O.S. Engines Support Ask Bill Baxter your questions about O.S. Engines.

.70 Surpass Prop and RPM

Old 06-01-2007, 03:04 AM
Thread Starter
My Feedback: (7)
Join Date: May 2005
Location: Oceanside, CA
Posts: 33
Likes: 0
Received 0 Likes on 0 Posts
Default .70 Surpass Prop and RPM

I am a new the 4 stoke engine and I am wondering what I RPM I should see for a given prop? Is there a chart I can use as a guide? I plan on trying a 12x8, 13x8, and a 14x7.

Any help would be appreciated.

Old 06-01-2007, 07:49 AM
Senior Member
My Feedback: (31)
Join Date: Mar 2002
Location: Kannapolis, NC
Posts: 7,415
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .70 Surpass Prop and RPM

13 x 6 high 8 or low 9k range depending on nitro
Old 06-01-2007, 10:23 AM
My Feedback: (11)
Join Date: Apr 2002
Location: Monticello, IL
Posts: 19,483
Likes: 0
Received 6 Likes on 5 Posts
Default RE: .70 Surpass Prop and RPM

We don't have a prop/RPM chart available for your engine. We normally prop the engine to turn around 10,000 RPM at full throttle when leaned to just rich of peak RPM. An APC 12 x 8 propeller will usually work well. What you want to do is select a propeller that will give you that RPM on the ground and still fly your airplane the way you want. Go for the RPM first. Larger propellers will turn lower RPM and won't allow the engine to develop its power as well.
Old 07-31-2007, 08:04 PM
My Feedback: (13)
baronbrian's Avatar
Join Date: Nov 2002
Location: Grand Forks, ND
Posts: 890
Likes: 0
Received 0 Likes on 0 Posts
Default RE: .70 Surpass Prop and RPM

The sweet spot I have found with the .70 is an APC 13x7 for most sport planes. this size is a next generation design and looks a little differnt that most of the other APC's in that size range. I had this combo on a sig kadet arf w/floats, around 8 lbs and it got of the water fast. and cruised reall well even with the extra drag of the flots in the air.

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
Trackbacks are Off
Pingbacks are Off
Refbacks are On

Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.