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TOPIC: Future Improvements

Future Improvements 1 year 3 weeks ago #528

  • Harry Smithard
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Hi guys

I'm a proud owner of a J120 and absolutely love this little plane.

I have noticed that the LSA industry is moving towards turbocharged engines and reflexed flaps to get that last bit of speed and altitude performance. Has Jabiru considered some of these options?

I,d be interested to hear everyone's thoughts

Regards
Harry

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Future Improvements 1 year 2 weeks ago #529

Hi Harry,
Glad to hear you're enjoying the 120... I've a bit of a soft spot for those myself!

The LSA regs in most countries limit the stall speed for the aircraft in the clean (no flap) configuration. Generally speaking there's no way to achieve that sort of stall speed other than to have a thumping big wing... which of course was the intent of the people writing the rules: for a given aircraft weight, the bigger the wing the slower the cruise speed and the slower the speed the lower the energy and the lower the energy the safer the aircraft are in a crash; one of the cornerstones of LSA categories. Of course you can fiddle around the edges with clever wing sections (and wing plans), variable props and reflexing flaps but it's a case of diminishing rewards; I'm reminded of the old racing truism - "How fast do you want to spend?" And that spend might be engine life, payload, real-world practicality, operational complexity, toughness or even just old-fashioned money.

From a technical point of view, reflexing flaps wouldn't work terribly well on a Jabiru wing; used correctly in the right circumstances they would give a handful of knots - but the difference would be pretty small and to date they've not justified the extra complexity and certification work that would be needed. We have looked into different wing sections a few times and there would be better gains to be had there but at the cost of stall handling and ease of rigging.

For now the certification cost of fuel injection (not to mention the cost of the system itself), combined with a higher degree of complexity mean it's not on the immediate agenda. Turbocharging in this category of aircraft doesn't strike me as a great idea due to our generally low operating ceiling (reducing the relevance of high altitude intake pressure normalisation), limited payloads and allergy to complexity.

Best Regards,
Doug.

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Future Improvements 1 year 2 weeks ago #531

"For now the certification cost of fuel injection (not to mention the cost of the system itself), combined with a higher degree of complexity mean it's not on the immediate agenda"

Fuel injection for this little engine would be high on my list after my experience trying to balance the EGTs and getting even flow - I dream of a Jab engine that we could tune with GAMI type injector noozles.

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Future Improvements 1 year 2 weeks ago #532

  • Harry Smithard
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Thanks for your reply Doug.

As I say I love my current Jab120. I spend a lot of time on YouTube and there are a lot of manufacturers videos and reviews from the US. There are a lot of developments occurring. As a proud Australian I like to see our home products competing well on the world stage.

Are you able to hint at new developments coming from Jabiru? Can Jabiru get some videos on you tube etc?

Regards
Harry

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Future Improvements 1 year 1 week ago #533

Well at the moment most of our R&D time is going into the new gen engines so there's not a huge amount to spare for anything else, though Jamie gets up in the twin whenever he gets a chance:

www.youtube.com/watch?v=zm-OTOSHSOQ

We'll see what else we can dig up :-)
D.

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