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