On 19/09/2012 11:50, The Natural Philosopher wrote:
harry wrote:
On Sep 19, 12:55 am, The Natural Philosopher
wrote:
Dave Plowman (News) wrote:
In article ,
Doctor Drivel wrote:
"Dave Plowman (News)" wrote in message
...
In article ,
Doctor Drivel wrote:
Audi are looking into using a very small Wankel engine as a range
extender genny slapped under the boot. For the rare times it will be
used it is fine. Wankels are efficient running at their constant
high
speed "sweet spot", so come into their own as a genny. The very
small
size and no vibration is also a great major advantage.
That'll be why all generators already use them.
This man is senile.
The rotary engine has been around for many many years. Petrol engine
powered generators too. The need for a quiet smooth running economical
generator also in great demand - many pay a great deal more for
this, over
a basic type.
But all of a sudden the Wankle engine is ideal for this job?
You really are the most gullible of idiots, dribble.
The one thing you need on generators is the ability to run long periods
without breaking. Wankel engines wore the seals out in a few hundred
hours if that.

You wont find them in aircraft either. Nor will you find an aircraft
engine revving much over 2500 rpm. That way the bloody things are
reliable for extended periods of high throttle running.


There ARE Wankel aircraft engines, I have seen them.
http://en.wikipedia.org/wiki/Aircraf...#Wankel_engine

The reason traditional aircraft engines rev slowly is to do with
propellor requirements. The alternative being heavy gearboxes back
than.

No its not, because...

There are some more modern ones that drive the propellor with a
toothed belt for speed reduction.


..you can gear them. In fact just about every large engine ever made
for aircraft from the 30s onwards was geared. Only light plane engines
and WWI engines ran ungeared. The RPM at the crank was still limited at
most to 4000 RPM. And that was on fighter engines with a life expectancy
measured in weeks.

If you want reliability on a big reciprocating aircraft engine you run
it sub 3000 rpm. End of.

So true for any reciprocating engine. Not aircraft related, but I used
to work for a compressor manufacturer and their long life (20 years
plus) gas engine driven compressors used to produce 4500 BHP at only 300
rpm (250l, V12, turbocharged).

But the tendency is toward small gas turbines.

which run at over 10K RPM and are of course geared.