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

Three Blade

Reply

Old 12-09-2017, 07:53 PM
  #1  
mashp39
Thread Starter
My Feedback: (1)
 
Join Date: Mar 2003
Location: THE VILLAGES, FL
Posts: 157
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Cool Three Blade

Every time the words"3-blade prop"are used someone always jumps in and says it cuts the efficiency of the engine.What does it actually change in the flight of the plane? Is it a great big something or only a slight something? Slower speed, slower engine response or what?I have used a 3-blade and then a 2-blade prop on sport planes and don't see any real difference.Do the nay- sayers have any real experience or only just want to offer their opinion? Most all the electrics use 3 and sometimes 4 blade props.Should not they just fall from the sky?
mashp39 is offline  
Reply With Quote
Old 12-10-2017, 05:03 AM
  #2  
j.duncker
My Feedback: (2)
 
j.duncker's Avatar
 
Join Date: Jun 2004
Location: Sailing in the Eastern Caribbean
Posts: 4,043
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

The most efficient prop is a slow turning single blader sometimes seen on competition rubber models with limited rubber. Coupe d'Hiver.

In practice for general model use a 2 blade prop is the way to go but using a 3 blade prop although bringing a small performance loss say 3% is generally OK as our setups usually have excess power.

More here Click image for larger version

Name:	cruise_propeller_efficiency_screen.pdf
Views:	20
Size:	101.5 KB
ID:	2247356
j.duncker is offline  
Reply With Quote
Old 12-10-2017, 06:46 AM
  #3  
mashp39
Thread Starter
My Feedback: (1)
 
Join Date: Mar 2003
Location: THE VILLAGES, FL
Posts: 157
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Thanks for the reply! I have heard the comments about loss of performance but have always wondered about the amount. The 3% doesn't seem to be critical so I see no reason not to use 3-blade. They look so good.
mashp39 is offline  
Reply With Quote
Old 12-10-2017, 07:24 AM
  #4  
rgburrill
 
rgburrill's Avatar
 
Join Date: Dec 2010
Location: Trumbull, CT
Posts: 2,133
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Electric motors have most of their torque at the low end so they can turn 3 and 4 blade props better than internal combustion engines. I've always thought it strange that people will significantly overpower their warbirds, put non=scale 2 blade props on them and then run them a half throttle.
rgburrill is offline  
Reply With Quote
Old 12-13-2017, 03:59 AM
  #5  
jetmech05
 
Join Date: Jul 2005
Location: Jacksonville, FL
Posts: 4,855
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Imho

3 blade props allow for more ground clearance, are quieter than the equivalent 2 blade, help slow you down on vertical down lines and on approach.
jetmech05 is offline  
Reply With Quote
Old 12-13-2017, 07:06 AM
  #6  
mashp39
Thread Starter
My Feedback: (1)
 
Join Date: Mar 2003
Location: THE VILLAGES, FL
Posts: 157
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 3-blade

Sounds like a good deal.Slowing down but still being good for landings is an asset.
mashp39 is offline  
Reply With Quote
Old 12-13-2017, 10:02 AM
  #7  
blvdbuzzard
 
Join Date: Jun 2002
Location: high deserts, CA
Posts: 3,704
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

This has nothing to do with how they preform, but I do like the way they look. I have run a 3 blade on a ST 45 for years never really noticed any loss of performance. I have had to go to 3 and 4 blade props or make landing gear so tall it looks like a clown car bouncing down the runway. With how over powered our planes really are, if they do loose anything, not sure we would even notice it.

Buzz.
blvdbuzzard is offline  
Reply With Quote
Old 12-13-2017, 03:06 PM
  #8  
Desertlakesflying
My Feedback: (28)
 
Join Date: Jul 2005
Location: Sun Valley, NV
Posts: 2,538
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by rgburrill View Post
Electric motors have most of their torque at the low end so they can turn 3 and 4 blade props better than internal combustion engines. I've always thought it strange that people will significantly overpower their warbirds, put non=scale 2 blade props on them and then run them a half throttle.
+1

i had a 3 blade on my old Marie Mustang with the OS 120 4 stroke. The speed difference wasn't even noticeable when I threw a 2 blade on to see if it was faster one time.
Desertlakesflying is offline  
Reply With Quote
Old 12-13-2017, 05:44 PM
  #9  
mashp39
Thread Starter
My Feedback: (1)
 
Join Date: Mar 2003
Location: THE VILLAGES, FL
Posts: 157
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Great! This what I came to believe after trying a 3-blade a time or two but everytime a 3- blade is mentioned someone always says' It will not be as efficient" and so I went back to 2-blade.The 2-blade worked good so I just stuck to it as a matter of cost and availability.
mashp39 is offline  
Reply With Quote
Old 12-14-2017, 01:18 PM
  #10  
jaka
 
Join Date: Dec 2001
Location: Upplands Vasby, SWEDEN
Posts: 7,786
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Hi!
I think when fliers say that two blade propellers are "better" they think of high perfomance planes like low winged advanced planes, pylon planes and F3A pattern planes, not the ordinary high winged trainer or warbird.
jaka is offline  
Reply With Quote
Old 12-15-2017, 07:57 AM
  #11  
speedracerntrixie
My Feedback: (29)
 
speedracerntrixie's Avatar
 
Join Date: Jun 2010
Location: Sacramento, CA
Posts: 6,736
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I've been using 3 blade props on IMAC and pattern airplanes for years. They are gaining popularity in pattern.
Attached Thumbnails Click image for larger version

Name:	IMG_2602.JPG
Views:	16
Size:	1.93 MB
ID:	2247728   Click image for larger version

Name:	IMG_3428.JPG
Views:	16
Size:	1.73 MB
ID:	2247729  
speedracerntrixie is offline  
Reply With Quote
Old 12-15-2017, 05:54 PM
  #12  
kenh3497
 
kenh3497's Avatar
 
Join Date: Jan 2010
Location: Rockwell, IA
Posts: 1,497
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Originally Posted by speedracerntrixie View Post
I've been using 3 blade props on IMAC and pattern airplanes for years. They are gaining popularity in pattern.
I've heard the three blade prop being referred to as "the poor mans contra" . I think the reference is to the extra drag produced by the third blade helping to slow down lines

Ken.
kenh3497 is offline  
Reply With Quote
Old 12-16-2017, 08:38 AM
  #13  
speedracerntrixie
My Feedback: (29)
 
speedracerntrixie's Avatar
 
Join Date: Jun 2010
Location: Sacramento, CA
Posts: 6,736
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

Yes, a 3 blade along with the ESC brake can really slow the airplane down. Thinking about that a bit more, I think I have too much brake set and my downlines could be a tad too slow however it's nice to have a fair amount of brake to help slow down for landings. Maybe the next generation ESCs should have Brake rates switchable at the TX.
speedracerntrixie is offline  
Reply With Quote
Old 12-16-2017, 05:20 PM
  #14  
Stick 40
 
Join Date: Jun 2003
Location: quincy, MI
Posts: 1,205
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default

I have used three blade props for many years and have had good luck. But not all three blade props are the best.

I picked up a FMS P51 elect that used a 4 cell and came with a 4 blade prop. I toyed with others, 2 or 3 blade and different sizes, but the four blade pulled it around very well and better than any other prop I tried.

sticksl
Stick 40 is offline  
Reply With Quote

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