Canard Community Forum  

Go Back   Canard Community Forum > Firewall Backward and Forward > Propellors
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #16  
Old 03-21-2005, 02:58 PM
leeschaumberg leeschaumberg is offline
Used to know everything
 
Join Date: Mar 2005
Location: Eagle River , Wi
Posts: 7
Smile 2 versus 3 blade props

Two blade props are more eficient than three blade props. One blade props are more eficient than two blade props. Imagine what a one blade prop sounds like. Balance is very important with any propeller. Because a prop is basicly repetitions of airfoils. Each airfoil causes drag. When some one says a 3 blade prop flys better it means the prop maker did a better job on the 3 blade. (Period) Sorry this means a turbine with no prop is better. Wrong A turbine has multple props with many blades.
Lee


________________________________________________


I'm between a rock and a hard spot
Reply With Quote
  #17  
Old 03-21-2005, 03:02 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

Read about a guy that made a 1 blader for his 150 or something - had a ball with everyone starin at it
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #18  
Old 03-21-2005, 03:16 PM
leeschaumberg leeschaumberg is offline
Used to know everything
 
Join Date: Mar 2005
Location: Eagle River , Wi
Posts: 7
Default Props

Dust
Neet a one blade prop! Thats something I don't have. By the way (eich kanicht sara gut duetsch sprekin) (no parla vou francai) and (no habla espanol) just english!
Lee


__________________________________________

Smile your on the spot
Reply With Quote
  #19  
Old 03-21-2005, 03:44 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Consider some of the highest performance prop-driven aircraft ever created, WWII aircraft. Why did they all have multi-blades? Was it just a style? Was it just a fad? I make no claims about what performs better, I don't know.
Reply With Quote
  #20  
Old 03-21-2005, 03:49 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

those are BIG props and the limiting factor on a prop is tip speed, i think the number is .92 mach.

if you go less number of blades you usually go to a bigger prop, or so i have seen, well being that big, they were probably at the prop tip speed limit and to go bigger meant slowing down the engine and losing HP

just a guess
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #21  
Old 03-21-2005, 04:19 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Quote:
Originally Posted by Dust
if you go less number of blades you usually go to a bigger prop, or so i have seen, well being that big, they were probably at the prop tip speed limit and to go bigger meant slowing down the engine and losing HP, just a guess
You had me going 'oh yeah' after the first sentence. But then I caught myself. We know changing prop lengths has an effect. But when it's claimed that adding blades does nothing, I assumed they were also saying 'for a given prop diameter'. If so, adding blades to BIG props that are near the max tip speed doesn't buy you anything, per the claim. Still doesn't add up to me. Whatever.
Reply With Quote
  #22  
Old 03-21-2005, 04:24 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

but TNT - you have to understand the forum, some here will not answer a question, only correct a bad answer, so ifin you want an answer - answer it wrong and a correction will be seen shortly
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #23  
Old 03-21-2005, 05:02 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Quote:
Originally Posted by Dust
but TNT - you have to understand the forum, some here will not answer a question, only correct a bad answer, so ifin you want an answer - answer it wrong and a correction will be seen shortly
I agree that disagreements power continued discussion. So I must correct you. When I ended my post with 'Whatever', it was to indicate that I really don't have much more to say and wasn't expecting anybody to comment on the post. And then you step in and tell me I don't know how to post.
Reply With Quote
  #24  
Old 03-21-2005, 05:06 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default

TNT - just makin a funny and sorta jibin those that withhold info until a correction is needed - ya know - just a little forum humor - and - you are a great poster
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #25  
Old 03-21-2005, 05:14 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Dust, I don't like compliments. Back off!
Reply With Quote
  #26  
Old 03-21-2005, 05:17 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

two vs three blades
Reply With Quote
  #27  
Old 03-21-2005, 05:31 PM
Waiter's Avatar
Waiter Waiter is offline
LongEZ-RG
 
Join Date: Dec 2004
Location: Northwestern Ohio
Posts: 1,096
Default

Tis better to be silent and be thought a fool, then to open my mouth and remove all doubt.

Waiter
Reply With Quote
  #28  
Old 03-21-2005, 05:35 PM
tnt's Avatar
tnt tnt is offline
Member
 
Join Date: Apr 2004
Location: Denver Colorado
Posts: 1,202
Default

Yes, I'm different. Oh sorry, I thought you were talking about me.

Yes I know you were joking around Dust, and of course you know I was throwing some back at you.

two blades vs 3 blades

Last edited by tnt : 03-21-2005 at 07:01 PM.
Reply With Quote
  #29  
Old 03-22-2005, 12:07 AM
David Staten's Avatar
David Staten David Staten is offline
Rotary Powered Velocity
 
Join Date: Jul 2004
Location: KEFD, Houston Area, Texas
Posts: 441
Default It was all about the POWER...

Quote:
Originally Posted by tnt
Consider some of the highest performance prop-driven aircraft ever created, WWII aircraft. Why did they all have multi-blades? Was it just a style? Was it just a fad? I make no claims about what performs better, I don't know.
There is a finite limit that can be absorbed by a propeller blade in a given configuration (area, length, RPM, Airspeed etc..)... if you can't absorb the developed power effectively with fewer blades, then you have to use more.. the benefits of translating this power to thrust offset the disadvantage of having the blades travel a little in each other's disturbed air.

Given that some of these piston warbirds developed over 1000 hp, its no surprise that the props were multibladed and paddle shaped.. look at the P47 and Corsair for examples.. lots of blade area and 4 blades...

Dave
Reply With Quote
  #30  
Old 04-06-2005, 10:54 AM
snappy snappy is offline
Member
 
Join Date: Mar 2005
Location: Klamath Falls, OR
Posts: 3
Default

Shaping a prop is a combination of science and art. I have cut several for lower powered ultralights and they all worked, just some better than others. If you are serious about carving your own, I would suggest starting with something small and easy. Maybe a wall clock?? And there are books on the subject, check out the EAA library and you will be able to go as deep as you want to go. Get ready for some trig.

Good luck,
Snappy
Long Ez 988AB
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump


All times are GMT -4. The time now is 09:37 PM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.