A high speed nose lift; a high speed crow hop; and finally off and away
around the pattern; the 20B powered Velocity, N755V maid its maiden flight
yesterday, 8/04/06.  What an exciting milestone – even though in this case I
was watching from the ground as the test pilot did his thing.

The engine performed well, and the pilot reported that all handling
characteristics were good.  The flight was short, however; because the oil
temp was 10-15F higher than the limit I had set, and the pilot did the right
thing in abbreviating the flight so that can be evaluated and changes made
as necessary.  All in all, with that as the only issue of note at this
point; it was a good day.

It’s such a common thing, isn’t it – these cooling issues.  The oil temp
(downstream from the cooler) peaked at 230F, somewhat after the end of the
climb (OAT about 80F); I guess it takes a little while for the hot oil to
get to the bottom of the 8 qt sump and back through the cooler.  The main
concern was that the temp didn’t drop more that 3-4 degrees as he went
around the pattern, and after landing and rolling out it was still 225F.
Coolant temps peaked about 190F.

I had a video camera mounted reading the engine monitor display which is
great for review later.  Unfortunately, even though I have all sorts of
instrumentation for doing diagnostics, in his focusing on flight
characteristics, and the concern about the high oil temp the pilot forgot to
push the ‘page up’ button; so the only data I have is page 1.  Regardless of
further data, it seems clear that there is insufficient air flow through the
wing root oil cooler – a condition that was not entirely unexpected.

Another major step in an on-going process.

Al


Congratulations Al. You have a very nice airplane there.

Here are some pictures of Al's oil cooler installation. It is a big mystery
to me why this does not work but this is the second pusher aircraft with this
configuration that has a problem with this. Perry's was the first.
I suspect the boundary layer back there has higher pressure than one
would think. We measured it on Perry's airplane and it was much
higher than I expected.

Time for Me 109 flaps Al :)  Perhaps modifying the exit duct as
per red line would help.

BTW Al, I don't have any pictures of the air intake. Can you send me some?