Ed Huntress wrote:

"Ignoramus10802" wrote in message
...

On 2009-10-29, ATP* wrote:

True. Yet I still hear this type of "reasoning" all the time. Should be a
simple concept even for the technically challenged, for example, people
who
argued here that you can compress air and allow it to expand (while doing
no
useful work) with no loss of energy.

That would be almost possible if compressing and expanding was done
very quickly, before compressed air cools.

i


But it has to be done *awfully* quickly. That's why there's a minimum
cylinder size for diesel engines -- something like 300 cc. Below 3,000 rpm
or so, the compressed air cools too quickly to ignite the fuel. And heat
transfer gets worse as compression goes up.


That statement may not be entirely correct, Ed.

Remembering waaaay back to my childhood playing around with control line
model aircraft. before the glow plug engine was developed we had but two
choices, conventional spark plug engines and diesel engines.

The diesels were never very popular, but they are still being made for
thos who want to add a bit of "authenticity" to replicas of vintage
model aircraft. Those are surely far below 300 cc, but the fuel they
burn may not be quite the same as what cars and trucks use. G

http://www.eifflaender.com/enginepics.htm

I also remember my not terribly successful efforts at flying RC models
back then. My ham ticket let me do that legally on 28 Mhz (the 10 meter
ham band) using a one tube receiver in the plane which triggered a
rubber band energized "escapement" that moved a combination
rudder-stabilizer at the rear of the plane.

How the heck I just remembered that the tube used in those receivers was
an RK61, a gas filled triode, I'll never understand.

http://tubedata.milbert.com/sheets/138/r/RK61.pdf

Thaks for the mammaries though.

Jeff



--
Jeffry Wisnia
(W1BSV + Brass Rat '57 EE)
The speed of light is 1.8*10e12 furlongs per fortnight.