Ram air

On Jun 3, 5:41 pm, wrote:

The prop does not throw air outward. We've been over that
one before. The air column actually narrows behind the prop, due to
the lowered pressure caused by the air's acceleration. We can see it
on cool mornings when the dew point is just below ambient temperature,
and the vapor trails off the prop tips outline the periphery of the
air column, showing it to be squeezing inward.


More on the narrowing of fluid flows behind propellers:

Marine propeller: http://www.aip.org/pt/feb00/maris.htm

Helicopter rotor: http://www.camrad.com/CAMRADIIresults.html

Behind transport props: http://home.att.net/~polar/130contrail.jpg

Behind an F4U's prop: http://people.bath.ac.uk/ensmjc/Research/corsair.gif

In no case do we see air (or any other fluid) being thrown out
centrifugally.

Dan

"Ken S. Tucker" wrote in news:7bcb3e2e-b411-
:

On Jun 1, 11:26 pm, Gezellig wrote:
Ken S. Tucker explained on 6/2/2008 :

I confess to enjoying ancedotal stories.
As a monster nut brat I got some tin cans together
and built a pulse jet, complete with a flapping duct
input, and used a hair dryer for my air input source,
in my parents downstairs fireplace.
So I pour in some gas into the thing, lite it up,
turn on the hair dryer and holy poop, the duct starts
fluttering and flames are fluttering out the ass end!
It worked! It buzzed!
I probably used a pint of gasoline per minute of
operation, but that wasn't the point, it was actually
seeing the damn thing in operation.
Hands on is good stuff.
Ken

Proof there is a God, you survived yourself.

I'm very safety conscious, I have 3 fingers and 1 eye
left over that I haven't used up yet. No point in taking
all that stuff to the grave where they will just rot.

My flame holder was steel wool (aka Brillo soap pad),
and my throttle was a rubber squigy loaded with gasoline
...actually that was one of my safer experiments.


If there's a God, that's not what he's saying about you.


Bertie

"Maxwell" luv2^fly99@cox.^net wrote in
:



Turbocharging can be set to two different levels:
Turbonormalizing, which brings manifold pressure to sea level
pressure; and boosting, which raises manifold pressures to more than
30" Hg. If an engine is boosted, the air density in the cylinder at
the bottom of the intake stroke could be well above atmospheric.

Dan

Careful, Bertie the ButtlippS cross-posted this a few messages back.
You're trying to explain something to someone on a kook group.


Or someone here who is just a k00k.



Bertie

Billy Crabs wrote in news:30acf9c1-0253-49b5-
:

On Jun 2, 9:28*am, Bertie the Bunyip wrote:
"Maxwell" luv2^fly99@cox.^net wrote in news:jTR0k.192$js1.25
@newsfe24.lga:









"Bertie the Bunyip" wrote in message
.. .
"Maxwell" luv2^fly99@cox.^net wrote in
:

"Bertie the Bunyip" wrote in message
...
Didn't know any production aircraft had that. Well, to some
extent
almost every lightplane does . that's why the carb air intake
faces
forwards in most of them.Everything is a balancing act with an
airplane. More air = more drag. You could try putting a couple
of
woks with tubes out the back to boost your MP, but you're going
to
pay for it. !Moooney must have spotted an area of the cowl that
would
not penalise you in this way and decided to utilise it. Really
clever
homebuilders do a lot of this kind of stuff as well as, and
probably
more more importantly, dealing with cooling drag.
Have you put the other speed mods on your airplane? I think
there's
nearly ten knots available in seals and various other tidy it up
fairings.

Bertie

Dumb ass.

Its because the size of the scoop increases volume (not
pressure),
and
you already have too much.

Nope.

Bertie

How would you know, dumb ass?

I know everything, obviously.

Bertie- Hide quoted text -

- Show quoted text -

Ram air is only as useful the allowing air to get to your carburater
faster but is not necessarily used. When your piston is on its intake
stroke(vaccum) your combustion chamber can only draw in enough air
that is in conjuction to the chambers volume and all other air that is
present after the compression stroke is exported to engines smog
devices and is recirculated only AFTER being filtered. All engines
come off the assembly lines, be it an airplane motor or a vehicle
motor, to draw the amount of air that it needs to run at opptimum
performance. Ram Air is a myth and don't try to throw "turbo" into
the conversation because turbo is recircualted exhaust and still has
unburnt fuel in the fumes.


Yeah, of course, As i think someone else pointed out elsewhere in this
thread, there were some installations where the prop was positioned to
provide a pulse at the time the intake valves opened. Easy on a four
cylinder. There were props made for these that had a slightly larger
chord at the point on the prop span where the intake was. Didn't seem to
become popular for whatever reason..


Bertie

"Ken S. Tucker" wrote in news:5b076ae7-9924-
:

On Jun 3, 7:54 am, wrote:
On Jun 2, 9:45 pm, Billy Crabs wrote:

let me try to explain myself better, the amount of air that is
drawn
into an engine is in direct coralation to cylinder volume and the
cam
shafts "lift and duration" A valve can only stay open as long as
the
cam lobe holds the lifter up, therefore only allowing as much
air/fuel
as was scientificly formulated for the cylinder.
for instance, lets say you have two guys who are going to breath in
deep, now even if you are blowing an air hose in their faces, they
are
only going to be able to inhale as much as there lungs will hold.
Now
lets say they are inhaling pot and when they blow out its put into
a
"turbo", the turbine spins and sends the unused pot back to their
lungs, but it's still only as much as they hold in their
lungs(cylinder volume)

Air density in the cylinder is governed by its pressure and
temperature. MUCH more air can be forced into the cylinder if the
manifold pressure is boosted; this is the principle behind getting
more power out of a given number of cubic inches. You need to do some
studying on the matter. I have, and I teach this stuff in college.
Dan

I wonder if ram scoops were ever installed near the
prop tips. Probably too expensive for GA, but a WW2
A/C with tips spinning at what(?) 500-600 mph would
give a nice pressure boost.
I've read dual phase superchargers were used in recon
A/C to get the speed and altitude.


Why don't you make one and try it? You could use the engine out of the
Camaro on cinder blocks in front of your trailer.


Bertie

"Ken S. Tucker" wrote in
:

On Jun 3, 11:18 am, wrote:
On Jun 3, 10:18 am, "Ken S. Tucker" wrote:

I wonder if ram scoops were ever installed near the
prop tips. Probably too expensive for GA, but a WW2
A/C with tips spinning at what(?) 500-600 mph would
give a nice pressure boost.
I've read dual phase superchargers were used in recon
A/C to get the speed and altitude.

Airspeed off the tips is the same as the speed off the inner
blade areas, due to the pitch washout across the blade span, so
there'd be no advantage to having scoops behind the tips. The
propeller's blades are flying at an AOA of between 2 and 4 degrees in
cruise flight, anywhere between the tips and hub, because of that
pitch variation.
See Figure 6-4 of this
page:http://www.allstar.fiu.edu/aero/flight63.htm
Dan

Dan it was a trick question I asked you.




Bwawhawhhahwhahwhahwhahwhahhwhahwhahwhahwhahwhahhw haw!



Bertie

Big John wrote in
:

On Mon, 2 Jun 2008 12:31:53 +0000 (UTC), Bertie the Bunyip
wrote:

"Ken S. Tucker" wrote in
:

On Jun 1, 7:59 pm, wrote:
On Jun 1, 8:06 pm, Gezellig wrote:



It happens that formulated :

In the 1970's Ford sold some cars with "Ram-Air Induction"
systems. A scoop mounted on the carb that stuck out above the
hood, to ram vast volumes of air into the carb and get way more
horsepower. That's what they wanted you to believe. At 60 mph
the
pressure recovery would have been laughably tiny, but Ford's
profits were impressive.

Had a Trans Am, scoop was reversed, facing the windshield, had a
flap that opened when MP increased. They claimd that the reversed
position was at the low pressure point at the base of the
windshield hence enhancing the rammed air effect. I don't know,
it
was cool, the scoop assembly was attached to the engine so that
on
acceleration you could see the engine sitting down on its mounts
as
the scopp popped open and lowere ever so slightly.

Locating the scoop at the low-pressure point wouldn't do
much
for ram-air effect, would it? I think the real idea would have been
to make sure the driver heard that thing sucking loudly so it
sounded
like a real powerhouse
I once converted a 14 foot outboard runabout to a 13 foot
inboard Cracker Box with a Chev 283 straight-shaft setup. The
exhausts were water-cooled and exited through the transom. Made so
much noise that I made two mufflers and quieted it right down. The
carb's flame arrestor stuck up far enough that I had a scoop on the
deck, facing away from the cockpit (which was at the back).
Everything else was covered. I dropped my Dad off on a gravel bar
on
a lake once, so he could fish off it while I ran to the far end of
the lake to try the fishing there, three or four miles away. He
told
me he knew when I was coming back; he could hear that Rochester
Quadrajet four-barrel open up and suck vast quantities of air; the
boat got one mile per gallon at full throttle with that huge carb.
But went real fast. I sold it years ago and I bet it don't go real
fast no more, with fuel prices the way they are now.
Dan

I confess to enjoying ancedotal stories.
As a monster nut brat I got some tin cans together
and built a pulse jet, complete with a flapping duct
input, and used a hair dryer for my air input source,
in my parents downstairs fireplace.
So I pour in some gas into the thing, lite it up,
turn on the hair dryer and holy poop, the duct starts
fluttering and flames are fluttering out the ass end!
It worked! It buzzed!

I probably used a pint of gasoline per minute of
operation, but that wasn't the point, it was actually
seeing the damn thing in operation.
Hands on is good stuff.


Please do build another one just like that and put it on youtube,
then..


I've only ever seen one person die right in front of my eyes before.


Bertie
************************************************** *******

Bertie

I've seen two. Both stalled and spun in (

Big John


Neer seen one die in an airplane accident in front of my eyes, but seen
the aftermath, unfortunatley. Seen a girl crushed in a crowd right in
front of me. Yipes. Saw a few die in an ICU a few years ago. That wasnt
so bad, somehow.


Bertie

On Jun 4, 7:56 am, Big John wrote:
On Mon, 2 Jun 2008 11:19:41 -0700 (PDT), "Ken S. Tucker"



wrote:
On Jun 2, 10:13 am, Tina wrote:
On Jun 2, 12:01 pm, "Ken S. Tucker" wrote:

On Jun 1, 4:39 pm, Tina wrote:

The induction port for the ram air on the m20J bypasses the air filter
as well, so we typically observe about a half inch improvement in MP.
That's in line with some of the other numbers offered here.

I guess there's no free lunch. There is no way we want to have an
IO540 pull the airplane along, nor do we want the fuss with turbo
charging. The payback for our typical for real flight mission is just
not there. My thought was and is that if it was something pretty
obvious someone would have done it on a homebuilt. Actually, knowing
some of those guys, it does not have to be obvious at all, they are
really creative designers.

Tina, I think this analysis you posted is good,
" It's only a 360 cubic inch engine turning at 2300 RPM or so. Isn't
that a demand of, let's see, at 23 inches mp at sea level that's
23/30 * 2300/2 * 360 / 12^3 or 180 cubic feet a minute? "

I see Tango 2 Denny has some interesting ideas.
Ken

Well, I think it's a dead issue for us. What is fun to think about is,
let's see, about 200 cubic feet a minute, that's 40 cubic feet of
oxygen a minute, or about 3 pounds. For 50% more O2, 1.5 pounds a
minute, or say 20 pounds to get to a pleasantly high altitude. Maybe
that translates in to dewer weighing a total of 50 pounds with liquid
O2? But it would make 15 inches of MP look like 22 or so as far as the
engine is concerned. I better get back to my day job.

Without crackin' the books and pounding the abacus,
you look like +/- 20% using BoE (Back of Envelope)
calculation, which means you get either 80% or 120%
on your physics exam, you choose.

Resolved: psychologists should not be permitted to minor in the
physical sciences. All in favor?

OR pilots should not be permitted to engage in
psychology in this group, now what's the chances
of that happening...is "nil" close :-).
Ken
PS: What's the rationale of the 12,000' cruise?
You know about the "bends" don't you, if not
just read Berties post!

************************************************** *

Ken

Have you ever talked to anyone who got the bends flying? I have
thousands of hours and never have.

I have gone to 43K+ and made supersonic dives to 10K +/- with no
problems.

I have cruised for hours at 30K cockpit pressure and no problems
during let down and landing.

Is Mt. Everest summit at ~29K?
You can get a quick overview here,
http://en.wikipedia.org/wiki/Decompression_sickness
Ken






Big John

"Ken S. Tucker" wrote in
:

On Jun 2, 10:13 am, Tina wrote:
On Jun 2, 12:01 pm, "Ken S. Tucker" wrote:

On Jun 1, 4:39 pm, Tina wrote:

The induction port for the ram air on the m20J bypasses the air
filter as well, so we typically observe about a half inch
improvement in MP. That's in line with some of the other numbers
offered here.

I guess there's no free lunch. There is no way we want to have an
IO540 pull the airplane along, nor do we want the fuss with turbo
charging. The payback for our typical for real flight mission is
just not there. My thought was and is that if it was something
pretty obvious someone would have done it on a homebuilt.
Actually, knowing some of those guys, it does not have to be
obvious at all, they are really creative designers.

Tina, I think this analysis you posted is good,
" It's only a 360 cubic inch engine turning at 2300 RPM or so.
Isn't that a demand of, let's see, at 23 inches mp at sea level
that's 23/30 * 2300/2 * 360 / 12^3 or 180 cubic feet a minute? "

I see Tango 2 Denny has some interesting ideas.
Ken

Well, I think it's a dead issue for us. What is fun to think about
is, let's see, about 200 cubic feet a minute, that's 40 cubic feet of
oxygen a minute, or about 3 pounds. For 50% more O2, 1.5 pounds a
minute, or say 20 pounds to get to a pleasantly high altitude. Maybe
that translates in to dewer weighing a total of 50 pounds with liquid
O2? But it would make 15 inches of MP look like 22 or so as far as
the engine is concerned. I better get back to my day job.

Without crackin' the books and pounding the abacus,
you look like +/- 20% using BoE (Back of Envelope)
calculation, which means you get either 80% or 120%
on your physics exam, you choose.

Resolved: psychologists should not be permitted to minor in the
physical sciences. All in favor?

OR pilots should not be permitted to engage in
psychology in this group, now what's the chances
of that happening...is "nil" close :-).
Ken
PS: What's the rationale of the 12,000' cruise?
You know about the "bends" don't you, if not
just read Berties post!


I double everyone up.


Bertie

"Ken S. Tucker" wrote in
:

On Jun 4, 7:56 am, Big John wrote:
On Mon, 2 Jun 2008 11:19:41 -0700 (PDT), "Ken S. Tucker"



wrote:
On Jun 2, 10:13 am, Tina wrote:
On Jun 2, 12:01 pm, "Ken S. Tucker" wrote:

On Jun 1, 4:39 pm, Tina wrote:

The induction port for the ram air on the m20J bypasses the
air filter as well, so we typically observe about a half inch
improvement in MP. That's in line with some of the other
numbers offered here.

I guess there's no free lunch. There is no way we want to have
an IO540 pull the airplane along, nor do we want the fuss with
turbo charging. The payback for our typical for real flight
mission is just not there. My thought was and is that if it
was something pretty obvious someone would have done it on a
homebuilt. Actually, knowing some of those guys, it does not
have to be obvious at all, they are really creative designers.

Tina, I think this analysis you posted is good,
" It's only a 360 cubic inch engine turning at 2300 RPM or so.
Isn't that a demand of, let's see, at 23 inches mp at sea level
that's 23/30 * 2300/2 * 360 / 12^3 or 180 cubic feet a minute? "

I see Tango 2 Denny has some interesting ideas.
Ken

Well, I think it's a dead issue for us. What is fun to think about
is, let's see, about 200 cubic feet a minute, that's 40 cubic feet
of oxygen a minute, or about 3 pounds. For 50% more O2, 1.5 pounds
a minute, or say 20 pounds to get to a pleasantly high altitude.
Maybe that translates in to dewer weighing a total of 50 pounds
with liquid O2? But it would make 15 inches of MP look like 22 or
so as far as the engine is concerned. I better get back to my day
job.

Without crackin' the books and pounding the abacus,
you look like +/- 20% using BoE (Back of Envelope)
calculation, which means you get either 80% or 120%
on your physics exam, you choose.

Resolved: psychologists should not be permitted to minor in the
physical sciences. All in favor?

OR pilots should not be permitted to engage in
psychology in this group, now what's the chances
of that happening...is "nil" close :-).
Ken
PS: What's the rationale of the 12,000' cruise?
You know about the "bends" don't you, if not
just read Berties post!

************************************************** *

Ken

Have you ever talked to anyone who got the bends flying? I have
thousands of hours and never have.

I have gone to 43K+ and made supersonic dives to 10K +/- with no
problems.

I have cruised for hours at 30K cockpit pressure and no problems
during let down and landing.

Is Mt. Everest summit at ~29K?
You can get a quick overview here,
http://en.wikipedia.org/wiki/Decompression_sickness
Ken


You're an idiot.


How's that kill file working out, BTW?

Bwsawahwhahwhahwhahwhahhw!



Bertie