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#1
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Is there a drag rake guru out there?
Can anyone help with the design and installation details of a drag
rake? I'm interested in: Pitot tube sizing ( ID and length ) Span of the rake. Positioning of the dynamic pressure port. Plenum chamber/s dimensions. Positioning of a rake on or behind the trailing edge. Ian |
#2
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Ian,
Here's a link I was given last year, looks like a pretty good description: http://www.owp.us/Althaus/AlthausDragProbe.asp Jim nimbusgb wrote: Can anyone help with the design and installation details of a drag rake? I'm interested in: Pitot tube sizing ( ID and length ) Span of the rake. Positioning of the dynamic pressure port. Plenum chamber/s dimensions. Positioning of a rake on or behind the trailing edge. Ian |
#3
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You could buy mine:-) Made by Replogle in the late
eighties to Dick Johnson's specifications - with meter and tubing. Used once. John Galloway Scotland At 13:00 31 March 2005, Jphoenix wrote: Ian, Here's a link I was given last year, looks like a pretty good description: http://www.owp.us/Althaus/AlthausDragProbe.asp Jim nimbusgb wrote: Can anyone help with the design and installation details of a drag rake? I'm interested in: Pitot tube sizing ( ID and length ) Span of the rake. Positioning of the dynamic pressure port. Plenum chamber/s dimensions. Positioning of a rake on or behind the trailing edge. Ian |
#4
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Here is a link that may be helpful.
http://www.soaridaho.com/Schreder/Te...ck_Johnson.htm Wayne http://www.soaridaho.com/ "nimbusgb" wrote in message ps.com... Can anyone help with the design and installation details of a drag rake? I'm interested in: Pitot tube sizing ( ID and length ) Span of the rake. Positioning of the dynamic pressure port. Plenum chamber/s dimensions. Positioning of a rake on or behind the trailing edge. Ian |
#5
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Thanks Wayne,Jim
I am already aware of Johnson articles and Althaus's improved version. Neither article actually discusses any of the maths behind the design and positioning of a rake. I'm looking for a little more detail. I have a prototype rake I built and I'll be testing its operation this weekend. www.internationalsoaring.org/dragrake1.htm Regards Ian |
#6
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How much do you want for it?
Brian |
#7
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What are you using for meter?
Thanks Brian |
#8
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I have a differential pressure gauge built around a Honeywell DUXL01D.
Measuring 0 - 1" H20 which is the same range that I've seen used on the old 80's repogle systems and in Dick Johnsons tests. At the moment, during testing I'll be using an analog meter, my amplifier outputs a signal between .6 and 4 volts. Ultimately it'll go into an A/D converter on a digital system I have. Ian |
#9
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Nice looking rake Ian.
It appears to be per the Althaus drawing? Jmi Ian Molesworth wrote: Thanks Wayne,Jim I am already aware of Johnson articles and Althaus's improved version. Neither article actually discusses any of the maths behind the design and positioning of a rake. I'm looking for a little more detail. I have a prototype rake I built and I'll be testing its operation this weekend. www.internationalsoaring.org/dragrake1.htm Regards Ian |
#10
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An analog meter does a nice job of smoothing the information in mild
turbulence. Additional smoothing may be needed with a digital system. If a pitot that is used to sample the airspeed at the other port of the pressure gauge has the same hose size and length as the hose coming from the rake, the pressure gauge output should be smoother. You might consider using a Kiel tube for the pitot and mounting it on you drag probe. I hope to hear more about your tests. Bob "nimbusgb" wrote in message ups.com... I have a differential pressure gauge built around a Honeywell DUXL01D. Measuring 0 - 1" H20 which is the same range that I've seen used on the old 80's repogle systems and in Dick Johnsons tests. At the moment, during testing I'll be using an analog meter, my amplifier outputs a signal between .6 and 4 volts. Ultimately it'll go into an A/D converter on a digital system I have. Ian |
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