Item 1122

OTHER: Aerodynamics - Rotor Disk - Dual Configuration - Intermeshing

Overview:

Intermeshing Craft:

Inside Concepts:

Pros & Cons:

Outside Helicopters and Outside Concepts:

Outside Technical Reports:

• Technical Note - Twin Rotor Hover Performance, by Franklin D. Harris ~ January 1999 Journal of the American Helicopter Society. Have on disk E: and hard copy.
• Influence of Lift Offset on Rotorcraft Performance, by Wayne Johnson ~ AHS Conference 2008. Have hard copy.

Disk Area:

Calculation used for obtaining the area of overlap: Angle is in Radians.

A = 1/2 (R2 (θ - sinθ)) = 1/2 (10 * 10 (2.878 - sin(2.878))) = 1/2 (100 (2.8784 - 0.261)) = 1/2 (100 *2.617) = 130.9

 Individual Twin Disk: Combined Twin Disks: Single Disk: Radius: 10 ~ 14.14 Area: 314.3 628.6 628.6 Area of Overlap (Circular Segment): 130.9 261.8 ~ Area Excluding Overlap: 183.4 366.8 366.8 Radius based on Area of Twin Disks with Overlaps Excluded: ~ ~ 10.8 Total Lateral Span: ~ 22.63 21.6 Total Longitudinal Span: ~ 20.0 21.6

The above data and the comments below only consider the main rotors. They do not include the 10-12% tail-rotor power consumption, nor do they include the downwash velocity on the fuselage, which is dependent on its location under the disk(s).

The area of the circular segment is 41.6% of the disk's total area. This would suggest that the power should be considered as; 2 * (17% * isolated rotor power + 83% * co-located rotor power). Using the figures from OTHER: Aerodynamic - Rotor Disk - Dual Configurations, 17% * 65 hp + 83% * 100 hp = 94 hp. In other words to provide a specific thrust will require 65 hp form the side-by-side configuration, 77 hp from the Interleaving configuration, 94 hp from the Intermeshing configuration, and 100 hp from the coaxial configuration.

Induced Power:

xxx (κint)

copied over Intermeshing (Synchropter):

The required power is increased by a factor (K) = 1.46 - (0.253 * (Stagger / R))

Dual Rotor Configurations:

Last Revised: July 6, 2011