You are properly paranoid about hardware ingestion Todd, I am equally
so. I missed where Leon warned about cardboard but that would surprise
me. I have used plastic steel (JB Weld, etc) in my intake systems without
any problems (being very careful about details, surface prep, etc). On my
test stand I am not so careful and the engine has ingested small pieces of
epoxy, JB weld and super-fill during test runs. No guarantees of
course, but that engine is still running fine.
Air filters are a good idea and I'd never argue against them but OTOH I
have never used them in the 1500+ hours of flying. My first engine went
856 hours (only replaced so I could try a different port scheme) and had
no noticeable wear on rotor housings, barely measurable wear on side
housings, apex seals had about .012 total wear on height. This is
one of the many areas where details and pilot technique can make a night and day
difference. My air intakes have always been at the top of the cowl (dirt
& sand density are highest near the ground of course (a bottom scoop without
filter would be 'not good') and I am careful about the dust conditions when I am
forced to taxi with traffic (avoid when possible).
On the subject of ram air, it really is not much of a factor below 120 mph
and no factor at all on takeoff. It becomes significant at top speed
which is about 225 mph on my RV-4.
Tracy (waiting for runway to emerge before departing for
Colorado)
This
thread has gotten me thinking about things that make rotors stop.
So tonight I removed the an item of concern. There
was a screw inside my airbox (under the filter) holding it down onto it's
proper position. This was due to the shape of the intake hose trying to move
it a little. However the heat from the engine and turbo over the last 50+
hours has made it sit perfectly without the screw to hold it and once the top
cowl is in position it is captured and cannot move.
But more disconcerting is another mod. Many builders have
done this and that is the plastic steel (JB weld or Devcon) inside the
secondary intakes in the end plates. During my first build I was all
ready to perform this task when I had thoughts about a piece of plastic weld
breaking loose and going through a rotor, so I omitted it. On my second
rebuild (after detonation incident), I went ahead with it, thinking that if
anything like this was going to happen I'd likely have heard about it and also
thinking that the engine would likely just pass it through without incident.
Now after reading Leon's testimonials about things as trivial as a bit of
cardboard taking out a rotor, I'm again thinking about this.
Plastic steel is incredibly tough, but when I need to
remove some, I use my acetylene torch to heat it and it will crumble away in
chunks. Now if the engine is properly cooled it should never get anywhere near
hot enough to compromise the strength of this stuff, would it? What about
on a loss of coolant or other overheat situation. Even if the engine doesn't
appear to be damaged from this, what about the plastic steel?
I'm not being paranoid or anything here, but just asking
questions to promote thought about plastic steel. Don't get me wrong, I think
it is wonderful stuff.
Todd