.015		-0.006	26
VR-8b - 3	0		0.082	0.002		0	25
	1		0.193	0		0	25
	2		0.307	-0.002		0.001	24
	4		0.533	-0.003		-0.001	24
	6		0.759	-0.003		0.001	24
	8		0.985	0		0.001	24.5
	10		1.21	0.006		0.001	25
	12		1.433	0.014		0.001	25.5

Outside Web Sites:

http://naca.larc.nasa.gov/reports/1949/naca-tn-1998/

http://naca.larc.nasa.gov/reports/1946/naca-rb-l5k02/

Last Revised: Sunday, February 11, 2009