redrives

Lazair Parts for sale

Postby mgodwin12 » Mon Jul 17, 2006 10:47 pm

am getting a reduction drive built for the rotax 185. it will bolt right on the front of the engine. no screwing around with new engine mounts or whatever. can swing a 44 inch prop. if you're interested , let me know.
mike
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Postby uscgairdale » Tue Jul 18, 2006 6:45 am

Do you have pictues of the design? I am curious to see how you move the engine to account for the change of thrust line.

Dave
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Postby JPXman » Tue Jul 18, 2006 8:57 am

the BC lads have been flying for 20 years with the dropped props redrive system. 20 years is a pretty good track record if you ask me. its still only 9HP going to the prop, the thrust really doesn't increase that much, however it is available over a much broader speed range with the slower turning, coarser pitched props.
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Postby mgodwin12 » Tue Jul 18, 2006 8:58 am

i will have pictures available as soon as i get a unit from the machinist. the thrust line will be slightly lower that the current crankshaft. basically about as much distance as is needed to provide room for the 2 pulleys. my guy knows that it is desireable to keep the thrust line as close to original as possible. this system is a copy of a design that is being used on 2 lazairs in my area and they have had great success with it. there is also a chance that the system can be reversed, that is installed upsidedown, so that the thrust line moves up rather that down . however , this will "blanket" the cooling air to the cylinder. with the size of the cooling fins and considering how the engine was used in the water pump, this may not be a problem but i don't know so i'm keeping with the original plan.
thanks for the interest.
mike
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Postby crazyneosimpson » Tue Jul 18, 2006 7:30 pm

The thrustline on mine drop less than 120mm, it's not a real issue. I can put some pics up of parts if that helps anyone.
Carl
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Postby uscgairdale » Wed Jul 19, 2006 6:52 pm

I have no personal experience using redrives on the Lazair so if "the BC Lazairheads" like them then cool. I just assumed, scary word, that the change in thrust line would make a difference.

A comparison of performance would be neat to see if anyone is able to compile the data.

Dave
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Postby mgodwin12 » Sun Jul 23, 2006 12:03 pm

when the things are done i'll be doing a series of flights with and with out the redrives to compare performance.
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