X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Received: from elasmtp-dupuy.atl.sa.earthlink.net ([209.86.89.62] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6509660 for lml@lancaironline.net; Thu, 10 Oct 2013 09:24:10 -0400 Received-SPF: none receiver=logan.com; client-ip=209.86.89.62; envelope-from=colyncase@earthlink.net DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=dk20050327; d=earthlink.net; b=OU2PbymXX05bdhiu7C/TQM5Ymw+S0QdSlg/77MfRvZE1RNB8yherhA0v20J+ovGr; h=Received:From:Mime-Version:Content-Type:Subject:Date:In-Reply-To:To:References:Message-Id:X-Mailer:X-ELNK-Trace:X-Originating-IP; Received: from [70.20.45.147] (helo=[192.168.1.24]) by elasmtp-dupuy.atl.sa.earthlink.net with esmtpa (Exim 4.67) (envelope-from ) id 1VUGDH-0005Od-Vb for lml@lancaironline.net; Thu, 10 Oct 2013 09:23:36 -0400 From: Colyn Case Mime-Version: 1.0 (Apple Message framework v1085) Content-Type: multipart/alternative; boundary=Apple-Mail-105--622711649 Subject: Re: [LML] Vacuun for pressurization Date: Thu, 10 Oct 2013 08:23:33 -0500 In-Reply-To: To: "Lancair Mailing List" References: Message-Id: X-Mailer: Apple Mail (2.1085) X-ELNK-Trace: 63d5d3452847f8b1d6dd28457998182d7e972de0d01da9405fb1b814e8e39cd8a4fd6c5eb1bccbe7350badd9bab72f9c350badd9bab72f9c350badd9bab72f9c X-Originating-IP: 70.20.45.147 --Apple-Mail-105--622711649 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii Jack, what you describe below sounds like pin 4. Did you happen to = determine what pin 13 does exactly? Also, in case there is anyone out there that does not have A/C, another = use of pin 4+vac is to open the outflow valve fully to maximize fresh = air flow through the cabin when not pressurized. For this you would = need a manual switch to pin for which bypasses the usual gear/airspeed = interlock. Colyn On Oct 10, 2013, at 7:39 AM, Jack Morgan wrote: Hello Dico, I talked directly with Dukes engineering while I was sorting out my IVP. = The only function the vacuum performs is to fully open the valve when = the dump solenoid is activated. Dukes advised that providing vacuum was = optional and not a requirement for proper operation. Graig correctly = describes the system behavior without vacuum. I did not opt for the = complexity of an electric vacuum pump and get the same slight pressure = bump Craig describes if throttle is firmly advanced on takeoff. So....... the addition of an electric vacuum pump is up to the builder. = I doubt most pilots would be able to ascertain that the pump had failed = during their normal operations. The vacuum is not required for proper = valve operation if the dump valve solenoid is activated for some reason = during flight. If you choose to go without vacuum, Dukes advised you = close off the port with an appropriate sealing method. Regular servicing = of the filter is not required if you omit the vacuum. If you choose to go with a vacuum pump, make sure the dump valve is = properly wired so it is activated with the gear down or else you will = not get the slight (and only) benefit from the pump on takeoff. Jack Morgan On Oct 10, 2013, at 6:01 AM, Lancair Mailing List wrote: > I have an all-electric airplane as well and chose to not have any = vacuum supplied to the Dukes valve. The only difference is the rate in = which pressurization starts building in the cabin on takeoff roll. Once = airborne, vacuum has no effect on the pressurization system. I choose = to apply power a little more slowly than some pilots. This prevents any = pressurization discomfort and typically I don't need any right brake to = hold centerline. Takeoff distance is not an issue. If I can land = there, I can easily takeoff there. I know one pilot who has developed = an electronic circuit to control a small electric vacuum pump based on = the landing gear position. So there are several options. In my = opinion, keeping the engine driven pump is the least desirable. >=20 > Craig Berland > N7VG --Apple-Mail-105--622711649 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii Jack, =  what you describe below sounds like pin 4.  Did you happen to = determine what pin 13 does exactly?

Also, in case = there is anyone out there that does not have A/C, another use of pin = 4+vac is to open the outflow valve fully to maximize fresh air flow = through the cabin when not pressurized.  For this you would need a = manual switch to pin for which bypasses the usual gear/airspeed = interlock.

Colyn

On Oct = 10, 2013, at 7:39 AM, Jack Morgan wrote:

Hello = Dico,

I talked directly with Dukes engineering while = I was sorting out my IVP. The only function the vacuum performs is to = fully open the valve when the dump solenoid is activated. Dukes advised = that providing vacuum was optional and not a requirement for proper = operation. Graig correctly describes the system behavior without vacuum. = I did not opt for the complexity of an electric vacuum pump and get the = same slight pressure bump Craig describes if throttle is firmly advanced = on takeoff.

So....... the addition of an electric = vacuum pump is up to the builder. I doubt most pilots would be able to = ascertain that the pump had failed during their normal operations. The = vacuum is not required for proper valve operation if the dump valve = solenoid is activated for some reason during flight. If you choose to go = without vacuum, Dukes advised you close off the port with an appropriate = sealing method. Regular servicing of the filter is not required if you = omit the vacuum.

If you choose to go with a = vacuum pump, make sure the dump valve is properly wired so it is = activated with the gear down or else you will not get the slight (and = only) benefit from the pump on takeoff.

Jack = Morgan

On Oct 10, 2013, at 6:01 AM, Lancair = Mailing List wrote:

I have an all-electric airplane as well and chose to not have = any vacuum supplied to the Dukes valve.  The only difference is the = rate in which pressurization starts building in the cabin on takeoff = roll.  Once airborne, vacuum has no effect on the pressurization = system.   I choose to apply power a little more slowly than = some pilots.  This prevents any pressurization discomfort and = typically I don't need any right brake to hold centerline.  Takeoff = distance is not an issue.  If I can land there, I can easily = takeoff there.  I know one pilot who has developed an electronic = circuit to control a small electric vacuum pump based on the landing = gear position.  So there are several options.  In my opinion, = keeping the engine driven pump is the least desirable.

Craig = Berland
N7VG

=

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