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
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Copyright 1998-2006 All world wide rights reserved.
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
I think I heard/saw it run (in flight). I was a kid, so I didn't
have much to compare it to, but I recall that it made a strange
warbling, screeching, groaning sound. Maybe like having your ear
right next to a skill saw going through MDF. And was VERY loud.
Soon after, I saw a harrier fly at Oshkosh, and it seemed comparably
loud even though I was significantly closer to the harrier.
Obviously a very different sound - qualitatively.
Matt-
Oh yeah.. It was attached to an MD-80 if I recall correctly.
Matt-
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2006 All world wide rights reserved.