Item 0931

DESIGN: UniCopter ~ Rotor - Blade - NACA 00xx - Planform & Thrust

Overview:

Go to; UniCopter Characteristics ~ Blade

 

The thrust (moment arms) may be moved to its separate page 

Blade Loading:

See: DESIGN: UniCopter ~ Rotor - Hub - Blade Generated Forces - Preliminary:

See: DESIGN: UniCopter ~ Rotor - Hub - Blade Generated Forces - Intermediate for 4-blade rotor only. Separate page required for 3-blade rotor.

See: DESIGN: UniCopter ~ Rotor - Blade - General - Spar

 

See this page as well. MAKE: UniCopter ~ Rotor - Blade - General -Test Spar (test blade?) The material from here may be move to other NACA00xx page(s) and this page deleted.

See DESIGN: UniCopter ~ Rotor - Disk - Pre-cone ~ Thoughts re Angle: for a means to improve the clearances.

Drawing:

 

Note re Start of Chord at Root End:

The hubs are 30" ?? apart but because of the mast-mast angles and the pre-cone angle the blade, at azimuth 90º, closest to the other hub at about r = 24".

The bottom of this blade's spar is approximately 2.5" above the top of the other hub, at it center. This might mean that the inner taper (toward the root) can be shallower; for slightly more strength and lift.

 

All of the following must be updated

Calculations re Airfoil Profile Locations:

 

NACA airfoil and span location on the blade:

Maximum distance from chord line to top and to bottom of airfoil.

If R = 100" then r for the following is

Chord at 'r'. (theoretical for r < 36")

 

0027 ? mod-profile at 10.4% of R.

1.176" ?

10.4"

8.8"

 

0024 profile at 23.2% of R.

1.008"

23.2"

8.4"

 

0021 profile at 36.0% of R.

0.840"

36.0"

8.0"

 

0018 profile at 48.8% of R.

0..684"

48.8"

7.6"

 

0015 profile at 61.6% of R.

0.540"

61.6"

7.2"

 

0012 profile at 74.4% of R.

0..408"

74.4"

6.8"

 

0009 profile at 87.2% of R.

0.288"

87.2"

6.4"

 

0006 profile at the tip.

0.180"

100.0"

6.0"

The Moment stuff should maybe be on spar page.

Moments on Blade, about Center of Rotor:

The following is based on thrust = GW / 6 blades = 125 pounds.

 

Element:

Radius at outside of element (ft.)

Length of Arm to 75% of element (in.) (1)

Lift (pounds)@ hover

Moment (lb.-in.) @ hover (2)

 

0

0

0

 

0

 

1

0.8333

7.5"

3.17

24

 

2

1.6667

17.5"

5.82

102

 

3

2.5

27.5"

8.10

223

 

4

3.3333

37.5"

10.14

380

 

5

4.1667

47.5"

12.01

570

 

6

5.0

57.5"

13.76

791

 

7

5.8333

67.5"

15.46

1044

 

8

6.6667

77.5"

17.12

1327

 

9

7.5

87.5"

18.82

1647

 

10

8.3333

97.5"

20.60

2008

 

 

Total =

 

125

8116

(1) Element is 10.0" long. Moment arm is at the 75% point of element (7.5") radius. The arm lengths should be reduced by 4" (radius of bearing) when considering the rotor hub bearing and it should be reduced by 9" (distance to outer pitch bearing) when considering the pitch bearings and the blade strength.

(2) At; hover, gross weight & out of ground effect. From Access Database calculations.

Moment Calculations for Blade Spar Strength:

 

Profile:

Chord:

Thick:

Distance from outer feathering bearing to 75% of profile: (5)

Moment (lb.-in.) @ hover (3)

 

????

???

 

11.075" - 12.8" = -1.725"

3.17 * 7.1 = 23

 

 

 

 

 

5.82 * 17.1 = 100

 

 

 

 

 

10.14 * 27.1 = 275

 

 

 

 

 

12.01 * 37.1 = 449

 

 

 

 

 

13.76 * 47.1 = 648

 

 

 

 

 

15.46 * 57.1 = 883

 

 

 

 

 

17.12 * 67.1 = 1149

 

 

 

 

 

18.82 * 77.1 = 1451

 

 

 

 

 

20.60 * 87.1 = 1794

 

 

 

 

 

 6772

 

NACA 0024 (mod)

4.8888"

1.173"

23.875" - 12.8" = 11.075"

5.82 * 4.3 = 25

 

 

 

 

 

10.14 * 14.3 = 145

 

 

 

 

 

12.01 * 24.3 = 292

 

 

 

 

 

13.76 * 34.3 = 472

 

 

 

 

 

15.46 * 44.3 = 685

 

 

 

 

 

17.12 * 54.3 = 934

 

 

 

 

 

18.82 * 64.3 = 1210

 

 

 

 

 

20.60 * 74.3 = 1531

 

 

 

 

 

5294

 

NACA 0021

8.0"

1.68"

36.675" - 12.8" = 23.875"

12.01 * 11.5 = 138

 

 

 

 

 

13.76 * 21.5 = 296

 

 

 

 

 

15.46 * 31.5 = 487

 

 

 

 

 

17.12 * 41.5 = 710

 

 

 

 

 

18.82 * 51.5 = 969

 

 

 

 

 

20.60 * 61.5 = 1267

 

 

 

 

 

3867

 

NACA 0018

7.6"

1.368"

49.475" - 12.8" = 36.675"

13.76 * 8.7 = 120

 

 

 

 

 

15.46 * 18.7 = 289

 

 

 

 

 

17.12 * 28.7 = 491

 

 

 

 

 

18.82 * 38.7 = 728

 

 

 

 

 

20.60 * 48.7 = 1003

 

 

 

 

 

2631

 

NACA 0015

7.2"

1.08"

62.275" - 12.8" = 49.475"

15.46 * 5.9 = 91

 

 

 

 

 

17.12 * 15.9 = 272

 

 

 

 

 

18.82 * 25.9 = 487

 

 

 

 

 

20.60 * 35.9 = 740

 

 

 

 

 

1590

 

NACA 0012

6.8"

0.816"

75.075" - 12.8" = 62.275"

17.12 * 3.1 = 53

 

 

 

 

 

18.82 * 13.1 = 247

 

 

 

 

 

20.60 * 23.1 = 476

 

 

 

 

 

776

 

NACA 0009

6.4"

0.576"

87.875" - 12.8" = 75.075"

20.60 * 10.0 = 206

 

NACA 0006

6.0"

0.36"

100.0" - (9 + 3.125)" = 87.875"

0

(3) Summation of moments to indicated radius. I think.

(4) Noted profiles are 12.8" apart.

(5) Outer pitch bearing is 9" from mast axis. Center of lift is concentrated at 75% of distance out from a profile to the next profile. The distance between profiles is 12.5" therefore 75% of this as 9.375" and 25% as 3.125"

Calculations re Strength:

 

NACA airfoil:

Length (bearing to profile):

Chord at 'r'. (theoretical for r < 36")

Thickness:

Moment: (in-lb)

Spread:

Area of 1/2 spar:

Centroid:

 

0027 ?

01.4"

8.8"

2.376" ?

6772

 

 

 

 

0024

14.2"

8.4"

2.016"

5294

1478

 

 

 

0021

27.0"

8.0"

1.680"

3867

1427

27*.0625=1.6875sq-in

1.1"

 

0018

39.8"

7.6"

1.368"

2631

1236

 

 

 

0015

52.6"

7.2"

1.080"

1590

1041

 

 

 

0012

65.4"

6.8"

0.816"

0776

814

 

 

 

0009

78.2"

6.4"

0.576"

0206

570

 

 

 

0006

91.0"

6.0"

0.360"

 

 

 

 

 

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Last Revised: June 2, 2005