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I asked this in passing in another thread and it got lost in the chatter there, but I'd be interested to know...

 

Is it possible, physically and/or in terms of regulations, to hang a non-Jabiru engine off the front of a Jabiru? Like a Rotax 915, perhaps? UL Power? I'm assuming the aircraft would need to be amateur-built, and registered as VH experimental. But if that was done, does it mean there are workable choices in the engine department? If yes, has it ever been done, and if so how did it work out? Just wondering...

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There was a Jabiru with a Rotax engine a few years ago. I think the rotax is quite a bit heavier. There is more to this story than I know.

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I asked this in passing in another thread and it got lost in the chatter there, but I'd be interested to know...

 

Is it possible, physically and/or in terms of regulations, to hang a non-Jabiru engine off the front of a Jabiru? Like a Rotax 915, perhaps? UL Power? I'm assuming the aircraft would need to be amateur-built, and registered as VH experimental. But if that was done, does it mean there are workable choices in the engine department? If yes, has it ever been done, and if so how did it work out? Just wondering...

Use the search feature. Put in Rotax then by member Planesmaker. This will bring up all his posts and comments re Rotax in Jab. Cheers

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Looking at UL Power, they seem to be Jabiru type engines with the main differences being: a bit heavier, a bit more power, fuel injection as standard, (which has its pros and cons. )

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Is it possible, physically and/or in terms of regulations, to hang a non-Jabiru engine off the front of a Jabiru?

 

 

 

There is experimental LSA ie ELSA within RAA a from memory

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https://www.recreationalflying.com/threads/rotax-914-jabiru-j230.72438/

 

The 915 fuel burn concerns me. I'm unsure why such a high technology engine (turbo and fuel injected) uses so much fuel. 40 lph plus at WOT. Even the cruise figures are not flash.

Perhaps at 16 000 feet it becomes reasonable.

For range and economy, the 912iS or even the 914 runs rings around it if you don't need that ultimate power.

Edited by Downunder
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There is one Rotax 914 motivated Jab for sale, at the moment. I think this one is a 2 seat RAA registered aircraft (but not sure).

 

There is another Rotax 914 Jab, a 4 seater, so I assume GA experimental, based at Tumut. The owner of this aircraft waxes lyrical about its many great attributes (He also reads & contributes to this Forum)

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From a report on the 915......

 

The initial climb rate was almost 2,000fpm at 70kt which (bearing in mind the density altitude) was pretty respectable, while at 7,000ft MSL the increase in performance really was very noticeable. The turbocharger worked as advertised, with no discernible reduction in manifold pressure, and having trimmed forward and set ‘max cruise’ of 5,500rpm and 37 inches of manifold pressure the IAS soon settled on 135kt for a TAS of 150 while burning 34-35 lit/hr.

 

Pretty impressive numbers, and although if you’re a long-term Rotax pilot you might be thinking that 35 lit/hr is quite thirsty, I’d counter that 150kt TAS is quite fast! Pull the power back a long way to say 4,800rpm and seventeen inches, and the engine is now just barely sipping litres per hour at 80kt TAS, while a good compromise (Bristell call it the ECO setting) of 5,000rpm and 36ins of manifold pressure still give a TAS of around 145kt at 7,000ft AMSL.

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The Rotax literature says 135HP max continuous at 5500rpm. 33-34 liters/hour at 135HP is actually pretty good. My O-320 runs 29-30 lph at 110HP.

 

Rotax 915 would be interesting in a BD-4.

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why would you want to put a rotax or a ul motor in one with the reliability of the Jab gen 4 engine anyway? Someone please tell me if they have heard anything but good reports on these engines. ( and please, truthful fact, not just something someone heard from his mates brothers, sons, girlfriends, stepdads LAME over in some hanger at who knows where.)

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why would you want to put a rotax or a ul motor in one with the reliability of the Jab gen 4 engine anyway? Someone please tell me if they have heard anything but good reports on these engines. ( and please, truthful fact, not just something someone heard from his mates brothers, sons, girlfriends, stepdads LAME over in some hanger at who knows where.)

True my observation is subjective, however I find my Rotax 912 ULS to be comparatively (to other aircraft engines) smooth running , low noise, lowish prop speed, low oil & fuel consumption. The only down side for me, is the initial high purchase cost, offset a little by the low running costs. I have no experience of the Jab Gen 4

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Each Jabiru airframe is well matched to the Jab engines fitted to them. That's how they are built. I'd think long and hard before changing the engine. It's a free country tho (maybe). .When you are operating to strict weight limits any extra weight is a penalty you carry constantly. Nev

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There is also a J430 for sale with the R914 turbo engine and in flight ajustable prop. The owner did some rerouting of the fuel system (the Rotax engine has a fuel return system) and it apparently performs very well. Also there needed to be a few Kg's added to the tail and apparently it flies well and is under experimental category.

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How it would recover from a spin is another matter. Weight at the tail predisposes a plane to flat spin more readily and no doubt THAT has not been tested. Nev

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How it would recover from a spin is another matter. Weight at the tail predisposes a plane to flat spin more readily and no doubt THAT has not been tested. Nev

Good point, Nev. In an effort to make it more reliable, they might have thrown away some of the impressive safety advantage of the Jabiru airframe. One year at Narromine an ex-RAAF test pilot told us about doing 80 spin tests in various configurations in just one Jab model.

I doubt they tested for a heavier engine with matching lead in the tail...

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I put a 912ULS into a 160. Worked fine, although the arithmetic was bananas.

 

I can provide all the (Oz) paperwork to anyone who is interested. I dealt with the W/B thing by moving the battery from the firewall to behind the luggage space. That was not on the paperwork. Numbers all worked good .... not sure if you would be allowed to do that in Oz.

 

It is ZK-BGY

ZK-CPA is a J200 with a 912ULS and an Idrovario CS prop

 

BGY started life as actually a 24-regd aircraft so changing the engine required lots of paperwork, but it all got done. I bought it from the Adelaide Soaring Club with a 1000-hour engine that was running fine and had had a valve grind. Was actually pretty stuffed.

 

I purchased a copy of the Oz paperwork and used it as the basis for my conversion in (the less rule-bound) NZ microlight world. Had silly stuff like "engine revs must be limited to 5000" in it. It's the plane in my picture.

 

FWIW

 

"The modification was done in 2010 on a similar aircraft in Australia owned by Paul Crowfoot. After an initial test flying period of 50-odd hours, the aircraft has accumulated about 650 trouble-free hours in a flight training environment.It is a factory-built J160C (serial #80). ZK-BGY is a factory-built J160C serial #127. (This was in 2013)

 

The modification is documented in a CASA Engineering Order raised by Southdown Engineering Ltd. Southdown was operated by Dafydd Llewellyn (a CAR35 design engineer now retired). It was the equivalent of a NZ Part 146 design organisation. The detailed work was done by Bob Llewellyn working for Southdown through his organization Bob Llewellyn Designs Ltd (BLD). The material in this document is from BLD.

 

The modification is specified in a CASA Engineering Order (EO), which is roughly equivalent to a NZ CAA 337. It is signed off For LSAs (like the J160) CASA delegates the signoff authority for EOs to CAR35 engineers."

 

Go figure .....

Edited by ianboag
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Of course it can be done but you move weight around further back. The Jab 6 is certainly heavier than the 4 which is a very light engine. The Jab 6 is 120 hp which is more than a 912uls I better prop would even things up if you want to spend $$$'s Nev

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  • 3 weeks later...

I recall seeing a Jab here in W.A. with a Smart car engine.

 

Crikey, I wouldn't have expected that as a choice of aircraft engine. I just looked up specs for the Smarts, and looks like there was an 800cc diesel and a 1-litre petrol., with and without turbo. None of them would exactly give neck-snapping performance, I suspect. It would be interesting to know how that turned out.

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