X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail07.syd.optusnet.com.au ([211.29.132.188] verified) by logan.com (CommuniGate Pro SMTP 5.2.12) with ESMTPS id 3526276 for flyrotary@lancaironline.net; Tue, 03 Mar 2009 23:33:01 -0500 Received-SPF: pass receiver=logan.com; client-ip=211.29.132.188; envelope-from=lendich@optusnet.com.au Received: from ownerf1fc517b8 (d220-236-255-172.dsl.nsw.optusnet.com.au [220.236.255.172]) by mail07.syd.optusnet.com.au (8.13.1/8.13.1) with SMTP id n244WHF3024554 for ; Wed, 4 Mar 2009 15:32:19 +1100 Message-ID: <211F523415E045DD96B84C9EBCA192E7@ownerf1fc517b8> From: "George Lendich" To: "Rotary motors in aircraft" References: Subject: Re: [FlyRotary] Re: Questions on buying a rotary plane Date: Wed, 4 Mar 2009 14:32:18 +1000 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_002D_01C99CD6.053A21C0" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5512 X-MIMEOLE: Produced By Microsoft MimeOLE V6.00.2900.5579 X-Antivirus: avast! (VPS 0617-3, 04/28/2006), Outbound message X-Antivirus-Status: Clean This is a multi-part message in MIME format. ------=_NextPart_000_002D_01C99CD6.053A21C0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Mike, From what I can gather, The rotary runs a BSFC of .5 and the Lyc/ Cont = run at .45. However the Rotary can match the BSFC of .45 with leaning - the thing is = you can lean a rotary more safely and more aggressively than a piston = engine. Now you may be able to lean to .4 but some performance may be = lost. That's my perspective on what I've read over the years. George (down under) ----- Original Message -----=20 From: Mike Wills=20 To: Rotary motors in aircraft=20 Sent: Wednesday, March 04, 2009 1:55 PM Subject: [FlyRotary] Re: Questions on buying a rotary plane Glad I woke you guys up! :-) While it may appear from my post that I was trying to discourage this = guy and am not happy with my rotary powered airplane that is not the = case. I'm very happy with it. Will be even happier once I get all of the = little glitches fixed so I can just fly it. I simply wanted to make sure William understands what he's getting = into. What appears to be a fairly straight forward mod is a lot more = complicated than it appears and there are potential pitfalls that are = not necessarily obvious. My bad on the misread regarding fuel efficiency - he was talking = about homebuilt aircraft versus factory built planes, not rotaries = versus certified engines. I think he's still way off base here which was = why I replied to his post. Al, I dont know anyone who actually KNOWS what BSFC they acheive with = their Lyc/Cont. I know that low .40s is a published number that is stuck = in my head. I know what kind of fuel consumption I got with my Lyc = powered RV-6A at cruise and I know there are certainly enough flying Lyc = powered RVs to pretty firmly establish a cruise performance baseline. = Since there are more flying rotary powered RVs than other types, seems = like we should be able to get at least an idea of how they compare. Lets = challenge the rotary RV fliers here to post real cruise performance = (altitude, TAS, fuel consumption) and answer the question. Or give me a = year and 100 hours and I'll let you know how my RV-4 stacks up against = the -6A for a data point. As for your performance against conventional powered Velocities, = thats great news. I think thats one of the significant short comings of = our little group here. Common perception is that rotaries are gas hogs = and we dont do anything to accurately document and advertise our = performance. Mark, I agree that burning Mogas definitely makes a big difference = economy-wise. But that's a red herring. You could legally burn Mogas in = a Lyc/Cont also - just that most guys who are too conservative to choose = an auto conversion are also too conservative to burn Mogas. Burning = Mogas isnt the exclusive territory of the rotary. I personally know a = guy with a 200HP Lyc in an RV-8 who has burned Mogas exclusively for = years. Really what it comes down to is convenience and comfort. Lets be = fair, compare apples to apples, and while we're at it throw in the = additional cost and hassle of having to pour in 2 stroke oil for your = rotary (assuming you do that as most seem to do). I do totally agree with you on the price of parts. And that was one = of my huge motivations for going this route. But really the biggest = motivation was to do something a little different. When my RV-4 finally = makes it's appearance at a fly-in (hopefully this year) it's not going = to be lost in the sea of belly button RVs that show up. Mike Wills RV-4 N144MW ----- Original Message -----=20 From: Al Gietzen=20 To: Rotary motors in aircraft=20 Sent: Monday, March 02, 2009 9:51 PM Subject: [FlyRotary] Re: Questions on buying a rotary plane I dont know where you got the idea that rotaries are more fuel = efficient. Lycosaurs/Continentals typically have BSFCs in the low .40s. = The commonly accepted number for a rotary is about .50. Some here seem = to do better, others worse.=20 Mike; I'm not disagreeing with the points in your message; but I am = wondering if you know anybody actually flying a Lyc/Cont and achieving = BSFC in the low 40's. I see numbers like .43 or .45 bandied about, but = I guess no one leans enough when flying to get that for fear of burning = out a valve - or worse. I've yet to hear from anyone flying a Velocity = like mine with a Lyc who can surpass the speed/fuel burn that I get with = the 20B. I don't know why - it surprised me; but there it is. I think in the real world operation the BSFCs are comparable. I = may have a bit lower drag because of smaller cowl; or other factors. Al =20 ------=_NextPart_000_002D_01C99CD6.053A21C0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Mike,
From what I can gather, The rotary runs = a BSFC=20 of .5  and the Lyc/ Cont run at .45.
However the Rotary can match the BSFC = of .45 with=20 leaning - the thing is you can lean a rotary more safely and more = aggressively=20 than a piston engine. Now you may be able to lean to .4 but some = performance may=20 be lost.
That's my perspective on what I've read = over the=20 years.
George (down under)
----- Original Message -----
From:=20 Mike = Wills
Sent: Wednesday, March 04, 2009 = 1:55=20 PM
Subject: [FlyRotary] Re: = Questions on=20 buying a rotary plane

Glad I woke you guys up! = :-)
 
While it may appear from my post that = I was=20 trying to discourage this guy and am not happy with my rotary powered = airplane=20 that is not the case. I'm very happy with it. Will be even happier = once I get=20 all of the little glitches fixed so I can just fly = it.
 
 I simply wanted to make sure = William=20 understands what he's getting into. What appears to be a fairly = straight=20 forward mod is a lot more complicated than it appears and there are = potential=20 pitfalls that are not necessarily obvious.
 
 My bad on the misread regarding = fuel=20 efficiency - he was talking about homebuilt aircraft versus = factory=20 built planes, not rotaries versus certified engines. I think he's = still=20 way off base here which was why I replied to his = post.
 
 Al, I dont know anyone who = actually=20 KNOWS what BSFC they acheive with their Lyc/Cont. I know that low .40s = is a=20 published number that is stuck in my head. I know what kind of = fuel=20 consumption I got with my Lyc powered RV-6A at cruise and I know = there=20 are certainly enough flying Lyc powered RVs to pretty firmly establish = a cruise performance baseline. Since there are more flying rotary = powered=20 RVs than other types, seems like we should be able to get at least an = idea of=20 how they compare. Lets challenge the rotary RV fliers here to = post real=20 cruise performance (altitude, TAS, fuel consumption) and answer the = question.=20 Or give me a year and 100 hours and I'll let you know how my RV-4 = stacks up=20 against the -6A for a data point.
 
 As for your performance against = conventional powered Velocities, thats great news. I think thats one = of the=20 significant short comings of our little group here. Common perception = is that=20 rotaries are gas hogs and we dont do anything to accurately document = and=20 advertise our performance.
 
 Mark, I agree that burning = Mogas definitely=20 makes a big difference economy-wise. But that's a red herring. You = could=20 legally burn Mogas in a Lyc/Cont also - just that most guys who are = too=20 conservative to choose an auto conversion are also too conservative to = burn=20 Mogas. Burning Mogas isnt the exclusive territory of the = rotary. I=20 personally know a guy with a 200HP Lyc in an RV-8 who has burned Mogas = exclusively for years. Really what it comes down to is convenience and = comfort. Lets be fair, compare apples to apples, and while = we're at=20 it throw in the additional cost and hassle of having to pour in 2 = stroke oil=20 for your rotary (assuming you do that as most seem to = do).
 
 I do totally agree with you on = the price of=20 parts. And that was one of my huge motivations for going this route. = But=20 really the biggest motivation was to do something a little different. = When my=20 RV-4 finally makes it's appearance at a fly-in (hopefully this year) = it's not=20 going to be lost in the sea of belly button RVs that show = up.
 
Mike Wills
RV-4 N144MW
 
 
----- Original Message -----
From:=20 Al = Gietzen=20
To: Rotary motors in = aircraft=20
Sent: Monday, March 02, 2009 = 9:51=20 PM
Subject: [FlyRotary] Re: = Questions on=20 buying a rotary plane

 I dont know=20 where you got the idea that rotaries are more fuel efficient.=20 Lycosaurs/Continentals typically have BSFCs in the low .40s. The = commonly=20 accepted number for a rotary is about .50. Some here seem to do = better,=20 others worse.

 

Mike;

 

I=92m = not=20 disagreeing with the points in your message; but I am wondering if = you=20 know anybody actually flying a Lyc/Cont and achieving BSFC in the = low=20 40=92s.  I see numbers like .43 or .45 bandied about, but I = guess no=20 one leans enough when flying to get that for fear of burning out a = valve =96=20 or worse.  I=92ve yet to hear from anyone flying a = Velocity like = mine with=20 a Lyc who can surpass the speed/fuel burn that I get with the 20B. = I don=92t=20 know why =96 it surprised me; but there it is.

 

I = think in the=20 real world operation the BSFCs are comparable.  I may have a = bit=20 lower drag because of smaller cowl; or other = factors.

 

Al=20 =  

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