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Permalink Reply by Ralph Sanson on September 12, 2010 at 5:28pm

My and another 701 with 2200 have changed from the Jabiru 60x38 standard prop to the wood props made by Brent Thompson (thompsonaeronatical.com). The sizing he did was 64x30 and that gives me a climb rpm 3200 and cruise 3050 on an average day.
The torque settings, pitch and track differentials do not change, a significant improvement on the old one which was out of limits by 200hrs.
Being made locally they will be the best cost option, otherwise I'd be looking at Sensenich wood props or Tennessee both seem to have good reputation on the 701

Ralph

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Permalink Reply by Shafid Khan on September 12, 2010 at 7:08pm

Thanks for the info Ralph. Brent Thomspson have non in stock, they will have to make one before I can fly again. I was told that the wood props are no good flying in the rain, is this true ??? Silly question, why some props are two blades and some are three blades ???

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Permalink Reply by Ralph Sanson on September 13, 2010 at 1:03am

Yes wooden props get damaged by rain easily, the Brents ones and Jabiru ones both come with a black urethane (or something) insert on the leading edge to reduce this problem, but the lesson is the 701 is VFR weather only and you wont enjoy flying in much rain. I have flown through some light rain, reducing rpm to transit, without incident, also seen fiberglass props like the Warpdrive (old Ivoprop) ruined by showers so its not just a problem with direct drive and wooden props.

Don't worry about 3 blade vs 2 blade, with the 2200 you have no choice, there is plenty of prop info on the Jabiru website, also read all the issues of Jaba chat they contain useful information not repeated elsewhere. For the record, I had a Bantam with Rotax and used both adjustable 2 blade and 3 blades, 2 blades was streaks ahead and cheaper too, I asked the manufacturer and he agreed, quoting some had tried 4 or even 6 blade assemblies in their quest for the ultimate.

The real reason has to do with power loading of the blades, and how long the blades can be - ground clearance and engine rpm affect this too. The 2200 can do up to 68" with limited rpm if you don't get 3300rpm you are flying at reduced performance so that keeps the theoretical max to about 64" although on some days I can get 3500rpm without the prop going barking mad

Is your plane the one that already had a Thompson prop?

Ralph

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Permalink Reply by Shafid Khan on September 13, 2010 at 2:14am

Thank you very much for the info. I have just bought the aircraft and got the engineers to change from one single stick in the middle to dual control and throttle in the middle, this is what I am used to. Last Sunday, while testing the controls, the front wheel dropped in the hole while taxing and the Thompson prop shattered. I think the Thompson workshop is going to make a new one and this could take some time. I don't know if it is possible to borrow a prop to get the aircraft home, maybe not..

Do you think a smaller diameter three blade prop is better than longer two blade ???

I am looking forward to flying the aircraft when it is all ready to go.

Cheers. Shafid

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