X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Mon, 24 Sep 2007 10:55:57 -0400 Message-ID: X-Original-Return-Path: Received: from [68.168.78.254] (HELO mta1.adelphia.net) by logan.com (CommuniGate Pro SMTP 5.1.12) with ESMTP id 2348634 for lml@lancaironline.net; Mon, 24 Sep 2007 09:30:09 -0400 Received-SPF: pass receiver=logan.com; client-ip=68.168.78.254; envelope-from=glcasey@adelphia.net Received: from [75.82.253.35] by mta9.adelphia.net (InterMail vM.6.01.05.02 201-2131-123-102-20050715) with ESMTP id <20070924124652.OJMK16948.mta9.adelphia.net@[75.82.253.35]> for ; Mon, 24 Sep 2007 08:46:52 -0400 Mime-Version: 1.0 (Apple Message framework v752.2) In-Reply-To: References: Content-Type: multipart/alternative; boundary=Apple-Mail-4--270069952 X-Original-Message-Id: From: Gary Casey Subject: Re: 360 engine baffling installation- Lack of Power X-Original-Date: Mon, 24 Sep 2007 05:46:51 -0700 X-Original-To: "Lancair Mailing List" X-Mailer: Apple Mail (2.752.2) --Apple-Mail-4--270069952 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=US-ASCII; delsp=yes; format=flowed Grayhawk, Yes, I neglected to bring in humidity into the calculation, but the reason was that for normal flying it probably represents a small error. For instance, most of the cruise flight temperatures are probably at 60F or lower. Saturated conditions (100% relative humidity, or a dew point of 60) imply that water vapor takes up 1.7% of the air, so it would reduce power by that amount. Its effect on density altitude is less than that since its density is a little more than half that of air so it would reduce density by about 0.8%. Given all the other approximations I was using I felt that humidity could be left out. That would not be true for a takeoff at 100F under very humid conditions when water vapor could make up 6% of the air. Gary > > Gary, > > Try this calculator and see what the dew point does to % power. > > http://wahiduddin.net/calc/calc_hp_dp.htm > > Grayhawk > > PS: I have an inexpensive instrument that I stick into the cabin > air inlet in flight to measure the dew point or % humidity. > Temperature isn't enough. > > PPS: The sq rt of .75 is .866. 86.6% of 30" is 26" and 86.6% of > 2700 is 2300. But since I fly at 2500 rpm, using your adjustment, > then a MAP of 24" would approximate 75% power. Since I also like > to fly at WOT and anytime I see a MAP that low, I must be at or > below 75% power. Normally that would be at or above 6500 MSL. > Since I also use ram air induction at around 175 KIAS at that > altitude, I have to go up another 1000 feet and fly in the opposite > direction (towards O'Hare) in order to conduct the GAMI lean test. > Bummer. > > --Apple-Mail-4--270069952 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=ISO-8859-1 Grayhawk,
Yes, I neglected = to bring in humidity into the calculation, but the reason was that for = normal flying it probably represents a small error.=A0 For instance, = most of the cruise flight temperatures are probably at 60F or lower.=A0 = Saturated conditions (100% relative humidity, or a dew point of 60) = imply that water vapor takes up 1.7% of the air, so it would reduce = power by that amount.=A0 Its effect on density altitude is less than = that since its density is a little more than half that of air so it = would reduce density by about 0.8%.=A0 Given all the other = approximations I was using I felt that humidity could be left out.=A0 = That would not be true for a takeoff at 100F under very humid conditions = when water vapor could make up 6% of the = air.
Gary
=
Gary,
=A0
Try this calculator and see what = the dew point does to % power.
=A0
=A0
Grayhawk
=
=A0
PS:=A0 I have an inexpensive instrument that I stick = into the cabin air inlet in flight=A0to measure the dew point or % = humidity.=A0 Temperature isn't enough.
=A0
PPS: = The sq rt of .75 is .866.=A0 86.6% of 30" is 26" and 86.6% of 2700 is = 2300.=A0 But since I fly at 2500 rpm, using your adjustment, then a MAP = of 24" would approximate 75% power.=A0 Since I also like to fly at WOT = and=A0anytime I see a MAP that low, I=A0must be=A0at or below 75% = power.=A0 Normally that would be at or above 6500 MSL.=A0 Since I also = use ram air induction at around 175 KIAS at that altitude, I have to go = up another 1000 feet and fly in the opposite direction=A0(towards = O'Hare) in order to conduct the GAMI lean test.=A0 = Bummer.



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