In an interview, Al Klapmeier talked about changes in the production
model of the Kestrel, including fuselage dimensions and wing. I read
somewhere that they will go to a less-complex/straighter wing. At
Mondays announcement they had the prototype aircraft sitting on display
out if front of their hangar, and a mock-up fuselage sitting inside. The
small crowd did not spend much time looking at the aircraft, nor did
they have company reps outside to answer questions while I was there
because the January weather was rather nippy at the 09:30 AM gathering
time.

Kestrel announced in July that they will be using a Honeywell engine
tuned for around 1000HP.  Goal is 350 KTS, but I've read that they may
back off a bit on that number

http://www.kestrel.aero/pdfs/KAC%20PR%2007.21.11%20HONEYWELL%20POWERS%
20KESTREL.pdf

Taking a look at the attached photo from Kestrel web site .... now THAT
is a PSRU.  No wonder those engines go for about a $million each.


Robin Bergland


Huh..  Spur driving planetary.  I guess they have to get from
30,000RPM down to 1700RPM somehow..


Regards,

Matt-

A good reason for the spur is the prop shaft offset. Turbines like ram
air so that is a good way to get direct ram air in under the prop to the
compressor. The flaw in the PT6, if any, is forcing the ram air to turn
a 90 degree corner. My guess is this improves the BSFC somewhat.

Paul Lamar


I chatted with a young guy from the UK that had a booth at OSH couple of
years ago.  He was making/selling very small turbines designed for UAVs
and such.  He had the time/courtesy to answer a lot of my silly
questions.  He explained to me that a lot of turbine design , including
the 90  and 180 degree corners, is dictated by bearing technology.
Most designs that try take advantage of ram-air in tractor configuration
require concentric shafts to get the power to the prop and presents
major reliability problems.  He did mention development of the then new
ceramic-bearings as being absolutely necessary for some implementations.
What really made my day after that OSH conversation occurred not 15
minutes later at the nearby P&W booth.  A group of guys standing around
the P&W cut-way demo engine started asking the very same questions and
I, trying to keep a straight face, was able to answer them.  I soon
noticed that even the P&W reps were standing there listening to my
'professional' presentation. Wish I could now remember half of what I
learned and then forgot that day :)

Robin Bergland


The P&W PT6 is concentric.
They don't send their best people to air shows :)
Here are some shots of Robin and I visiting P&W in Connecticut
a few years ago. This was when Robin was still working for UAL.

Paul Lamar



One thing PW gets out of reverse flow is inertial separation for FOD.


Matt-