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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