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Props and engine mount

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captainron1(at)cox.net
Guest

Posted: Tue Mar 27, 2007 6:13 pm Post subject: Props and engine mount

for all the senior Kolbers here is a question. I am about to weld in place the engine mount. I have now the option of lowering the mount a bit to reduce thrust line. I have done some measuring and it looks like I can reduce it some with a 2 inch prop clearance from the tail boom and have a max size of a 68 inch prop. I figure that at best the rubber mount would flex .5 inch which would still give me ample clearance, from the boom. Or I could of course go to a 3 inch clearance from the boom and raise the mount an inch. 

I guess the best question to ask is what is the minimum prop I can use and still be on par with the best performance. I know there are some more variables I can throw into this. But some ideas from which I can work will be real good. 

The next item is the angle of the mount. I am following the original mount bed angle on the assumption that Dennis Souder got it right when he figured it. Any opinions about that, shell I change it and if so why?

John H what prop size and kind are you using?

Anyone using a 4 blade?

Richard Pike

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

Posted: Tue Mar 27, 2007 6:21 pm Post subject: Props and engine mount

What engine and reduction ratio?

Richard Pike

MKIII N420P (420ldpoops)

do not archive



---

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

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

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Mar 27, 2007 6:32 pm Post subject: Props and engine mount

| John H what prop size and kind are you using?

| Anyone using a 4 blade?  Ron Mason

Ron:



I am a Warp Drive man.  Been using strickly Warp Drive since September 

1993.



I have used 70 and 72 inch three blade props.  Both work well.  The 6 

ft prop is a little noiser than the 70" prop.



I like to keep the thrust line as low as possible.  The 72" prop had 

3/4" tail boom clearance.  Close proximity to tail boom and other 

structure may increase the noise level.



I have a 70" prop waiting to be mounted on the new 912ULS.



I see no reason to change the design and attitude of the standard Kolb 

engine mount.  I think Homer Kolb knew what he was doing a lot better 

than most of us.



As far as what prop to use for your Geo engine and redrive, I have no 

idea.



john h

mkIII



PS:  John W uses a 68" 3 blade Warp Drive on his Kolbra.

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

captainron1(at)cox.net
Guest

Posted: Tue Mar 27, 2007 11:23 pm Post subject: Props and engine mount

"This gearbox was designed for aviation conversion of engines up to 160 h.p. It is in production since 2000. The available reduction ratios are 2.03, 2.34, 2.5. There is a German (BMW) rubber damper between the gear box and the engine. The propeller moment of inertia up to 9,000 kg/cm2. Rotax-style propeller hub, propeller shaft with a hole so it can be used with variable pitch prop or for glider towing. It is possible to use this gearbox for both (tractor and pusher) layouts, install it up, down and any degrees left or right. "



The motor is a 105-110 hp Suzuki. The above is a quote from the vendor's web site.



Ron (Arizona)

================================

---- Richard Pike <richard(at)bcchapel.org> wrote:



=============




What engine and reduction ratio?

Richard Pike

MKIII N420P (420ldpoops)

do not archive



---

biglar

Joined: 14 Jan 2006
Posts: 457

Posted: Wed Mar 28, 2007 2:58 am Post subject: Props and engine mount

I'd be interested in more info about the redrive, Ron.  Who's the manufacturer, and what's his website ??                 Thanks                    Lar.



 On 3/28/07, Ron <captainron1(at)cox.net (captainron1(at)cox.net)> wrote: [quote]--> Kolb-List message posted by: Ron <captainron1(at)cox.net (captainron1(at)cox.net)> 



"This gearbox was designed for aviation conversion of engines up to 160 h.p. It is in production since 2000. The available reduction ratios are 2.03, 2.34, 2.5. There is a German (BMW) rubber damper between the gear box and the engine. The propeller moment of inertia up to 9,000 kg/cm2. Rotax-style propeller hub, propeller shaft with a hole so it can be used with variable pitch prop or for glider towing. It is possible to use this gearbox for both (tractor and pusher) layouts, install it up, down and any degrees left or right. " 



The motor is a 105-110 hp Suzuki. The above is a quote from the vendor's web site.



Ron (Arizona)

================================

---- Richard Pike < richard(at)bcchapel.org (richard(at)bcchapel.org)> wrote:



=============

--> Kolb-List message posted by: "Richard Pike" <richard(at)bcchapel.org (richard(at)bcchapel.org)>



What engine and reduction ratio? 

Richard Pike

MKIII N420P (420ldpoops)

do not archive

[b]

_________________
Larry Bourne
Palm Springs, CA
Building Kolb Mk IIIC
"Vamoose"

MKIIIX040

Joined: 31 Mar 2006
Posts: 123
Location: Millinocket, Maine

Posted: Wed Mar 28, 2007 6:16 am Post subject: Props and engine mount

Anyone,

 I always wondered why the plans called for 3 washers in  the back and 2 in front for the 912 mount. Why not 2 in rear and 1 in  front? 

 Can 1/16" make that much difference anyway? 

  

 John , I thought you were running a 74''  Warp.

  

  Vic

 912 UL Extra

 Maine

 do not archive



   [quote][b]

_________________
MKIIIX040
912UL

NeilsenRM(at)comcast.net
Guest

Posted: Wed Mar 28, 2007 6:30 am Post subject: Props and engine mount

Ron



I don't know about that senior thing but.... I built my VW mount with two 

inch clearance for a 72 inch prop. I also set the thrust line just slightly 

up from being even with the bottom of the wing. I figured the wing would fly 

with just a bit of up angle of attack.



My assumption is that the most efficient thrust angle would be straight back 

at cruise. A thrust line pushing the plane down would not be good and having 

the thrust line lifting the plane would not be as efficient as lift from the 

wing.



Rick Neilsen

Redrive VW powered MKIIIc



---

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Mar 28, 2007 6:39 am Post subject: Props and engine mount

Can 1/16" make that much difference anyway?



John , I thought you were running a 74'' Warp.



Vic

Vic:



1/16" will not make any difference.



I discovered many years ago the amount of engine movement with a 447 

powered Firestar.  Was amazed at how much the engine tilted under full 

power.



I experimented with different angles of mounting the engine on the 

mkIII and came to the conclusion I was wasting my time.  Now I fly 

with the engine as low as possible and in the standard configuration 

with the hardest Lord mounts available.  Travis sends these hard Lord 

mounts with the mkIII kits.



72" is largest prop I have flown with.



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

by0ung(at)brigham.net
Guest

Posted: Wed Mar 28, 2007 6:57 am Post subject: Props and engine mount

for all the senior Kolbers here is a question. I am about to weld in place

the engine mount. I have now the option of lowering the mount a bit to

reduce thrust line.



Ron



I guess it depends on what engine you will be using,,,  what altitude you

will be flying at most,,,  and what properties  you want your plane to have.



When I called warp drive and asked for my application.  I was told 68 inch 3

blade full width tips. Darrell at warp drive told me that the full width

tips were best suited for sea plane and / or high altitude applications.

I have a mark III with a 912 80 hp.  field elevation is 4426 ft and density

altitudes in the summer of 6000 + or -  and to fly over the mountains I go

to 8000 ft msl on a regular basis.

John H  has the 912s  100 hp version. And uses a 72 inch taper tip blade.

Which warp drive told me was best suited for his plane and application.



In short, I think I would call Darrell at Warp Drive,  explain your

situation,  and ask for his advice. I don't think he would steer you wrong.



As for tip boom clearance,,, I think 1 1/2 to 2 inch should be ok it seems

that some are using on inch or so.   The biggest problem would be involved

in how much shake the engine has during start up and shutdown.  



Boyd

captainron1(at)cox.net
Guest

Posted: Wed Mar 28, 2007 11:21 am Post subject: Props and engine mount

I think I want to stay with the 2 inch clearance that is mandated for          standard airworthiness aircraft. It specifies a 2 inch clearance as a          minimum. I suppose with super rigid mounts less would be safe, but I          am not sure vibration was the only reason for the clearance. I've          wanted a 4 blade prop for some time, I think it probably gives better          thrust effect (I don't want to start up the old debate of how many          blades are better). I mostly want to do it for my own gratification          and to validate my theory. That is why I figure a 68" would be fine.          But if it does not work out I certainly want the option of going to a          larger diameter prop. I think JH probably experimented with most of          that stuff, but I would want to know if there was any side by side          comparisons. I think that lowering back drag from the rear engine          mount supports and prop eficiency all else equal may give the best          return on effort spent.              

         I will call the fellow at Warp Drive and see what he has to say.              

         Ron (Arizona)              

                       

                       

         

         ---- boyd <by0ung(at)brigham.net> wrote:



=============

-->          Kolb-List message posted by: "boyd" <by0ung(at)brigham.net>

for          all the senior Kolbers here is a question. I am about to weld in place

the          engine mount. I have now the option of lowering the mount a bit to

reduce          thrust line.



Ron



I guess it depends on what engine you          will be using,,, what altitude you

will be flying at most,,, and          what properties you want your plane to have.



When I called warp          drive and asked for my application. I was told 68 inch 3

blade full          width tips. Darrell at warp drive told me that the full width

tips          were best suited for sea plane and / or high altitude applications.

I          have a mark III with a 912 80 hp. field elevation is 4426 ft and          density

altitudes in the summer of 6000 + or - and to fly over the          mountains I go

to 8000 ft msl on a regular basis.

John H          has the 912s 100 hp version. And uses a 72 inch taper tip blade.

Which          warp drive told me was best suited for his plane and application.



In          short, I think I would call Darrell at Warp Drive, explain your

situation,          and ask for his advice. I don't think he would steer you wrong.



As          for tip boom clearance,,, I think 1 1/2 to 2 inch should be ok it seems

that          some are using on inch or so. The biggest problem would be involved

in             

      [quote][b]

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Wed Mar 28, 2007 1:40 pm Post subject: Re: Props and engine mount

Why would anyone want a 4 blade prop on a Kolb ?  The climb would be horrible.   With a 4 blade prop, you have less area producing a faster airstream, so IF you had a plane with a high top speed, 4 blades would make it faster.   



A Kolb is so slow, that you would never see any advantage of the higher velocity from the prop.   Its kind of like putting a small jet engine on a Kolb, you would have a huge amount of air velocity out of the enigne, but not that much thrust in pounds..   All that HP with a low static thrust would be wasted on a slow and draggy plane.



With a 4 bladed prop, you will be lucky if you dont lose so much thrust that the plane not only climbs horribly, but will be acutally slower than the 3 bladed prop.   It looks like you have been looking at to many fast GA airplanes with 4 bladed prop, and not understanding that it just wont work well on a Kolb.     But Im all for having real life testing over theory, as long as its someone else paying for the testing      I look foward to seeing the results.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

captainron1(at)cox.net
Guest

Posted: Wed Mar 28, 2007 6:34 pm Post subject: Props and engine mount

         If I ever wanted proof that I never get what I want here it is. I did          not want a debate about props. But I must say and I will not explain          as I am holding out for consultation fees, that a 4 blader will be          better especially in climb and throughout the range.              

         We shall see stay tuned, mmm unless I run out of money first. I will          borrow a 3 blader from whoever, whenever install it on my flyer and          will do both time to climb and cruise. That is the only way to do it.          Maybe next year at Monument V we can test it.              

                       

         ,Ron (Arizona)              

         ========================================

---- JetPilot          <orcabonita(at)hotmail.com> wrote:



=============

-->          Kolb-List message posted by: "JetPilot" <orcabonita(at)hotmail.com>



Why          would anyone want a 4 blade prop on a Kolb ? The climb would be          horrible. With a 4 blade prop, you have less area producing a faster          airstream, so IF you had a plane with a high top speed, 4 blades would          make it faster.



A Kolb is so slow, that you would never see any          advantage of the higher velocity from the prop. Its kind of like          putting a small jet engine on a Kolb, you would have a huge amount of          air velocity out of the enigne, but not that much thrust in pounds..          All that HP with a low static thrust would be wasted on a slow and          draggy plane.



With a 4 bladed prop, you will be lucky if you          dont lose so much thrust that the plane not only climbs horribly, but          will be acutally slower than the 3 bladed prop. It looks like you have          been looking at to many fast GA airplanes with 4 bladed prop, and not          understanding that it just wont work well on a Kolb. But Im all for          having real life testing over theory, as long as its someone else          paying for the testing  I look foward to seeing the results.



Mike



--------

&quot;NO          FEAR&quot; - If you have no fear you did not go as fast as you could             

      [quote][b]

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Thu Mar 29, 2007 8:43 am Post subject: Re: Props and engine mount

 	  captainron1(at)cox.net wrote: 	
		           If I ever wanted proof that I never get what I want here it is. I did          not want a debate about props. 	




Hahaha,



That was just an irresistable subject      I just bought a 3 blade warp to replace my 3 blade Kiev, so that 4 blade had better not perform better !  What engine do you have, and are you going to get the Warp Drive 4 blade ?



I went to the war drive, because the Kiev is so light is scares me to use it.  On a pusher if anything goes through it from the engine, it will explode into a million peices.   I also had an airline inspector look at it ( he also flys ultralights ) and he was worried about how light the hub was, and if it would hold up over time.    I think a Kiev would be perfect for a 2 stroke engine, but I just dont trust it on a 912 - S.



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

Richard Pike

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

Posted: Thu Mar 29, 2007 9:08 am Post subject: Props and engine mount

I borrowed a 3 blade Kiev from a friend, size and shape optimized for an 

HKS, 2 seat CGS Hawk, and mounted it on the Kolb with 582, B box, similar 

reduction ratio. Compared against a 68" two blade Ivo, the Ivo gave better 

results. Details in the archives.

Richard Pike

MKIII N420P (420ldPoops)



---

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

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

jb92563

Joined: 23 Mar 2007
Posts: 314
Location: Southern California

Posted: Thu Mar 29, 2007 10:07 am Post subject: Re: Props and engine mount

Knowing a fair bit about props I though that  i would mention that

more blades increase the thrust but reduce the top end.



So if you want more low end thrust as in a climb optimized prop then go for the extra blade, but if you are lacking top end speed the the 4th blade will slow you even more than the 3 blade.



Ray

_________________
Ray

Kolb UltraStar (Cuyuna UL-202)
Moni MotorGlider
Schreder HP-11 Glider
Grob 109 Motorglider

Do Not Archive

captainron1(at)cox.net
Guest

Posted: Thu Mar 29, 2007 10:12 am Post subject: Props and engine mount

I was looking at that wood prop in 4 blades, I forget the name          Kentucky props or something like that. Seemed fairly reasonable price          wise for a starter prop.              

         Ron (Arizona)              

         ========================================

---- JetPilot          <orcabonita(at)hotmail.com> wrote:



=============

-->          Kolb-List message posted by: "JetPilot" <orcabonita(at)hotmail.com>

 captainron1(at)cox.net wrote:

 	  Quote: 	
		  If I ever wanted proof that I never get what          I want here it is. I did not want a debate about props.


	




         Hahaha,



That was just an irresistable subject  I just bought          a 3 blade warp to replace my 3 blade Kiev, so that 4 blade had better          not perform better ! What engine do you have, and are you going to get          the Warp Drive 4 blade ?



I went to the war drive, because the          Kiev is so light is scares me to use it. On a pusher if anything goes          through it from the engine, it will explode into a million peices. I          also had an airline inspector look at it ( he also flys ultralights )          and he was worried about how light the hub was, and if it would hold          up over time. I think a Kiev would be perfect for a 2 stroke engine,          but I just dont trust it on a 912 - S.



Mike



--------

         &quot;NO FEAR&quot; - If you have no fear you did not go as fast as          you could have !!!





Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=103682#103682



         http://www.matronics.com/Navigator?Kolb-List

 --

kugelair.com

            

      [quote][b]

HShack(at)aol.com
Guest

Posted: Thu Mar 29, 2007 7:25 pm Post subject: Props and engine mount

In a message dated 3/29/2007 12:46:02 PM Eastern Daylight Time, orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  I think a Kiev would be perfect for a 2 stroke engine, but I just dont trust it on a 912 - S. 	


  

 Robert Broadwell of the Trenton Flyers has a 3 blade Kiev on a Mk III with 912S; no problems in approx. 300 hrs. & over 900 water landings, shows no wear.

  

 I have one on my FSII; it replaced a Warp 3 blade.  It's quieter than the Warp, I like the scimitar shape & the bronze leading edge.  I think it is much easier on the gearbox.

  

 To each his own.....



  

 Howard Shackleford

FS II

SC



See what's free at AOL.com. 

  [quote][b]

JetPilot

Joined: 10 Jan 2006
Posts: 1246

Posted: Fri Mar 30, 2007 4:28 am Post subject: Re: Props and engine mount

 	  HShack(at)aol.com wrote: 	
		  



I have one on my FSII; it replaced a Warp 3 blade.  It's quieter than the Warp, I like the scimitar shape & the bronze leading edge.  I think it is much easier on the gearbox.

  

 Howard Shackleford

FS II

SC



	




What kind of engine do you have on your FS II ?   Did you notice any differences in the performance between the Warp and the Kiev ?



Mike

_________________
"NO FEAR" - If you have no fear you did not go as fast as you could have !!!

Kolb MK-III Xtra, 912-S

HShack(at)aol.com
Guest

Posted: Sun Apr 01, 2007 5:55 pm Post subject: Props and engine mount

In a message dated 3/30/2007 8:29:58 AM Eastern Daylight Time, orcabonita(at)hotmail.com writes:

  	  Quote: 	
		  What kind of engine do you have on your FS II ?   Did you notice any differences in the performance between the Warp and the Kiev ? 	


  

 I have a 503DCDI.  I expected better performance because it "looks" like a more efficient shape, but no performance increase.  Lighter, quieter, better looking.



  

 Howard Shackleford

FS II

SC



See what's free at AOL.com. 

  [quote][b]

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