props: tractor v pusher, q tip, ducted?

"Kyle Boatright" wrote

Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
based on absolute temperature, which is measured in kelvin. Kelvin is
Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
(350/300 -1) = 1/6th = about 17%...

OK. I have always heard the approximate rule for good cooling is double the
intake size for the exit size. Guess it doesn't transfer to expansion.
--
Jim in NC

"Morgans" wrote in message
...

"Kyle Boatright" wrote

Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
based on absolute temperature, which is measured in kelvin. Kelvin is
Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
(350/300 -1) = 1/6th = about 17%...

OK. I have always heard the approximate rule for good cooling is double
the intake size for the exit size. Guess it doesn't transfer to
expansion.
--

Maybe the velocity of the exit gasses are less. This would cause them to
need more area.

Danny Deger

Jim Morgans wrote

OK. I have always heard the approximate rule for good cooling is double
the intake size for the exit size. Guess it doesn't transfer to
expansion.

Did you mean to write, "... double the exit size for the intake size?" If
not, you lost me.

"Jon Woellhaf" wrote in message
...
Jim Morgans wrote

OK. I have always heard the approximate rule for good cooling is double
the intake size for the exit size. Guess it doesn't transfer to
expansion.

Did you mean to write, "... double the exit size for the intake size?" If
not, you lost me.

Difficult to communicate that clearly, I guess. Try this.

If the cooling intake is 50 square inches, the exit for the cooling air is
100 square inches. For planes with moveable cowl openings, that would be
with the cowl open full.
--
Jim in NC

Doh! I get what you wrote now. Ain't English great. So easy to be almost
mostly not misunderstood. g

"Morgans" wrote in message
...

"Jon Woellhaf" wrote in message
...
Jim Morgans wrote

OK. I have always heard the approximate rule for good cooling is double
the intake size for the exit size. Guess it doesn't transfer to
expansion.

Did you mean to write, "... double the exit size for the intake size?" If
not, you lost me.

Difficult to communicate that clearly, I guess. Try this.

If the cooling intake is 50 square inches, the exit for the cooling air is
100 square inches. For planes with moveable cowl openings, that would be
with the cowl open full.
--
Jim in NC

"Morgans" wrote in message
...

"Kyle Boatright" wrote

Double? Naah. It expands, but doesn't double. Boyle's law (PV=NRT) is
based on absolute temperature, which is measured in kelvin. Kelvin is
Celsius plus 273 degrees. Guessing now, if the air temp went from 300k to
350k (or about 80F/27C to about 160F/70C) you'd see volume increase by
(350/300 -1) = 1/6th = about 17%...

OK. I have always heard the approximate rule for good cooling is double
the intake size for the exit size. Guess it doesn't transfer to
expansion.

Thanks for the info on the air expanding. Does this translate into more
drag if the engine is running?

Danny Deger

("Jon Woellhaf" wrote)
Doh! I get what you wrote now. Ain't English great. So easy to be almost
mostly not misunderstood. g

My niece spent a year in Denmark as a foreign exchange student ("Fez"). Her
classmates were learning French. The French teacher spoke no English. My
niece spoke little Danish and NO French. They both spoke Spanish. So..., she
had a year of French class, translated to/from Spanish, while attending
school in Denmark.


Paul-Mont

Montblack wrote:
("Jon Woellhaf" wrote)
Doh! I get what you wrote now. Ain't English great. So easy to be
almost mostly not misunderstood. g

My niece spent a year in Denmark as a foreign exchange student
("Fez"). Her classmates were learning French. The French teacher
spoke no English. My niece spoke little Danish and NO French. They
both spoke Spanish. So..., she had a year of French class, translated
to/from Spanish, while attending school in Denmark.


Paul-Mont

So what was the outcome? Does she speak French with a Spanish accent?

("Gig 601XL Builder" wrote)
So what was the outcome? Does she speak French with a Spanish accent?


She's got a couple of degrees in science (chemistry? physics? geology?) I
think. She spent some time in the field doing geological work with oil
drilling companies, then decided (at 29) to go back to school and get a law
degree - like her parents. So in the end, she's headed for a career of

(you guessed it) ... double-talk! g


Paul-Mont

On Aug 9, 10:47 am, "Montblack" Y4_NOT!...
wrote:

She's got a couple of degrees in science (chemistry? physics? geology?) I
think. She spent some time in the field doing geological work with oil
drilling companies, then decided (at 29) to go back to school and get a law
degree - like her parents. So in the end, she's headed for a career of

(you guessed it) ... double-talk! g

Paul-Mont

Ugh. If only I could reach you with this paintball gun - or grenade...
G