expo

My Feedback: (20)

I've got a couple of wood props that say 12 6-10 on them. What's the pitch on it? 6 or 10? I'd like to use one on a O.S. .46 FXi. Would that be too big a prop or would it be more for a .61?

daven

My Feedback: (1)

It is a variable pitch prop. Starts at 6 near the hub and ends at 10 near the tips.

Too much prop for a .46.

expo

My Feedback: (20)

What's the advantage to this twist instead of the same pitch throughout?

Would you think it would be a good prop on my .61 Fox Eagle instead?

oscar2005

having an increased pitch at the tips makes the prop more efficient and keeps the tips from going supersonic by loading the engine more.most of the thrust is generated by the tips anyway,also makes a stronger prop at the hub.it may be a bit too much but try it.

mikekosatka

My Feedback: (7)

.61 probabably.... 46 is not strong enough. Try it and see for yourself since you already have it
Good Flying,
MIke

BiplaneLem

in addition to what the other guys said....... the 6 pitch at the hub alows for a faster idle speed with a slower air speed. At low throtle the tips are lest effective and the hub area takes over. The idea is all about efficiency. A 10 pitch is good for speed. A 6 pitch is good for power. A 6-10 pitch prop gives you both.... more speed at high throttle and more power at low throttle. I use an 18 x 6-10 pitch prop on my Quadra 35 in a 100" wing span Super Cub. It really made the difference in flight caracteristics. I have good speed and plenty of power. Think you will like the 6-10 prop once you use it. Also agree that the 12 x 6-10 prop would work on the .61 engine but may depend on the plane it is attached to.

Joe

HighPlains

My Feedback: (1)

What a bunch of ......(select your own adjective)

The real reason for the 6-10 prop was the thickness of the wood the prop was carved from. In order to have enough meat at the hub, the pitch was cut way back to the 6 pitch. This allows the manufacturer to use a much thinner block of wood (and cut the cost of the blank).

How well does it work? Most modelers are really not that discriminating. Sorry, but it's the sad truth. While it is very true that the air right at the fuselage is moving slower than the free stream air going past the fuselage, it is a rather thin layer of air, and the most you would lower the pitch no more than an inch or so (10 % of the pitch is close).

In all honesty, I would use that prop to stir paint.

BiplaneLem

HighPlains..... If you see any 6-10 props laying around your shop...... send them to me before you stir paint with them. I have used 6-10 props and like them in specific instenses. you should open your mind to new ideas before you spout off at the mouth. Oh yeah another thing...... you forgot something about making the prop.... it is much easier to make a straight pitch than to make a variable pitch so the cost reduction in the wood block blank is off set by the production cost of milling the variable pitch..... so either try one first or send me your paint stirers.
Joe

BiplaneLem

You probably say the same thing about three bladed props also......

HighPlains

My Feedback: (1)

Oh, maybe I should have mentioned that I worked at a place that actually made wood propellers while in college studing for my engineering degree. The owner of the business had been making model airplane propellers since 1949 commercially, and knew all the principles in the industry. When these propellers came out, he called the guy, and they talked about it, so he really did know the reason. Since they served different market segments, they didn't directly compete.

BiplaneLem

My appologies...... but whatever the reason they made them...... I thank them because my Super Chipmunk would not perform half as good as it does without it. No matter what anyone says...... I believe the variable pitch props work well for certain planes and I know this from using a variety of props on the same plane. They work even if it is a fluke!

HighPlains

My Feedback: (1)

It's rare these days that anyone actually uses a wood propeller. And that's too bad, because for a varity of reasons, wood props are much better than plastic, and worse for other reasons.

The benefits? less gyroscopic effects when you are rapidly changing direction of the model, like snap rolls, etc so your engine's bearing last longer and the airplane handles better. The throttle response is usually much quicker due to the lower rotating mass. The break when they hit the ground, so the loads on the engine are lower.

Downside? Really much higher costs to manufacture. Plastic, you just mold and eject. Wood props take about 20 steps, and require a bit of hand work. Consider that you take a plank of Maple of the correct thickness (measured in quarters or fourth's). Typical for a 40 sized prop would be 4/4 or 5/4 for the width of the blade. So what you have to do:

1.) Cut the plank to length for the prop diameter
2.) Rip the plank to a block that holds three blanks (3 typical), thickness depends on pitch
3.) Drill the 1/4 shaft hole
4.) Shape 1/2 of the blade outline
5.) Shape the second side of the blade outline - maintain .003 blade to blade, top to bottom
6.) Rip the block to independent propeller blanks, thickness depends on the pitch
7.) Shape the first blade back side to the pitch curve desired (flat side of blade)
8.) Shape the second blade back side......
9.) Shape the front side of the first blade (curved front side)
10.) Shape the second blade.....
11.) Drum sand the flat side of the blades
12.) Airbag drum sand the curved side of the blades
13.) Sanding sealer soak props
14.) Hand sand blades after sanding sealer
15.) Add prop markings with size on one blade, brand on the other with stamp
16.) Paint with clear fuel-proof finish
17.) Second coat with finish
18.) Bag props, 12 to a bag
19.) Fill orders to distributers.
20.) Maintain equipment, sharpen carbide cutters, develop new products, deal with government regulations, OSA, EPA, IRS, etc.
21.) Unload 100,000 lbs of maple from a rail car