Matronics Email Lists :: View topic

Matronics Email Lists
Web Forum Interface to the Matronics Email Lists

Get Email Distribution Too! FAQ Search Memberlist Usergroups Register

Profile Log in to check your private messages Log in

FireFly prop

Matronics Email Lists Forum Index -> Kolb-List

View previous topic :: View next topic

Author Message

DAquaNut(at)aol.com
Guest

Posted: Sun May 13, 2007 2:08 pm Post subject: FireFly prop

Fireflyers, 

 

    Anyone out there flying with a 2-blade 64" prop. Seems my Ivo has cratered and it is only about 30% more for a whole new prop than a single replacement blade. Is anyone flying a warp drive on a 447 W/ b box. I am intertaining that thought as John H has had good luck with his. Does the Warp flex more than the Ivo? Is it too heavy for the b box . Any Thoughts? 

 

            Ed Diebel  

**************************************

 See what's free at http://www.aol.com.  [quote][b]

Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Sun May 13, 2007 2:38 pm Post subject: FireFly prop

Do not know the weight of that prop, but I think a 64" 2 blade Warp ought  to be safe with a B box, but I would use Mobil One synthetic or equivilent  and change it often. I put a Warp 66" 2 blade on a used B box, total time  unknown, and it ended up making metal. But since total time was unknown,  that proves nothing. The Warp does not flex like an Ivo. Nothing flexes like an  Ivo...

  

 Richard Pike

 MKIII N420P (420ldPoops)

  

 [quote]   ---

_________________
Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

HShack(at)aol.com
Guest

Posted: Sun May 13, 2007 3:16 pm Post subject: FireFly prop

In a message dated 5/13/2007 6:09:27 PM Eastern Daylight Time, DAquaNut(at)aol.com writes:

  	  Quote: 	
		  Does the Warp flex more than the Ivo? Is it too heavy for the b box . Any Thoughts? 	


 The Warp does not flex hardly at all, but it's way too heavy for the b box.



  

 Howard Shackleford

FS II

SC



See what's free at AOL.com. 

  [quote][b]

Snoopy Baxley

Joined: 09 Jan 2006
Posts: 42

Posted: Mon May 14, 2007 7:30 pm Post subject: FireFly prop

Hey Ed

 I fly with a 3 bladed 64 " Warp Drive Prop on a 447 with a 'B" box . 

 It performs very well on  my Firefly . Got 142 hours on the Prop .

 A friend of mine has an 2-bladed 64 "Ivo on his GT400  which seems to have more flex to it and of course is a lighter prop . He can out climb me but I'm much faster than he is .

  

 Stephen

 Firefly

 S.W. Georgia

  

 Do Not Archive

  



See what's free at AOL.com. 

  [quote][b]

jimhefner

Joined: 11 Jan 2006
Posts: 91
Location: Tucson, AZ

Posted: Tue May 15, 2007 5:35 am Post subject: Re: FireFly prop

A 3 blade prop should out climb a 2 blade prop when everything is apples - apples.... different props and configs on different type aircraft don't tell you much conclusive about the props.  Comparing a Firefly climb and cruise to a GT400 is apples and molasses...   Sorry, I couldn't resist.... no offense intended!

_________________
Jim Hefner
Tucson, AZ
Do Not Archive

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Tue May 15, 2007 7:53 am Post subject: FireFly prop

But a two blade prop will out perform a three blade every time when  

everything is optimized, especially prop diameter and prop speed.

On May 15, 2007, at 9:35 AM, jimhefner wrote:



 	  Quote: 	
		   



 A 3 blade prop should out climb a 2 blade prop when everything is  

 apples - apples.... different props and configs on different type  

 aircraft don't tell you much conclusive about the props.  Comparing  

 a Firefly climb and cruise to a GT400 is apples and molasses...    

 Sorry, I couldn't resist.... no offense intended!



 --------

 Jim Hefner

 Kolbless in Tucson  

 Do Not Archive





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=112922#112922

jimhefner

Joined: 11 Jan 2006
Posts: 91
Location: Tucson, AZ

Posted: Tue May 15, 2007 9:20 am Post subject: Re: FireFly prop

Eugene said:  But a two blade prop will out perform a three blade every time when everything is optimized, especially prop diameter and prop speed.



Eugene, you might be right, but according to my limited research back in the early days of my Firefly, a 3 blade prop, also optimized on length and pitch will out climb a 2 blade (more bite), but a 2 blade wins on all other scores, including cruise (less drag).  I had a 2 blade IVO on a 4" extender on the 447 and was very happy with it's performance, including climb, but I didn't care to climb at 1100'/min either.

_________________
Jim Hefner
Tucson, AZ
Do Not Archive

ElleryWeld(at)aol.com
Guest

Posted: Tue May 15, 2007 9:44 am Post subject: FireFly prop

This is just my experience with props but I have better climb rate with a two blade prop eventhough the three blade runs with less vibration and in more than one case  I have found the same results but this might change if you have more power than I have  in the 447 Rotax

 

 Ellery in Maine 

 

 do not archive

**************************************

 See what's free at http://www.aol.com.  [quote][b]

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Tue May 15, 2007 2:35 pm Post subject: FireFly prop

Jim, I'll  agree a three blade may be "better" it you factor in  

personal preference.  ;^)



On May 15, 2007, at 1:20 PM, jimhefner wrote:



 	  Quote: 	
		    I had a 2 blade IVO on a 4" extender on the 447 and was very happy  

 with it's performance, including climb, but I didn't care to climb  

 at 1100'/min either.

d-m-hague(at)comcast.net
Guest

Posted: Tue May 15, 2007 6:58 pm Post subject: FireFly prop

The problem with comparing two and three blade props is that you're always 

comparing apples with oranges.  All things being equal, the two blade prop 

should be the better performer... but things are never equal.  I'm not that 

familiar with the Firefly, so I'm speaking in general terms:



The fewer blades, the more efficient.  Yes, a ONE blade prop is most 

efficient... but the weight penalty for the counterweight and a crankshaft 

strong enough to handle the asymmetric loading probably negates the 

advantages.  One bladed props have been used successfully on racing model 

airplanes, though.  The faster the prop is turning, and the smaller the 

prop, the bigger the advantage to fewer blades (which is why they work well 

on a model engine turning a tiny prop at 20,000+ rpm!)



The only reason to use more than two blades is if the two bladed prop can't 

efficiently absorb the engine's power in the space available.  Typically 

this is due to ground clearance issues (or tail boom clearance in the case 

of a Kolb).



Regardless of the number of blades, any prop will be most efficient if the 

blade pitch is set so that each point on the prop is acting at the maximum 

L/D.  This usually involves a compromise (unless you have an adjustable 

prop) since you want the prop to perform well both during climb as well as 

cruise.  A flatter pitch is better for climb and vice versa.  Generally you 

optimize it for some speed between climb and cruise.



Now, what if your engine produces more power than the prop can handle?  It 

overspeeds, so you increase the pitch somewhat, effectively you now have 

more of a "cruise prop" than a "climb prop".  Since you're off the best L/D 

point, it's less efficient.  However, you can also absorb more power by 

adding blade area: making the blades wider, or adding blades (or both... 

look at the huge paddles on a T-2.  With more blade area you don't have 

to add pitch to prevent overspeeding, so you're still in the better L/D 

area, or you're back in the "climb prop" area... which explains why the 3 

blade props may perform better on takeoff and climb, at the expense of cruise.



				-Dana

--

--

Okay, who put a "stop payment" on my reality check?

Display posts from previous:

	Matronics Email Lists Forum Index -> Kolb-List	All times are GMT - 8 Hours
Page 1 of 1

Jump to:

You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum