Mailing List lml@lancaironline.net Message #67337
From: Craig Berland <cberland@systems3.net>
Sender: <marv@lancaironline.net>
Subject: [LML] Re: Removing vacuum pump?
Date: Thu, 10 Oct 2013 08:39:05 -0400
To: <lml@lancaironline.net>
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Bill, 
You are correct. That is what the Lancair build manual calls for. Some aircraft have that wire removed. 
I have not tested this....but my understanding is the vacuum opens the dump valve enough so no cabin pressure change is possible. I am very happy with mine and have not tested other options.
Craig Berland

Sent from my iPad

On Oct 9, 2013, at 5:14 PM, "William A. Hogarty" <billhogarty@gmail.com> wrote:

I understood that the outflow valve was grounded whenever the gear switch was down.
 
Is this wrong?
 
Bill Hogarty


On Wed, Oct 9, 2013 at 9:13 AM, Craig Berland <cberland@systems3.net> 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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