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Jabiru 2200 and prop combination
I'm reposting this question from the main forum. It was brought to my attention that this would be the best place to ask.
The Jabiru 2200a on my 701 is able to reach 3300 rpm without opening the throttle completely. Because of that, I'm stopping short of going wide open, since I don't want to run above red line. My primary suspicion is that the propeller is too low in pitch/diameter for the engine if it's able to easily exceed max rpm in a static run. My secondary suspicion is that I need to confirm the tach's accuracy, and I'm working on that. The currently installed prop is a Sensenich W-64-PJ-38-G. My understanding is that this means a wooden or wooden/composite prop with 64" diameter and a pitch that travels 38" at 75%.
What props are others using on this engine? If this is my problem, what would be a good prop to pick up? The seller has another which is 62" and 42 pitch. With the shorter diameter and greater pitch, I'm not sure if that is going to be more of an increase or decrease on the whole.
Replies to This Discussion
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Permalink Reply by Cody Barringer on
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I finally found some documentation. Jabiru recommends 60" diameter props, pitch can be anywhere from 38-44. (JPM3L1-5, 2.6.1)
This answers some questions but opens up new ones. The prop in question is on the low end of the pitch range, but 4" longer. That is not a combination that should be able to overspeed if it's on the type certificate list.
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Permalink Reply by Ralph Sanson on
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I built in 2004 started with the 60 x 36 Jabiru prop which seemed too much load for the engine. Max static rpm 2800 climb 2900 level flight 3200
Later I had a prop manufactured 64 x 30 and this gave a better match, climb performance improved. Max rpm static 3010 level flight 3350
Later Jabiru issued an advisory to certain engines, mine was affected and after the througbolt nuts were reworked my climb rate improved with climb rpm 3230 and level flight max. 3540, these were confirmed with a digital tacho as I thought my analogue gauge was overeading - it wasnt.
A few years ago the local prop was split in ground handling so the original 60 x 36 is back on and - as the engine is now developing proper power that it didnt when new, this combination is OK.
There is efficiency advantage to using 64" if your ground clearance can stand it. I would probably use 64 x 32 next time.
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Wow! That's so much different than what I'm seeing, it's crazing that we are even talking about the same engine. I'll start with some RPM checks to try to get to the bottom of this.
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It's taken a while to get back here and give an update, but I found the answer. I tried two different tachs bought online. One was the reflective laser type and the other was spark plug lead inductance type. The both showed that the true rpm was about 87% of what the onboard tach was showing, right at 1/8th below the reading. When applying that, all the readings from idle, to static, to cruise were where they should be. The next project will be trying to find the issue with the onboard tach. In the meantime, it's running great with the prop that is installed and we ended up not buying the climb prop from the previous owner.
Both of the tachs were about $20 online. I would high recommend this little guy. All we had to do is the recommended 5 wraps around a lead. Nice for troubleshooting and for backup. https://www.amazon.com/gp/product/B078Z541CN/ref=ppx_yo_dt_b_search...
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