Ram air

On Jun 1, 4:35 am, Tina wrote:
The Mooney 201 has a ram air port, a half a foot under the prop
spinner. The POH tells us it can be opened at altitude for a very
modest increase in MP and we find maybe a half inch increase in
pressure. The idea of the thing is, if the port is looking right at
the air being thrust toward it by the prop (it can't be more than 6
inches or so behind it) as well as the air impact from the airplane's
motion the air being 'rammed' into it should effectively lower the
altitude the engine thinks it's at. Well, a half inch of Hg is about
500 feet or so. The question is, though, wouldn't you think there
would be a way to capture a great deal more of the ram air effect and
really boost the engine performance? Who wouldn't like to fly at 24
square at 12000 feet without a turbo charger?

What makes me wonder about it is, even at 60 mph holding your hand out
of the window of a car subjects it to a significant backward pressure,
so the energy must be there.

The energy is there but it's no bigger than what Mooney claims.
Flat-plate drag at 100 knots is 29 pounds; dicide that by 144 square
inches and get around 0.2 psi, or about 0.4" Hg. Not much. AT 200
knots it will be four times that, which still isn't a lot.
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.
On airplanes like the Cessna singles, the air intake faces
forward but it doesn't get much ram advantage. The airflow striking
the cowling is deflected around it, which means that the airflow in
the vicinity of the intake is across that intake, not ramming directly
against it. Since Mr. Bernoulli told us that pressure drops with
velocity, the pressure at the face of the air filter is likely lower
than ambient. Homebuilders can tackle that to some degree and get some
improvements in manifold pressure, but those improvements will come
mostly as a result of airflow control, not ram recovery.
And a funnel, contrary to popular belief, does not increase
the pressure within it when facing the airflow. It increases velocity,
which must decrease pressure. It's a convergent duct. A divergent
duct, on the other hand, slows the airflow and increases pressure, and
we find such shapes on jet engine intake ducts, where the cross-
section increases just ahead of the fan or first compressor stage.
See http://www.aoxj32.dsl.pipex.com/NewF...TWPhysics.html
and http://www.thaitechnics.com/engine/e...struction.html


Dan

On Jun 1, 11:48 am, wrote:
On Jun 1, 4:35 am, Tina wrote:



The Mooney 201 has a ram air port, a half a foot under the prop
spinner. The POH tells us it can be opened at altitude for a very
modest increase in MP and we find maybe a half inch increase in
pressure. The idea of the thing is, if the port is looking right at
the air being thrust toward it by the prop (it can't be more than 6
inches or so behind it) as well as the air impact from the airplane's
motion the air being 'rammed' into it should effectively lower the
altitude the engine thinks it's at. Well, a half inch of Hg is about
500 feet or so. The question is, though, wouldn't you think there
would be a way to capture a great deal more of the ram air effect and
really boost the engine performance? Who wouldn't like to fly at 24
square at 12000 feet without a turbo charger?

What makes me wonder about it is, even at 60 mph holding your hand out
of the window of a car subjects it to a significant backward pressure,
so the energy must be there.

The energy is there but it's no bigger than what Mooney claims.
Flat-plate drag at 100 knots is 29 pounds; dicide that by 144 square
inches and get around 0.2 psi, or about 0.4" Hg. Not much. AT 200
knots it will be four times that, which still isn't a lot.
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.

That was the good old days!
A jig saw and some sheet metal BLASTED your 427 cube
inch engine to over 600 hp!!!, and at 400-500 mph, you'd be
economizing on fuel to boot!.
Ken

"Ken S. Tucker" wrote in news:94016f66-e3ab-
:

On Jun 1, 11:48 am, wrote:
On Jun 1, 4:35 am, Tina wrote:



The Mooney 201 has a ram air port, a half a foot under the prop
spinner. The POH tells us it can be opened at altitude for a very
modest increase in MP and we find maybe a half inch increase in
pressure. The idea of the thing is, if the port is looking right at
the air being thrust toward it by the prop (it can't be more than 6
inches or so behind it) as well as the air impact from the
airplane's
motion the air being 'rammed' into it should effectively lower the
altitude the engine thinks it's at. Well, a half inch of Hg is
about
500 feet or so. The question is, though, wouldn't you think there
would be a way to capture a great deal more of the ram air effect
and
really boost the engine performance? Who wouldn't like to fly at 24
square at 12000 feet without a turbo charger?

What makes me wonder about it is, even at 60 mph holding your hand
out
of the window of a car subjects it to a significant backward
pressure,
so the energy must be there.

The energy is there but it's no bigger than what Mooney claims.
Flat-plate drag at 100 knots is 29 pounds; dicide that by 144 square
inches and get around 0.2 psi, or about 0.4" Hg. Not much. AT 200
knots it will be four times that, which still isn't a lot.
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.

That was the good old days!
A jig saw and some sheet metal BLASTED your 427 cube
inch engine to over 600 hp!!!, and at 400-500 mph, you'd be
economizing on fuel to boot!.
Ken


And another happy ford customer.




Bertie

"Bertie the Bunyip" wrote in message
...
"Ken S. Tucker" wrote in news:94016f66-e3ab-
:

On Jun 1, 11:48 am, wrote:
On Jun 1, 4:35 am, Tina wrote:



The Mooney 201 has a ram air port, a half a foot under the prop
spinner. The POH tells us it can be opened at altitude for a very
modest increase in MP and we find maybe a half inch increase in
pressure. The idea of the thing is, if the port is looking right at
the air being thrust toward it by the prop (it can't be more than 6
inches or so behind it) as well as the air impact from the
airplane's
motion the air being 'rammed' into it should effectively lower the
altitude the engine thinks it's at. Well, a half inch of Hg is
about
500 feet or so. The question is, though, wouldn't you think there
would be a way to capture a great deal more of the ram air effect
and
really boost the engine performance? Who wouldn't like to fly at 24
square at 12000 feet without a turbo charger?

What makes me wonder about it is, even at 60 mph holding your hand
out
of the window of a car subjects it to a significant backward
pressure,
so the energy must be there.

The energy is there but it's no bigger than what Mooney claims.
Flat-plate drag at 100 knots is 29 pounds; dicide that by 144 square
inches and get around 0.2 psi, or about 0.4" Hg. Not much. AT 200
knots it will be four times that, which still isn't a lot.
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.

That was the good old days!
A jig saw and some sheet metal BLASTED your 427 cube
inch engine to over 600 hp!!!, and at 400-500 mph, you'd be
economizing on fuel to boot!.
Ken


































































































































































You're clueless.

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.

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

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.
Ken

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.

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.
Ken

"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