Return-Path: Received: from imf20aec.mail.bellsouth.net ([205.152.59.68] verified) by logan.com (CommuniGate Pro SMTP 4.2b7) with ESMTP id 311684 for flyrotary@lancaironline.net; Sun, 11 Jul 2004 21:08:13 -0400 Received: from bellsouth.net ([209.214.146.52]) by imf20aec.mail.bellsouth.net (InterMail vM.5.01.06.08 201-253-122-130-108-20031117) with ESMTP id <20040712010741.FFHZ1701.imf20aec.mail.bellsouth.net@bellsouth.net> for ; Sun, 11 Jul 2004 21:07:41 -0400 Message-ID: <40F1E45E.5000101@bellsouth.net> Date: Sun, 11 Jul 2004 20:07:42 -0500 From: Charlie England User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 (ax) X-Accept-Language: en-us, en MIME-Version: 1.0 To: Rotary motors in aircraft Subject: Re: [FlyRotary] Re: Powersport RV8 in the RVator References: In-Reply-To: Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit IIRC, at low cruise they had comparable burns, but when they got up around 180-190mph, Tracy was crying 'uncle' due to fuel flow. The problem is that Bernie's -6A was much, much cleaner than most RV's, with aftermarket cowl, pants, etc. He could flight plan a cruise speed as high as my 1st RV-4, but with almost 1 GPH lower fuel burn. That -4 was very clean for a stock early '90's era -4, running at ~ 190-195mph burning between 9 & 9.5 gph depending on altitude & speed. That's roughly 75% power on a 160 hp Lyc. (Bernie's -6A had a 160 also.) Here are Van's numbers: RV-6 Performance 150 hp 160 hp 180 hp Speed - Solo Weight Top Speed 198 mph 202 mph 210 mph Cruise [75% @ 8000 ft] 187 mph 191 mph 199 mph Cruise [55% @ 8000 ft] 169 mph 172 mph 179 mph Stall Speed 49 mph 49 mph 49 mph Speed - Gross Weight Top Speed 197 mph 201 mph 209 mph Cruise [75% @ 8000 ft] 186 mph 190 mph 198 mph Cruise [55% @ 8000 ft] 168 mph 171 mph 178 mp Fuel burn of the 160 hp at 75% & .45 lb/hp/hr is 9 GPH. Fuel burn of the 180 hp at 75% & .45 lb/hp/hr is 10.1 GPH. I think the cruise numbers above might be a little optimistic, but aren't that far off for Lyc powered RV's. To get the typical RV builder's attention, the rotary's numbers need to at least come close to these figures. I suspect that Van would publish an accurate report showing equal or superior performance by a rotary, but he's not going to endorse anything because he wants testimonials to how simple it is to build an RV. Is anyone coming close to the Lyc numbers at 75% cruise? Charlie Ed Anderson wrote: >Charlie, I believe that Tracy Crook and Bernie Kerr have done side by side >comparisons. I don't recall all the details, but my recollection is that >they were very similar at some speeds and diverged a bit at others, but >nothing dramatic either way. >Of course, Tracy was in his 4 and Bernie in his 6 so was not quite a one for >one, but I think a reasonable comparison. > >Unfortunately, I can't recall the Lycoming Bernie had installed. Perhaps >Tracy will jump in - although have not heard from him on the list recently. > >Ed > > >Ed Anderson >RV-6A N494BW Rotary Powered >Matthews, NC >----- Original Message ----- >From: "Charlie England" >To: "Rotary motors in aircraft" >Sent: Sunday, July 11, 2004 9:01 AM >Subject: [FlyRotary] Re: Powersport RV8 in the RVator > > > > >>DaveLeonard wrote: >> >> >> >>>>Dave you need to write up an article for Rvator!!. >>>> >>>> >>>> >>>> >>>> >>>You bet I will. As soon as I install my intersection fairings and my new >>>Harmon rocket gear leg fairings and improve cooling and "borrow" an O2 >>>bottle from the hospital. Perhaps even a bigger prop. That might be a >>> >>> >good > > >>>chance to go up into the flight levels and give Tracy Sailor a number to >>>work toward. >>> >>>That would make a good article. :-) >>> >>>Dave Leonard >>> >>> >>> >>A couple of questions/comments: >> >>Tracy & Ed both seem to have respectable fuel burns at *low* cruise >>settings. Unfortunately, other RV flyers seem to be quoting burns in the >>10 GPH range at cruise speeds noticably lower than Lyc powered RV's at >>the same burn (and 'reasonable' VFR altitudes). >> >>10 GPH is the ~burn of a 180 Lyc at 75% power (full throttle, properly >>leaned, 7k-8k feet). Is anyone able to match Van's published 75% cruise >>numbers, both speed & fuel burn? >> >>One of the biggest knocks against the rotary is the perceived excessive >>fuel burn. I think that we need to see side-by-side flights with Lyc 160 >>& 180 HP RV's at commonly flown VFR cruise altitudes (6k-10k feet). >>Until there are well documented comparisons showing similar fuel burns, >>the fence sitters will remain on the fence or fall on the Lyc side. >> >>Comments? >> >>Charlie >>