REFLECTOR: ram air

[Andrew Ellzey]

The M20E had a black rubber bellows that allowed the engine to move and still allowed the connection of the ram air door and induction intake, which as you know, was mounted to the forward cowling. Most pilots and mechanics don't inspect this bellows for holes or cracks on the annual inspection as recommended. I replaced mine early in my ownership of this aircraft and immediately saw the difference. This part had to be purchased directly from Mooney and was very pricey for what it was. Mooney also changed the size and shape of the intake and door in later models, I think it was your J model, round verses rectangular. All these factors could attribute to the differences that we see between aircraft and models. There were several articles, that I have read on this issue, that stated that Mooney added the ram air to compensate for design errors with the fuel/air intake metering system in the early years. This could also attribute  to the differences seen in the later models. My fuel system was a Bendix system, if I remember correctly. Yours could be an improved model or different vender and not need the improvement in MP that was gained in my earlier M20E.

Andy
  ----- Original Message ----- 
  From: Donald Royer 
  To: Velocity Aircraft Owners and Builders list 
  Sent: Tuesday, July 04, 2006 4:44 PM
  Subject: Re: REFLECTOR: ram air


  My 1978 M20J  has never given me more than an extra 1/4 of an inch when I open the ram air door. I think that the difference may be that the clean up of the cowl between the E and the J gives the J better breathing with the ram air door closed.

  Don

    ----- Original Message ----- 
    From: Andrew Ellzey 
    To: djroyer at earthlink.net;Velocity Aircraft Owners and Builders list
    Sent: 7/4/2006 2:32:00 PM 
    Subject: Re: REFLECTOR: ram air


    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 ic! e 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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