I see that APC lists different glow prop types - sport, pattern, pylon, combat... What are the differences? I could not find an explanation on their web site.

I think there just grouped so as to make it easier to find the prop for your application

In very basic terms. For a given size of engine a different combination of prop dia/pitch would be used for different applications. Hence the APC descriptions.

Ed S

Hi!
The difference is just their different uses. Pylon racing props are specially made to be used for certain pylon racing classes . Of course they can be used for sport flying too...or any other application in model flying. Same with the other prop categories.
There isn't water tight locks! You must try for yourself what works best.

I have no idea if there is a difference in how they are made.

They charge a lot more for pattern props
13x9 pattern 7.95
13x8 sport 4.89

I can't see the 13x9 having an extra $3 of materials compared to the 13x8.

Well, I guess I did not phrase the question very well. What are the differences in airfoil and propeller shape? Why are they different for the different applications? I recall the pylon "toothpicks" from the late 60's but the pylon props now do not look like that at all. I see that the current pylon props are more curved but...

If you want real information you should go to the source.

From the APC web site

APC Propellers are manufactured by:
Landing Products
1222 Harter Ave.
Woodland, CA 95776

Email: [email protected]
Our Business Hours are 6 AM to 2 PM PST
Phones:
530-661-0399
530-666-6661 Fax

I did email them, but have not received a reply. Guess I'll need to phone them on Monday. I did think that someone here would have the answers.

Hi!
Being a pylon racer for many years, making my own carbon fiber props I can perhaps shed some light on props.
Propellers should move air rearwards! Right! To do so requires an engine that can turn the prop as fast as possible.
But our engines (glow and petrol) aren't that good at turning large diameter high pitch props at high speed so if we want to fly fast we make the prop thin and with small diameter to have it perform as good as posible.
Certain prop parameters like diameter, thickness, with and pitch are some of the important things to have in mind when making a prop. You also have to take into consideration airfoil shape (mostly some kind of Clark -Y shape) and tip shape of the prop...those 5 things are all important.

Propeller making is art and science mixed! You have to know some facts to improve things. In pylon for instance you know that you have fast rewing engine! To have that engine perform best you must have a small diameter and thin prop so that the engine can reach it peak horse power.
Propeller making is facts gathered from many, many cut and try sessions.
When it comes to ordinary sport propellers it's common knowledge today in the R/C world that APC makes some of the best all around plastic props. There are other prop manufacturers that make good props like the British "RAM", Australian "Bolly" and German "Graupner".

So in the end you have to try for yourself what prop works best for what plane. But from experience you can narrow it down fairly easy.
Small fast planes requires small props with thin narrow blades. Large, slow flying planes requires large diameter low pitched props.

Thanks, Jan. Can you explain why some props are curved spanwise the scimitar shape? I would think it would be much harder to make than a straight prop so it must have some benefit.

Hi!
That is just something some manufacturer fancy, could as well be straight!!

The Simitar shape was used in full size Formula One (Goodyear) racer in an attempt to have a prop that changes it's pitch depending on load and RPM. I believe it was originally developed by Steve Wittman.

As to the major diffences between sport props and racing props for models, the most obvious is diameter and pitch as well as blade area. But more subtle effects are the pitch curve over the length of the blade. Pylon props generally have the highest pitch at the tips (washed out at the hub), while many sport props are slightly washed out at both the hub and tips. As far as the outline of the prop, much attention is paid to keeping the mass inline with the hub to minimize stress.

Yeah, good luck on the email response. Emailed them a couple years ago to ask how they recomend a prop should be balanced. I’m still waiting for a response.

So when you call can you ask that question too?

Best answer yet!!!!

Well, I finally got through to Fred at APC. Not the chattiest guy. Pattern and sport props are now the same. The pattern ones used to be heavier to cope with the impact loads from engines running too lean. The pylon props have a heavier hub, presumably to cope with the higher power from these engines, and the higher rpm's.

As for balancing, he mentioned drilling holes in the hub and adding lead weights (!) Another option was to put lead in the recess in the hub. Seems odd to me! Other options are to sand the front of the heavier blade, or add some CA to the lighter blade. (I use clear nail polish. It seems to stand up pretty well.)

Guess I'll order a selection of props and see what works best.

Hey thanks for asking about the balancing. I generally opt for sanding but wondered if that method was recomended or discouraged by APC, however not enough to make a call.