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Where's Kitfox IV-1200 line of thrust?

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tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Sun Nov 08, 2009 4:32 am Post subject: Where's Kitfox IV-1200 line of thrust?

Can anybody tell me where the line of thrust for a Kitfox Model IV-1200 should be located? I've looked through my manual a bit and haven't found it yet.



I'm not sure how the factory described it, but if you can use the plane of the firewall as one reference point, and the horizontal line through the middle engine mount points as a second, that would be easiest for me to follow.



I'm assuming the line is perpendicular to the plane of the firewall (can someone confirm this?) and x number of inches above the middle engine mounts.



Thomas

_________________
Kitfox Model IV-1200

Last edited by tleed on Sun Nov 08, 2009 5:58 am; edited 2 times in total

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Nov 08, 2009 5:08 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Not sure of angle but I think it up a few degrees from the firewall centerline.  I have wanted to  shim the mount out more at bottom with washers but works so damn good I have not yet. 



I was thinking adding 2 on bottom and 1 on middle of mount at firewall to start then go  4 at bottom  then 2  ..............



Anyone try this ?



build em light and make them perform .



http://www.youtube.com/watch?v=nZEIzmyyPFY

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tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Sun Nov 08, 2009 5:51 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

What is the "firewall centerline" you're referring to? Is that the lateral line drawn through the two middle engine mounts I'm looking at?



A few degrees? What does that mean? Angles are described in degrees, distances in inches. What does this tell me?

_________________
Kitfox Model IV-1200

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Sun Nov 08, 2009 6:58 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

What you are looking for is likely built into your engine mount.



Works great on mine



Just in from 1 hour flight on wheels . Getting those amphibs off makes it a real hot road again

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Sun Nov 08, 2009 7:28 pm Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Again: what are you talking about, Dave? Whatever it is you are saying, I appreciate the effort, but it is no response to what I"m asking.



Let me try again.



I have a Kitfox Model IV-1200. There's nothing built into my engine mount because I have no engine mount for it. That's because I plan to mount a Corvair on it. So the engine mount will have to be custom-made.



I have a viable sketch done by a pair of competent airframe guys. But in order to come up with some final dimensions, I need the proper location of the line of thrust. Or I need to know where the factory designer assumed that line of thrust would best be located.



I haven't seen this information on paper or on the net anywhere, though I've looked in my factory manual. That manual just describes how to mount a 582 Rotax, but it doesn't have a diagram that I've yet found that shows the line of thrust, much less one that illustrates the relationship of the line of thrust to the plane of the firewall with measurable dimensions.



Perhaps someone with a 582 Rotax on a Model IV and a factory mount can tell me where the centerline of that prop is in relationship to the firewall?



Thomas

_________________
Kitfox Model IV-1200

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Sun Nov 08, 2009 8:14 pm Post subject: Where's Kitfox IV-1200 line of thrust?

At 07:28 PM 11/8/2009, you wrote:

 	  Quote: 	
		  Perhaps someone with a 582 Rotax on a Model IV and a factory mount 

can tell me where the centerline of that prop is in relationship to 

the firewall?


	


Thomas,

         There's a wide variety of vertical placements, depending on 

your choice of cowl and engine. The round cowl IV with a 912 (and 

most every other engine) places the prop in the middle of the big 

hole. The same cowl with a 582 is about 4" higher. (. . .to make it 

fit.) With the "speed" cowl the thrust line is much higher. 

Personally I don't think the vertical placement matters a whole lot. 

What might matter more is the vertical and horizontal angles. 

Unfortunately I can't help you with those without some serious work. 

There has been a lot of discussion amongst my friends about thrust 

angles and the current fad is setting all to zero. Don't know what 

mine's at now. John McBean at Kitfox LLC might be able to help you.

Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 400 hrs. and counting

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Sun Nov 08, 2009 9:44 pm Post subject: Re: Where's Kitfox IV-1200 line of thrust?

I don't have a "factory" cowl either. I'm using a custom cowl that fits the Corvair engine better than the usual round Kitfox cowls. I can put this cowl wherever I want after I get the engine located properly.



But let me see if I get what you're telling me:



1) the absolute height of the center of the crankshaft really isn't critical, give or take a few inches; and,



2) whether the center of rotation of the crankshaft deviates from a line perpendicular to the plane of the firewall in any direction is much more important; and,



3) most people nowadays are orienting the center of the crankshaft 90 degrees from the plane of the firewall in every direction to eliminate unusual settings.

_________________
Kitfox Model IV-1200

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Mon Nov 09, 2009 12:20 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Sounds like you gonna be in R & D yourself for a while. 

I am pretty sure you will want to angle your engine up a few degrees from centre line of longitudinal axis.  If you mount perpendicular to the firewall them you will likely have to adjust up once going or have alot of trim on elevator.



I got a used 912 for sale   6k  1849 hours out of a certified trainer.



Your choice of course. I know that the time proven Rotax engines are proven  to out perform most other engines s in the Kitfox and Avids so I stick to what works well.  



I do wish you luck though.  

 	  tleed wrote: 	
		  I don't have a "factory" cowl either. I'm using a custom cowl that fits the Corvair engine better than the usual round Kitfox cowls. I can put this cowl wherever I want after I get the engine located properly.



But let me see if I get what you're telling me:



1) the absolute height of the center of the crankshaft really isn't critical, give or take a few inches; and,



2) whether the center of rotation of the crankshaft deviates from a line perpendicular to the plane of the firewall in any direction is much more important; and,



3) most people nowadays are orienting the center of the crankshaft 90 degrees from the plane of the firewall in every direction to eliminate unusual settings.

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Mon Nov 09, 2009 4:52 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

I'm trying very hard not to appear snippy or ungrateful, but all I really want to know is what the line of thrust is supposed to be. Is there anybody who actually knows what that is? Please don't distract me from finding that information or offer me other information. That's actually what I need and all I want.

_________________
Kitfox Model IV-1200

napierm(at)cisco.com
Guest

Posted: Mon Nov 09, 2009 8:10 am Post subject: Where's Kitfox IV-1200 line of thrust?

Hello,



My 582, for the best I could tell, had a little left thrust.  Not much.

No down thrust.  It looked dead level.



My HKS mount is dead level and strait.  As others have said, the

vertical placement of the thrust line (the center of the dang prop)

varies all over the place with different engines.



And not to belabor the obvious, but a corvair engine weighs a bit more

than an O-200 installation.  The ones I've seen on Zenith's look a tad

nose heavy and the battery is typically back in the tail.  This is way

heavy on a KF-IV.  Even a VW engine is pushing it weight wise and

doesn't have good low speed thrust.  There is a local guy who has a

KF-IV with a VW in it.  He doesn't fly it much.  I think he is afraid of

it.  The 4-cylinder Jabiru does better.  Much more power and less

weight.  



I'll admit to not being a big fan of Rotax engines because every dang

nut, gasket and O-ring has a hideous price tag attached.  But the power

and thrust you get out of them is great.  Even the 2-stroke engines are

reliable as long as you stay right on top of all the maintenance and

operate them correctly.



I don't think this plane is a good match for the corvair engine.



FWIW,



Mark Napier



Time: 09:47:12 PM PST US

Subject: Re: Where's Kitfox IV-1200 line of thrust?

From: "tleed" <tleed(at)naxs.net>

I don't have a "factory" cowl either. I'm using a custom cowl that fits

the Corvair

engine better than the usual round Kitfox cowls. I can put this cowl

wherever

I want after I get the engine located properly.



But let me see if I get what you're telling me:



1) the absolute height of the center of the crankshaft really isn't

critical, give

or take a few inches; and,



2) whether the center of rotation of the crankshaft deviates from a line

perpendicular

to the plane of the firewall in any direction is much more important;

and,



3) most people nowadays are orienting the center of the crankshaft 90

degrees from

the plane of the firewall in every direction to eliminate unusual

settings.



--------

Kitfox Model IV-1200

Read this topic online here:



http://forums.matronics.com/viewtopic.php?p 71783#271783

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Mon Nov 09, 2009 9:32 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Thanks, Mark, for your helpful and thoughtful reply. I really don't want to turn this thread into an extensive discussion of the merits of various Kitfox engine/airframe combinations. If that happens every time I ask a question I'll burn a lot of months off the calendar and not have much to show for it. Suffice it to say I did a lot of research before I started down this path. And if I decide I want to change engines after I've got it flying, I will be among a large company of other Kitfox owners who've done the same. And I'll be the first to say it wasn't such a great idea if it really works out that way.



That said, if anybody else wants to join Mark with observations about the line of thrust, I'm still all ears on that subject.



Thomas

_________________
Kitfox Model IV-1200

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Mon Nov 09, 2009 3:13 pm Post subject: Re: Where's Kitfox IV-1200 line of thrust?

 	  tleed wrote: 	
		  I'm trying very hard not to appear snippy or ungrateful, but all I really want to know is what the line of thrust is supposed to be. Is there anybody who actually knows what that is? Please don't distract me from finding that information or offer me other information. That's actually what I need and all I want. 	




Actually  I have given you the answer now  



You are in R & D land now my friend.  Mark gave you some good insight as well.   I will tell you that Rotax are a excellent combo for the Kitfox.  Other alternatives have their pros and cons as well - Jab, Soobs BMW and VW  but  you will lose performance overall in most cases and might save a dollar or two?   



I would suggest if you want a 4 stroke  that your best bang for buk will be a used 912 6 to 10k  plus mount ......... 



If you want to play with all the others it it not like you are the first to do it but the resale of your plane will be less than a Rotax in most cases. 



Talk to Mc bean, he will tell you what he has to offer as well. 



>> Sounds like you gonna be in R & D yourself for a while.

I am pretty sure you will want to angle your engine up a few degrees from centre line of longitudinal axis. If you mount perpendicular to the firewall them you will likely have to adjust up once going or have alot of trim on elevator.   <<

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Mon Nov 09, 2009 4:27 pm Post subject: Where's Kitfox IV-1200 line of thrust?

At 09:44 PM 11/8/2009, you wrote:

 	  Quote: 	
		  3) most people nowadays are orienting the center of the crankshaft 

90 degrees from the plane of the firewall in every direction to 

eliminate unusual settings.


	


I don't know about this last. I said the "current" fad is 0 thrust 

angles. However, I don't know if that's what was built in the past, 

or if that's what mine is. I also don't know if that's what John's 

engine mounts provide.





Guy Buchanan

San Diego, CA

K-IV 1200 / 582-C / Warp / 400 hrs. and counting

_________________
Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

Pat Reilly

Joined: 06 Aug 2009
Posts: 345

Posted: Mon Nov 09, 2009 4:45 pm Post subject: Where's Kitfox IV-1200 line of thrust?

Thomas, I have no Corvair KF experience, but from the KF experience I do have that Corvair engine seems mighty heavy.

  

 Pat Reilly

 Mod 3 582 Rebuild

 Rockford, IL

 On Sun, Nov 8, 2009 at 9:28 PM, tleed <tleed(at)naxs.net (tleed(at)naxs.net)> wrote:

 [quote]--> Kitfox-List message posted by: "tleed" <tleed(at)naxs.net (tleed(at)naxs.net)>

 

Again: what are you talking about, Dave? Whatever it is you are saying, I appreciate the effort, but it is no response to what I"m asking.



Let me try again.



I have a Kitfox Model IV-1200. I have no engine mount for it. I plan to mount a Corvair on it. The engine mount will have to be custom-made. I have a viable sketch done by a pair of competent airframe guys. But in order to come up with some final dimensions, I need the proper location of the line of thrust. Or I need to know where the factory designer assumed that line of thrust would best be located.

 

I haven't seen this information on paper or on the net anywhere, though I've looked in my factory manual. That manual just describes how to mount a 582 Rotax, but it doesn't have a diagram that I've yet found that shows the line of thrust, much less one that illustrates the relationship of the line of thrust to the plane of the firewall with measurable dimensions.

 

Perhaps someone with a 582 Rotax on a Model IV and a factory mount can tell me where the centerline of that prop is in relationship to the firewall?



Thomas



--------

Kitfox Model IV-1200



 

Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=271768#271768



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grcolquhoun(at)xtra.co.nz
Guest

Posted: Tue Nov 10, 2009 1:04 am Post subject: Where's Kitfox IV-1200 line of thrust?

Hi Thomas



My model 5 Vixen firewall  I am sure is the same dimension as yours.



Measuring from centre firewall base (floor) from top of cross member  

up 17 inches.

That is what the manual says.



Graeme Colquhoun

Skystar Vixen

On 9/11/2009, at 1:33 AM, tleed wrote:



 	  Quote: 	
		   



 Can anybody tell me where the line of thrust for a Kitfox Model  

 IV-1200 should be located? I've looked through my manual a bit and  

 haven't found it yet.



 I'm not sure how the factory described it, but if you can use the  

 plane of the firewall as one reference point, and the horizontal  

 line through the middle engine mount points as a second, that would  

 easiest for me to follow.



 I'm assuming the line is perpendicular to the plane of the firewall  

 (can someone confirm this?) and x number of inches above the middle  

 engine mounts.



 Thomas



 --------

 Kitfox Model IV-1200





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p 71667#271667

MDKitfox(at)aol.com
Guest

Posted: Tue Nov 10, 2009 5:06 am Post subject: Where's Kitfox IV-1200 line of thrust?

Caution Thomas, the Vixen and all the other Series 5, 6, & 7's are larger than the IV's.  The firewall sizes are much different and the thrust line may or may not be the same.  Sorry about that Graeme.



Why not call the experts at Kitfox?

 Rick Weiss

N39RW Series V Speedster, 912ULS

SkyStar S/N 1

Port Orange, FL

 

 

On Nov 10, 2009, at 3:49 AM, grcolquhoun(at)xtra.co.nz (grcolquhoun(at)xtra.co.nz) wrote:

[quote]--> Kitfox-List message posted by: "grcolquhoun(at)xtra.co.nz (grcolquhoun(at)xtra.co.nz)" <grcolquhoun(at)xtra.co.nz (grcolquhoun(at)xtra.co.nz)>



Hi Thomas



My model 5 Vixen firewall  I am sure is the same dimension as yours.



Measuring from centre firewall base (floor) from top of cross member up 17 inches.

That is what the manual says.



Graeme Colquhoun

Skystar Vixen

On 9/11/2009, at 1:33 AM, tleed wrote:



[quote]--> Kitfox-List message posted by: "tleed" <tleed(at)naxs.net (tleed(at)naxs.net)>



Can anybody tell me where the line of thrust for a Kitfox Model IV-1200 should be located? I've looked through my manual a bit and haven't found it yet.



I'm not sure how the factory described it, but if you can use the plane of the firewall as one reference point, and the horizontal line through the middle engine mount points as a second, that would easiest for me to follow.



I'm assuming the line is perpendicular to the plane of the firewall (can someone confirm this?) and x number of inches above the middle engine mounts.



Thomas



--------

Kitfox Model IV-1200





Read this topic online here:



http://forums.matronics.com/viewtopic.php?p=271667#271667



www.aeroelectricp;   * HomebuiltHELP

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Tue Nov 10, 2009 6:37 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Thanks, Rick. Yes, I know the Series 5-7 is larger at the firewall.



But if the Series 5-7 manual has the line of thrust I would expect the Series IV to have it also. Anybody better at finding it than me? It wasn't in the Rotax 582 engine mounting section.



I have plenty of questions for the McBeans. I just figured I'd try this list first. I didn't think it was that hard a question. But here we are well over a dozen posts later...



Thomas

_________________
Kitfox Model IV-1200

valleyairport(at)cotterwe
Guest

Posted: Tue Nov 10, 2009 8:57 am Post subject: Where's Kitfox IV-1200 line of thrust?

Thomas,



        I built my motor mount for a Lycoming powered S-6. Skystar gave me a 

measurement of 15 1/2 inches above the center of lower mount hole for the 

thrust line (center of crankshaft). That is what I used. Seems correct. 

Measurement is not in builders manual.



Jay C.

S-6

Lyc O-290-D2



---

tleed

Joined: 04 Jun 2007
Posts: 18
Location: Blacksburg, VA

Posted: Tue Nov 10, 2009 11:22 am Post subject: Re: Where's Kitfox IV-1200 line of thrust?

Thanks, Jay. Any more Model IV owners want to chime in on the location and alignment of the line of thrust?



Incidentally, I'm not averse to discussing the merits of my engine choice, but that discussion could easily consume bits and bytes by the cubic mega-bucket. I just can't have that discussion every time I need to figure out how to attach a door handle.



Thomas

_________________
Kitfox Model IV-1200

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