X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from mail-ew0-f52.google.com ([209.85.215.52] verified) by logan.com (CommuniGate Pro SMTP 5.3.10) with ESMTP id 4551355 for flyrotary@lancaironline.net; Mon, 01 Nov 2010 21:45:05 -0400 Received-SPF: pass receiver=logan.com; client-ip=209.85.215.52; envelope-from=msteitle@gmail.com Received: by ewy1 with SMTP id 1so3485542ewy.25 for ; Mon, 01 Nov 2010 18:44:29 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=wXFgErRILsfcM5sVOEHEXKQ9FUkrNVM5+LFFm8EvIOQ=; b=xs3K7/NyOoJKrOgEMTQZDXpCWGHFK/XQflgL5EFUnkTtaCtl+ai8B7lTDbMRViCy/P RmOsIezqn45SOQIT3hcshEODz/b8NJWZ/MsZ206ffE7QW9DH6SjJSS9+vnQKe4DKxXvM V0y6Bs6wtcAppe2SbrPPMoxkPbtaTlpztmk9c= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=RzvxkirWprj++jGjAso02huKsiK0poHZF6NFSwUkJa19AYoQrgj4Exo7yIrgRzyycp aPAOoAr3pC1qwuTVDIuxhNwYQwmP+S5YUOcG3NU2Mi6yjzsC8+r+Q9zhMgBD5wUaBKeE ESwB9cfWSRO5j39/4qexrbEHwDE1VOQvF/E/E= MIME-Version: 1.0 Received: by 10.213.10.197 with SMTP id q5mr1742185ebq.48.1288662269505; Mon, 01 Nov 2010 18:44:29 -0700 (PDT) Received: by 10.213.33.131 with HTTP; Mon, 1 Nov 2010 18:44:29 -0700 (PDT) In-Reply-To: References: Date: Mon, 1 Nov 2010 20:44:29 -0500 Message-ID: Subject: Re: [FlyRotary] Re: EM2 Numbers From: Mark Steitle To: Rotary motors in aircraft Content-Type: multipart/alternative; boundary=0015174c0cbecf333804940810d3 --0015174c0cbecf333804940810d3 Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Al, A while back Ed Anderson posted a spreadsheet that compared speed vs. cost. Maybe he can re-post it for the newbies in the group. As I recall, the faster you go, the lower your mpg... big surprise. But you reach a point with reducing speed that your burn rate is lower, but you're flying longer, so it evens out to a zero sum gain. Mark On Mon, Nov 1, 2010 at 9:36 PM, Al Gietzen wrote: > > > No, we sure didn't. In fact, I like going faster than my wallet can keep > up. > > Yeah; me tooJ > > > > In doing some searching for LDmax for the Lancair ES, I read the statemen= t > that best economy would be the same as best glide. That makes sense to m= e. > Probably close enough for our purposes. What say you? > > I found my data. I think it may be just a bit more complicated. Best gli= de > will likely give you the lowest fuel burn rate (gph); but since you=92re = going > fewer miles in an hour; it=92s not the best mpg. My best glide speed is = about > 90 kts; but my best mpg is about 130kts - quite flat from about 140 =96 1= 20 > kts. The burn rate was continuing to go down at 110 kts; which was as fa= r > as I took data. > > > > So minimum trip cost is at max MPG; if you consider your time as free. B= ut > my plane seems to have a =91sweet=92 spot at 5500-5700 rpm, and at 10,500= I can > go about 170 KTAS at a tad over 10 gph, so that=92s what I do. I could s= low > to 130 Kts and burn a tad under 7.0 gph; but would I be happyJ? > > > > Al > > > > Mark > > On Mon, Nov 1, 2010 at 5:53 PM, Al Gietzen wrote: > > Where does one find the "most efficient operationg point" for a particula= r > airframe? Is this the same as LDmax? > > > > Mark; > > > > The EM2 reads out MPG. Most efficient operation would be where you get th= e > highest MPG. So go fly at 100F, or so; lean of peak EGT and take some dat= a > of MPG and speed. You=92ll find a max MPG point that is slower than you= =92ll > typically want to fly. I think for my Velocity it was a fairly broad pea= k > around 125 (I don=92t even remember now if that was MPH or Kts; because I > never fly there in level flight). We didn=92t build sleek airplanes with= more > powerful engines to go the speed of a Skyhawk =96 did we? > > > > Al > > > --0015174c0cbecf333804940810d3 Content-Type: text/html; charset=windows-1252 Content-Transfer-Encoding: quoted-printable Al,

A while back Ed Anderson posted a spreadsheet that c= ompared speed vs. cost. =A0Maybe he can re-post it for the newbies in the g= roup. =A0As I recall, the faster you go, the lower your mpg... big surprise= . =A0But you reach a point with reducing speed that your burn rate is lower= , but you're flying longer, so it evens out to a zero sum gain.=A0

Mark =A0

On Mon, Nov = 1, 2010 at 9:36 PM, Al Gietzen <ALVentures@cox.net> wrote:

=A0

No, we sure didn't. = =A0In fact, I like going faster than my wallet can keep up.

Yeah; me tooJ

=A0

In doing some searching f= or LDmax for the Lancair ES, I read the statement that best economy would be the same as best glide. =A0That makes sense to me. =A0Probably close enough for our purposes. =A0What say you? =A0

I found my dat= a.=A0 I think it may be just a bit more complicated. Best glide will likely give you the lowest fue= l burn rate (gph); but since you=92re going fewer miles in an hour; it=92s not the best mpg. =A0My best glide speed is about 90 kts; but my best mpg i= s about 130kts - quite flat from about 140 =96 120 kts.=A0 The burn rate was continuing to go down at 110 kts; which was as far as I took data.

=A0

So minimum tri= p cost is at max MPG; if you consider your time as free.=A0 But my plane seems to have a =91sweet=92 spot at 5500-5700 rpm, and at 10,500 I can go about 170 KTAS at a tad over = 10 gph, so that=92s what I do. =A0I could slow to 130 Kts and burn a tad under 7.0 gph; but would I be happyJ<= span style=3D"font-size:11.0pt;font-family:Verdana;color:blue">?

=A0

Al

=A0

Mark

On Mon, Nov= 1, 2010 at 5:53 PM, Al Gietzen <ALVentures@cox.net> wrote:

Where does one find the = "most efficient operationg point" for a particular airframe?=A0 Is this the same as=A0LDmax?

=A0

Mark;

=A0

The EM2 reads out MPG. Most efficient operation would be where you get the high= est MPG. So go fly at 100F, or so; lean of peak EGT and take some data of MPG a= nd speed. =A0You=92ll find a max MPG point that is slower than you=92ll typically want to fly.=A0 I think for my Velocity it was a fairly broad pea= k around 125 (I don=92t even remember now if that was MPH or Kts; because I never fly there in level flight).=A0 We didn=92t build sleek airplanes with more powerful engines to go the speed of a Skyhawk =96 did we?<= /font>

=A0

Al

=A0


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