What about Warp Drive carbon fiber blades? That is what I'm using on a
Mustang II, with auto engine.
AI Nut
posted aft, per request
People have had some problems with those failing on the higher HP piston engines
like the O-360. Also the twist of the blade is less than optimum for
an airplane that flies at 200 MPH. They work fine at the lower speed ranges
as Ken Welter uses a five blade version on his rotary powered Coot amphibian.
The third problem we have with them is they are not wide enough for a two
blade version to absorb 200 HP. Our hub will be limited to two blade
props for quite some time as they are more efficient than multi blade
versions.
A fourth problem we have with them is the center of pressure does
not coincide with the hub axis so the force or torquerequired to change
pitch in the air would be higher than an optimized blade plan form design.
Did I forget anything Bill? :-)
Oh perhaps Bill does not like the air foil used either. I know I am skeptical
about it.
Paul Lamar
To address some of the comments:
Warp Drive says their blades will bend (not the term they used) while in
flight to give a better bite. I had not heard of any upper speed
limits, so will ask them tomorrow.
Regarding their use in a Lyc or Continental, they are expressly
discouraged. The carbon fiber blades cannot absorb the huge power
pulses that the O-360s, for example, incur. However, they are ideal for
an auto engine conversion with PSRU that will smooth out those power
pulses. Also, 2 blades are not enough to absorb over 120 hp (I think
that was the cut-off, but not sure.) 3 blades should go to about
180-200 hp. My engine is 143, so it should be just right 8-). The
mechanics of blade flex while in the air borders on magic for me, as I
have zero theoretical background in that area. They are supposed to be
like a mini-constant speed prop (my term.)
I understand the inappropriateness of your other points, though. Too
bad.
IIRC, I have seen anther 5 blader working on a 350 mph plane. Maybe a
Lancair?
Thanks,
AI Nut
Yes the wankel two rotor is smoother. The Mazda has the same two power pulses
per revolution as a four cylinder piston engine. When you gear
that down, two to one, it is four power pulses per prop revolution.
The other fact is the torque in a two rotor wankel never goes negative
unlike a four cylinder piston engine.
Yes multi blades do indeed work and they are probably quieter and smoother
and may even climb better. I emphasize cruise prop efficiency however because
that is done hour after hour and fuel consumption will become more and more
important as fuel prices increase.
Paul Lamar
That is another reason I like the Warp Drive props. They are ground
adjustable so each owner can pick their own efficiency point. I prefer
the cruise setting myself, too. However, only testing will tell if the
cruise setting will still give me acceptable take off and climb rates.
I hope so.
AI Nut
You are barking up the wrong tree Mr. Nut. The Warp Drive blade has no
twist what so ever and so it is optimized for absolutely nothing!
Not even zero forward velocity static thrust. You don't need testing
to tell you that. Just read up a bit on props and review high school
geometry. Even the Wright brothers were fully aware of that.
If the Warp Drive carbon blade twist at all under load (unlikely as carbon
is very stiff) the twist will be in the wrong direction as the torsional
flexural axis is behind the center of lift. The outer portions of the prop
blade will increase in pitch while what is called for is a reduction in
pitch at the tips.
Paul Lamar
The AirCraft Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://home.earthlink.net/~rotaryeng/ http://www.linux.org
Six foot diameter prop and 2700 RPM
Prop radius is in feet.
Circ MPH is the velocity of the prop segment at that radius.
MPH = 40.9
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 63.2 40.33
0.5 96.4 104.7 23.00
0.8 144.6 150.3 15.80
1.0 192.8 197.1 11.98
1.3 241.0 244.4 9.64
1.5 289.2 292.0 8.05
1.8 337.4 339.8 6.92
2.0 385.6 387.7 6.06
2.3 433.8 435.7 5.39
2.5 481.9 483.7 4.85
2.8 530.1 531.7 4.41
3.0 578.3 579.8 4.05
Twist = 36.28 Ratio Twist/Root = 0.90 Ratio Twist/Tip = 8.96
----------------------------------------------------------------
MPH = 54.5
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 72.8 48.54
0.5 96.4 110.8 29.51
0.8 144.6 154.5 20.67
1.0 192.8 200.3 15.80
1.3 241.0 247.1 12.76
1.5 289.2 294.3 10.68
1.8 337.4 341.7 9.19
2.0 385.6 389.4 8.05
2.3 433.8 437.2 7.17
2.5 481.9 485.0 6.46
2.8 530.1 532.9 5.88
3.0 578.3 580.9 5.39
Twist = 43.15 Ratio Twist/Root = 0.89 Ratio Twist/Tip = 8.01
----------------------------------------------------------------
MPH = 68.2
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 83.5 54.75
0.5 96.4 118.1 35.27
0.8 144.6 159.9 25.25
1.0 192.8 204.5 19.48
1.3 241.0 250.4 15.80
1.5 289.2 297.1 13.27
1.8 337.4 344.2 11.43
2.0 385.6 391.5 10.03
2.3 433.8 439.1 8.93
2.5 481.9 486.7 8.05
2.8 530.1 534.5 7.33
3.0 578.3 582.3 6.72
Twist = 48.02 Ratio Twist/Root = 0.88 Ratio Twist/Tip = 7.14
----------------------------------------------------------------
MPH = 81.8
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 95.0 59.50
0.5 96.4 126.4 40.33
0.8 144.6 166.1 29.51
1.0 192.8 209.4 23.00
1.3 241.0 254.5 18.75
1.5 289.2 300.5 15.80
1.8 337.4 347.1 13.63
2.0 385.6 394.1 11.98
2.3 433.8 441.4 10.68
2.5 481.9 488.8 9.64
2.8 530.1 536.4 8.77
3.0 578.3 584.1 8.05
Twist = 51.45 Ratio Twist/Root = 0.86 Ratio Twist/Tip = 6.39
----------------------------------------------------------------
MPH = 95.5
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 106.9 63.21
0.5 96.4 135.7 44.72
0.8 144.6 173.3 33.43
1.0 192.8 215.1 26.34
1.3 241.0 259.2 21.61
1.5 289.2 304.5 18.27
1.8 337.4 350.6 15.80
2.0 385.6 397.2 13.91
2.3 433.8 444.1 12.41
2.5 481.9 491.3 11.20
2.8 530.1 538.7 10.21
3.0 578.3 586.2 9.37
Twist = 53.84 Ratio Twist/Root = 0.85 Ratio Twist/Tip = 5.74
----------------------------------------------------------------
MPH = 109.1
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 119.3 66.17
0.5 96.4 145.6 48.54
0.8 144.6 181.1 37.04
1.0 192.8 221.5 29.51
1.3 241.0 264.5 24.36
1.5 289.2 309.1 20.67
1.8 337.4 354.6 17.92
2.0 385.6 400.7 15.80
2.3 433.8 447.3 14.12
2.5 481.9 494.1 12.76
2.8 530.1 541.3 11.63
3.0 578.3 588.5 10.68
Twist = 55.48 Ratio Twist/Root = 0.84 Ratio Twist/Tip = 5.19
----------------------------------------------------------------
MPH = 122.7
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 131.9 68.56
0.5 96.4 156.1 51.85
0.8 144.6 189.6 40.33
1.0 192.8 228.5 32.48
1.3 241.0 270.4 26.99
1.5 289.2 314.1 23.00
1.8 337.4 359.0 19.99
2.0 385.6 404.6 17.66
2.3 433.8 450.8 15.80
2.5 481.9 497.3 14.29
2.8 530.1 544.2 13.04
3.0 578.3 591.2 11.98
Twist = 56.58 Ratio Twist/Root = 0.83 Ratio Twist/Tip = 4.72
----------------------------------------------------------------
MPH = 136.4
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 144.6 70.54
0.5 96.4 167.0 54.75
0.8 144.6 198.7 43.32
1.0 192.8 236.1 35.27
1.3 241.0 276.9 29.51
1.5 289.2 319.7 25.25
1.8 337.4 363.9 22.01
2.0 385.6 409.0 19.48
2.3 433.8 454.7 17.45
2.5 481.9 500.9 15.80
2.8 530.1 547.4 14.43
3.0 578.3 594.2 13.27
Twist = 57.27 Ratio Twist/Root = 0.81 Ratio Twist/Tip = 4.32
----------------------------------------------------------------
MPH = 150.0
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 157.6 72.19
0.5 96.4 178.3 57.28
0.8 144.6 208.3 46.05
1.0 192.8 244.3 37.89
1.3 241.0 283.8 31.90
1.5 289.2 325.8 27.42
1.8 337.4 369.2 23.97
2.0 385.6 413.7 21.26
2.3 433.8 459.0 19.08
2.5 481.9 504.8 17.29
2.8 530.1 551.0 15.80
3.0 578.3 597.5 14.54
Twist = 57.65 Ratio Twist/Root = 0.80 Ratio Twist/Tip = 3.96
----------------------------------------------------------------
MPH = 163.6
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 170.6 73.59
0.5 96.4 189.9 59.50
0.8 144.6 218.4 48.54
1.0 192.8 252.9 40.33
1.3 241.0 291.3 34.18
1.5 289.2 332.3 29.51
1.8 337.4 375.0 25.88
2.0 385.6 418.8 23.00
2.3 433.8 463.6 20.67
2.5 481.9 509.0 18.75
2.8 530.1 554.8 17.15
3.0 578.3 601.0 15.80
Twist = 57.79 Ratio Twist/Root = 0.79 Ratio Twist/Tip = 3.66
----------------------------------------------------------------
MPH = 177.3
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 183.7 74.79
0.5 96.4 201.8 61.47
0.8 144.6 228.8 50.80
1.0 192.8 261.9 42.60
1.3 241.0 299.2 36.34
1.5 289.2 339.2 31.51
1.8 337.4 381.1 27.72
2.0 385.6 424.4 24.69
2.3 433.8 468.6 22.23
2.5 481.9 513.5 20.20
2.8 530.1 559.0 18.49
3.0 578.3 604.9 17.04
Twist = 57.75 Ratio Twist/Root = 0.77 Ratio Twist/Tip = 3.39
----------------------------------------------------------------
MPH = 190.9
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 196.9 75.83
0.5 96.4 213.9 63.21
0.8 144.6 239.5 52.86
1.0 192.8 271.3 44.72
1.3 241.0 307.4 38.39
1.5 289.2 346.5 33.43
1.8 337.4 387.6 29.51
2.0 385.6 430.2 26.34
2.3 433.8 473.9 23.76
2.5 481.9 518.4 21.61
2.8 530.1 563.5 19.81
3.0 578.3 609.0 18.27
Twist = 57.56 Ratio Twist/Root = 0.76 Ratio Twist/Tip = 3.15
----------------------------------------------------------------
MPH = 204.5
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 210.1 76.74
0.5 96.4 226.1 64.77
0.8 144.6 250.5 54.75
1.0 192.8 281.1 46.70
1.3 241.0 316.1 40.33
1.5 289.2 354.2 35.27
1.8 337.4 394.5 31.23
2.0 385.6 436.5 27.95
2.3 433.8 479.6 25.25
2.5 481.9 523.6 23.00
2.8 530.1 568.2 21.10
3.0 578.3 613.4 19.48
Twist = 57.26 Ratio Twist/Root = 0.75 Ratio Twist/Tip = 2.94
----------------------------------------------------------------
MPH = 218.2
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 223.4 77.54
0.5 96.4 238.5 66.17
0.8 144.6 261.7 56.47
1.0 192.8 291.1 48.54
1.3 241.0 325.1 42.16
1.5 289.2 362.2 37.04
1.8 337.4 401.8 32.89
2.0 385.6 443.0 29.51
2.3 433.8 485.5 26.70
2.5 481.9 529.0 24.36
2.8 530.1 573.3 22.37
3.0 578.3 618.1 20.67
Twist = 56.87 Ratio Twist/Root = 0.73 Ratio Twist/Tip = 2.75
----------------------------------------------------------------
MPH = 231.8
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 236.8 78.26
0.5 96.4 251.1 67.42
0.8 144.6 273.2 58.05
1.0 192.8 301.5 50.25
1.3 241.0 334.4 43.89
1.5 289.2 370.6 38.72
1.8 337.4 409.3 34.50
2.0 385.6 449.9 31.02
2.3 433.8 491.8 28.12
2.5 481.9 534.8 25.69
2.8 530.1 578.6 23.62
3.0 578.3 623.1 21.84
Twist = 56.41 Ratio Twist/Root = 0.72 Ratio Twist/Tip = 2.58
----------------------------------------------------------------
MPH = 245.5
Radius Circ MPH Cord MPH 0 Angle of Attack
0.3 48.2 250.1 78.89
0.5 96.4 263.7 68.56
0.8 144.6 284.9 59.50
1.0 192.8 312.1 51.85
1.3 241.0 344.0 45.53
1.5 289.2 379.3 40.33
1.8 337.4 417.2 36.04
2.0 385.6 457.1 32.48
2.3 433.8 498.4 29.51
2.5 481.9 540.9 26.99
2.8 530.1 584.2 24.84
3.0 578.3 628.3 23.00
Twist = 55.89 Ratio Twist/Root = 0.71 Ratio Twist/Tip = 2.43
----------------------------------------------------------------