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Rotax Engine Alternatives - Aeromomentum

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graemeh

Joined: 15 Jun 2017
Posts: 17

Posted: Thu Jul 13, 2017 8:06 pm Post subject: Rotax Engine Alternatives - Aeromomentum

Hi All

I'm starting to look at engine options for my XS Trigear.

Rotax 912 ULS looks a great option (factory supported and well understood) apart from the cost.

Aeromomentum claim they have a 100hp engine that is only 5 pounds heavier than a Rotax 912 ULS and lighter than a 914.Â  Claimed TBO is 1500 hours.

The conversion is based on a new Suzuki engine and has fuel injection so no carb balancing required.

I understand the Europa is quite sensitive to engine weight but as there are quite a few 914 powered machines and this is lighter than a 914 then it should be OK.

I'd appreciate hearing from anyone with any experience with Aeromomentum or with Europa experience with non Rotax engines.





Thanks



Graeme

peterz(at)zutrasoft.com
Guest

Posted: Fri Jul 14, 2017 1:24 am Post subject: Rotax Engine Alternatives - Aeromomentum

Im watching this thread with great interest 



Cheers,

Pete 

A239



 	  Quote: 	
		   On Jul 14, 2017, at 12:06 AM, Graeme Hart <graeme.hart(at)onecoolkat.com> wrote:

 

 Hi All

 

 I'm starting to look at engine options for my XS Trigear.

 

 Rotax 912 ULS looks a great option (factory supported and well understood) apart from the cost.

 

 Aeromomentum claim they have a 100hp engine that is only 5 pounds heavier than a Rotax 912 ULS and lighter than a 914.  Claimed TBO is 1500 hours.

 

 The conversion is based on a new Suzuki engine and has fuel injection so no carb balancing required.

 

 I understand the Europa is quite sensitive to engine weight but as there are quite a few 914 powered machines and this is lighter than a 914 then it should be OK.

 

 I'd appreciate hearing from anyone with any experience with Aeromomentum or with Europa experience with non Rotax engines.

 

 

 

 Thanks

 Graeme

graemeh

Joined: 15 Jun 2017
Posts: 17

Posted: Fri Jul 14, 2017 1:33 am Post subject: Rotax Engine Alternatives - Aeromomentum

I forgot to mention I am in New Zealand so LAA paperwork is not a factor in my decision.Â 



On Fri, 14 Jul 2017, 21:27 Pete <peterz(at)zutrasoft.com (peterz(at)zutrasoft.com)> wrote:



 	  Quote: 	
		  --> Europa-List message posted by: Pete <peterz(at)zutrasoft.com (peterz(at)zutrasoft.com)>

 

 Im watching this thread with great interest 

 

 Cheers,

 Pete

 A239

 

 > On Jul 14, 2017, at 12:06 AM, Graeme Hart <graeme.hart(at)onecoolkat.com (graeme.hart(at)onecoolkat.com)> wrote:

 >

 > Hi All

 >

 > I'm starting to look at engine options for my XS Trigear.

 >

 > Rotax 912 ULS looks a great option (factory supported and well understood) apart from the cost.

 >

 > Aeromomentum claim they have a 100hp engine that is only 5 pounds heavier than a Rotax 912 ULS and lighter than a 914.Â  Claimed TBO is 1500 hours.

 >

 > The conversion is based on a new Suzuki engine and has fuel injection so no carb balancing required.

 >

 > I understand the Europa is quite sensitive to engine weight but as there are quite a few 914 powered machines and this is lighter than a 914 then it should be OK.

 >

 > I'd appreciate hearing from anyone with any experience with Aeromomentum or with Europa experience with non Rotax engines.

 >

 >

 >

 > Thanks

 > Graeme

 

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JonathanMilbank

Joined: 14 Apr 2012
Posts: 390
Location: Aberdeen area

Posted: Fri Jul 14, 2017 2:09 am Post subject: Re: Rotax Engine Alternatives - Aeromomentum

Hello Graeme,



Having looked at their website, I can't avoid the impression that it "looks" heavy. I've read their explanation of comparisons with other engines, yet the fact that there are no cylinder cooling fins makes me wonder.



The engine which interests me quite a lot is the 6 cylinder D-Motor, although there doesn't seem to be enough information or history, at least not that I can find. But the combination of side-valve and modern technology seems a great concept for aircraft applications.



I'll also watch Aeromomentum with interest.

Richard Lamprey

Joined: 15 Jul 2011
Posts: 95
Location: Kenya

Posted: Sat Jul 15, 2017 2:44 am Post subject: Re: Rotax Engine Alternatives - Aeromomentum

Graeme,

In regards to engines, I think it all boils down to how many headaches you want to give yourself before you actually fly your Europa.  In changing from the 'normal' type of engine (Rotax 912 range) to one that has not been tested, certified in a Europa somewhere else will give you so many problems that your head will spin... engine mounts, new cowlings, cooling problems, propeller types, not to mention of the miles of paperwork for/ with your regulator.  The small savings you may make on the engine cost will be gobbled up, 5 times, by all these issues above.  But if you want to be part of the R&D, by all means give it a go... !

Richard

Classic Monowheel, Rotax 912UL, 5Y-LRY, Kenya

houlihan(at)blueyonder.co
Guest

Posted: Sat Jul 15, 2017 3:04 am Post subject: Rotax Engine Alternatives - Aeromomentum

I concur with Richard, , a new engine installation can be done and may turn out to be an improvement , developing new ideas is essential all our installations were new once. 

BUT as Richard suggests it will inevitably take longer than first thought and my in the end have insurmountable problems , I know of more than one installation that could not be made to work due to torsional vibration that would possibly require a redesign of major engine components. I also know of a successful installation that is now working well but took ten years of steady development to make it work and it is still a "one off" with all that entails.

Do go ahead if you want to develop this system but if you want to fly your aeroplane sooner take the easy way otherwise all the development time and money will be on your shoulders.

Tim

G-BZTH a simple basic Classic with a 912 ul  	  Quote: 	
		  

On 15 July 2017 at 11:44 Richard Lamprey <lamprey.richard(at)gmail.com> wrote:

--> Europa-List message posted by: "Richard Lamprey" <lamprey.richard(at)gmail.com>



Graeme,

In regards to engines, I think it all boils down to how many headaches you want to give yourself before you actually fly your Europa. In changing from the 'normal' type of engine (Rotax 912 range) to one that has not been tested, certified in a Europa somewhere else will give you so many problems that your head will spin.. engine mounts, new cowlings, cooling problems, propeller types, not to mention of the miles of paperwork for/ with your regulator. The small savings you may make on the engine cost will be gobbled up, 5 times, by all these issues above. But if you want to be part of the R&D, by all means give it a go... !

Richard

Classic Monowheel, Rotax 912UL, 5Y-LRY, Kenya

rlborger(at)mac.com
Guest

Posted: Sat Jul 15, 2017 10:35 am Post subject: Rotax Engine Alternatives - Aeromomentum

Graeme,



I concur with the commentary by others warning of very long term project to implement a non-supported engine.  Unless the vendor has already designed and built engine mounts, cowling molds, electrical system, fuel system, cooling system and power train you will be the development and test item for him.  



You can buy all the necessary elements for a successful engine installation and be flying quickly or you can spend years (decades?) trying to develop them yourself.  If you want to become an aeronautical engineer, go for it.  If you want to build and fly your Europa, go for the Rotax or other supported engine.



Blue skies & tailwinds,

Bob Borger

Europa XS Tri, Rotax 914, Airmaster C/S Prop (75 hrs).

Little Toot Sport Biplane, Lycoming Thunderbolt AEIO-320 EXP

3705 Lynchburg Dr.

Corinth, TX  76208-5331

Cel: 817-992-1117

rlborger(at)mac.com



On Jul 13, 2017, at 11:06 PM, Graeme Hart <graeme.hart(at)onecoolkat.com> wrote:



Hi All



I'm starting to look at engine options for my XS Trigear.



Rotax 912 ULS looks a great option (factory supported and well understood) apart from the cost.



Aeromomentum claim they have a 100hp engine that is only 5 pounds heavier than a Rotax 912 ULS and lighter than a 914.  Claimed TBO is 1500 hours.



The conversion is based on a new Suzuki engine and has fuel injection so no carb balancing required.



I understand the Europa is quite sensitive to engine weight but as there are quite a few 914 powered machines and this is lighter than a 914 then it should be OK.



I'd appreciate hearing from anyone with any experience with Aeromomentum or with Europa experience with non Rotax engines.



Thanks

Graeme

wdaniell.longport(at)gmai
Guest

Posted: Sat Jul 15, 2017 1:27 pm Post subject: Rotax Engine Alternatives - Aeromomentum

I concurr with all comments...i looked at the subaru options but changed my mind after some very strong recommendations from the forum.



On Jul 15, 2017 06:46, "Richard Lamprey" <lamprey.richard(at)gmail.com (lamprey.richard(at)gmail.com)> wrote: 	  Quote: 	
		  --> Europa-List message posted by: "Richard Lamprey" <lamprey.richard(at)gmail.com (lamprey.richard(at)gmail.com)>

 

 Graeme,

 In regards to engines, I think it all boils down to how many headaches you want to give yourself before you actually fly your Europa.Â  In changing from the 'normal' type of engine (Rotax 912 range) to one that has not been tested, certified in a Europa somewhere else will give you so many problems that your head will spin... engine mounts, new cowlings, cooling problems, propeller types, not to mention of the miles of paperwork for/ with your regulator.Â  The small savings you may make on the engine cost will be gobbled up, 5 times, by all these issues above.Â  But if you want to be part of the R&D, by all means give it a go... !

 Richard

 Classic Monowheel, Rotax 912UL, 5Y-LRY, Kenya

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=471013#471013

 

 

 

 

 

 

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gilles.thesee(at)free.fr
Guest

Posted: Sat Jul 15, 2017 3:15 pm Post subject: Rotax Engine Alternatives - Aeromomentum

Le 15/07/2017 à           20:34, Robert Borger a écrit :

         

      	  Quote: 	
		          	  Quote: 	
		  

You can buy all the necessary elements for a successful engine installation and be flying quickly or you can spend years (decades?) trying to develop them yourself. 	
     	
     

     Hi Graeme and all,

     

     It is very difficult to develop a reliable and successful PSRU with     a 4 cylinder engine.

     If this new engine had succeeded, no doubt they would mention it     with pride. The fact that they just casually talk about it might     indicate they did not spend much time designing and developing it.

     Be prepared to help develop the engine and its reduction unit as     well.

     -- 

       Best regards,

       Gilles

       http://contrails.free.fr

       http://lapierre.skunkworks.free.fr

peterz(at)zutrasoft.com
Guest

Posted: Sat Jul 15, 2017 6:06 pm Post subject: Rotax Engine Alternatives - Aeromomentum

I agree that the PSRU is the biggest issue with any auto conversion due to resonance issues, and why I would not buy a Viking, as Egenfeller is not an engineer and is continually developing his installations at his customer's expense.  I still awaiting a gearbox faliure due to Viking 100% reliance on a chopped up Mercedes rubber coupling.

I chatted with the Aeromomentum folks at last years Osh, and will watch to see how his gearbox solution holds up over the longer term.

The neatest pipedream I could figure would be add diesel to the wings in addition to the main tank and throw in one of these .... can you say smoooooooooth?

https://www.turb.aero/ta120tp-turboprop

I'll be watching closely to see how they deal with the materials science demands of a turbine. Their efficiency isn't bad for a TP .... using regen to help.

Im planning on chatting with the principles of the company at Osh to see what their plans are.   Would that be too cool though?

Failing all the above, my stretch goal will be the 915is .... I wonder what kind of performance numbers the Europa would get with this...

Cheers,

Pete



On Jul 15, 2017, at 7:15 PM, GTH <gilles.thesee(at)free.fr (gilles.thesee(at)free.fr)> wrote:

 	  Quote: 	
		                     Le 15/07/2017 Ã            20:34, Robert Borger a Ã©crit :

         

      	  Quote: 	
		          	  Quote: 	
		  

You can buy all the necessary elements for a successful engine installation and be flying quickly or you can spend years (decades?) trying to develop them yourself. 	
     	
     

     Hi Graeme and all,

     

     It is very difficult to develop a reliable and successful PSRU with     a 4 cylinder engine.

     If this new engine had succeeded, no doubt they would mention it     with pride. The fact that they just casually talk about it might     indicate they did not spend much time designing and developing it.

     Be prepared to help develop the engine and its reduction unit as     well.

     -- 

       Best regards,

       Gilles

       http://contrails.free.fr

       http://lapierre.skunkworks.free.fr

John Wighton

Joined: 18 May 2010
Posts: 241

Posted: Sun Jul 16, 2017 3:00 am Post subject: Re: Rotax Engine Alternatives - Aeromomentum

With all due respect putting a new engine into an existing airframe is the job for a professional aerospace engineer (Co) - for a light aircraft (non-certified) this might take 3-4 years and gobble up around Â£200k of funds.  Success is thereafter not guaranteed. At some point you will need to negotiate the authorities.  



My experience is the lower down the food chain the local authority is the more finickity they are.  Our LAA is now hobbled with a CAA A8-26 organisation approval, which they seem to interpret as needing to add an additional layer of conservatism (and possibly suspicion) to everything they deal with.  They are all sterling chaps, just doing a job, but the iterative process of making MOD/design submissions to them can try the patience - especially for those of us who deal direct with EASA, the CAA and other organisations who hold their own DOA/POA or hold Form 4 posts themselves.



The Europa is a brilliant aeroplane that performs fantastically well on a Rotax 912S. My advice is to bite the bullet (sign the cheque), buy the Rotax and get into the air as soon as you can.

_________________
John Wighton
Europa XS trigear G-IPOD

peterz(at)zutrasoft.com
Guest

Posted: Sun Jul 16, 2017 4:01 am Post subject: Rotax Engine Alternatives - Aeromomentum

Agreed, but in in NA it is indeed under the domain of "amateur built *experimental* aircraft".  Here in Canada i could legally even strap on jet engines and as long as it meets the build 549 standards, im good to go with a normal rec license...... as long as i could find a company to insure the monstrosity   



Not saying its right or wrong, just continentally different.  



Cheers,

Pete 



 	  Quote: 	
		   On Jul 16, 2017, at 7:00 AM, John Wighton <john(at)wighton.net> wrote:

 

 

 

 With all due respect putting a new engine into an existing airframe is the job for a professional aerospace engineer (Co) - for a light aircraft (non-certified) this might take 3-4 years and gobble up around Â£200k of funds.  Success is thereafter not guaranteed. At some point you will need to negotiate the authorities.  

 

 My experience is the lower down the food chain the local authority is the more finickity they are.  Our LAA is now hobbled with a CAA A8-26 organisation approval, which they seem to interpret as needing to add an additional layer of conservatism (and possibly suspicion) to everything they deal with.  They are all sterling chaps, just doing a job, but the iterative process of making MOD/design submissions to them can try the patience - especially for those of us who deal direct with EASA, the CAA and other organisations who hold their own DOA/POA or hold Form 4 posts themselves.

 

 The Europa is a brilliant aeroplane that performs fantastically well on a Rotax 912S. My advice is to bite the bullet (sign the cheque), buy the Rotax and get into the air as soon as you can.

 

 --------

 John Wighton

 Europa XS trigear G-IPOD

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=471039#471039

John Wighton

Joined: 18 May 2010
Posts: 241

Posted: Sun Jul 16, 2017 11:13 am Post subject: Re: Rotax Engine Alternatives - Aeromomentum

Believe it or not the engineering activity surrounding fitting a new engine, including the challenges mentioned by the other forum contributors (engine mounts, props, vibration, fuel systems, etc etc) - these things HAVE to be tackled whether you deal with the LAA or not.  



The reasons why these things are important don't just get diluted all because you CAN just strap on a new motor and go fly.  To engineer a robust, safe and long term powerplant solution into a light aircraft  requires knowledge, training and experience.  People who are successful either possess these attributes or acquire them on the way.  There is no short cut (aside from your buddies chipping in, which is the same thing).



Fortunately the insurance companies in Canada and the USA have their heads screwed on and will evaluate risk based on the aforementioned attributes, alongside pilot experience, etc.



I am not trying to kill innovation, just giving you a heads up on the probable pitfalls and issues that building a Europa with a new powerplant may bring.



Safe flying.

_________________
John Wighton
Europa XS trigear G-IPOD

peterz(at)zutrasoft.com
Guest

Posted: Sun Jul 16, 2017 1:07 pm Post subject: Rotax Engine Alternatives - Aeromomentum

Thankfully not all EAA'ers are apparently incompetent 



I have a solid engineering background as do many others who do enjoy the systems engineering challenges.  Add those to incredibly tight packaging constraints and my humelbird 1/2vw fwf  installation was fun indeed. 



Lets not kill the spirit of innovation for the sake of argument. Those happy with the bolt it in blindly rotax path (and there are even shortcomings with that) shouldn't dissuade others.



Oh, btw, my hummel costs all of 200$ cdn annually to insure 



Cheers and blue skies!

Pete

A239

 	  Quote: 	
		   On Jul 16, 2017, at 3:13 PM, John Wighton <john(at)wighton.net> wrote:

 

 

 

 Believe it or not the engineering activity surrounding fitting a new engine, including the challenges mentioned by the other forum contributors (engine mounts, props, vibration, fuel systems, etc etc) - these things HAVE to be tackled whether you deal with the LAA or not.  

 

 The reasons why these things are important don't just get diluted all because you CAN just strap on a new motor and go fly.  To engineer a robust, safe and long term powerplant solution into a light aircraft  requires knowledge, training and experience.  People who are successful either possess these attributes or acquire them on the way.  There is no short cut (aside from your buddies chipping in, which is the same thing).

 

 Fortunately the insurance companies in Canada and the USA have their heads screwed on and will evaluate risk based on the aforementioned attributes, alongside pilot experience, etc.

 

 I am not trying to kill innovation, just giving you a heads up on the probable pitfalls and issues that building a Europa with a new powerplant may bring.

 

 Safe flying.

 

 --------

 John Wighton

 Europa XS trigear G-IPOD

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=471061#471061

AirEupora

Joined: 01 Nov 2009
Posts: 186
Location: Dixon, CA

Posted: Sun Jul 16, 2017 3:17 pm Post subject: Re: Rotax Engine Alternatives - Aeromomentum

I'd think long and hard about going to a different engine combination.  Those of us who have put a different engine on, had a lot of extra work.  I put a Jabiru on mine,  It came with an engine mount and cowling.  The first engine mount was the wrong one,  the cowling had to be modified to fit correctly, the shape was wrong for the oil cooler and there no draw to put air out of the cowl.  The Jabiru plenum chambers didn't fit correctly and had to be modified a lot.  There was no customer support as the gentleman that  I it bought from went out of business and the factory was 12,000 miles away and about ten time zones.  The engine was cheaper, but weigh 54 lbs. more than the Rotax 912,  The Jabiru was $18.7K Rotax 912 was $24K.   I use about 1.5 gallons more per hour than the 912 going the same speed.



I have had four years of headaches,  Just now, I almost have a good flying plane.  That 54lbs, when I bough it.  I didn't think to much about it, but now having gained 40 lbs,  My plane is a 1/1/2 person plane.



Build it light and keep it light

peterz(at)zutrasoft.com
Guest

Posted: Sun Jul 16, 2017 5:55 pm Post subject: Rotax Engine Alternatives - Aeromomentum

Indeed a new installation is alot of work....no question.  Sadly the jabiru engines have always been under performers with many technical issues. There are however very well designed alternatives, such as the ULpower engines. If the smaller UL was turbo-normalized to 130hp (design rating of the longer stroke derivative - same heads), with inverted oil, it would be a strong alternative to the rotax, with less complexity.



The D-motor is also an intriguing design, with minimized parts count and light weight....although they will likely end up on the trash heap of other designs such as the gemini junker diesel after being squashed by rotax.



The only point i am trying to make is that there are potential alternatives.  My perfect engine would be the 915iS......if one can ignore/tolerate rotax's part price gouging policies.



Cheers and blue skies,

Pete



 	  Quote: 	
		   On Jul 16, 2017, at 7:17 PM, AirEupora <AirEupora(at)sbcglobal.net> wrote:

 

 

 

 I'd think long and hard about going to a different engine combination.  Those of us who have put a different engine on, had a lot of extra work.  I put a Jabiru on mine,  It came with an engine mount and cowling.  The first engine mount was the wrong one,  the cowling had to be modified to fit correctly, the shape was wrong for the oil cooler and there no draw to put air out of the cowl.  The Jabiru plenum chambers didn't fit correctly and had to be modified a lot.  There was no customer support as the gentleman that  I it bought from went out of business and the factory was 12,000 miles away and about ten time zones.  The engine was cheaper, but weigh 54 lbs. more than the Rotax 912,  The Jabiru was $18.7K Rotax 912 was $24K.   I use about 1.5 gallons more per hour than the 912 going the same speed.

 

 I have had four years of headaches,  Just now, I almost have a good flying plane.  That 54lbs, when I bough it.  I didn't think to much about it, but now having gained 40 lbs,  My plane is a 1/1/2 person plane.

 

 Build it light and keep it light

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=471077#471077

graemeh

Joined: 15 Jun 2017
Posts: 17

Posted: Wed Jul 19, 2017 2:37 am Post subject: Re: Rotax Engine Alternatives - Aeromomentum

Thank you to everyone who has contributed to this discussion via this forum or directly to me via email.



I particularly appreciate hearing from those who have tried an alternative installation.



If money were no object I'd just buy the Rotax.  I realise that installing an alternative engine will be more work and take more time.  My challenge is to assess the extra build time vs how long it would take me to save for the Rotax and also add in a risk factor to allow for the extra risk in going for an alternative engine.



There are a number of positives with the Aeromomentum engine:

* The designers are engineers

* In one of his videos the subject of torsional vibration is addressed

* When I asked Aeromomentum about using the engine on a Europa Mark checked the Europa build manual for the engine install before replying - the man does his research

* Aeromomentum have been around for a number of years, starting with jetboats then moving to airboats and finally aircraft.  One of their airboat engines lasted to 4,000 hours before lack of maintenance finally broke it



Also as I'm in NZ I have ready access to Airmaster so I am confident that an appropriate Prop will not be an issue.



Fortunately I'm in the position where I won't at the point of having to decide on an engine for a little while so I can continue to watch engine developments before I make my decision.



Thanks again for all who have contributed and I'd appreciate hearing further from anyone with direct experience in using alternative engines (on a Europa or other aircraft).



 	  peterz(at)zutrasoft.com wrote: 	
		  Indeed a new installation is alot of work....no question.  Sadly the jabiru engines have always been under performers with many technical issues. There are however very well designed alternatives, such as the ULpower engines. If the smaller UL was turbo-normalized to 130hp (design rating of the longer stroke derivative - same heads), with inverted oil, it would be a strong alternative to the rotax, with less complexity.



The D-motor is also an intriguing design, with minimized parts count and light weight....although they will likely end up on the trash heap of other designs such as the gemini junker diesel after being squashed by rotax.



The only point i am trying to make is that there are potential alternatives.  My perfect engine would be the 915iS......if one can ignore/tolerate rotax's part price gouging policies.



Cheers and blue skies,

Pete



 	  Quote: 	
		   On Jul 16, 2017, at 7:17 PM, AirEupora <AirEupora> wrote:

 

 

 

 I'd think long and hard about going to a different engine combination.  Those of us who have put a different engine on, had a lot of extra work.  I put a Jabiru on mine,  It came with an engine mount and cowling.  The first engine mount was the wrong one,  the cowling had to be modified to fit correctly, the shape was wrong for the oil cooler and there no draw to put air out of the cowl.  The Jabiru plenum chambers didn't fit correctly and had to be modified a lot.  There was no customer support as the gentleman that  I it bought from went out of business and the factory was 12,000 miles away and about ten time zones.  The engine was cheaper, but weigh 54 lbs. more than the Rotax 912,  The Jabiru was $18.7K Rotax 912 was $24K.   I use about 1.5 gallons more per hour than the 912 going the same speed.

 

 I have had four years of headaches,  Just now, I almost have a good flying plane.  That 54lbs, when I bough it.  I didn't think to much about it, but now having gained 40 lbs,  My plane is a 1/1/2 person plane.

 

 Build it light and keep it light

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=471077#471077

gilles.thesee(at)free.fr
Guest

Posted: Wed Jul 19, 2017 8:11 am Post subject: Rotax Engine Alternatives - Aeromomentum

Le 19/07/2017 à 12:37, graemeh a écrit :

 	  Quote: 	
		   I realise that installing an alternative engine will be more work and take more time.  My challenge is to assess the extra build time vs how long it would take me to save for the Rotax and also add in a risk factor to allow for the extra risk in going for an alternative engine.



 [...]

 Thanks again for all who have contributed and I'd appreciate hearing further from anyone with direct experience in using alternative engines (on a Europa or other aircraft).

Graeme and all,
	




As one who made an alternative engine *installation* albeit with a 

proven engine, I hope you'll allow me to express my opinion 

Devising a correct engine installation from scratch is not really the 

problem. It takes time, research an lots of common sense, you'll find 

lots of info on Contrails !



The problem is with those alternative engines. The best way would be to 

interview several knowledgeable people with direct experience of a 

working installation, and a few hundred (preferably thousand) happy 

engine flight hours in their logbook.

But if those people did exist, then we would not be talking about an 

*alternative* engine, but about a *proven* engine.



Bottom line, if you have time and money, and are eager to help develop 

the engine, by all means go for it. You'll be a pioneer, have lots of 

fun, learn lots of things, and discover there is no substitute for 

thousands of engineer hours, test cell time, destroyed engines, and 

thousands of flight hours before you achieve a reliable aero engine.



But don't trust the degree on the wall, the videos and the "we addressed 

the torsional" blah blah. Ask for the blueprints, the actual number of 

engines actually flying, the address of actual users atctually flying 

the engine, study the Service Bulletins - if there are none, caveat 

emptor, the engine has no flight experience.



On the other hand, if money, or time, or workshop equipment is key, then 

go for a Rotax (even a second hand one), devise a correct cooling 

installation, and you'll soon be a member of the happy flyer-builder family.



FWIW

-- 

Best regards,

Gilles

http://contrails.free.fr

http://lapierre.skunkworks.free.fr

peterz(at)zutrasoft.com
Guest

Posted: Thu Jul 20, 2017 11:18 am Post subject: Rotax Engine Alternatives - Aeromomentum

I have no first hand experience, but have been watching these auto conversions for many years.  My conclusion is that the gearbox is always the weakest link. The Honda fit core for example is an amazingly durable engine (also used in their outboard marine engines).  The issue with the geared engines is one of harmonic resonance - but contrary to what most think the issue is not when loaded, but rather when the prop is unloaded - typically at idle or on approach.  Regardless of the engine's HP, when resonance feedback peaks it can be very destructive, needing to dissipate possibly hundreds of HP to dampen it back down.  The simple rubber isolators used by Viking (and also aeromomentum) are IMHO totally inadequate...... indicated finally by a VIking in-flight failure (I expect more to come).   Rotax have dealt with the issue using dog-clutches etc., a high idle and other tricks?  Could it be that the airboat application mentioned is different in that the engine is either at idle (normally set above the resonance frequency to avoid the issue) or high power.... no approach-no-prop-load conditions.

I concur that if one is only looking to save money:  don't - go with the rotax, or a direct-drive non-geared engine, it will be cheaper in the long-run (no bent airplane parts).  As others have already mentioned an auto-conversion is an exercise in engineering ... which can be a fun and rewarding effort.

Cheers,

Pete

A239

PS - Looks as if the D-Motor folks are getting their act together and will soon have a very nice liquid cooled, light, direct drive, simple, durable engine - the 6cyl will be about equivalent to the 914 (tho not normalized obviously).

PPS- At osh now.... the place is looking good and the weather is great. B52 just landed. Don't forget to drop by and grab a beer/pop 

 	  Quote: 	
		   On Jul 19, 2017, at 11:11 AM, GTH <gilles.thesee(at)free.fr> wrote:

> Le 19/07/2017 Ã  12:37, graemeh a Ã©crit :

> I realise that installing an alternative engine will be more work and take more time.  My challenge is to assess the extra build time vs how long it would take me to save for the Rotax and also add in a risk factor to allow for the extra risk in going for an alternative engine.

> 

> [...]

> Thanks again for all who have contributed and I'd appreciate hearing further from anyone with direct experience in using alternative engines (on a Europa or other aircraft).

 Graeme and all,

 As one who made an alternative engine *installation* albeit with a proven engine, I hope you'll allow me to express my opinion 

 Devising a correct engine installation from scratch is not really the problem. It takes time, research an lots of common sense, you'll find lots of info on Contrails !

 The problem is with those alternative engines. The best way would be to interview several knowledgeable people with direct experience of a working installation, and a few hundred (preferably thousand) happy engine flight hours in their logbook.

 But if those people did exist, then we would not be talking about an *alternative* engine, but about a *proven* engine.

 Bottom line, if you have time and money, and are eager to help develop the engine, by all means go for it. You'll be a pioneer, have lots of fun, learn lots of things, and discover there is no substitute for thousands of engineer hours, test cell time, destroyed engines, and thousands of flight hours before you achieve a reliable aero engine.

 But don't trust the degree on the wall, the videos and the "we addressed the torsional" blah blah. Ask for the blueprints, the actual number of engines actually flying, the address of actual users atctually flying the engine, study the Service Bulletins - if there are none, caveat emptor, the engine has no flight experience.

 On the other hand, if money, or time, or workshop equipment is key, then go for a Rotax (even a second hand one), devise a correct cooling installation, and you'll soon be a member of the happy flyer-builder family.

 FWIW

 -- 

 Best regards,

 Gilles

 http://contrails.free.fr

 http://lapierre.skunkworks.free.fr

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