Helicopter - Disk and Power Specifications

Item Nbr:

0986

Sunday, November 129, 2003

1:42:40 PM

Name:

Dragonfly (the following is based on a complete 550 GW craft)

Black is input.

Blue is calculated.

Blade Element Data It looks like the blade cutout ratio in the above FORM may not be working.

Test Conditions:

Collective Pitch: (used for Flight - Hovering w/ Blade Element Theory)

7.6

deg

Forward Speed: (used for Flight - Forward w/ Momentum Method)

55

knots

Rate of Vertical Climb: (used for Flight - Vertical w/ Momentum Method)

500

ft/min

Weight:

Empty Weight: [EW]

254

lb.

Payoad: [Load]

296

lb.

Gross Weight: [GW = EW + Load]

550

lb.

Rotor:

Blade:

Type of airfoil

VR-7

Angle of attack for zero lift [AlphaL0] (0 for 0012. >0 for cambered)

-1.4

deg.

Number of blades: [bb]

6

Radius: [R]

8

ft.

Chord at root: [cc]

0.382

ft.

Blade Area: [Ab]=[bb*cc*R]

18.34

sq-ft

Aspect Ratio: [AR] = R / (cc - (R * (cct / 12) / 2))

20.94

:1

Blade cutout ratio: (The blade root radius divided by the tip radius.)

0.25

Taper: [cct]

0

in/ft

Twist Type;

linear

Pitch that the blade would have if extended into center of rotation.

9

deg.

Angle of twist (washout). Tip pitch - root pitch. i.e.negative value.

-8

deg.

Pitch at the blade tip: [Theta_t] (for ideal only)

1

deg.

Hub(s):

Configuration:

Intermeshing

The angle of each mast off of vertical Re synchropter: [Angle]

11.00

deg.

The horizontal distance between twin rotor hubs: [Stagger]

2.00

ft.

Disk:

Disk area (1 rotor); [A1]

201.06

sq-ft

Total disk area: [AT]

233

sq-ft

Effective disk area: [A]

288

sq-ft

Rotor solidity ratio: [Sigma] = [Ab] / [A]

0.0637

%

Speed:

RPM of Rotor: [RPM Hub]

643

rpm

Tip speed: [Omega_R]

539

ft/sec

Tip mach number: [TipM]

0.48

% M1

Flight - Hovering:

Momentum Method

Disk Loading: [DL] (calculated using gross weight)

2.36

lb/ft2

Blade Loading: [BL] (calculated using gross weight)

??

lb/ft2

Velocity: [V1hov] (Average of velocities through the disk.)

22.3

ft/sec.

Power; [P] (ISA i.e. Sea level, 59 deg F.)

33

hp.

Power Loading (for hover ONLY): [PLh] (ISA i.e. Sea level, 59 deg F.)

16.8

lb/hp

Nondimensional Coefficients;

Thrust: [CT]

0.0034

.

Power: [CP]

3.78E-07

CT / Sigma

0.0524

Combined Momentum and Blade Element Theory w/ Emphirical Corrections

Coefficients of:-

Thrust: [CTntl] (w/o tip loss)

0.002826

Tip loss factor: [B]

0.99

Thrust: [CT] (with tip loss)

0.00276

Profile; [CQo]

9.20E-05

Induced: [CQi]

9.45E-05

Torque: [CQ]

0.000179

Disk loading: [DL] (calculated using thrust)

1.91

lb/ft2

Thrust Solidity: [CT/Sigma]

0.0434

[(DL)(CT/Sigma)]

0.0829

Measured power / Calculated power

0.96

CQ / Sigma

0.0028

Thrust: [T] (ISA i.e. Sea level, 59 deg F. ~ drive losses not inc.)

550

lb

Horsepower: [hp] (ISA i.e. Sea level, 59 deg F. ~ drive losses not inc.)

35

hp

Flight - Vertical:

Momentum Method

Velocity: [V1ver] (Average of velocities through the disk.)

26.8

ft/sec.

Change in power; [DeltaP]

12

hp.

Change in blade pitch; [DeltaTheta]

0.319

deg.

Combined Momentum and Blade Element Theory w/ Emphirical Corrections

Not done.

Flight - Forward:

Momentum Method

Velocity: [V1fwd] (Average of velocities through the disk.)

xx

ft/sec.

Change in Power:

xx

Induced: [HPind]

8.0

hp.

Parasite: [HPp]

5.2

hp.

Profile: [HPOH]

13.7

hp.

Main (sub total): [HPm]

26.9

hp.

Combined Momentum and Blade Element Theory w/ Emphirical Corrections

Not done.