Although the outflow valve is held open with the dump valve switch on, it is not nearly as far open as it is when using the vacuum line.

Typing and grammar errors courtesy of Siri and the iPhone.

> On Oct 9, 2013, at 13:13, Colyn Case <colyncase@earthlink.net> wrote:
>
> maybe Pete (leapfrog) can chime in here but I don't really understand why Dukes put that in there.  You could have the dump switch on during takeoff, and there's another way to wire it that holds the outflow valve full open.
>
> On Oct 9, 2013, at 11:13 AM, Craig Berland 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
>
>
> Hello Dico,
> You will need a vacuum port to the Dukes pressure valve for the pressurization to work correctly, I do not have any gyro instruments either but I needed to install an electric vacuum pump near the Dukes valve
> Kamal T
> N1104T
>
>
>
>
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