X-Virus-Scanned: clean according to Sophos on Logan.com Return-Path: Sender: To: lml@lancaironline.net Date: Thu, 10 Oct 2013 08:39:16 -0400 Message-ID: X-Original-Return-Path: Received: from qmta12.westchester.pa.mail.comcast.net ([76.96.59.227] verified) by logan.com (CommuniGate Pro SMTP 6.0.7) with ESMTP id 6509478 for lml@lancaironline.net; Thu, 10 Oct 2013 07:58:53 -0400 Received-SPF: pass receiver=logan.com; client-ip=76.96.59.227; envelope-from=jmorgan1023@comcast.net Received: from omta06.westchester.pa.mail.comcast.net ([76.96.62.51]) by qmta12.westchester.pa.mail.comcast.net with comcast id bP231m00216LCl05CPyKQa; Thu, 10 Oct 2013 11:58:19 +0000 Received: from [192.168.1.102] ([24.11.157.196]) by omta06.westchester.pa.mail.comcast.net with comcast id bPyJ1m00a4EXR5U3SPyKZK; Thu, 10 Oct 2013 11:58:19 +0000 From: Jack Morgan Mime-Version: 1.0 (Apple Message framework v1283) Content-Type: multipart/alternative; boundary="Apple-Mail=_D5565626-14FC-4D03-B9E4-D5F9A8D6B558" Subject: Vacuun for pressurization X-Original-Date: Thu, 10 Oct 2013 07:54:31 -0400 In-Reply-To: X-Original-To: "Lancair Mailing List" References: X-Original-Message-Id: X-Mailer: Apple Mail (2.1283) --Apple-Mail=_D5565626-14FC-4D03-B9E4-D5F9A8D6B558 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=iso-8859-1 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=_D5565626-14FC-4D03-B9E4-D5F9A8D6B558 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=iso-8859-1 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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