I do not use an air filter.  I tried one of the K&W foam ones one time -
fortunately I had a stainless steel wire mesh over my throttle body intake -
which is all that stopped the foam from being ingested by the engine.  I
don't necessarily think the foam would have hurt the engine - given what
some 13Bs had ingested - but it certainly reduced the airflow.  My rpm went
from around 5200 rpm down to 4000 rpm when that foam got sucked up against
the screen.  It had been over 2 feet from the throttle body.  Poor design on
my part, no doubt, but decided to go without it.

Tracy Crook has over 1500 hour flying a rotary with no filter.  Of course, I
think it depends on what type of flying you do and where.  Dusty regions off
of dirt strips might make a filter a smart move.

Can't speak for the pressure recover scoops. Tracy Crook does use the
dynamic pressure to aid his intake air flow and has reported seeing 31"
manifold pressure at 1000 MSL and 215 MPH.

Ed

Ed Anderson
RV-6A N494BW Rotary Powered
Matthews, NC
----- Original Message -----
From: "Alex Madsen" <madsena@rose-hulman.edu>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
Sent: Friday, July 09, 2004 2:33 AM
Subject: [FlyRotary] air filters and scoop intakes


> Hi All
>
> I have 2 questions that people have alluded to on the list but I have
> not seen them addressed directly.
>
> 1) Do rotary aircraft engines need air filters?  I have seen pictures of
> engines with air filters but man pictures comments on the list,
> particularly from Jerry have led me to believe that not every one uses
> air filters. No air filters would greatly simplify design of CF p-port
> (eliminate plenum) and other manifolds.
>
> 2) Do most planes have scoop intakes for pressure recovery from air
> going intake manifold?  It seem to me a lot of the intakes terminate
> after the throttle. While this would make construction easer it is a
> loss of some potential HP.
>
> Alex Madsen
>
>
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