X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from cdptpa-omtalb.mail.rr.com ([75.180.132.121] verified) by logan.com (CommuniGate Pro SMTP 5.2.2) with ESMTP id 2874154 for flyrotary@lancaironline.net; Sun, 27 Apr 2008 10:31:43 -0400 Received-SPF: pass receiver=logan.com; client-ip=75.180.132.121; envelope-from=eanderson@carolina.rr.com Received: from edward2 ([75.191.186.236]) by cdptpa-omta05.mail.rr.com with SMTP id <20080427143105.JMLE5568.cdptpa-omta05.mail.rr.com@edward2> for ; Sun, 27 Apr 2008 14:31:05 +0000 Message-ID: <000d01c8a873$6c6dcde0$2402a8c0@edward2> From: "Ed Anderson" To: "Rotary motors in aircraft" Subject: Electric Water pumps - Interesting Date: Sun, 27 Apr 2008 10:31:47 -0400 MIME-Version: 1.0 Content-Type: multipart/alternative; boundary="----=_NextPart_000_000A_01C8A851.E52A2160" X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.3138 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.3198 This is a multi-part message in MIME format. ------=_NextPart_000_000A_01C8A851.E52A2160 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable I was just thumbing through a recent catalog from Summit Racing and came = across a couple of pages on electric water pumps. There has always been = a degree of interest (and some debate {:>)) regarding the use of = electric water pumps in aircraft. It was interesting to read some of = the descriptions, but basically the current consumed ranged from 4 - 9 = amps and the quoted flow rate (presumably without back pressure) was = from 16-35 gpm. So if you take 9 amps at say 14 volts =3D 126 watts =3D 0.167 HP to get = that flow. However, some of them indicate you can save 15 - 20 engine = HP at HIGH rpm. So why the difference? Apparently (my best guess) is that they are advertising their product = to best advantage (surprise?). I would suspect that the flow rates = shown are without back pressure and that when attached to a real engine = coolant system that : 1. The flow rates would decrease=20 2. The current requirements would increase.=20 However, not to the point the electric pump would be required to make = 10HP or more to provide the required flow. I suspect there are = considerable losses (such as pump cavitation and pressure drops through = the cooling galleys)with mechanical pumps at high pump rpm as driven by = a high revving engine which accounts for the high power requirements. = Whereas the electric driven pumps may operate at lower and more = efficient rpm without the majority of those losses. That said, the pumps cost range from around $200 - $400 and while no = weights were given, basic on the photographs showing the heavy electric = motors and additional plumbing would not appear to offer any = significant weight savings over the proven, reliable mechanical pumps = most of us are using.=20 So while certainly interesting and perhaps of value in some aircraft = installations(how would you like to gain an additional 10 HP on = takeoff?), I remain confident in my old 86 13B water pump housing and = cartridge which is still going strong after 10 years. I have moved it = from my first 86 N/A engine to my current 91 turbo block, so it has = performed for over 10 years in two different engines without any = problem. Interestingly, of the 11 electrical water pumps advertised, only one = was specified for drag race use only - and it had the lowest current = drain - 3.5 amps. Ed Ed Anderson Rv-6A N494BW Rotary Powered Matthews, NC eanderson@carolina.rr.com http://www.andersonee.com http://members.cox.net/rogersda/rotary/configs.htm#N494BW http://www.dmack.net/mazda/index.html ------=_NextPart_000_000A_01C8A851.E52A2160 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable

I was just thumbing through a recent = catalog from=20 Summit Racing and came across a couple of pages on electric water=20 pumps. There has always been a degree of interest (and some = debate=20 {:>)) regarding the use of electric water pumps in aircraft. = It=20 was interesting to read some of the descriptions, but basically the = current=20 consumed ranged from 4 - 9 amps and the quoted flow rate = (presumably=20 without back pressure) was from 16-35 gpm.

So if you take 9 amps at say 14 volts = =3D 126 watts=20 =3D 0.167 HP to get that flow. However, some of them indicate you = can save=20 15 - 20 engine HP at HIGH rpm. So why the = difference?

Apparently (my best guess) is = that they=20 are advertising their product to best advantage (surprise?). I = would=20 suspect that the flow rates shown are without back pressure and that = when=20 attached to a real engine coolant system that :

1. The flow rates would decrease=20

2. The current requirements would = increase.

However, not to the point the = electric pump=20 would be required to make 10HP or more to provide the required = flow. I=20 suspect there are considerable losses (such as pump cavitation and = pressure=20 drops through the cooling galleys)with mechanical pumps at high = pump rpm=20 as driven by a high revving engine which accounts for the high power=20 requirements. Whereas the electric driven pumps may operate at = lower and=20 more efficient rpm without the majority of those losses.

That said, the pumps cost range from = around $200=20 - $400 and while no weights were given, basic on the = photographs=20 showing the heavy electric motors and additional plumbing would = not appear=20 to offer any significant weight savings over the proven, reliable = mechanical=20 pumps most of us are using.

So while certainly interesting = and perhaps=20 of value in some aircraft installations(how would you like to gain an = additional=20 10 HP on takeoff?), I remain confident in my old 86 13B water pump = housing and=20 cartridge which is still going strong after 10 years. I have moved = it from=20 my first 86 N/A engine to my current 91 turbo block, so it has performed = for=20 over 10 years in two different engines without any problem.

Interestingly, of the 11 = electrical=20 water pumps advertised, only one was specified for drag race use only - = and it=20 had the lowest current drain - 3.5 amps.

Ed Anderson
Rv-6A N494BW Rotary=20 Powered
Matthews, NC
eanderson@carolina.rr.comhttp://www.andersonee.com
http:/= /members.cox.net/rogersda/rotary/configs.htm#N494BW
http://www.dmack.net/mazda= /index.html

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