REFLECTOR: ram air

[Andrew Ellzey]

My 1964 M20E IO-360A1A (200 hp) had the original cowl with the ram air door and would increase the MP a full 1". At higher altitudes this made a big difference in the climb performance. The cruse increase on this non speed modified airframe was only about 3 knots increase. From my experience with flying this aircraft for 19 years, its well worth you time to add it to your aircraft. The difference with our Velocities is that you can't get a straight shot at the air induction like Mooney's could. But our air speed might compensate for this difference. Another interesting note and the reason for the ram air door was that this wasn't filtered air with the ram air open. If you attempt to add this feature, as I intend to, you should install a controllable ram air door if you take your ram air from the bottom of your aircraft. Your induction air box assembly should also have a sprigged flapper door that can be sucked open in the event of something like ice build up or say a bird becoming lodged in your air intake. There is a NTSB report of a Mooney's forced landing from a duck becoming lodged in its induction air intake while flying low over a lake. Mooney's operating manuals stated that the ram a was not to be used on the ground or in dusty conditions. Your manual should state the same, again if you intake is from the bottom of the aircraft. I would say that a competent FAA inspector wouldn't except your air intake design, unless the same sort of emergency alternate air source is included. Those that are already flying can report on this issue. I also would add that your design should have a way for rain water it exit you intake if your aircraft is left on the ramp during a rain storm. My thoughts, now you add yours.

Andy
  ----- Original Message ----- 
  From: Donald Royer 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Tuesday, July 04, 2006 2:26 PM
  Subject: Re: REFLECTOR: ram air


  The  older Mooneys had a valve that you could open to provide ram air. You could barely see the MP gauge flicker when you opened it. About 1/4 of an inch. They eventually gave it up as not worth the effort, and the newer Mooneys do not have it.
  Don


    ----- Original Message ----- 
    From: Douglas Holub 
    To: reflector at tvbf.org
    Sent: 7/4/2006 11:50:53 AM 
    Subject: REFLECTOR: ram air


    To any of you engine guys out there, how much of a performance boost will I get from a normally aspirated, fuel injected Lycoming if I provide ram air for the intake? 


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