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From: RicArgente@cs.com
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Date: Tue, 22 Feb 2000 10:17:51 EST
Subject: RAM Air (Again...)
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Two weeks ago, at 8,500 MSL (7,500 Density ALT), I tried to play around with 
my RAM air set-up to see how well it works.  The manifold pressure was 
happily giving me 23.8".  I pushed the RAM air cable and walla, MP is now at  
23.3".  A half-inch LOSS in MP instead of the expected 1-inch increase   :-(  
 

I now have an interesting problem and a new challenge, also confirming that 
my set-up sucks (or should I say, doesn't suck enough?!?) <G>.

For most of my flights, I have been using filtered air and have hardly ever 
used the ram air at all.  The air filter (Cessna foam filter) is located 
below the upper right engine baffle and hoses down to the air box.  Diameter 
of the hose is only 2 1/2".    The RAM air intake hole was only 2 1/4".  The 
way this set up works is once the RAM air is opened, the filtered air source 
gets closed off, just like the manual instructed.   I used the Lancair 
supplied air box.  The "RAM air inlet-TO-air box" connection was done simply 
by using silicone baffle material (lots of leaks I suspect).  The top of the 
air box has a 2 1/2" AL flange riveted to it and the filtered air is 
connected to this flange.

I looking a several other RAM air systems, I discovered that most simply 
opens and closes the RAM air source, leaving the filtered air source open all 
the time, as opposed to my set-up, where I close off the filtered air.  
Getting air from two sources simultaneously sounds like a good idea but I am 
hoping some confirmation on this.  Comments anyone??  

For now, I have increased the size of the RAM air intake hole to 3-inches.  I 
also made a 1 1/2" flange so I can attach a SCAT tube to this intake hole and 
connect it to another flange (to be fabricated) on the air box.   I will 
probably also increase the filtered air hole and tubing to 3 inches also.   
Lastly, depending on feedback I get, I will fabricate a butterfly door to 
open and close the RAM air.    

Hey Scott, when you got your 1.5" MP boost, how much TAS/IAS increase did you 
get?  (LML: Ram Air - The Final Frontier  2 Sep 1999 06:11:38 -0700 ).


Rick Argente
N360ZR
http://ourworld.cs.com/ricargente
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