----- Original Message -----
Sent: Wednesday, February 03, 2010 7:42
AM
Subject: [LML] Re: Airspeed sensing
switch: Pressurization (IV-P)
I have flown with the Duke's Valve completely occluded via duct tape
fully across the rear seat opening (for several month, in fact, part fo an
experiment). I was ready to puncture the tape if needed. The cabin
did not over pressurize, but it would have above ~13,000' to ~15,000' during
power climb. The initial slam of higher pressure during power up and
take off was noticible, but not in excess of 3psi (it was just immediately
noted). Over pressurization at anytime was avoided with a controlled
reduction of the throttle (MAP) to demonstrate cabin pressure correlation to
MAP. Upon landing, with outflow still occluded, cabin was always at
airport ambient pressure before door seal was dropped. Again, this zero
differential is notable on short final, door seal tight, Duke's outlet
occluded, engine below 11.5".
During flight, outlet occluded, a small puncture through the occluding
tape demonstrated brisk exiting air through the puncture out the Duke's Valve,
but without a rapid cabin decompression (like one might experience with door
seal deflation). At any altitude, door seal deflation results in
immediate cabin decompression and cabin climb to current flying
altitude.
I also have a cabin alert above 10,000' and panel light
notification.
Jeff L