----- Original Message -----
Sent: Tuesday, September 16, 2003 1:48
AM
Subject: [FlyRotary] Re: turbo
performance?
Hi
Rusty;
You're probably not as curious now about this since you've been out
wrangling up some extra ponies, but here it is anyways...
Just
how much below your expectations was you climb
performance?
Lots. I had dreams
of 2000fpm, but was expecting 1200fpm without using boost, but managed a
dismal 500fpm. However aircraft weight was approx 1700 lbs, as there was two
of us on board and I was carrying more fuel than
necessary.
How much boost were you running?
Full throttle, or part throttle to lower boost?
We were
running 0psi boost, which is less than 3/4 throttle. At one point it
creeped up to 2 psi but I throttled back. I had been running under the idea
that 0 boost would equal an NA, even though in the back of my mind I
remembered someone speculating that it would require at least 2 psi to
overcome the backpressure caused by the turbo. Leon has confirmed this for
me.
You're initial speculation of being over
propped might put you in the same boat I'm in, that is, having less
power than you should.
I spoke
with Dave Atkins as I knew he was also using an IVO Magnum. His is also a 76"
3-blade, so maybe I'm as overpropped as I had thought. He has reprofiled his
blades, but he says that only helped at the top end. Apparently some NASA
engineer helped him with it and it allowed him to get the top end numbers that
are otherwise elusive for IVO props. I can't tell you what pitch I'm running
as mine is cockpit adjustable, so I've cycled through a few times. A big
priority will be to calibrate the electronic constant speed governor so then I
should be able to dial it in for the climb RPM. This has to be done under
flight conditions.
I know you've run as much as 6 psi
on the ground, so I'm guessing that you were probably running more than I
was for these flights, so you may not be as far behind the curve as I
am.
The plan
for flight #5 was to "press the go button":-), and use all available boost on
take-off, just to see what she really had in her, unfortunately the EWP
seizing moments before we taxied onto the active runway put a halt on that
idea.
The
weather here has really cooled off in the last week, this evening as I was
riding my motorbike home, it was downright freezing, so by the time I get
going again I'll do some air density calcs before I pour all the coals on the
fire.
I'm also
considering removing my wings and bringing my plane home, but for different
reasons. In less than a week I have to go to the bush to work as a hunting
guide for a few weeks, then when I return I have less than three weeks before
I return to tech school. Since we have an incoming exam that is worth 25% of
final mark, I'd best get my nose in the books. I don't return from school till
Christmas, so realistically I'm looking at January before I can resume flight
testing. As a rookie pilot, flight testing in the winter might not be the best
idea, so it may even be spring before I can get really serious about again.
Right now I pay a pretty reasonable rate for hangar space, but it goes up
substantially in the winter, so bringing it home may be the best option. I
can't say that I'm very happy about this, in fact I'm downright pissed off
:-(, but as everyday goes by with an empty mailbox and no EWP, I'm running out
of options.
This is
not to say that I regret trying the EWP. It was really promising right up
until it quit working :-). As even the best products can fail, I'm willing to
give it the benefit and try a replacement. Leon has helped by sending a
replacement right away, but somewhere it got lost, so he has sent yet another,
but I'm beginning to lose faith in our mail system. I'm really hoping I can
get another chance to try this pump before I'm forced to bring it home, as if
it is not successful it would be allot easier to convert to a mechanical pump
here in my own shop.
S. Todd Bartrim
Turbo 13B RV-9Endurance
C-FSTB
http://www3.telus.net/haywire/RV-9/C-FSTB.htm
"Whatever you vividly imagine, Ardently desire, Sincerely believe in,
Enthusiastically act upon, Must inevitably come to pass".