Return-Path: Received: from mxsf02.cluster1.charter.net ([209.225.28.202] verified) by logan.com (CommuniGate Pro SMTP 4.2b2) with ESMTP id 3208110 for flyrotary@lancaironline.net; Wed, 05 May 2004 23:26:46 -0400 Received: from [10.0.1.2] ([68.189.49.127]) by mxsf02.cluster1.charter.net (8.12.11/8.12.11) with ESMTP id i463NLZU029089 for ; Wed, 5 May 2004 23:23:21 -0400 (EDT) Mime-Version: 1.0 (Apple Message framework v613) In-Reply-To: References: Content-Type: text/plain; charset=US-ASCII; format=flowed Message-Id: Content-Transfer-Encoding: 7bit From: kelseyjewett Subject: Re: [FlyRotary] Re: Coolant Pressure Gauge Date: Wed, 5 May 2004 20:23:18 -0700 To: "Rotary motors in aircraft" X-Mailer: Apple Mail (2.613) Mike Is the dynafocal mount adapter you are developing something that would work with a Renisis on my RV-7A? Kelsey Jewett On May 5, 2004, at 2:03 PM, Michael McGee wrote: > The alternator speed isn't a problem, it doesn't care how fast you > spin it (unless you have an alternator that is way out of balance). > On my RV-4 with Lycoming engine the alternator is over-driven about > 4:1, I have the 2-1/2 inch stock alternator pulley, the crank/ring > gear pulley is about 10" diameter so the alternator will see 10,000 at > cruise. This is typical of most Lycoming installations on > experimentals and is not a problem on thousands of planes. > > My e-shaft pulley is 4-1/2 inches dia. I think it is a stock pulley > as the timing pointer is at the edge of the pulley. That makes the > alternator over-driven at 1.8:1. Using a 6000 rpm cruise with my > RD-1C that makes the alternator spin at 10,800. Close enough. > > There are enough Lyc drivers that were uncomfortable with this that > someone makes a 4" pulley for the alternator. Aircraft Spruce 02-03 > catalog page 245, p/n 07-06828 $48.95. (A waste o' money except for > the feel good factor. If you'll accept MY explanation I'll accept > your 48.95 and SAVE YOU shipping costs! > P-) > > Regarding water pump speed, I've been working on this for a few weeks > with my 13B dynafocal adaptor. I've mostly come to the conclusion > (yet open to more data or ideas) that the factory pump and pulley are > sized to provide the needed flow capacity at any given engine speed at > the horsepower levels we are running at. So, to make it easy I'm > sticking with the stock pump at the stock pulley ratio. > > Mike > Mike McGee, RV-4 N996RV, O320-E2G, Hillsboro, OR > 13B in gestation mode, RD-1C, EC-2 > > At 12:06 2004-05-05, you wrote: >> Well, that's interesting. This reminds me of a nagging question I >> have had, but haven't asked. >> >> I was curious about the need to go to a smaller crank pulley to slow >> down the water pump and alternators. >> From memory, the crank pulley is about 5-1/2", the alternator pulleys >> are about 2-1/2", and the water pump >> pulley is about 4" diameter. >> >> So, running an RD-2C (2.85 ratio), the alternators will be turning >> about 20k during climb-out and the wp will be turning >> about 10K rpm. That seems too fast to me. I could probably find >> larger pulleys for the alternators, but >> then there's the water pump pulley. Your unplanned experiment would >> suggest that we can run the wp slower >> and still cool adequately. >> >> This brings me to a second option. I think a simpler approach would >> be to reduce the size of the crank pulley. >> The problem is that I haven't found a multi-V reducing pulley at any >> of the after-market suppliers. I really don't >> want to change over all the multi-V pulleys to single V pulleys, but >> that is one option. >> >> Another solution might be to find a smaller pulley from another >> vehicle and adapt it to fit the rotary. If that doesn't >> work, I could have one made. >> >> So, am I worrying about nothing, or is this a real problem? >> >> Mark > > > >>> Homepage: http://www.flyrotary.com/ >>> Archive: http://lancaironline.net/lists/flyrotary/List.html >