Return-Path: Received: from fed1rmmtao05.cox.net ([68.230.241.34] verified) by logan.com (CommuniGate Pro SMTP 4.2.3) with ESMTP id 433396 for flyrotary@lancaironline.net; Sun, 26 Sep 2004 20:59:38 -0400 Received-SPF: none receiver=logan.com; client-ip=68.230.241.34; envelope-from=ALVentures@cox.net Received: from BigAl ([68.107.116.221]) by fed1rmmtao05.cox.net (InterMail vM.6.01.03.04 201-2131-111-106-20040729) with ESMTP id <20040927005906.MPUX1489.fed1rmmtao05.cox.net@BigAl> for ; Sun, 26 Sep 2004 20:59:06 -0400 From: "Al Gietzen" To: "'Rotary motors in aircraft'" Subject: RE: [FlyRotary] Re: Still high temperature Date: Sun, 26 Sep 2004 17:59:19 -0700 Message-ID: <000001c4a42d$38e34ac0$6400a8c0@BigAl> MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01C4A3F2.8C8472C0" X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.6626 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2180 This is a multi-part message in MIME format. ------=_NextPart_000_0001_01C4A3F2.8C8472C0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable >=20 > My analysis of air flow required for 200 hp climb at 120 kts on a=20 > 95F day, > and a very effective scoop is 65 sq.in. inlet area - just for the=20 > coolantrads. Another 25 sq. in. inlet for the oil cooler. This is=20 > more than > typically needed for cruise, but it's a tradeoff. >=20 =20 Al, how do you correlate your figures with Ed's results. I believe he has said that the estimates only 170Hp, but I don't think he could get away with half the the scoop area. =20 The analysis uses the amount of heat rejected to the coolant, airspeed, = the specific heat of air, and the increase in the temp of the air going = through the core. The first three of these are known quantities, so the last is really the only variable. I assumed a 50F delta T for the air, which is conservative for an effective cooler in most conditions; except when the = OAT gets up toward 100. At 160 hp and about 80F air temp increase (say from = an OAT of about 70 F) you could get by with about 30 sq. in. =20 This assumes an ideal scoop, which you may attain on the nose of an = airplane where you have external diffusion (slowing) but difficult in a scoop somewhere back on the fuselage like I'm dealing with on a pusher. =20 The analysis also assumes steady-state conditions as would occur at sustained high power. If you only need the high power for a few = minutes, you get the benefit of the heat absorbing capacity of the coolant, oil, = and entire engine block getting it up to max temps; but I think it makes = more sense to design for sustained power. I prefer taking a conservative = approach to cooling system design because experience shows that in the majority = of cases of auto engine conversion there is a cooling shortfall. And I = don't want to be stuck in Vegas on a 110F day (should I ever chose to go = there) because I couldn't take off without over heating. =20 Al =20 =20 ------=_NextPart_000_0001_01C4A3F2.8C8472C0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

>

> My analysis of air flow required for 200 hp climb

at 120 kts on a

> 95F day,

> and a very effective scoop is 65 sq.in. inlet area

- just for the

> coolantrads. Another 25 sq. in. inlet for the = oil

cooler. This is

> more than

> typically needed for cruise, but it's a tradeoff.

>

Al, how do you correlate your figures with Ed's

results. I believe he has said that the estimates

only 170Hp, but I don't think he could get away with

half the the scoop area.

The analysis = uses the amount of heat rejected to the coolant, airspeed, the specific heat of air, and = the increase in the temp of the air going through the core. The first = three of these are known quantities, so the last is really the only = variable. I assumed a 50F delta T for the air, which is conservative for an = effective cooler in most conditions; except when the OAT gets up toward 100. = At 160 hp and about 80F air temp increase (say from an OAT of about 70 F) you = could get by with about 30 sq. in.

<= /font>

This assumes = an ideal scoop, which you may attain on the nose of an airplane where you have = external diffusion (slowing) but difficult in a scoop somewhere back on the = fuselage like I’m dealing with on a pusher.

<= /font>

The analysis = also assumes steady-state conditions as would occur at sustained high = power. If you only need the high power for a few minutes, you get the benefit = of the heat absorbing capacity of the coolant, oil, and entire engine block = getting it up to max temps; but I think it makes more sense to design for sustained = power. I prefer taking a conservative approach to cooling system design because = experience shows that in the majority of cases of auto engine conversion there is a cooling shortfall. And I don’t want to be stuck in Vegas on = a 110F day (should I ever chose to go there) because I couldn’t take off = without over heating.

<= /font>

Al

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