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Gemini Diesel engine

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nwcmc(at)tiscali.co.uk
Guest

Posted: Mon Nov 19, 2007 3:16 am Post subject: Gemini Diesel engine

This engine looks interesting especially as we may have a problem in the

future using unleaded due to the increased level of ethanol in unleaded.



Having read the links below I have a few comments to make.



1. A cruise power of 4.75gall/hr is not as impressive as I was hoping.

Even if we are talking US gallons this equates to about 19litres/hr. The

article quotes the Rotax 912 at 6.6gall/hr. This equates to

26.5litres/hr. The only time I see such a high fuel flow on my Rotax

912S is at full power. At cruise power I get 18litres/hr at 120kts. 



2. They quote a 2000hrs TBO whereas the Rotax is stated to be 1200hrs.

In the Europa we are running Rotax engines uncertified on condition. I

think that it is highly likely that many will exceed 1200hrs by a

considerable margin. When starting with a new engine, for many owners

this will provide 20 years at average useage.



2. Jet-A and diesel is without doubt a better fuel for the future.

However if there is not a significant benefit in fuel flow it must be

remembered that it is denser than unleaded or Avgas. In a Europa this

adds a weight penalty of about 12lbs for each tankful. We have yet to

see a complete installed weight of the Gemini engine. I suspect that it

will have a final weight penalty of at least 20lb over a Rotax. Remember

that it will probably need a higher capacity battery.



3. Matching the engine to a prop might be an issue. In the past other

engines have had torsional load problems which finally caused them to be

impractical.



4. The Europa was designed around the Rotax. So far we have had at least

6 attempts to change to another engine. These include Subaru, Mid West

rotary, Continental O-100, Wilksch, BMW and Jabiru. Only the Jabiru has

succeeded to any meaningful degree. Let's hope the Gemini will prove to

be different.

Nigel Charles



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fklein(at)orcasonline.com
Guest

Posted: Mon Nov 19, 2007 1:39 pm Post subject: Gemini Diesel engine

On Monday, Nov 19, 2007, at 03:14 US/Pacific, nigel charles wrote:



 	  Quote: 	
		   

 <nwcmc(at)tiscali.co.uk>



 This engine looks interesting especially as we may have a problem in 

 the

 future using unleaded due to the increased level of ethanol in 

 unleaded.



 The article quotes the Rotax 912 at 6.6gall/hr. This equates to

 26.5litres/hr. The only time I see such a high fuel flow on my Rotax

 912S is at full power. At cruise power I get 18litres/hr at 120kts.


	


Nigel,



Thanks for clarifying fuel burn...I noticed that 6.6 gph and it seemed 

higher than what most Europas are using.



 	  Quote: 	
		   We have yet to see a complete installed weight of the Gemini engine. I 

 suspect that it

 will have a final weight penalty of at least 20lb over a Rotax.


	


What do you peg the installed weight of your 912S?



 	  Quote: 	
		   Matching the engine to a prop might be an issue. In the past other

 engines have had torsional load problems which finally caused them to 

 be

 impractical.


	


One of the links I posted was to the DieselAir Newsletter which 

included the following comment:



 	  Quote: 	
		   DieselAir Comment: The Gemini is obviously a pursuit of the British 

 D-Air project: A scaled down Junkers Jumo diesel 2-stroke 

 Opposite-Piston engine, which has been flying for many years on a 

 Luscombe demonstrator.


	


If this is so, I would think the "torsional load" issue has been 

addressed. Does anyone know anything about the "British D-Air project"?



 	  Quote: 	
		   The Europa was designed around the Rotax. So far we have had at least

 6 attempts to change to another engine. These include Subaru, Mid West

 rotary, Continental O-100, Wilksch, BMW and Jabiru. Only the Jabiru has

 succeeded to any meaningful degree.


	


 	  Quote: 	
		   Let's hope the Gemini will prove to be different.


	


Amen to that!



For anyone interested, here's another link for additional info, 

drawings, and dimensions (click on pdf files):



	www.ppdgemini.com



Fred

A194

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jan.de.jong(at)xs4all.nl
Guest

Posted: Tue Nov 20, 2007 7:50 am Post subject: Gemini Diesel engine

1.

Even though PPD nowhere refers to Rotax it is not necessarily a 

coincidence that the width of the Gemini100 is to the millimeter 

identical to that of the Rotax 912/914: 576 mm.

Compared to Rotax 912:

depth is 31 mm less (912 starter motor sticking out), height below 

propellor axis is 18 mm less, height above propellor axis 12 mm more.

Compared to Rotax 914:

depth and height below/above propellor axis is less by several centimeters.

I wonder whether the engine attach point locations may just happen to be 

identical to those of Rotax.

2.

Gemini125 (turbo) may be more fuel-efficient than Gemini100.

3.

Battery weights may halve before too long. There seems to be quite rapid 

development of safe high current lithium-ion batteries.

See http://en.wikipedia.org/wiki/A123Systems

There are competitors.



All in all I am hopeful.

Maybe the slowness of my build will acquire a good reason after all.



Cheers,

Jan de Jong

#461

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fklein(at)orcasonline.com
Guest

Posted: Tue Nov 20, 2007 11:57 am Post subject: Gemini Diesel engine

On Tuesday, Nov 20, 2007, at 07:53 US/Pacific, Jan de Jong wrote:



 	  Quote: 	
		   1. I wonder whether the engine attach point locations may just happen 

 to be identical to those of Rotax.


	


Jan,



I asked PPD 3 questions regarding the Gemini 100/125; see #2; answers 

are as follows in italics:



 	  Quote: 	
		   1. Required fuel system: I have installed 5/16" i.d. fuel injection 

 hose to the R9 specification; will this serve the Gemini?

  The 5/16 I.D. fuel lines will not be an issue with the Gemini 100.



  2. Will engine mounting locations be compatible with those for the 

 Rotax 912S/914 engines?

 No the Gemini Engine will mount differently than a Rotax and require a 

 new Mount Frame.



  3. What is your anticipated time frame for getting the turbocharged 

 Gemini on the market?

 We expect to have the Gemini 125 available to the market in December 

 2008.


	


Fred

A194



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jan.de.jong(at)xs4all.nl
Guest

Posted: Tue Nov 20, 2007 1:54 pm Post subject: Gemini Diesel engine

Fred Klein wrote:

 	  Quote: 	
		  

      2. Will engine mounting locations be compatible with those for

     the Rotax 912S/914 engines*/?

     /*/No the Gemini Engine will mount differently than a Rotax and

     require a new Mount Frame/



Well, too bad. But it wouldn't be a simple dropin anyway. Maybe a UK 
	


builder and/or E2004 will take the lead if and when.



Further on the subject of lightweight batteries:

https://s.p10.hostingprod.com/(at)voltphreaks.com/ssl/catalog/



Not so cheap as yet, but available...



Jan de Jong

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