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<DIV>Jerry I can definitely see issues with a 4C powering a belt drive. I am talking 2C 120-145. It's a smoother delivery to the belt.</DIV>
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<DIV>I haven't really looked all that close at Heli power distribution but heck, these fellows are running belt driven rotors through a clutch arrangement, and are turning 80 and 90 2 cycle powerplants. The rotors are around 55" or so and turn about 1800 rpm at full revs. </DIV>
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<DIV>Surely we can fashion a smaller main gear, changing the reduction from the 7:1 in the heli to about 1.7:1 in our planes. With such an arrangement there's no reason to be down on power anywhere in the rpm range, I don't believe. The helis weigh in at about the same as our planes do I think.</DIV>
<DIV>rgds,</DIV>
<DIV>Matt</DIV>
<BLOCKQUOTE style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: blue 2px solid"><FONT face=Arial>>Jerry, we have some pretty good carbs so the idle and mid range <BR>>shouldn't be too much of a problem, as long the timing is <BR>>appropriate. I was even thinking of something along the Koger belt <BR>>drive reduction unit powered by something like a 120 or 145.<BR><BR>Hi Matt,<BR><BR>IIRC, Dean Koger flew a YS120 powered belt drive biplane at the 93 <BR>Team Trials called a Dazzle-U-2. It didn't have any advantage over <BR>the COTS motors of the day due to the weight of the flywheel needed <BR>to keep from stripping the teeth off the belt. It wasn't the <BR>eye-opener that his Webra 61 powered belt drive Vortex was. Dean <BR>didn't use it for very long.<BR><BR>>If Nat can turn a 17x10 in his OS 90 straight out at 7.5K, then it <BR>>should be possible to reduce the output of a 145 down to about 6K on <BR>>a 22-24" prop and keep the engine happy. It's times like this that I <BR>>wish I had a real machine shop around. I can only do so much with <BR>>hand tools.<BR><BR>Unless you can shift the middle of the torque curve to the left by <BR>about 3000 rpm while simultaneously increasing its torque level by <BR>30% you're going to be way down on power (remember power = torque x <BR>rpm). Prop efficiency will go up with the reduction in rpm but not <BR>enough to make up the difference.<BR><BR>>The webra 160 is a nice rig but it will not turn the large dia I <BR>>want unless it is reduced.<BR><BR>Agreed. I've heard of some folks turning some pretty big props at <BR>surprisingly high rpms with their Webra 160's but trying to match the <BR>electric's output profile would likely be futile - with any glow <BR>motor.<BR><BR>>BTW did you put the electric on the back burner?<BR><BR>Only until I get time to start on the two ePartner kits sitting in my <BR>garage/workshop. I learned a few interesting things at the Nats this <BR>year flying Frackowiak's ePartner that keep me headed in that <BR>direction.<BR><BR>1. Electric has a distinct advantage over glow (and it doesn't <BR>matter whose/what glow motor we're talking about either). If you <BR>tend to fly fast with minimal speed control the advantage is minimal. <BR>If you strive to fly at a very constant pace the advantage is huge <BR>(even in Masters). If you've seen the plane fly you probably know <BR>what I mean.<BR><BR>2. Electric still has a ways to go wrt battery longevity and system <BR>reliability (cost issues aside - weight is no longer a problem with <BR>the new Generation II Lite LiPoly packs). But overall, we're just <BR>not there - yet.<BR><BR>Nonetheless, I plan on flying electrics at the Nats next year (see #1 above).<BR><BR>Thx, Jerry</FONT></BLOCKQUOTE></DIV>
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