guille2006

Can anybody explain what's te meaning of 15X6-10? Obviously, 15 is diameter but my question is pointed to the double digit on the pitch number...
Thanks on advance
Guille

adstott

I think it means the pitch has a gradual change from the begining of the prop to the tip. If I remember correctly it tries to take advantage of the different aerodynamic properties of the prop related to the different speeds of the prop for a given point from the center of the prop.

2slow2matter

My Feedback: (1)

That is correct. THe propeller has a root pitch of 6 inches, and a tip pitch of 10 inches. THere is a gradual increase in pitch throughout the length of the blade.

HighPlains

My Feedback: (1)

Partially correct. A lower pitch at the hub does help because the air moves slower next to the fuselage.

BUT, not that much slower.

The real reason for this pitch curve is the cost of the wood to make the prop. If you kept the 10" pitch down to the hub of the prop, you would need a much thicker prop blank, of which most of it would be reduced to shavings during the carving process.

2slow2matter

My Feedback: (1)

I don't see how what we said was partially correct. It is correct, plain and simple. I've not noticed a decrease in the price of variable pitch props over fixed pitched props.

britbrat

2slow is right. Just to add even more fun -- the varying pitch props can be made with no twist, automatically giving a varying pitch with greater tip pitch, & making the props easier & cheaper to make (fewer shavings)

HighPlains

My Feedback: (1)

Did either of you ever work for a major manufacturer of wood props?

jetmech05

also the difference in pitch is a prop does not produce thrust the whole length of the prop blade a prop produces no thrust at the hub nor at the tip. thrust is produced for about 1/3 of the blade starting at about 7/8 ths of the blade length from the tip.
just some gee whiz info

pettit

My Feedback: (23)

"Did either of you ever work for a major manufacturer of wood props?"

No, but I bet they stayed at a Holiday Inn Express last night...

CVN-71

Now that's funny , I dont care who ya R..

HighPlains

My Feedback: (1)

They might have saved on auto insurance too, but have plenty of bliss in regards to props. I posted the actual reason, but the rest of you seem to have bought into the marketing hype. My inside information came from a person who started making props commerically in the late 40's. While in college working toward my engineering degree, I worked part time making a few hundred thousand props.

2slow2matter

My Feedback: (1)

So aparently you've never worked for a major man. either. Show me some real data supporting the fact that variable pitch props are cheaper than fixed pitch, and I'll bite. Otherwise, I'll stick to what I've learned.

HighPlains

My Feedback: (1)

Ok, measure the width of the blade as you approach the hub. Wood props are beefy in that area to hold the blades together, and the aerodynamics suffer. It takes a certain cross sectional area to keep the prop blades from fluttering, plus a bit extra to prevent failure due to less than optimum grain. Now if that same blade width is pitched up to a more normal pitch curve, then the block of wood it is carved from would need to be thicker. So if you can cut a particular size of prop from thinner stock, then a company can earn a bit more. It also allows the engine to turn more on the ground, but it may not work as well in the air, though that is highly dependent on the airframe drag.

I don't know what you consider "major", but if someone's company made more than 10 million props over a lifetime, for a hobby application - I would consider it a major player.

RITTMEISTER

HIGH PLAINS GOOD MAN!!! VERY VERY VERY IMPRESSED!!! AND LMAO!!!!!!!!! DJCIII