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Firestar II HKS Conversion
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Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Wed Aug 09, 2006 8:14 pm Post subject: Firestar II HKS Conversion

I've been working with Jerry Olenick of Green Sky Adventures over the past month or so to determine the feasibility of converting my Firestar 2 from Rotax 503 power to HKS 700E power.  After lots of tape measure work and study of the engine drawings, plus a number of pictures and emails back and forth, we believe the conversion can be done without modification of the orginal Firestar engine mounts.  I ordered the engine today, and it should arrive sometime in the next month or so.



Assuming the conversion works OK, Jerry will produce a kit to sell with the HKS that will be designed specifically for the Firestar 2.  Since the HKS has worked out quite well as a direct replacement for Rotax 582's on other ultralights, there is some possibility that the HKS could be used on the Mark III and Slingshot also.



If there is interest here on the Kolb List, I'll periodically post pictures and progress reports.  Let's keep questions and comments on the List, rather than private emails.  I have a question for the "conversion master", John Hauck, if he will be so kind as to post that he's seen this thread.

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

Richard Pike

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

Posted: Wed Aug 09, 2006 8:25 pm Post subject: Firestar II HKS Conversion

I will be extra interested, because by comparing the performance of the 

HKS FSII with our 582 FSII, we ought to be able to do a pretty good job 

of comparing the 582 to the HKS.



Richard Pike

MKIII N420P (420ldPoops)



do not archive



Dave Bigelow wrote:

 	  Quote: 	
		   



 I've been working with Jerry Olenick of Green Sky Adventures over the past month or so to determine the feasibility of converting my Firestar 2 from Rotax 503 power to HKS 700E power.  After lots of tape measure work and study of the engine drawings, plus a number of pictures and emails back and forth, we believe the conversion can be done without modification of the orginal Firestar engine mounts.  I ordered the engine today, and it should arrive sometime in the next month or so.



 Assuming the conversion works OK, Jerry will produce a kit to sell with the HKS that will be designed specifically for the Firestar 2.  Since the HKS has worked out quite well as a direct replacement for Rotax 582's on other ultralights, there is some possibility that the HKS could be used on the Mark III and Slingshot also.



 If there is interest here on the Kolb List, I'll periodically post pictures and progress reports.  Let's keep questions and comments on the List, rather than private emails.  I have a question for the "conversion master", John Hauck, if he will be so kind as to post that he's seen this thread.



 --------

 Dave Bigelow

 Kamuela, Hawaii

 FS2, Rotax 503 DCDI





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=53795#53795

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

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

WillUribe(at)aol.com
Guest

Posted: Wed Aug 09, 2006 8:32 pm Post subject: Firestar II HKS Conversion

Hi Dave,

I would be very interested in know how it works out for you. Please keep us

posted.

Do not archive



Regards,

Will Uribe

FireStar II

El Paso, TX

http://home.elp.rr.com/airplane/ 



--

Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Thu Aug 10, 2006 6:57 pm Post subject: Re: Firestar II HKS Conversion

Just found out that John Hauck is on his way to PA.  Here's the question:  Does the Rotax 912 conversion on the Mark III involve a higher thrust line than the original Rotax 582 design?  If so, how many inches, and was the pitch trim change appreciable?



The HKS Firestar conversion will involve a higher thrust line than that of the 503.

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

NeilsenRM(at)comcast.net
Guest

Posted: Thu Aug 10, 2006 8:25 pm Post subject: Firestar II HKS Conversion

Dave



When you put a different engine on a Kolb you will want to mount it so that 

it has a minimum amount of clearance between the prop tips and the fuselage 

tube. When I first mounted a direct drive VW on my MKIIIc I had a fairly 

high thrust line but because it was direct drive turning the prop at a 

extremely high prop RPM (3200-3600) it didn't produce enough thrust to be a 

problem. When I later switched the engine to a reduction drive VW I used the 

same engine mount but the reduction drive placed the prop 5 inches higher. 

With the higher prop and the increased thrust the pitch trim got so bad that 

I had to drastically reduce the forward CG limits. I would literally run out 

of up elevator with high thrust levels at lower airspeeds.  A missed 

approach with its lower airspeed, hi thrust and flaps wow. A go around would 

involve raising the flaps and gaining airspeed before climbing. Also I 

always had to add power slowly on the ground. A basis for comparison is that 

most engines on MKIIIs are set up to have around 2-3 inches of prop 

clearance. On my first redrive engine I had 7 inches of clearance with a 72" 

prop. My new redrive VW engine has a new lowered engine mount that brings 

the clearance down to 2 inches with a 72" prop.



In summary the lower the thrust line the better these Kolb fly. The HKS on a 

Firestar II could cause you problems with a higher thrust line. You say it 

is higher. How much higher? An inch or two may not be too bad but if that 

engine produces allot more thrust than a 503 you may want to be careful. 

When you make these kinds of changes you become the designer and things like 

CG ranges may be completely different.



Again this information is worth just what you paid for it.



Rick Neilsen

Redrive VW powered MKIIIc



---

Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Fri Aug 11, 2006 12:37 am Post subject: Re: Firestar II HKS Conversion

Thanks for the feedback, Rick.  The HKS gearbox can be mounted in an up or down position just like the Rotax.  If I mount it with gearbox down (2.58:1 ratio), I have to raise the engine 3 inches higher than the Rotax 503 to get 1.5 inches of clearance with a 66 inch prop from the fuselage tube.  I don't want any less than 1.5 inches clearance, and don't like the idea of raising the HKS 3 inches.



If I mount the HKS with the gear box up (3.47:1 ratio), I can keep the HKS at a reasonable height on the mounts, but end up with a thrust line 4.75 inches higher than the Rotax 503 thrust line.



I'm looking at a 3 blade 70 inch prop.  I believe there will be more thrust than the 503 produces, but not a lot more.



Here's a link to the Green Sky Adventures web site.  There's a world of information on the HKS and lots of pictures of other ultralights using the HKS.  http://www.greenskyadventures.com/EnginePricing/HKS/home.htm

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

John Hauck

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

Posted: Fri Aug 11, 2006 11:57 am Post subject: Firestar II HKS Conversion

and Slingshot also.

|

| If there is interest here on the Kolb List, I'll periodically post 

pictures and progress reports.  Let's keep questions and comments on 

the List, rather than private emails.  I have a question for the 

"conversion master", John Hauck, if he will be so kind as to post that 

he's seen this thread.

|

| --------

| Dave Bigelow



Hi Dave B:



Don't know about the "conversion master" handle, but I have read your 

email.



john h

mkIII

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

John Hauck

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

Posted: Fri Aug 11, 2006 12:18 pm Post subject: Firestar II HKS Conversion

| Just found out that John Hauck is on his way to PA.  Here's the 

question:  Does the Rotax 912 conversion on the Mark III involve a 

higher thrust line than the original Rotax 582 design?  If so, how 

many inches, and was the pitch trim change appreciable?

|

| The HKS Firestar conversion will involve a higher thrust line than 

that of the 503.

|

| --------

| Dave Bigelow



Dave B:



I am a firm believer in getting the thrust line as low as possible.



I am running a 72" three blade Warp with 3/4" clearance between prop 

tip and tail boom.  Most of you all will think I am off my rocker, as 

usual, but that is ok.  With more than 1,000.00 hours in this 

configuration, I think I am flying safely.



Higher thrust lines kill power and reduce performance, especially 

getting off the ground.  Takes a lot of nose up pitch to overcome high 

thrust.  Would think it much better to raise the engine and lower the 

thrust line.



No difference between mounting 582 and 912, if I remember correctly.



Again, pitch trim is governed by thrust line and hp.



Talked with Gerry Olenik at Oshkosh.  He briefed me on your 

participation.



john h

mkIII

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

Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Fri Aug 11, 2006 6:57 pm Post subject: Re: Firestar II HKS Conversion

 	  Quote: 	
		   am running a 72" three blade Warp with 3/4" clearance between prop 

tip and tail boom. Most of you all will think I am off my rocker, as 

usual, but that is ok. With more than 1,000.00 hours in this 

configuration, I think I am flying safely 	




John,

Thanks for the info - I was thinking that 1.5 inches clearance from the tail boom would be about as close as I would be comfortable with, but you can't argue with success......  I spoke to Jerry Olenik today, and changed the HKS order to an A gear box (2.58:1) mounted down.  That way, I should be able to use my 66 inch Powerfin two blade prop, and still have more than 3/4 inch clearance from the tail boom.



Should be an interesting comparison between the two engines, since I'll be using the same gear ratios in a similar engine and prop RPM range.

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

NeilsenRM(at)comcast.net
Guest

Posted: Sat Aug 12, 2006 9:11 am Post subject: Firestar II HKS Conversion

Dave



John obviously gets away with 3/4" clearance but be very careful cutting 

that clearance any further. There is a lot of gyroscopic forces acting on 

that prop as you go thru turbulence. Make sure with any engine mounting that 

the engine can't flex on its mount enough to have a prop strike on the 

fuselage tube.



Rick Neilsen

Redrive VW powered MKIIIc

---

rsanoa

Joined: 10 Jan 2006
Posts: 71
Location: Bell Buckle,TN

Posted: Sat Aug 12, 2006 10:28 am Post subject: Firestar II HKS Conversion

Man , a half inch clearance to me is scary unless one has a BRS attached, forward of the prop radius.  But sometimes it's fun to live dangerously.

   

  Do not archive



Richard & Martha Neilsen <NeilsenRM(at)comcast.net> wrote:

  [quote]--> Kolb-List message posted by: "Richard & Martha Neilsen" 



Dave



John obviously gets away with 3/4" clearance but be very careful cutting 

that clearance any further. There is a lot of gyroscopic forces acting on 

that prop as you go thru turbulence. Make sure with any engine mounting that 

the engine can't flex on its mount enough to have a prop strike on the 

fuselage tube.



Rick Neilsen

Redrive VW powered MKIIIc

---

_________________
Ray S.Anderson

John Jung

Joined: 10 Jan 2006
Posts: 108
Location: Surprise, AZ, USA

Posted: Fri Aug 18, 2006 9:55 am Post subject: Re: Firestar II HKS Conversion

Dave and Group,



I, also, have an interest in the HKS. I just didn't want to be the first one to put one on a Firestar. So, I will be following your reports on this project.



I've been away from my Firestar for the summer, but I'll be back in a few weeks, and ready to start flying and working on it again.

_________________
John Jung
Firestar II N6163J
Surprise, AZ

Dave Bigelow

Joined: 29 Jan 2006
Posts: 103
Location: Kamuela, Hawaii

Posted: Sun Nov 12, 2006 7:03 pm Post subject: Re: Firestar II HKS Conversion

I have the HKS mounted on the Firestar, and am working on hooking things up.  The ignition modules and coils are mounted on the aircraft frame (not on the engine).  There is also an oil tank and oil radiator to mount.  



The engine is beautifully engineered and looks right sitting there on the Firestar.  The final gearbox will be the 2.58:1 B Box mounted down.  The A Box (mounted up) in the pictures will be replaced.  The thrust line is too high with that setup.  I plan on using the same 66 inch two blade Powerfin prop that I used with the Rotax 503.  Looks like the fuselage boom clearance will be about one inch.



The engine had to be mounted forward enough so the exhaust manifold pipes clear the aileron torque tubes and control horn when folding and unfolding the wings.  This will require a prop spacer to give adequate prop clearance from the aileron torque tubes when flying.



Jerry Olenik from Green Sky Adventures has been working closely with me throughout this project.  He plans on offering a mounting kit for the Firestar after we finalize the installation and do the test flights. 



I'm hoping to test fly it shortly after the first of the year.

Kolb-HKS WingFold Clearance.JPG

Description:

Clearance between Exhaust and Aileron control horn and torque tube is very tight.

Filesize:

77.56 KB

Viewed:

744 Time(s)

Kolb-HKS Mounts.JPG

Description:

Tempory mount clamped on while checking wing fold.

Filesize:

87.24 KB

Viewed:

762 Time(s)

_________________
Dave Bigelow
Kamuela, Hawaii
FS2, HKS 700E

Last edited by Dave Bigelow on Sat Nov 18, 2006 2:20 pm; edited 1 time in total

Denny Rowe

Joined: 10 Jan 2006
Posts: 89
Location: Leechburg, PA

Posted: Mon Nov 13, 2006 6:54 am Post subject: Firestar II HKS Conversion

Looking forward to hearing the results.

Denny Rowe

do not archive

---

John Hauck

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

Posted: Mon Nov 13, 2006 7:30 am Post subject: Firestar II HKS Conversion

| > I'm hoping to test fly it shortly after the first of the year.

| >

| > --------

| > Dave Bigelow



Dave:



Rather than place all your test results on one prop, coordination with 

Daryl at Warp Drive might get you some different props to test with 

the HKS and the FSII.



john h

mkIII

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

HShack(at)aol.com
Guest

Posted: Mon Nov 13, 2006 9:58 am Post subject: Firestar II HKS Conversion

In a message dated 11/13/2006 10:31:53 AM Eastern Standard Time, jhauck(at)elmore.rr.com writes:

  	  Quote: 	
		  Dave:



Rather than place all your test results on one prop, coordination with 

Daryl at Warp Drive might get you some different props to test with 

the HKS and the FSII.



john h

mkIII 	


 Since he will run a "B" box, maybe a Warp Drive will be too heavy?



  

 Howard Shackleford

FS II

SC

  [quote][b]

John Hauck

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

Posted: Mon Nov 13, 2006 11:38 am Post subject: Firestar II HKS Conversion

| Since he will run a "B" box, maybe a Warp Drive will be too heavy?

|

| Howard Shackleford



Shack:



I don't know.  Does the HKS, in fact, use a Rotax B gearbox?



I have very little, zero, knowledge of the HKS.



My concern is to give the engine a fair shake on the FSII.  Running 

one prop, which I also know nothing about, IMHO, would not be a fair 

test.



john h

mkIII

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

Jim Ballenger

Joined: 12 Jan 2006
Posts: 18
Location: Virginia Beach, Virginia

Posted: Mon Nov 13, 2006 12:46 pm Post subject: Firestar II HKS Conversion

Dave

I think you have a great combination of plane and engine and I  am very 

interested in the outcome. Keep us posted.

Jim Ballenger

MK III X 912uls

Virginia Beach, VA



Do Not Archive

---

jindoguy(at)gmail.com
Guest

Posted: Mon Nov 13, 2006 1:42 pm Post subject: Firestar II HKS Conversion

John, HKS specs their 2.58 box for the same inertia limits as the Rotax B, 3000kg/cm^2. The 3.47 box is rated the same as the Rotax C and E, 6000kg/cm^2.

At the flex wing and powered parachute LSA repairman classes I was at last week we did an inertia check on a 68 X 40 Tennessee Props wood two blade. According to the charts published by CPS, it was right at the upper limit for the Rotax B. 



Rick



On 11/13/06, John Hauck <jhauck(at)elmore.rr.com (jhauck(at)elmore.rr.com)> wrote: 	  Quote: 	
		   --> Kolb-List message posted by: "John Hauck" <jhauck(at)elmore.rr.com (jhauck(at)elmore.rr.com)>

 | Since he will run a "B" box, maybe a Warp Drive will be too heavy?

 |

| Howard Shackleford



Shack:



I don't know.  Does the HKS, in fact, use a Rotax B gearbox?



I have very little, zero, knowledge of the HKS.



My concern is to give the engine a fair shake on the FSII.  Running 



	


-- 

Rick Girard

"Ya'll drop on in"

takes on a whole new meaning

when you live at the airport.  [quote][b]

John Hauck

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

Posted: Mon Nov 13, 2006 2:28 pm Post subject: Firestar II HKS Conversion

| According to the charts published by CPS, it was right at the upper 

limit

| for the Rotax B.

|

| Rick



Rick:



That is not much capability.



john h

mkIII

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

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