I had a GWS EPS300C-C drive in my Park Cap powered by 8x1100 HECells and a 11x7 APS thin electric prop. It flew around ok but acrobatics were weak and Perry said it looked really under powered and I should try 720s and/or a APS SlowFiler prop. I moved up to the 'D' gearing and noticed some improvement but no much, even tried the 720s, blech. But then I stuck in a 11x7 APS SlowFlier prop with the 720s and WOW, I could pull off the ground almost verticle, do 15'+ verticle climbs in the air, and pull out of inverted sometimes. When I put the HECells back in it was even better, 20'+ verticle climbs, and pull out of inverted no problem. Its all about the SlowFlier props.
The only reason I bought a TE Prop was because thats all my hobby shop had, aeromicro came to the rescue

Yeah, I've noticed similar results using "Slow-Flyer" APC props. I have planes that won't even fly unless I use the APC slow props. (Waiting on a shipment of 20 of them )

Here's a question for the groups - why are these props so effective? And what reason is there to use any other type of prop?

-rt

1. Good design and manufacturing by one of the best in the business.

2. Applications that will turn a prop faster than the SF's rated limit. It is: RPM=63330/D where D is in inches. So, a 10 inch APC SF prop should be limited to 6333 RPM, a 9 inch to 7037, and the new 12 inch to 5277 RPM. For higher RPMs, the Thin-Es are the way to go.

and therefore also the reason to use larger ratio gearboxes for larger props...to limit the rpm right?

So spinning a larger prop faster is a bad idea why?

-rt

I’ve noticed a few threads lately that compare the Thin E vs. SF props and question why one works better than another. We should keep in mind that most of these threads are in Parkflyer forum and concern highly geared low RPM drive systems. So most come to the same conclusion you have, i.e. SF is better than Thin E. But that’s only true for relatively high thrust, low speed planes. If you think of a propeller as a rotating wing (which is exactly what it is) you should be able to start to see why we have so many different shapes and sizes of props. They are all suited to a particular task. So to answer your original question:

Q) So spinning a larger prop faster is bad idea why?
A) Because:

1) Over propping can damage the motor or any other electronic component not rated for the amp load. This doesn’t just mean a longer or more pitched prop, but also a wider cord (i.e. SF style) prop as well.
2) Assuming the electronics can take it, exceeding the manufacturer's RPM limit can produce enough centrifugal force to blow apart the prop. Really not a good thing.
3) At higher RPM the prop design will not be as efficient as a propeller specifically designed for that regime (like putting an undercambered Tiger Moth wing on a pylon racer).

Can anyone think of any others?

As you can see, spinning a larger prop faster is usually good, so long as you don’t break any of those three conditions above.

Hope that helped.

Spinning a larger prop slower is more effective than spining a smaller prop faster, for a couple of reasons.

1. (Super)sonic tip speed. This is inefficient , because it produces turbulence and that reduces the effectivness of the propeller.

2. Turbulence. Turbulence reduces the effectivity of a propeller. This only happens at high speed (ie high RPM), and can be avoided by slowing the propeller RPMs down.

3. Stalled propellers. This is partivularly annoying, and happens with high pitch propellers at extremely low, and extremely high speeds. This, like turbulence, can be avoided by putting a bigger diameter, lower pitch propeller on.

One of the best explanations I have ever seen on how to choose the best prop for your plane is in the article: "Match Propeller to Model Mission - How to do it," by Don Brooks. It appeared in the September, 2002, issue of Model Aviation. If you haven't read that article, get a copy and read it. Terrific article. Great help.

I like slow, if you spin a prop faster it is going to screw through the air faster. For slow flight, you want as big a diameters with as small a pitch turning as slow as you can get away with. Slow wing, slow prop, in your face flying=FUN
It isn't hard to steer a dart all over the sky.

This poses an interesting question...

I want a 13x10 or 14x10 slowflyer prop for a 32-3500 rpm application but it looks like the slowflyer APC props only go to 12x6. If I use the APC E prop will I get the performance I expect with this slow of a rpm?

Grant

Call me a rebel but as far as I'm concerned, the APC props are a waste of money on any of the smaller gear driven motors. On all of the IPS drives and the two EPS 100C drives I use, the GWS props not only provide more thrust but more duration too. And yes, I've tried both thin electric and slowflyer props.

I know from my slimers that APC props blow most others, ie. master airscrew, zinger, ect. out of the water. However, my slow stuff just doesn't seem to like them too much.

-Adam

Ahawk,

I like the GWS props too! My application is on a Mega 7 turn motor and they won't go on a shaft that big. If I drill it out, I won't have any hub left I don't think.

Any suggestions?

Grant

Holding all other power parameters constant (motor,gear ratios,battery,etc.), has anyone really compared the APS SF props to the various GWS props starting with the same diam & pitch....... i'm very interested in that comparison... i've been pleased with the GWS props so far with my slow-flyer applications but always looking for proven, valid perf increases............ kw

oops....i meant APC of course... really too late for this stuff!!!!

An APC 11x9 makes my Dirty Birdy "whistle" unlike any other prop I've tried....however on my electrics, GWS is the winner. The fastest electric I've had is a Sporty with Graupner speed 300/MPJ geardrive on 8 600ae's and the GWS 8x6 clearly outperformed the APC 8x6. On my Cubs, Sticks, and especially my Varmints, GWS is a clear winner.

Originally posted by Parkflyer
Ahawk,

I like the GWS props too! My application is on a Mega 7 turn motor and they won't go on a shaft that big. If I drill it out, I won't have any hub left I don't think.

Any suggestions?

Grant

http://www.aircraft-world.com/prodde...-DS002&from=63

Grant,

Would something like this work? I know this company is in Japan but they only charge 2.50 shipping and you ususally get your stuff in 5 working days!

-Adam