> The pitch of my old wood propeller which I am retiring is given
in
> inches, while my new Warp Drive uses degrees to set pitch. No
> reference
> to inches.
> What is the relationship between the two methods of
measurement?
> Can you direct me to reference material (for the layman)?
> Yvon
>
> Good question.
>
> --
> Paul Lamar ...No rotor no motor.
>
I suggest you call Warp drive with your engine/airspeed/aircraft
imfo. I was advised to set my prop
to about 12 degrees...It is now set to 11.5 degrees ! Adjust
the prop in VERY small increments...
,5 degrees or less.If you learn how to correlate degrees
to pitch please let me know : ))
Charles in south Mississippi
In order to figure out pitch in inches, you need to know the diameter
of
the prop. Think of it like this- the prop is turning through a medium
where there is no slippage. One revolution of the prop pulls (or
pushes)
the airplane how far forward (in inches)?
Get out your trigonometry textbook.
Not trying to be a smartass, but I'd have to dust mine off to give
you
an answer, if I knew your prop diameter, but I'm at work and don't
have
it here.
Brian Trubee
Thank you all people. I will keep you informed of my progress in
installation and testing.
Yvon.
Hi Yvon,
There is more to a prop than just pitch. Twist is also important.
Here are three examples. You need to add a few degrees
to these numbers to generate thrust.
Note that even at 100 MPH design speed a prop
needs 55 degrees twist. Unfortunately the Warp Drive blade has
very little twist. As speed increases the twist angle also
increases slightly. The IVO prop is also defective
in this regard with very little angle of attack near the hub.
RPM = 2700 MPH = 100
Radius Tang FPS Tang MPH Angle
3.00 71 48.2 64.3
6.00 141 96.3 46.1
9.00 212 144.5 34.7
12.00 283 192.7 27.4
15.00 353 240.9 22.5
18.00 424 289.0 19.1
21.00 495 337.2 16.5
24.00 565 385.4 14.5
27.00 636 433.5 13.0
30.00 707 481.7 11.7
33.00 777 529.9 10.7
36.00 848 578.0 9.8
RPM = 2700 MPH = 150
Radius Tang FPS Tang MPH Angle
3.00 71 48.2 72.2
6.00 141 96.3 57.3
9.00 212 144.5 46.1
12.00 283 192.7 37.9
15.00 353 240.9 31.9
18.00 424 289.0 27.4
21.00 495 337.2 24.0
24.00 565 385.4 21.3
27.00 636 433.5 19.1
30.00 707 481.7 17.3
33.00 777 529.9 15.8
36.00 848 578.0 14.5
RPM = 2700 MPH = 200
Radius Tang FPS Tang MPH Angle
3.00 71 48.2 76.5
6.00 141 96.3 64.3
9.00 212 144.5 54.1
12.00 283 192.7 46.1
15.00 353 240.9 39.7
18.00 424 289.0 34.7
21.00 495 337.2 30.7
24.00 565 385.4 27.4
27.00 636 433.5 24.8
30.00 707 481.7 22.5
33.00 777 529.9 20.7
36.00 848 578.0 19.1
I got kind curios about what happens to the twist if you slow
the RPM to 2100 at 150 MPH for cruise. The optimum
twist changes by almost one degree. Note the
zero thrust angle of attack only changes
by about 2 degrees. See the attached jpg.
Fixed pitch props are very point design
devices. You need to tell the prop guy
what you want to do. Tell him the prop RPM,
the HP at that RPM and the cruise speed you
you wish and probably the drag of the airplane
at that cruise speed. One blade design certainly
does not fit all requirements.
-----------------
ops pasted in the wrong chart.
Here is the corrected jpg. Twist changed only slightly.
Why didn't you guys catch that? :)
Paul Lamar ...No rotor no motor.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.
