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lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Sat Nov 17, 2007 8:22 am Post subject: Re: 2 stroke vs 4 stroke

 	  jindoguy(at)gmail.com wrote: 	
		  Lucien, It's okay to be a heretic. If you have the time, put Airbike

Ace into Google and read about Paul's adventures. He's a member of EAA

chapter 88 and flies his 503 equipped Airbike like most people fly

Cessnas. The story of his trip to Oshkosh this year is in the latest

issue of Sport Pilot. His 503 has over 650 hours and I don't think he

does anything but run it regularly.

As for the HKS, I have one on my trike, runs like a champ and sips

gas. I did 25 landings yesterday afternoon in two hours of flying and

it burned 4 gallons. Can't wait to get one on a Kolb.



Rick

	




Hey Rick,



Well you know, while I'm at it.....



I'd say the main thing I hear is that a 4-stroke will make it safer to fly over places they can't land on.



I hear that over and over, more than any other justification for the 4-stroke; even fuel economy is a distant second to this. Overwhelmingly, folks seem to want a 4-stroke so they can fly over hostile territory in more relative comfort.



Maybe I'm old school, or just chicken, but I dare not do that (unless it's necessary) in anything I fly anyway. So I guess I'm not subject to the allure of the "insurance" idea of the 4-stroke.



The only motor I've run that has given me trouble was my 447 on my trike - it shut down in the pattern on me once due to a wiring harness error on my part. 



Otherwise, I've lost count of the hours I have with 503's without so much as a cough. 



All that said, the one thing that I find advantageous about flying a 4-stroke is less concern about descents with the throttle closed. That's the only thing I had to pay attention operation-wise with my 2-stroke that I don't really with the 912.



Somehow tho I love my plane, I'm finding myself missing my fun racer with the 503 on it.... 



Oh well



do not archive



LS

_________________
LS
Titan II SS

lcottrell

Joined: 29 May 2006
Posts: 1490
Location: Jordan Valley, Or

Posted: Sat Nov 17, 2007 11:00 am Post subject: 2 stroke vs 4 stroke

---

_________________
do not archive

knowvne(at)aol.com
Guest

Posted: Sat Nov 17, 2007 2:54 pm Post subject: 2 stroke vs 4 stroke

Rotax to Discontinure the 503??

Who's starting that rumor????



Mark





--

grantr

Joined: 12 Sep 2007
Posts: 217

Posted: Sat Nov 17, 2007 5:27 pm Post subject: Re: 2 stroke vs 4 stroke

Someone told me that someone with Lockwood aviation said rotax was discontinuing the 447 and 503s

jindoguy(at)gmail.com
Guest

Posted: Sat Nov 17, 2007 9:52 pm Post subject: 2 stroke vs 4 stroke

I have a Northwing Apache Sport. It has an M-Pulse 19 wing on it

today, but it will have a Quest 14.5 on it tomorrow.

I finished setting up the new wing this afternoon, but decided to give

it a good going over in the morning before I put it on the trike. I've

been so spoiled by the way the big wing can use convective lift to

keep fuel consumption down about as low as it's possible to get. There

have been some days I've gotten the fuel burn down to under 2 gallons

an hour. I normally cruise at 4700 rpm which gets me an airspeed of

42. Aerial yachting at its finest. If Kamron is right I should pick up

20 mph with the smaller double surface wing.

Rick

On Nov 17, 2007 10:03 AM, JetPilot <orcabonita(at)hotmail.com> wrote:

 	  Quote: 	

 jindoguy(at)gmail.com wrote:

 >

 > As for the HKS, I have one on my trike, runs like a champ and sips

 > gas. I did 25 landings yesterday afternoon in two hours of flying and

 > it burned 4 gallons. Can't wait to get one on a Kolb.

 >

 > Rick

 >

 >

 >

 What kind of trike do you have Rick ?   I fly an Air Creations Racer, I would love the buggy with the HKS and KISS wing, but they are way expensive new !   There don't seem to be any used ones on the market yet, which also says a lot  

 JettPilot

 --------

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

 Kolb MK-III Xtra, 912-S

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=146637#146637

jindoguy(at)gmail.com
Guest

Posted: Sat Nov 17, 2007 10:11 pm Post subject: 2 stroke vs 4 stroke

Ceramic 4 stroke engines that produce 1.25 HP per LB and have fuel

burns in the .25 lb. per hp hour. Real Soon Now.



Rick



On Nov 17, 2007 4:53 PM,  <knowvne(at)aol.com> wrote:

[quote] 



 Rotax to Discontinure the 503??

 Who's starting that rumor????



 Mark





 --

jindoguy(at)gmail.com
Guest

Posted: Sat Nov 17, 2007 10:16 pm Post subject: 2 stroke vs 4 stroke

According to Eric Tucker, in 2006 Rotax made 900 two stroke aircraft

engines of all sizes. Not exactly a huge market. In contrast, they

made 4000 of the 912 / 914 series.



Rick



On Nov 17, 2007 7:27 PM, grantr <grant_richardson25(at)yahoo.com> wrote:

 	  Quote: 	
		   



 Someone told me that someone with Lockwood aviation said rotax was discontinuing the 447 and 503s





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146722#146722

olendorf

Joined: 06 Jul 2006
Posts: 140
Location: Schenectady, NY USA

Posted: Sun Nov 18, 2007 5:57 am Post subject: Re: 2 stroke vs 4 stroke

But how many crankshafts and other expensive parts do they sell each year?  I would keep the 503 and sell it at a lose if you have to and keep the parts orders rolling in.

_________________
Scott Olendorf
Original Firestar, Rotax 447, Powerfin prop
Schenectady, NY
http://sites.google.com/site/kolbfirestar/

jindoguy(at)gmail.com
Guest

Posted: Sun Nov 18, 2007 6:46 am Post subject: 2 stroke vs 4 stroke

Pretty cryptic there, Scott. I assume you're talking about Rotax

production numbers of two strokes. It would be an interesting study to

find out how many Rotax two stroke owners follow the  maintenance plan

to the letter. You also have to figure in all the bogus parts floating

around on eBay and elsewhere.

We'll get an idea from the small segment of the S-LSA guys who buy

aircraft with a 503 or 582. They have to follow the maintenance

schedule or their airworthiness certificate is void. Or they can go

E-LSA.



Rick



On Nov 18, 2007 7:57 AM, olendorf <olendorf(at)gmail.com> wrote:

 	  Quote: 	
		   



 But how many crankshafts and other expensive parts do they sell each year?  I would keep the 503 and sell it at a lose if you have to and keep the parts orders rolling in.



 --------

 Scott Olendorf

 Original Firestar, Rotax 447, Powerfin prop

 Schenectady, NY

 http://KolbFirestar.googlepages.com





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146846#146846

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Sun Nov 18, 2007 7:33 am Post subject: Re: 2 stroke vs 4 stroke

 	  jindoguy(at)gmail.com wrote: 	
		  Pretty cryptic there, Scott. I assume you're talking about Rotax

production numbers of two strokes. It would be an interesting study to

find out how many Rotax two stroke owners follow the  maintenance plan

to the letter. You also have to figure in all the bogus parts floating

around on eBay and elsewhere.

We'll get an idea from the small segment of the S-LSA guys who buy

aircraft with a 503 or 582. They have to follow the maintenance

schedule or their airworthiness certificate is void. Or they can go

E-LSA.



Rick

	




This should also be partially true for the 912 series. In a lot of cases I hear about, they're also throwing away perfectly good parts at 1500 hours when they get majored. Even now, flight training operations using the 912 are getting 2500 to 3000 hours out of them with the motors still running fine at that time.



I personally don't know anyone who's actually succeeded in literally wearing out a 912 to normal end-of-life, i.e. where it's starting to use oil, lose power, and just generally doing the normal falling apart. Unless the maint. was done wrong, I don't think this happens at 1500 hours currently.



I have seen a couple 2-strokes that have worn to that point, but that's because the overall lifetime is shorter and thus visible. Same thing here tho, I've never seen one worn out at 300 hours unless it was abused in some way.



So I think either engine will enrage each SLSA owner equally; both will be foreced to throw away still-good innards for new ones at the well-known crushingly high prices at the book values of 300 and 1500 hours.



More wrinkles:



The 912 has become staggeringly expensive to buy and worse to put parts in; its cost overall is now about the same as the big-iron (a factory new basic O-320 can be had for only slightly more than a new 912S). 



Also, I think the current drop in 2-stroke sales is only because of the furor surrounding the approaching death of "gELSA" at end of Jan. and all the hype from FnAA, EAA and everyone else about getting N-numbered else the world will come to an end for light aircraft.



Once that dies down, I predict the light a/c market in the 40 to 50 hp range will start to come back. Rotax is also doing the right thing by hedging on this - they're not discontinuing the motors right away but in a few years (2012 wasn't it?) and then continuing parts for 10 years after that.



Further more, the 912 is getting _more_ expensive even as the supply increases, not less, and the current spook about gELSA going away won't be permanent. The flying public is not getting richer, we're actually steadily getting poorer as the economy erodes and our paychecks stay the same. The folklore of the FnAA busting every illegal airplane out there will also wear off over time.



So I don't see the 912 taking over the world - the underlying fundamentals of buying power simply isn't there for that to happen. The economy isn't that good and our paychecks aren't getting larger at the required rate. There'll be a market for small, inexpensive motors, hopefully enough for Rotax to keep making the 447 and 503, or at least extending the support for them for a while.



So I'm not really worried yet...



That's what my crystal ball says anyway...



LS

_________________
LS
Titan II SS

mdnanwelch7(at)hotmail.co
Guest

Posted: Sun Nov 18, 2007 12:03 pm Post subject: 2 stroke vs 4 stroke

 	  Quote: 	
		         Lucien, Interesting and thoughtful "take" on the future of Rotax, and the high prices to own one. While it is true they are probably the leader in the SLSA & ESLA field , from our experience, anytime a product raises its prices so high the masses can barely afford it, along comes competition.And competition is a good thing. Not only does it give us consumers a choice, finally, but we also get the advantage of the new technology and improvements, when deciding on a competitive product.Case in point is the HKS. This engine is taking a small foothold in the Rotax 503 normally dominated field.As the reliability and ,therefore, popularity increases, we pilots benefit in being able to choose an engine that fits our preferences, and this helps hold down the price of other similar products. The fact is, I would like to see other engine companies make an engine for the experimental aircraft planes. Companies like Harley Davidson, Briggs and Stratton, and Honda, etc., etc. And I'm not talking about "conversions", where someone "adapts" a redrive unit to an existing motor (like Hog-Air), I'm talking about the engine manufacturer actually producing a 60-100 hp range of true aircraft engines. Much like Jabiru did. Lately I have been looking at some of the other engine choices. Personally, I am NOT looking to get a new engine, I will be staying with my GEO 1.0 liter 3 cyl., turbo, but I do like to see what other alternatives are out there.If I had to do it all over, I think I could have seriously considered a big bore VW based conversion like Great Plains Engines, or Aero-Vee Engines. http://www.greatplainsas.com/ http://www.aeroconversions.com/ Mike Welch MkIII with GEO turbo  Do Not Archive 	
Share life as it happens with the new Windows Live. Share now!  [quote][b]

lucien

Joined: 03 Jun 2007
Posts: 721
Location: santa fe, NM

Posted: Sun Nov 18, 2007 12:56 pm Post subject: Re: 2 stroke vs 4 stroke

[quote="mdnanwelch7(at)hotmail.co"] 	  Quote: 	
		         Lucien, Interesting and thoughtful "take" on the future of Rotax, and the high prices to own one. While it is true they are probably the leader in the SLSA & ESLA field , from our experience, anytime a product raises its prices so high the masses can barely afford it, along comes competition.And competition is a good thing. Not only does it give us consumers a choice, finally, but we also get the advantage of the new technology and improvements, when deciding on a competitive product.Case in point is the HKS. This engine is taking a small foothold in the Rotax 503 normally dominated field.As the reliability and ,therefore, popularity increases, we pilots benefit in being able to choose an engine that fits our preferences, and this helps hold down the price of other similar products. The fact is, I would like to see other engine companies make an engine for the experimental aircraft planes. Companies like Harley Davidson, Briggs and Stratton, and Honda, etc., etc. And I'm not talking about "conversions", where someone "adapts" a redrive unit to an existing motor (like Hog-Air), I'm talking about the engine manufacturer actually producing a 60-100 hp range of true aircraft engines. Much like Jabiru did. Lately I have been looking at some of the other engine choices. Personally, I am NOT looking to get a new engine, I will be staying with my GEO 1.0 liter 3 cyl., turbo, but I do like to see what other alternatives are out there.If I had to do it all over, I think I could have seriously considered a big bore VW based conversion like Great Plains Engines, or Aero-Vee Engines. http://www.greatplainsas.com/ http://www.aeroconversions.com/ Mike Welch MkIII with GEO turbo  Do Not Archive 	




Well there are a couple other complications with this that have to do with the 40 to 50 hp light a/c market (I like to call it).



a) As I said before, this market was very slow to adopt the 912 even back when it was reasonably priced - now with its cost is in the ludicrous GA territory its attraction to that market is about nil. The fundamentals for the 912 to penetrate this market are simply NOT there. The money isn't there, the growth of the buying power of those customers won't reach that level in a reasonable amount of time (if ever). 

This was one of the big expectations of the whole light sport movement and it was a big mistake.

The 912 and motors like the HKS aren't quite head to head competitors, since they power different planes for the most part.  So really the success of the HKS isn't going to affect much the 912's situation. 

The jabiru, on the other hand, has an opportunity here, though there are problems with it too (its cost is also going up soon, it's got some installation related bugs here and there, etc.).



b) The 40/50 hp light a/c market will NOT simply vanish. The expectation of the LSA movement seems to have been that suddenly everyone would get tired of their single-place UL like planes, small trikes, and other light planes and decide they wanted larger, faster 4-stroke powered planes of the LSA variety. I guess they thought the planes would just sell themselves once the light a/c pilots all woke up and saw the error of their ways.

Some would say that this is actually happening now - people are suddenly somehow content to opt for boats or computer games instead of flying an airplane through the air and the whole UL flying thing is imploding for good. 

I think this is a mistake - true it's in a lull right now, and a deep one, but like I said this is more sensationalism driven by the expiration of gELSA and the hoopla surrounding LSA than it is a sudden shift in the human race away from interest in flying light aircraft.

Forgetting this market going forward will be a large error I think.



c) Now the 912's competition besides the jab is basically the big iron. It hinges only on the legal issue - its the suitable pwerplant for LSA far more than the big iron that costs about the same.

The GA market, that would otherwise be buying used GA airplanes, DOES have the buying power for a 20 grand 912S, and will buy the 100k planes it powers for a while.



But the law of supply and demand can NOT support an _increasing_ price when supply continues to meet demand. It just doesn't work that way. Either supply has to tighten to maintain the cost increase (this would be very bad for Rotax) or demand has to rise dramatically, more dramatically than it is now (and I don't see that happening, we're already about in the Good Old Days of LSA at this point). 

This includes the exchange rate issue which amounts to a huge price hike - Rotax still has to deal with that and yes they truly are in a pickle with it.



The market also can't support increasing prices once they reach the level of viable competitors. This is a mixed bag - in some areas, like GA training, even exorbitant prices like 110 grand for an SLSA are far cheaper than the competition (third of a million for a new Cessna). In others, like the experimental market, there'll be trouble. I.e. if you're going to drop 100 grand on a plane, will it be a CTsw SLSA or a Vans RV-8 quick build + tools + goodies? 

Don't know about you, but medical or not, if I have to drop 100 large on an airplane I'm going for the best bang/buck which would be the RV.



In any case, the 912 is actually in a more precarious position than it used to be and Rotax will have to do something about it pretty quick. But at the same time, I don't see a permanent disappearance of the market for motors like the 447 and 503, or the HKS, etc.



Finally, I don't know about the 582. I might ring up lockwood next week and see what its status is...



LS

_________________
LS
Titan II SS

Jim Baker

Joined: 30 Mar 2006
Posts: 181
Location: Sayre, PA

Posted: Sun Nov 18, 2007 1:26 pm Post subject: 2 stroke vs 4 stroke

X-SpamReason %%SpamReason%%: 



 	  Quote: 	
		   Rotax

production numbers of two strokes. It would be an interesting study 
	


to

find out how many Rotax two stroke owners follow the  maintenance 

plan

to the letter. You also have to figure in all the bogus parts 

floating

around 



I'd think that it would be instructive (entertaining, as well) to 

have a side-by-side teardown, micrometer/caliper/bore gauge/ Rockwell 

hardness test and documentation of a Skidoo Rotax 503 and a UL Rotax 

503 to find the differences. My guess....either none at all or darn 

few. Bore/stroke, ring width, deck height, bearing numbers, con rod 

forging numbers...all of these and a lot more are exactly the same.

Jim Baker

580.788.2779

Elmore City, OK

jindoguy(at)gmail.com
Guest

Posted: Sun Nov 18, 2007 6:26 pm Post subject: 2 stroke vs 4 stroke

The killer of the 2 strokes will be pollution and high fuel usage.

Remember all those two stroke motorcycles? Seen any lately? All it

will take is for the State of California to extend its two stroke ban

to aircraft engines and the party is over for that, too. Don't get me

wrong, I'm not blaming anyone. I lived in California when only LA was

polluted. Now it covers the entire state. Worse yet, is that now it's

everywhere and has to be cleaned up. In a short time, most personal

flying will be electric powered. $100,000 can buy you an electric

motor glider today. It will require far more skill to do what gasoline

allows now relatively simply, but using a launcher / sustainer

powerplant can take you cross country, today, if you want it. There is

far greater interest in battery development than will ever be

available to do the cheap 4 stroke 40 HP engine weighing 80 lb. even

if you could sell 10,000 of them a year. Meanwhile, the cost of ever

increasing energy density storage is becoming cheaper.

FIre away.



Rick



PS Since utilization of convective activity to aviate is inherently

more risky and the shears encountered can result in loss of control or

structural failure, I would definitely recommend a BRS for such craft.



On Nov 18, 2007 2:56 PM, lucien <lstavenhagen(at)hotmail.com> wrote:

 	  Quote: 	
		   



 [quote="mdnanwelch7(at)hotmail.co"]

 >        Lucien, Interesting and thoughtful "take" on the future of Rotax, and the high prices to own one. While it is true they are probably the leader in the SLSA & ESLA field , from our experience, anytime a product raises its prices so high the masses can barely afford it, along comes competition.And competition is a good thing. Not only does it give us consumers a choice, finally, but we also get the advantage of the new technology and improvements, when deciding on a competitive product.Case in point is the HKS. This engine is taking a small foothold in the Rotax 503 normally dominated field.As the reliability and ,therefore, popularity increases, we pilots benefit in being able to choose an engine that fits our preferences, and this helps hold down the price of other similar products. The fact is, I would like to see other engine companies make an engine for the experimental aircraft planes. Companies like Harley Davidson, Briggs and Stratton, and Honda, etc., etc. A

 n!
	


 	  Quote: 	
		    d I'm not talking about "conversions", where someone "adapts" a redrive unit to an existing motor (like Hog-Air), I'm talking about the engine manufacturer actually producing a 60-100 hp range of true aircraft engines. Much like Jabiru did. Lately I have been looking at some of the other engine choices. Personally, I am NOT looking to get a new engine, I will be staying with my GEO 1.0 liter 3 cyl., turbo, but I do like to see what other alternatives are out there.If I had to do it all over, I think I could have seriously considered a big bore VW based conversion like Great Plains Engines, or Aero-Vee Engines. http://www.greatplainsas.com/ (http://www.greatplainsas.com/) http://www.aeroconversions.com/ (http://www.aeroconversions.com/) Mike Welch MkIII with GEO turbo  Do Not Archive

 Well there are a couple other complications with this that have to do with the 40 to 50 hp light a/c market (I like to call it).



 a) As I said before, this market was very slow to adopt the 912 even back when it was reasonably priced - now with its cost is in the ludicrous GA territory its attraction to that market is about nil. The fundamentals for the 912 to penetrate this market are simply NOT there. The money isn't there, the growth of the buying power of those customers won't reach that level in a reasonable amount of time (if ever).

 This was one of the big expectations of the whole light sport movement and it was a big mistake.

 The 912 and motors like the HKS aren't quite head to head competitors, since they power different planes for the most part.  So really the success of the HKS isn't going to affect much the 912's situation.

 The jabiru, on the other hand, has an opportunity here, though there are problems with it too (its cost is also going up soon, it's got some installation related bugs here and there, etc.).



 b) The 40/50 hp light a/c market will NOT simply vanish. The expectation of the LSA movement seems to have been that suddenly everyone would get tired of their single-place UL like planes, small trikes, and other light planes and decide they wanted larger, faster 4-stroke powered planes of the LSA variety. I guess they thought the planes would just sell themselves once the light a/c pilots all woke up and saw the error of their ways.

 Some would say that this is actually happening now - people are suddenly somehow content to opt for boats or computer games instead of flying an airplane through the air and the whole UL flying thing is imploding for good.

 I think this is a mistake - true it's in a lull right now, and a deep one, but like I said this is more sensationalism driven by the expiration of gELSA and the hoopla surrounding LSA than it is a sudden shift in the human race away from interest in flying light aircraft.

 Forgetting this market going forward will be a large error I think.



 c) Now the 912's competition besides the jab is basically the big iron. It hinges only on the legal issue - its the suitable pwerplant for LSA far more than the big iron that costs about the same.

 The GA market, that would otherwise be buying used GA airplanes, DOES have the buying power for a 20 grand 912S, and will buy the 100k planes it powers for a while.



 But the law of supply and demand can NOT support an _increasing_ price when supply continues to meet demand. It just doesn't work that way. Either supply has to tighten to maintain the cost increase (this would be very bad for Rotax) or demand has to rise dramatically, more dramatically than it is now (and I don't see that happening, we're already about in the Good Old Days of LSA at this point).

 This includes the exchange rate issue which amounts to a huge price hike - Rotax still has to deal with that and yes they truly are in a pickle with it.



 The market also can't support increasing prices once they reach the level of viable competitors. This is a mixed bag - in some areas, like GA training, even exorbitant prices like 110 grand for an SLSA are far cheaper than the competition (third of a million for a new Cessna). In others, like the experimental market, there'll be trouble. I.e. if you're going to drop 100 grand on a plane, will it be a CTsw SLSA or a Vans RV-8 quick build + tools + goodies?

 Don't know about you, but medical or not, if I have to drop 100 large on an airplane I'm going for the best bang/buck which would be the RV.



 In any case, the 912 is actually in a more precarious position than it used to be and Rotax will have to do something about it pretty quick. But at the same time, I don't see a permanent disappearance of the market for motors like the 447 and 503, or the HKS, etc.



 Finally, I don't know about the 582. I might ring up lockwood next week and see what its status is...



 LS



 --------

 LS

 FS II





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=146936#146936

NeilsenRM(at)comcast.net
Guest

Posted: Sun Nov 18, 2007 6:59 pm Post subject: 2 stroke vs 4 stroke

Lucien



I agree we need competition for the Rotax 912. They have gotten way too 

expensive.



I would like to comment on your suggestion about Areo-Vee. This engine is a 

direct drive VW and there is a world of difference between a direct drive VW 

and a reduction drive engine. I flew a Great Plains direct drive VW for four 

years on my MKIII it pushed me along at 65MPH running 80% power and was a 

dog in a climb. The same size VW with a reduction drive pushes the same 

plane 75MPH at 60% power and climbs. The Jabaru engine is a slightly slower 

RPM engine but still turns way too many RPMs to turn a large enough prop to 

give a Kolb the spirited performance we have come to expect with a 912 or 

even a redrive VW.



Rick Neilsen

Redrive VW powered MKIIIc



---

mdnanwelch7(at)hotmail.co
Guest

Posted: Sun Nov 18, 2007 9:42 pm Post subject: 2 stroke vs 4 stroke

Rick N.,



  That wasn't Lucien that suggested the VW engines, it was me, Mike Welch.  And I wasn't especially trying to push the Aero-Vee, either.  It was one of the two VW based engine I could find in a couple of minutes of Google searching.



  I absolutely agree with you in regard to everything you said in regards to engine rpms and redrives.  The fact is, Aero Vee direct drive engine are not a good way to go!!  I am fully informed, and versed in the evils of excessive prop tip-speed. (and multiple prop blades)



  My basic point is I think the VW engine with a reduction drive system should be a serious contender to be considered, for the "mid-sized experimental airplanes" engine. (Like the MkIII, or Kolbra, etc)



  So, in response to your response....I very much agree with you.



                           Mike Welch



Do Not Archive

[quote] From: NeilsenRM(at)comcast.net

 To: kolb-list(at)matronics.com

 Subject: Re: Re: 2 stroke vs 4 stroke

 Date: Sun, 18 Nov 2007 21:58:16 -0500



 



 Lucien



 I agree we need competition for the Rotax 912. They have gotten way too

 expensive.



 I would like to comment on your suggestion about Areo-Vee. This engine is a

 direct drive VW and there is a world of difference between a direct drive VW

 and a reduction drive engine. I flew a Great Plains direct drive VW for four

 years on my MKIII it pushed me along at 65MPH running 80% power and was a

 dog in a climb. The same size VW with a reduction drive pushes the same

 plane 75MPH at 60% power and climbs. The Jabaru engine is a slightly slower

 RPM engine but still turns way too many RPMs to turn a large enough prop to

 give a Kolb the spirited performance we have come to expect with a 912 or

 even a redrive VW.



 Rick Neilsen

 Redrive VW powered MKIIIc



 ---

j.codd(at)btopenworld.com
Guest

Posted: Mon Nov 19, 2007 3:29 am Post subject: 2 stroke vs 4 stroke

Hi Rick, here in the UK most of us run Jabiru 2200's with hydraulic lifters 

on our Mk3 Xtras and are well satisfied with the performance that we get, I 

run a Prince P tip wood/composite propellor on mine, Only one Xtra in the UK 

has a Rotax 912 to my knowledge and one has a Rotax 532 on it, I was 

wondering what the 'spirited performance' figures are that you say that you 

all get from a 912 or a re-drive VW in comparison to what we get from our 

Jabiru installations, I had thought sometime ago about a re-drive for the 

Jab, in fact I approached Valley Engineering to see if their re-drive could 

be adapted for the Jab, they sounded interested in the project but I haven't 

as yet taken it further, since that time I have fitted a Prince P tip 

propellor from your side of the pond and have seen a distinct improvement in 

performance, both climb and cruise and smoothness, as we have quite severe 

noise restrictions (we have to have a noise certificate issued by the CAA 

for every microlight engine/prop/aircraft combination) we do not usually 

prop for max rpm and aim for 2800/2900 with the Jab, this gives 100mph+ and 

1000+fpm climb, 2600 rpm gives a comfortable cruise around 80mph, if we do 

prop finer with a Prince P tip to 3300 max rpm we get substantially more 

performance but  exceed the noise levels that we are restricted to,  I will 

be interested to see the figures for a 912 or VW as we have no experience of 

these motors.

John Codd

Mk3Xtra/Jabiru2200/Prince P tip prop.



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John Hauck

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

Posted: Mon Nov 19, 2007 8:48 am Post subject: Re: 2 stroke vs 4 stroke

Morning John C:



 I am not aware of any direct drive engine, turning a small diamter prop, that will compete with a redrive engine that can turn a larger diameter prop at slower speeds.



Jabiru direct drive engines do not compare favorably with the 912UL and 912ULS powered Kolbs.   This is based on experience flying my 912ULS mkIII with John W's Jabiru powered Kolbra.  John W could answer your question much better than me, I am sure.  He repowered his Kolbra, some time ago, with a 912ULS and turned the performance chart completely around.



I can not speak for the Xtra, as I have very little experience flying that model.  For my particular mkIII, generally, it is an 85 mph cruise speed airplane no matter how much hp one tries to push it with.  This is based on flying it with a 582, 912UL, and a 912ULS.  I have always used  70" and 72" Warp Drive tapered three blade props with nickel leading edges with all three engines.  Climb is 1200 to 2000 fpm based on load and weather.  Normally, my max gross weight is 1000 to 1200 lbs.  Top speed is 95 mph for 65 to 95 hp (the 912ULS puts out 95 hp max continuous at 5,500 rpm which my engine is propped).  Based on weight and configuration of the mkIII xtra, I would make a WAG (wild ass guess)  that it is an 85 mph cruise aircraft also.



Cruise speed of the Jab powered Kolbra and my mkIII was about the same.  The 912ULS powered Kolbra is at least 10 mph faster.



Recommend you not fly a mkIII with a 912UL or 912ULS.  You will probably not want to go back to the Jab.



john h

mkIII - 2.700+ hours

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

NeilsenRM(at)comcast.net
Guest

Posted: Mon Nov 19, 2007 9:11 am Post subject: 2 stroke vs 4 stroke

John



I fly a ten year old MKIIIC so the comparisons are a bit difficult. My 

speeds are about 10 MPH less which is about the expected differences between 

the MKIIIC and the Xtra. I have never really done a climb test. I am very 

impressed with the figures you posted.



I flew with another Kolb that had a Jabiru on a Kolbra again not a good 

comparison but that plane when changed to a 912 was truly transformed. Also 

the New Kolb factory once offered the Jabiru on the MKIIIX in the USA and 

developed a light version of the plane to better fly with the reduced 

thrust. They have since dropped the Jabiru as a recommend option at least in 

the USA.



Prop selection can make a large impact on thrust and a plane's performance. 

It sounds like you have yours dialed in very well assuming you figures are 

accurate. I'm still working on getting my prop dialed in but even without 

the best prop tuning the performance is spirited.



Reduction drives are a pain but they do improve performance drastically. 

They would allow you to spin that Jabiru up to its rated power and keep the 

prop tip speed down where they don't turn horse power into noise. A long 

prop turns a greater percentage of a engines power into thrust just like a 

glider with long wings is more efficient.



Rick Neilsen

Redrive VW Powered MKIIIC



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