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3.47:1 gear box

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Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Wed Nov 25, 2020 3:39 pm Post subject: 3.47:1 gear box

My trusty old 582 is due for a full rebuild, and as part of the rebuild I have been thinking of either trying to milk a couple more horsepower out of it via some old 2-stroke polishing techniques, or maybe getting one of Rotax Rick's engines.

Either way, I will need either a C or an E gearbox. I have an opportunity to get an E box for a good price, but it is 3.47:1 ratio. 

I am in over my head. 

I flew a friends MKIII several years ago with a 582 and that ratio, but I don't remember what prop he had, how many blades, prop length, etc.

The gearbox is off a PPG/Trike rig and comes with a beat up 3 blade Warp Drive prop, blades will probably need replacing.

Seems I remember hearing years ago that either the Ivo or the Warp does not like turning slow with a LOT of pitch.

Anybody on the list using that ratio, and if so, what prop are you using and how do you like it?

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

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

George Alexander

Joined: 10 Jan 2006
Posts: 245
Location: SW Florida

Posted: Wed Nov 25, 2020 5:19 pm Post subject: Re: 3.47:1 gear box

 	  Richard Pike wrote: 	
		  

..S..N..I..P..



Anybody on the list using that ratio, and if so, what prop are you using and how do you like it? 	




Richard:  

May not be a good comparison, but for what it is worth, pushing my R503, DCDI, dual carb, I have a 'C' Box with the 3.47 ratio, driven by a Powerfin 3 Blade, F Model, 68".

Have no complaints with this set up.

_________________
George Alexander
FS II R503
E-LSA N709FS
http://www.oh2fly.net

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Wed Nov 25, 2020 8:20 pm Post subject: Re: 3.47:1 gear box

Thanks George, I am hoping that someone with a 3.47:1 reduction and a 68" three blade prop on a 582 will chime in.

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

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

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Thu Nov 26, 2020 7:16 am Post subject: Re: 3.47:1 gear box

Richard,



I’m presently using a 4/1 ration E box on my Mark 3 with a 70” three blade IVO medium prop.

My engine is a 670 rotax engine which I derated by lowering the compression ratio. 

The advantage of the deeper ratio is less prop noise from a slower turning prop. [/b]

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Thu Nov 26, 2020 7:34 am Post subject: 3.47:1 gear box

Richard, The 582 on my MkIII runs through a "C" gearbox at 4.00:1.  WOT gets me only 1500 prop rpm.  I have the 3.47:1 gearbox on my HKS.  I had a MkIIIX with an "E" gearbox with the conventional 2.62:1 gears.  As I was swapping around props I was surprised to find that the difference in pitch going from the 4:1 to the 2.62 was only .2 degrees of pitch.  I couldn't find that either ratio of gearbox worked better than another except in the category of noise.  Swinging a large dia. prop at low rpm's makes for a noticeably quieter aircraft.



Rick

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On Wed, Nov 25, 2020 at 5:42 PM Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:



 	  Quote: 	
		  --> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

 

 My trusty old 582 is due for a full rebuild, and as part of the rebuild I have been thinking of either trying to milk a couple more horsepower out of it via some old 2-stroke polishing techniques, or maybe getting one of Rotax Rick's engines.

 Either way, I will need either a C or an E gearbox. I have an opportunity to get an E box for a good price, but it is 3.47:1 ratio. 

 I am in over my head. 

 I flew a friends MKIII several years ago with a 582 and that ratio, but I don't remember what prop he had, how many blades, prop length, etc.

 The gearbox is off a PPG/Trike rig and comes with a beat up 3 blade Warp Drive prop, blades will probably need replacing.

 Seems I remember hearing years ago that either the Ivo or the Warp does not like turning slow with a LOT of pitch.

 Anybody on the list using that ratio, and if so, what prop are you using and how do you like it?

 

 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kolb Firefly Part 103 legal 

 Kingsport, TN 3TN0

 

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

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=499526#499526

 

 

 

 

 

 

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_________________
The smallest miracle right in front of you is enough to make you happy....

neilsenrm(at)gmail.com
Guest

Posted: Thu Nov 26, 2020 10:07 am Post subject: 3.47:1 gear box

Rick/All

I had a direct drive VW on my MKIIIC that had very poor performance. Switching to a reduction drive with a 1.6 to 1 reduction with a longer prop I got a considerable performance boost. Yes it got a lot quieter also. Consider that it takes HP to make noise. You may not be able to measure the difference in performance but It should be there somewhere. You also get more thrust accelerating a lot more air slowly than less air faster. Between the two my plane climbs faster, has a faster cruise, on less power with lower fuel consumption, lower oil and CHT temps. 

A bigger part of the equation might be prop diameter. I went from a two blade 66 to a 72" three blade. 

As usual, worth what you paid for it.

Rick Neilsen

Redrive VW Powered MKIIIC

On Thu, Nov 26, 2020 at 10:36 AM Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:



 	  Quote: 	
		  Richard, The 582 on my MkIII runs through a "C" gearbox at 4.00:1.  WOT gets me only 1500 prop rpm.  I have the 3.47:1 gearbox on my HKS.  I had a MkIIIX with an "E" gearbox with the conventional 2.62:1 gears.  As I was swapping around props I was surprised to find that the difference in pitch going from the 4:1 to the 2.62 was only .2 degrees of pitch.  I couldn't find that either ratio of gearbox worked better than another except in the category of noise.  Swinging a large dia. prop at low rpm's makes for a noticeably quieter aircraft.



Rick

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On Wed, Nov 25, 2020 at 5:42 PM Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:



 	  Quote: 	
		  --> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

 

 My trusty old 582 is due for a full rebuild, and as part of the rebuild I have been thinking of either trying to milk a couple more horsepower out of it via some old 2-stroke polishing techniques, or maybe getting one of Rotax Rick's engines.

 Either way, I will need either a C or an E gearbox. I have an opportunity to get an E box for a good price, but it is 3.47:1 ratio. 

 I am in over my head. 

 I flew a friends MKIII several years ago with a 582 and that ratio, but I don't remember what prop he had, how many blades, prop length, etc.

 The gearbox is off a PPG/Trike rig and comes with a beat up 3 blade Warp Drive prop, blades will probably need replacing.

 Seems I remember hearing years ago that either the Ivo or the Warp does not like turning slow with a LOT of pitch.

 Anybody on the list using that ratio, and if so, what prop are you using and how do you like it?

 

 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kolb Firefly Part 103 legal 

 Kingsport, TN 3TN0

 

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

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=499526#499526

 

 

 

 

 

 

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Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Thu Nov 26, 2020 7:37 pm Post subject: Re: 3.47:1 gear box

You guys are great, that is just what I needed to know, thanks.

So now it looks like the only real task is fabricating new taller motor mounts to fit the 72" prop?

Anybody want to send some pictures of how you did it?

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

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

jhauck

Joined: 02 Jan 2020
Posts: 25

Posted: Fri Nov 27, 2020 5:00 am Post subject: 3.47:1 gear box

I flew with a 72" WARP  Drive Prop on my 912 powered MKIII.  Had 3/4" prop to tail boom clearance.  Was not a problem.



I personally do not recommend raising the thrust line.  High thrust line in the pusher configuration is a problem to start with.  Increasing thrust line height increases that problem.



Is there a difference between center of thrust of a 912 and 582 on a MKIII?  I flew with both engines on my MKIII, but cannot remember.



john h

Titus, Alabama



--

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Fri Nov 27, 2020 8:42 pm Post subject: Re: 3.47:1 gear box

 	  jhauck wrote: 	
		  I flew with a 72" WARP  Drive Prop on my 912 powered MKIII.  Had 3/4" prop to tail boom clearance.  Was not a problem.



I personally do not recommend raising the thrust line.  High thrust line in the pusher configuration is a problem to start with.  Increasing thrust line height increases that problem.



Is there a difference between center of thrust of a 912 and 582 on a MKIII?  I flew with both engines on my MKIII, but cannot remember.



john h

Titus, Alabama

-- 	




Thanks for checking in John, I was planning to try and contact you tomorrow. 

For a number of years I have been using a 68" prop with 1.5" of clearance between the prop tips and the boom tube. The motor mounts have 1.5" spacers which you can see in two of the pictures here: http://oh2fly.net/oldpoops/pg2.htm



Obviously I do not want to raise the engine any higher, but going from a 68" to a 72", the prop blades are 2" longer and I don't see any way around it.



Just went out and measured both the B box and the E box, and each seems to have 3" between the crank centerline and the hub centerline so that would be a constant.



Open to suggestions - thanks.

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

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

jhauck

Joined: 02 Jan 2020
Posts: 25

Posted: Sat Nov 28, 2020 5:31 am Post subject: 3.47:1 gear box

Must be a difference in prop shaft location on the 582 and 912.



I'm fresh out of ideas right now.



john h 

Titus, Alabama



--

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Sun Nov 29, 2020 6:03 am Post subject: Re: 3.47:1 gear box

I'm good here: Bryan messaged me some pictures on FB and I can raise the engine  enough to have the starter motor clear the motor mounts w/o having any problems. Raising it any higher than that is bad for the thrust line.

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

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

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Tue Dec 01, 2020 9:55 pm Post subject: 3.47:1 gear box

Richard,  Try this, mount the fwd dampers upside (short side up) and the aft dampers as normal.  This will give you another inch and a half or so.



Rick

  	          		Virus-free. www.avg.com 		 	 [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2][/url]



On Thu, Nov 26, 2020 at 9:39 PM Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:



 	  Quote: 	
		  --> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

 

 You guys are great, that is just what I needed to know, thanks.

 So now it looks like the only real task is fabricating new taller motor mounts to fit the 72" prop?

 Anybody want to send some pictures of how you did it?

 

 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kolb Firefly Part 103 legal 

 Kingsport, TN 3TN0

 

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

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=499543#499543

 

 

 

 

 

 

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“Blessed are the cracked, for they shall let in the light.”   Groucho Marx

_________________
The smallest miracle right in front of you is enough to make you happy....

Richard Pike

Joined: 09 Jan 2006
Posts: 1669
Location: Blountville, Tennessee

Posted: Wed Dec 02, 2020 6:30 am Post subject: Re: 3.47:1 gear box

 	  rickofudall wrote: 	
		  Richard,  Try this, mount the fwd dampers upside (short side up) and the aft dampers as normal.  This will give you another inch and a half or so.



Rick	    	




Yeah it would. I am thinking it would also change the thrust line/angle, how would that work?

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

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

rickofudall

Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA

Posted: Wed Dec 02, 2020 6:47 am Post subject: 3.47:1 gear box

I never noticed any effect that wouldn't trim out easily.  It doesn't require any physical change to the aircraft and it's reversible.  Just eight AN-3 bolts and the two AN-6's.

Rick

PS  Trying to fix the need for the huge trim tab on the rudder I made a motor mount plate that turned the engine 5 degrees out of line to the boom C/L.  Didn't make any difference whether I turned the mount over to get that offset to the opposite side.  The only thing I found that did work was the lower prop rpm of the 4:1 gearbox.  My Mk IIIC had a rudder trim tab that was only 6 inches long and barely had a bend in it. I kept adjusting until I needed just a touch of left rudder while climbing and a touch of right rudder in cruise.

  	          		Virus-free. www.avg.com 		 	 [url=#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2][/url]

On Wed, Dec 2, 2020 at 8:34 AM Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:

 	  Quote: 	
		  --> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

 rickofudall wrote:

 > Richard,  Try this, mount the fwd dampers upside (short side up) and the aft dampers as normal.  This will give you another inch and a half or so.

 > 

 > Rick      

 Yeah it would. I am thinking it would also change the thrust line/angle, how would that work?

 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kolb Firefly Part 103 legal 

 Kingsport, TN 3TN0

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

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=499586#499586

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_________________
The smallest miracle right in front of you is enough to make you happy....

neilsenrm(at)gmail.com
Guest

Posted: Wed Dec 02, 2020 8:28 am Post subject: 3.47:1 gear box

Richard

When I switched from a direct drive VW to reduction drive VW I had a 72" prop with 7 inch clearance because of reduction drive. It was trimmable but the first flight was exciting. This added new meaning to power/pitch trim with the new set up also having about twice the thrust. To be clear the reduction drive raised the thrust line 6". I flew it that way for about a year. It is best to keep the trust line as low as possible because it flys better. I wouldn't be concerned about a 1.5 inch change. Also consider that the prop to boom clearance would be about the same so maybe the effective total thrust line change might be less than 1.5.

Rick Neilsen

Redrive VW Powered MKIIIC

On Wed, Dec 2, 2020 at 9:50 AM Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:

 	  Quote: 	
		  I never noticed any effect that wouldn't trim out easily.  It doesn't require any physical change to the aircraft and it's reversible.  Just eight AN-3 bolts and the two AN-6's.

Rick

PS  Trying to fix the need for the huge trim tab on the rudder I made a motor mount plate that turned the engine 5 degrees out of line to the boom C/L.  Didn't make any difference whether I turned the mount over to get that offset to the opposite side.  The only thing I found that did work was the lower prop rpm of the 4:1 gearbox.  My Mk IIIC had a rudder trim tab that was only 6 inches long and barely had a bend in it. I kept adjusting until I needed just a touch of left rudder while climbing and a touch of right rudder in cruise.

  	          		Virus-free. www.avg.com 		 	 [url=#m_-3005434832982732249_DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2][/url]

On Wed, Dec 2, 2020 at 8:34 AM Richard Pike <thegreybaron(at)charter.net (thegreybaron(at)charter.net)> wrote:

 	  Quote: 	
		  --> Kolb-List message posted by: "Richard Pike" <thegreybaron(at)charter.net (thegreybaron(at)charter.net)>

 rickofudall wrote:

 > Richard,  Try this, mount the fwd dampers upside (short side up) and the aft dampers as normal.  This will give you another inch and a half or so.

 > 

 > Rick      

 Yeah it would. I am thinking it would also change the thrust line/angle, how would that work?

 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kolb Firefly Part 103 legal 

 Kingsport, TN 3TN0

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

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=499586#499586

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