



Orange County, CA
Joined Feb 2002
2,875 Posts

These are the different gear ratios. Why they use both letters and numbers to designate the gear ratios is beyond me. Note that the ratios for the EPS400 are different from the EPS300, as are the IPS (DX). With enough time you may end up memorizing the more common ones (C=5.33, D=6.6, B=4.4 or so, A=3.75). The higher the gear ratio the larger the prop it can spin, which tends to be more efficient than spinning a smaller prop faster.




Prop size.
When figuring prop size is the 1st # the length and the 2nd # the aggresivness of the pitch on the blade? Give me an example, Of say a 12x4.




The best analogy for 'pitch' is to imagine your 12x4 prop is (a bit like a corkscrew) rotating in a mass of Jello. For each complete revolution of the prop it will move forward 4". A 6" prop would move 6" and so on. "Pitch speed" is important in flying planes at a suitable airspeed and can be calculated from an equation, simplified as: pitch speed (mph) = rpm x pitch (inches)/1052.
Cheers, Phil 




Thread Tools  
Similar Threads  
Category  Thread  Thread Starter  Forum  Replies  Last Post 
Discussion  difference in the Huey UH1 B and C model?  jeff262  Mini Helis  5  Dec 24, 2006 12:53 AM 
GWS Warbirds on GW/EPS300CBS  tec319  Parkflyers  3  Jul 11, 2003 11:50 PM  
What is the difference in Pico Combat Materials?  MarkChinery  Foamies (Kits)  1  Mar 01, 2003 12:54 AM  
What prop for GWS EPS300C (AS)?  Danny Troy  Power Systems  6  Nov 11, 2002 03:38 AM  
What's the deal with the EPS300C?  hardlock  Parkflyers  3  Sep 29, 2002 05:36 PM 