Go Back  RCU Forums > RC Airplanes > Questions and Answers
Reload this Page >

General question about prop pitch and diameter.

Notices
Questions and Answers If you have general RC questions or answers discuss it here.

General question about prop pitch and diameter.

Old 10-16-2009, 03:09 PM
  #1  
Matts175
Member
Thread Starter
 
Matts175's Avatar
 
Join Date: Oct 2009
Location: Harper Woods, MI
Posts: 52
Likes: 0
Received 0 Likes on 0 Posts
Default General question about prop pitch and diameter.

Hello guys, I'm building an RC airboat, but was told I might get more answers in the airplane section. My question is about props. Let's say that an engine was recommended to use a 5 x 5 prop. Could a 5.5 x 4.5 or 6 x 4 be used as a substitute? In other words, can you go a little bigger on the diameter If you drop pitch a little and vice versa?

Motor is a 2200Kv outrunner brushless, running on 11.1v if that matters.
Old 10-16-2009, 03:24 PM
  #2  
firstplaceaviator
My Feedback: (27)
 
firstplaceaviator's Avatar
 
Join Date: Feb 2004
Location: Norton, OH
Posts: 737
Likes: 0
Received 0 Likes on 0 Posts
Default RE: General question about prop pitch and diameter.

The best way to determine whether the props will work, is to install the prop, put a Watt meter in between the battery and speed control, and advance throttle making sure that you are not exceeding the lowest rated component. If you don't have an Watt meter, keep a close eye on how hot the motor, speed control, and battery. Make sure they are staying cool. When you switch to the larger diameter, it may pull too many amps, and fry any one of the components.
Doug
Old 10-16-2009, 04:18 PM
  #3  
carrellh
Senior Member
 
carrellh's Avatar
 
Join Date: Mar 2003
Location: Garland, TX
Posts: 6,544
Likes: 0
Received 0 Likes on 0 Posts
Default RE: General question about prop pitch and diameter.

There is a software called motocalc that is supposed to be pretty good for estimating electric power system requirements. You can download and use it for free for 30 days. Then it costs $39 if you want to keep using it. Type motocalc in the search box of www.google.com to find it.

There is a freeware program that shows a "load" number for whatever prop size you enter. It is generic but it does give a rough comparison. In theory,two props with the same load should turn the same rpm on your motor. Type thrusthp in the search box of www.google.com to find it.
A 5x5 has a load number of 3125
5.5x4.5 = 4118
6x4 = 5184
6x3 would be closer, 3888
Old 10-16-2009, 04:20 PM
  #4  
Matts175
Member
Thread Starter
 
Matts175's Avatar
 
Join Date: Oct 2009
Location: Harper Woods, MI
Posts: 52
Likes: 0
Received 0 Likes on 0 Posts
Default RE: General question about prop pitch and diameter.

thanks guys.
Old 10-16-2009, 04:24 PM
  #5  
Matts175
Member
Thread Starter
 
Matts175's Avatar
 
Join Date: Oct 2009
Location: Harper Woods, MI
Posts: 52
Likes: 0
Received 0 Likes on 0 Posts
Default RE: General question about prop pitch and diameter.

That thrusthp looks neat, but doesn't work with Windows 7 Ultimate 64 bit. Bummer.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off


Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.