HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Mar 22, 2004, 11:35 AM
Balsa!!!
Singapore
Joined Sep 2003
1,539 Posts
SF, E, HD props differences

OK, so I've seen these propellers around my LHS. There are 2 sorts of GWS propellers, one which is the SF style which is like the ones made by APC, and the other ones HD & E propeller are the ones that look like they are used in gassers.

But what is the difference between these an SF, E, and HD propeller? And what does HD stand for?
csisfun is offline Find More Posts by csisfun
Reply With Quote
Sign up now
to remove ads between posts
Old Mar 22, 2004, 11:46 AM
TRP
Registered User
TRP's Avatar
United States, CA, Morgan Hill
Joined Jun 2002
3,687 Posts
Heavy Duty?
TRP is offline Find More Posts by TRP
Reply With Quote
Old Mar 22, 2004, 12:26 PM
Registered User
College Park, MD
Joined Sep 2002
4,714 Posts
SF = APC SlowFlyer (geared electric)
E = APC Electric (direct drive glow/electric)
RS = GWS Reduction Series (geared electric)
HD = GWS Hyper Drive (direct drive electric)

In general the SF and RS props are intended for geared applications. They are optimized for the highest thrust at slow RPMs APC lists the SF props as being useful for 65000/diameter. So a 9 inch SF prop has a practical upper RPM limit of 7222RPM. The GWS RS props seem to have a lower upper RPM limit because they vibrate loudly when spinning fast.

The HD and E props are designed for direct drive so they have lower thrust than the SF or RS props for a given diameter at a given RPM. But they also seem to be slightly more efficient at any given RPM.

I've found that when you want to substitute an E or HD prop for an RS or SF prop you need to got up in diameter to have the same thrust.
thunder1 is online now Find More Posts by thunder1
Last edited by thunder1; Mar 22, 2004 at 02:41 PM.
Reply With Quote
Old Mar 22, 2004, 12:47 PM
Balsa!!!
Singapore
Joined Sep 2003
1,539 Posts
Perfect. Just what I needed to know. And:

Just what does more efficient mean? The GWS props are total crap and I'm not going to get another one. APCs are hard and they dont break easily. Unfortunately, the APC doesn't stock a 12x6 SF prop. Does it?

The closest I can find is a 11x4.7 SF prop. Nothing larger. I'm putting a 12x6E prop on the Slooooow Stick and I'm using an EPS350C (D gearing).

What do I gain from using an E prop instead of an SF?
csisfun is offline Find More Posts by csisfun
Last edited by csisfun; Mar 22, 2004 at 12:57 PM.
Reply With Quote
Old Mar 22, 2004, 01:28 PM
TRP
Registered User
TRP's Avatar
United States, CA, Morgan Hill
Joined Jun 2002
3,687 Posts
Hyper Drive! Very nice.

Thanks,
Ted
TRP is offline Find More Posts by TRP
Reply With Quote
Old Mar 22, 2004, 01:53 PM
Under tension
citabria's Avatar
Johnstown, Colorado
Joined May 2002
880 Posts
Quote:
Originally posted by csisfun

The closest I can find is a 11x4.7 SF prop. Nothing larger. I'm putting a 12x6E prop on the Slooooow Stick and I'm using an EPS350C (D gearing).
I own an 11x7 SF prop and Aeromicro.com has a 12x6 SF prop for sale. Take a look:
http://www.aeromicro.com/Catalog/pro...9_products.htm

Scott
citabria is offline Find More Posts by citabria
Reply With Quote
Old Mar 22, 2004, 02:06 PM
Balsa!!!
Singapore
Joined Sep 2003
1,539 Posts
Can't buy something off the net.
csisfun is offline Find More Posts by csisfun
Reply With Quote
Old Mar 22, 2004, 02:40 PM
Registered User
College Park, MD
Joined Sep 2002
4,714 Posts
Efficiency for props is the amount of thrust per energy input i.e. amps go down.

So the SF and RS props "waste" slightly more energy to give the same amount of thrust. The tradeoff is usually the ability to produce thrust in the lower end of the RPM range. Which is why I mentioned the HD and E props need to go up a diameter to produce the same amount of thrust at slower RPMs.
thunder1 is online now Find More Posts by thunder1
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Sold A HUGE LOT of electric props, APC E, SF and GWS HD and SF!! dawnron1 Aircraft - Electric - Power Systems (FS/W) 1 Aug 01, 2006 12:03 PM
Difference between APC SF and E props? Tram Power Systems 7 Dec 24, 2004 02:10 PM
Discuss the APC "E" props vs "SF" props Please CSI Power Systems 47 Dec 09, 2004 01:19 PM
Compare GWS SF and HD props on Razor-MH MKH Power Systems 26 Jul 03, 2003 10:54 AM
"sf" props and "e" props? FrankC29 Beginner Training Area (Aircraft-Electric) 4 Apr 25, 2003 09:11 AM