Item 0898

DESIGN: UniCopter ~ Dimension, Area & Drag - Dimension & Area - Front, Y-Z plane

Drawing:

Grid is 3" x 3"

Body Axis System is used.

 Indicates a calculated field.

Calculations re: Parasite Drag Moment of Fuselage about Horizontal Center of Rotor Hubs:

This table does not include the rotorhub or any landing gear.

 Fuselage: Tail: Arm Length: [inches] * Count of Area [1/16 sq. ft.] ** Arm x Area 1.5 6 9 4.5 12 54 7.5 11 83 10.5 9 95 13.5 10 135 16.5 11 182 10 165 19.5 12 234 9 176 22.5 12 270 9 203 25.5 11 281 9 203 28.5 9 257 31.5 8 252 34.5 7 242 37.5 7 263 40.5 5 203 43.5 3 131 Total 133 2691 Total / 16 **** 8.31 sq-ft. Total / (16 squares x 12") 15.58 sq-ft * feet ***

* Arm increments increase in 3" increments. The arm length is to the middle of each increment.

** 16 (3" x 3") areas equal one square foot.

*** Moment about Y-axis should be (if I am correct) drag per square foot x (arm * area)

**** Frontal Area AF

The mean arm length, based on the above will be (15.58 / 8.31) = 1.87 feet. This is the middle of the frontal area but because the tip of the nose is lower, I thing that the arm length to the center of drag should be longer. Consider testing a scale model in one of UBC's wind tunnels.

Some provision might have to be made for the fact that the opening for power train cooling will have more drag than the rest of the fuselage.

Calculations re: Parasite Drag Moment of Rotorhubs about Vertical Centerline:

10 squares each = 0.625 sq-ft x 2 rotorhubs = 1.25 sq-in.

Calculations re: Parasite Drag Moment of Landing Gear about Horizontal Center of Rotor Hubs:

Not yet done.

Fuselage:

 Arm Length: Lateral (a.c. to origin) yF 0.0 ft. Vertical (a.c. to origin) zF 2.0 ft.

Rotors:

 Arm Length: Lateral (a.c. to origin) yP & yS 1.125 ft. Vertical (a.c. to origin) zS & zS 0.0 ft.

Notes:

This view may never be used directly to calculate drag since it is of the helicopter while in hover, with no forward velocity. This view can probably be used with interpolation for the drag at various forward velocities.

Note The front view of the fuselage could have a different aerodynamic center to origin length on the vertical axis then the side view. The symbol above zF is the same for both. This could be applicable to the plan view as well.

Hub Drag Minimization:

It is nice to consider some sort of Beanie on the rotorhub that also provides lift (sort of like a sub lifting body), but this will be hard if not impossible to do considering that the Bernie is rotating. However, this does not have to be considered if the blades are given root control, in addition to the tip control. The root control on a blade with a very wide chord at the root should work exceptionally well.

Misc:

Width of Lycoming is 32.24".

Last Revised: July 22, 2008