> In a message dated 10/1/2007 2:58:40 AM Eastern Daylight Time,
> europa-list@matronics.com writes:
>
> Concerning the Jabiru, there is little room between the prop and the
> front cylinders to provide a correct diffuser, so the inlet must be of
> larger size, and the efficiency will be lower.
> But the engine can be adequately cooled all the same, at the price of a
> little more drag, of course.
On Monday, October 1, 2007, at 06:30 AM, TELEDYNMCS@aol.com wrote:
> -
> I've had a chance to test my turbulators installed at the mouth of my
> left cooling intake and they-worked exceedingly well. I've seen, on
> average, a 25F drop in CHT's on the left side now that I have
> turbulated the airflow entering the left side intake. One cylinder
> dropped-45F and went from being the-second hottest of the six to the
> coolest.-Interestingly, the engine is now running in the 240F-260F
> range on all CHT's, but the delta pressure-did not change!
> Clearly, Andy Silvester used the Lancair cowls as a model for his
> Europa cowl set. I've studied close up-pictures of the Lancair cowl to
> try and find out what the difference between the two really-is. The
> only thing I notice is the Lancair inlets protrude about-1"-farther i
n
> front of the cowl than mine do.,- I think this has something to do
> with the pressure wave I've observed in front of my left intake with
> my crude string tests. So Gilles, you are likley correct in your
> analysis.
As a (at this point at least) probable Jab buyer, I've been following
this thread w/ interest. Up til now, I had assumed that the difference
between right and left side cooling issues was a consequence of the
difference in prop wash. I've also assumed that references to "right"
and "left" were to starboard and port, i.e., as seen from the cockpit
rather than say from the front of the engine looking aft. I believe
that the protrusions around the circumference of the Lancair cowl
inlets are intended to minimize the effects of prop wash on air
entering the inlets. Also, from the pictures I've seen of the
Suncoast/Jab air ducting, it appears that the port and starboard ducts
have identical (but opposite hand) shapes which do not appear to factor
in the front to rear offsets of the port/starboard cylinder banks.
It just now occurs to me (after reviewing Giles's Contrails articles
referenced previously) that the difference in distance between the
inlets and the first cylinders seen by air entering the port and
starboard ducts may be of equal or even greater importance...and may be
the source of the differential in port/starboard cooling effectiveness.
This is conjecture on my part, and of course no substitute for the
rigorous testing John L. has done; still, it might be nice to get to
the heart of the problem. Please comment at will!
Incidentally Giles, 2 of the 3 articles you referenced come up in
french; could you offer any clues as to how I could view them in
english?
Fred
A194
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