Thread: Mini-HowTo Beginners Guide to Motor and Prop Selection View Single Post
May 13, 2010, 06:34 PM
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Quote:
 Originally Posted by HawkerTyphoon OK, here's one, When giving you your prop selection what does the TE stand for, I get SF stands for Slow Flyer but I can't figure the TE out Thanks, HT
Excellent question, and I'm glad you asked it. All props have a safe rpm level that we never want to exceed, else they might disintegrate and throw shrapnel everywhere. This ain't good. Let's look at some props and see what the maximum safe rpm levels are. Thanks go to Dr Kiwi for providing the data.

APC TE(Thin Electric) or sometimes called APC E (Electric) have a safe operating rpm of 190,000 divided by the prop diameter. So an 8" diameter APC TE prop would have a max safe speed of 190,000/8 = 23,750

And APC TE 10" prop would have a max speed of 190,000/10 = 19,000 rpm. And so on and so forth.

APC SF (Slo-Flyer) props have a safe rpm of 65,000/diam. So an 8" SF prop would be safely maxed out at 65,000/8 = 8125 rpm, and an APC 10" diameter SF prop would be 65,000/10 = 6500 rpm.

A typical GWS RS (Reduction Series) prop has a safe rpm of between 40,000/diam, and 50,000/diam.

It is interesting to note that you might be playing with WebOCalc one day, working on dialing in a prop, and all of a sudden the prop disappears from the chart! The reason is because WOC will not let you choose a prop that is unsafe for the plane. So if in the process of dialing the prop in, WOC sees the rpm going up to the danger level for that particular prop, it simply removes the prop from the chart...

Chuck