Pitch gauge

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FlyinFinn

Well-Known Member
Joined
Jan 21, 2007
Messages
206
So, I have this pitch gauge I haven't used in years. Does anyone know how to use it? I would like a refresher. Is there a tutorial on how to use this particular gauge? I know I obtained it from someone on this forum years ago.

Jeff

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Jeff,

Do you have the table to correlate measurements to pitch? Without that, the measurements do not tell anything.

Basically you measure the distance with the dial indicator on the prop (I use 70% distance out from the hub) at the different amount of degrees (5,10, 20 etc..) of rotation of the prop and use that measurement to go to the chart with to get the corresponding pitch.

Start at the trailing edge and set to zero. Rotate the desired degrees and record measurement. Do this for multiple angles and you can "map" your prop.

Duke
 
You don't really need the tables, just divide the no. of degrees you move the prop by 360 then multiply by the dial reading.

If you think about it a second pitch is how far the prop would advance in one complete revolution. If you just measure part of a rev. you just need to take that into account by dividing by 360.
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You don't really need the tables, just divide the no. of degrees you move the prop by 360 then multiply by the dial reading.

If you think about it a second pitch is how far the prop would advance in one complete revolution. If you just measure part of a rev. you just need to take that into account by dividing by 360.
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Good point Terry. I may not use tables anymore - always interpolating the table anyways.

Time to make a spreadsheet.
 
You don't really need the tables, just divide the no. of degrees you move the prop by 360 then multiply by the dial reading.

If you think about it a second pitch is how far the prop would advance in one complete revolution. If you just measure part of a rev. you just need to take that into account by dividing by 360.
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Good point Terry. I may not use tables anymore - always interpolating the table anyways.

Time to make a spreadsheet.

If you measure 15* just multiply the gauge reading by 24 (360/15=24).

If you use 45* multiply by 8 (360/45=8)

Etc.
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Terry they just numbers ,,bend and take degree of the clock ,then record.No need for headcase multiplications ha.
 
Terry they just numbers ,,bend and take degree of the clock ,then record.No need for headcase multiplications ha.

True, to a certain extent it's all relative.

But how ya gonna figure how fast (potentially) a prop can go w/o the total pitch for one revolution?
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MPH = PITCH X RPM / 1057
 
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I guess if veiwed from a SAW perspective that's understandable.Cheers
Any kind of racing! Take the first 15* from the LE about 3/4 out from the C/L, multiply by 24 to get "full circle" pitch then use that in the formula to see "potentially" how fast a prop will go.

For a light, clean running hydro I've found 10% - 15% slip is about right, monos as much as 25%.

Props I'm working with on my 40 hydro have about 4" of LE pitch. So 4 x 24,000 (guesstimate) / 1057 = 90.8 x 0.85 (15% slip) = 77.1 mph

Right in the ballpark!
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I guess if veiwed from a SAW perspective that's understandable.Cheers
Any kind of racing! Take the first 15* from the LE about 3/4 out from the C/L, multiply by 24 to get "full circle" pitch then use that in the formula to see "potentially" how fast a prop will go.

For a light, clean running hydro I've found 10% - 15% slip is about right, monos as much as 25%.

Props I'm working with on my 40 hydro have about 4" of LE pitch. So 4 x 24,000 (guesstimate) / 1057 = 90.8 x 0.85 (15% slip) = 77.1 mph

Right in the ballpark!
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I didn't reply correctly and yes you are right any racing,,I Just don't go into that depth of measure,,but thanks for the formula..
 
That gauge is for more than just a overall pitch #.

It dose any thing you want any where on the prop.

Lead in to trailing edge cup.

If you use it right and record your pitch at different points on the prop. You can learn a lot about what dose what as far as pitch is concerned.

Over all pitch average dose not tell the whole store at all.

The first 20deg from the leading edge will tell you how fast the prop can go with no slip % needed in the equation.

Have proved it to my self many times with a eagle tree. Also with the gas guys at the pond with there gun.

Read the 20 deg leading edge at the 70% mark on the prop and then use the equation. pitch x RPM /1057 = MPH always came in at around +/- 2 mph
 
That gauge is for more than just a overall pitch #.

It dose any thing you want any where on the prop.

Lead in to trailing edge cup.

If you use it right and record your pitch at different points on the prop. You can learn a lot about what dose what as far as pitch is concerned.

Over all pitch average dose not tell the whole store at all.

The first 20deg from the leading edge will tell you how fast the prop can go with no slip % needed in the equation.

Have proved it to my self many times with a eagle tree. Also with the gas guys at the pond with there gun.

Read the 20 deg leading edge at the 70% mark on the prop and then use the equation. pitch x RPM /1057 = MPH always came in at around +/- 2 mph

No slip?
 
That gauge is for more than just a overall pitch #.

It dose any thing you want any where on the prop.

Lead in to trailing edge cup.

If you use it right and record your pitch at different points on the prop. You can learn a lot about what dose what as far as pitch is concerned.

Over all pitch average dose not tell the whole store at all.

The first 20deg from the leading edge will tell you how fast the prop can go with no slip % needed in the equation.

Have proved it to my self many times with a eagle tree. Also with the gas guys at the pond with there gun.

Read the 20 deg leading edge at the 70% mark on the prop and then use the equation. pitch x RPM /1057 = MPH always came in at around +/- 2 mph

No slip?

not if you use the first 20 deg from the leading edge as your pitch for calculation.

Check a prop and map it with this gauge. take a reading at every 5 deg mark all the way across the blade at the 70% mark on the blade.

Use any prop you have a good log on the RPM and speed.

Let me know what you see?
 
I bought a Frank Orlic pitch gage that I bought about a year and a half ago and Ive never used it.

If anyones interested I could probably be talked into selling it.
 
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No slip?

not if you use the first 20 deg from the leading edge as your pitch for calculation.

Check a prop and map it with this gauge. take a reading at every 5 deg mark all the way across the blade at the 70% mark on the blade.

Use any prop you have a good log on the RPM and speed.

Let me know what you see?

I've been using the Eagle Tree with Frank's gauge since 2010 and have many hundreds of runs and the lowest slip I've seen is about 6%, typical is closer to 10-15%.

I use the first 15* of the LE at 75%. Props I'm running range between 5.5" to 7" of LE pitch.

Lately my 6" pitch prop has run close to 24K rpm, with no slip I should be doing 140+ mph!

Might be that lower pitch/rpm doesn't slip as much.
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Must be the prop you are using......... 3.8" to 4" is the range I like to stay in.

6" to 7" of lead in is a lot .....

Then again I never tried to set any speed records just heat race.

so how fast dose it go with 6" and 24K? my calculations show 136 with no slip.
 
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Must be the prop you are using......... 3.8" to 4" is the range I like to stay in.

6" to 7" of lead in is a lot .....

Then again I never tried to set any speed records just heat race.

so how fast dose it go with 6" and 24K? my calculations show 136 with no slip.
In the 115 mph range, 15% slip...
 
If you have 6" at 15 deg how much do you have from the 15 to the traling edge?

7.2 or more?
 
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