----- Original Message -----

Sent: Friday, December 13, 2002 = 12:31=20 AM

Subject: [LML] IV-P Cabin Air = System=20 Dukes Valve with An All Electric Panel

After going over LML Posts, talking = to Pat=20 Patrick at Dukes and applying all this knowledge gathered, I feel = quite=20 certain the following will get the Dukes valve to operate as=20 designed.

The solution is to simply use the = engine manifold=20 vacuum, tapped off of the manifold pressure line to the manifold = pressure=20 gauge. Put a check valve in after the tap off to prevent a = positive=20 pressure form being applied to the Dukes valve. Run the vacuum = line=20 directly to the Dukes valve. I am planning on using a check = valve from=20 McMasters - $2.90.

It was concluded that the engine = will=20 provide sufficient vacuum until the throttle is pushed in for take = off. =20 The check valve will hold the vacuum and Dukes valve open until = the valve=20 control system takes over.

The logistics of several approaches = were gone=20 over with Pat Patrick. He acknowledged the findings and confirms = that=20 the manifold system should work well. Pat also acknowledged the = problem=20 with the Venturi concept is that air has to be streaming into the = cabin before=20 the Venturi draws a vacuum on the Dukes valve. By that time, a = pressure=20 will build up in the cabin and the occupants will feel a pressure = surge. =20 Alternatives were discussed, such as, using the door seal pump and a = separate=20 pump. All the other approaches appear to require more complex or = involved procedures to get them to work properly.

One further advantage to the manifold = vacuum=20 approach is that all the parts should be inexpensive stock = items.

If anyone is interested, I will = submit what=20 should be a short bill of materials and a simple diagram of my final = system=20 after getting it installed. Be aware, though, it will be awhile = before=20 this approach is put to the acid test.

Thanks for your help.

Scott Turner =20

FOLLOW-UP: The concept has now = been=20 employed and it's been reported to work without a hitch. The = person who=20 used the method said he bought a plastic fitting at an auto supply = store along=20 with some 1/4" poly-flow tubing. For a check valve he used the = same=20 check valve which Lancair supplies for their door seal = system.

If anyone has any quesions you can = call me. =20 215-848-4500 (day) or 215-848-6605 (evening).

Scott Turner IV-P = builder -=20 90%/90%