Paul,
I wonder if you are focusing on the bearings in the planetary
shafts? Then
you would have a point. They would be doing elliptical loops around a
circle.
I'll go down to the office tomorrow and paint some white marks on the
different gears and take four or five pictures of what happens
during one
revolution of the sun gear. Like the rotary it was hard to get my head
around. This question is going to come up again and again so with Rolf's
explanations and picture proof it would make a good addition to your
website.
Meanwhile have a look at this NASA report on unducted fans. The last
part is
especially revealing about the issues that keep a 'good technology' from
coming to market. The author speaks about 'reverse salient issues'
Poignant info concerning the rotary and even the rotary turbo compound.
http://history.nasa.gov/SP-4219/Chapter14.html
DougFir
They underestimated the noise problem. Barely mentioned in this
paper. It was so bad that it affected the structure of the
airplane. GE felt they would have to add weight and cost to the
AC structure to counter the noise problem which off set the
20% fuel savings. BTW the fact that GE actually built
and flew the unducted fan full scale yet again proves private
innovation beats big gov bureaucracy every time.
Not really a good analogy with the turbo compound rotary.
There are no downsides to the turbo compound rotary compared
the smaller turbo prop engines. It has everything going for it with
the SAME noise. Less acquisition cost being a major advantage.
50% fuel savings being another. Only the weight issue is still
in question and the other shoe, namely the weight of an all
aluminum or some other alloy large rotary, has not dropped yet.
The real price of fuel over the years on average taking
into consideration inflation has remained pretty much the same.
What happened in 1973 as the price of fuel oil went up so did
everything else including wages. When I was a kid the cost of a loaf
of bread was about 20 cents, about the same as a gallon of fuel.
Now the cost of a loaf of bread is still about the same as
a gallon of fuel. If anything bread is now probably more
costly. Hybrid car sales are down if not dying.
I see no end to this cycle in our life time. Since Iraq is sitting
on the worlds second largest known reserves of crude oil
when they finally get finished killing each other off and this
huge source of crude is fully developed the real price will
drop yet again. IMHO a major factor, frequently not mentioned
in the sectarian war, is who gets to control the Iraq oil.
Waiting in the wings when crude oil pumped from the ground actually
(if ever) becomes a reduced source (hasn't happened yet) is the
Alberta, Utah, Wyoming tar sands.
Paul Lamar
Oops, forgot to attach the pic of the NASA and GE propfans.
Regards,
Gordon.
The two on the right are actually the GE concept
and not the NASA concept despite the NASA logo on the
cowl. I saw the test airliner with the unducted fan on it
out at Mojave where GE has a full scale test facility.
Unfortunately I did not hear it run.
Paul Lamar
Paul,
NASA did do flight tests with their propfan on a Gulfstream GII. I'm
sending you the paper. Also in there is a NASA contrarotating fan,
but geared down. It gave about six percent better efficiency than
the single rotating fan.
And btw, the GE team used NASA design codes for propeller ply
design, flutter analysis, aerodynamic design and noise predictions.
Yes, they beat the NASA team to the finish line and probably for a
whole lot less money and manpower invested. It illustrates that
small and nimble is often more productive than"big science."
I understand your criticism of NASA. Back in the early 1990s I had a
chance to spend a few days with the fine folks at NASA Ames just
south of San Francisco. At the time, there was a "big science"
project going on -- namely the International Space Station.
In my few days at Ames I got a very good sense of the Byzantine
bureaucracy at work. It's amazing that things eventually get done
and people fly into space when one sees the organizational
complexity involved.
What I found most interesting though was that there was still room
for individual creativity. I remember one guy who was working on a
neat project to use computer technology to control an airplane that
was rendered uncontrollable due to catastrophic airframe failure.
The germ of his idea came from an incident in the early 1980s
involving an Israeli F-15 in which the pilot had a midair in a
training exercise and his whole right wing was torn off at the root.
The instructor in the backseat yelled at the rookie pilot to eject
but he decided to try to keep flying. He actually brought the plane
in for a landing on one wing, something McDonnel Douglas thought
was impossible.
Inspired by this, the guy at Ames developed a fly-by-wire program
that would "translate" the pilot's control inputs into the kind
of control movements needed to keep the plane flying. I got a ride
in the simulator (non-motion, sorry to say) and it worked great.
This technology is now in use in the military and could be in
commercial planes in the future.
Just one example of individual initiative. It's not all big science,
big bureaucracy and paper studies at NASA.
Regards,
Gordon.
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.