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Jabiru Aircraft
(@jabiru)
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17/05/2018 6:10 am  

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CSU1 year 8 months ago#379

·         Gary Ressel

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send me an email address and ill send you the manual of what i'm using , very reliable and tested. Made and tested in South Africa, 230 hrs so far no issues huge difference in performance. We have the figures to prove it. In fact our aircraft was used to develop this prop. Also now approved for Rotax motors.

www.axsport.co.za/about-us

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CSU1 year 8 months ago#381

·         Doug Smith

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Hi Gary,
@jabiru.net.au">info@jabiru.net.au is your best bet.
Has that 230 hours included stress measurement, strength and endurance testing such as that detailed in ASTM2506? Have you documented compliance against that standard (or any other acceptable prop standard)?
Regards,
Doug.

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CSU1 year 8 months ago#366

·         Gary Ressel

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Hello,

Are CSU approved for use on the Jabiru Engine.

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CSU1 year 8 months ago#370

·         Doug Smith

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Hi Gary,
Assuming you're asking about constant speed propellers?
I'm not aware of any constant speed props which are approved. There are a few in-flight-adjustable props out there with various degrees of pedigree and various degrees of acceptance in their local markets... Are you in Australia?
Regards,
Doug.

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CSU1 year 8 months ago#371

·         Gary Ressel

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Hi Doug,

Thanks for your reply. Im in South Africa. Im using a CSU/ Electric which was developed for the Jabiru and Rotax engines. We have so much success with this prop. Done about 230 hrs so far .

I was wondering why this is something that Jabiru themselves have not looked at. Is there any issues running a CS prop?

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CSU1 year 8 months ago#372

·         Gary Ressel

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Maybe what I need to ask as well is: Does the prop used need to be approved by Jabiru?

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CSU1 year 8 months ago#374

·         Kai Lyche

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I have been looking for constant speed prop as well- one that won't disintergrate, that is.

I went to see most of the prop manufacturers at the last Aero'16 exhibition i Friederichshafen, but drew (almost) a total blank.

DUX prop of France has (had?) an electrically controlled csp for Jab, but "several knowledgeable parties" advised against any purchase, as their reliability history is inadequate for aircraft purposes: I was informed that the rpm span of the Jab is on the high side for their design. I also went to see Aeromaster of NZ. They maintained they would be able to supply an electrically controlled csp for the 3300, but became evasive when talking about the 2200. With this brand harmonic vibrations/torsionals are the culprit.

I far as I have been able to find out, Hoffman Propeller would be able to supply a certified unit (price??!) after firm order and advance down payment, subject to successfull testing: they have considerable experience with csp's installed on VW type 1 aeroderivatives, which have the same rpm span as the Jab.

So, in any case, no reliable off the shelf units.
Kai

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CSU1 year 8 months ago#375

·         Doug Smith

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Hi Gary,
There are several issues with variable props...

1. Anyone familiar with our engines or aircraft know how attached we are to the idea and practice of simplicity... meaning that we've got a bit of a philosophical objection to things like in-flight adjustable propellers.

2. To use a variable prop safely the pilot needs to know how much power the engine has at a given point and how much of that power they're applying. Normally power is measured using a manifold pressure gauge which is of course possible to do with a Jabiru, however we don't have MAP charts available - which is what pilots would need to judge safe power levels.

3. Most of the variable propellers available for Jabirus are "variable", not "constant speed". The difference there is that a constant speed prop is designed to adjust itself continually and automatically, adjusting the blade pitch to maintain a particular RPM, whereas variable propellers require operator input. In turn, because they're often not perfectly set up, that means variable props are harder on the engine. A variable prop which is being operated outside of its sweet spot is as bad or worse than a poorly matched fixed pitch prop and can do real damage to the engine.

4. Historically most variable propellers which could be fitted to a Jabiru didn't come with prop blade or crankshaft vibration / stress surveys. Needless to say, some of these have caused either propeller or engine failures. I know there are some better ones out there now but I've not personally looked at any in detail.

5. At the end of the day you've only got 80 or 120 hp (nominally) to play with. That means that on an aircraft like a Jabiru the performance gains from an in-flight adjustable propeller tend to be pretty small. Historically we've preferred 2-bladed props with relatively low blade area so that the propeller can "slip" at low speed to unload the engine a little and then work efficiently once up to speed.

Of course, if you're in an experimental category there's nothing to stop you fitting one and your local dealer will be able to give you an idea which ones tend to work best in your part of the world.

Regards,
Doug.


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