Ram air

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.

laid this down on his screen :
I normally don't go ram until I climb above the haze layer and my
power drops below %75. At that point the power goes up about 4-5% and
I can feel the acceleration.

What effect does air temps have on rammed air? Tina's Mooney in climb,
in a hot air environ, does she get anything of value? Above haze
(cooler air?), different story.

On Jun 2, 12:46 am, wrote:
On Jun 1, 6:35�am, Tina wrote:

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 and in a simplified discussion it is called
stagnation pressure, the sum of static pressure and ram air
pressure. As you go faster, static stays the same, ram goes up with
the square of velocity, as discussed already. Your airspeed
indicator uses the two pressures and does the math for you. On the
Tango 2, a homebuilt, we have a ram air scoop below the spinner and a
Y-valve and door for filtered or ram air. When I go to ram air at
150 kias, my manifold pressure goes up about .6 inch. Theoretically I
should recover 1.08 inches. I only have a single buttlerfly Y-valve;
we think some of the air is following the path of least resistance and
going back up the filtered tube. Another Tango 2 has a double
butterfly Y-valve that close off the escape route back through the
filter. His ram rise is about 1.1 or 1.2 inches, which is more than
stagnation. We put his ram air tube a little lower and closer to the
prop as discussed in SPEED WITH ECONOMY by Ken Paser. This seems to
capture the increased pressure behind the blade as it passes the
inlet, timed with the intake valve opening. When we are side by side,
flat out, when he goes ram air he pulls away from me.
I normally don't go ram until I climb above the haze layer and my
power drops below %75. At that point the power goes up about 4-5% and
I can feel the acceleration.
As someone else mentioned, you can't put a funnel out there and
get even more boost. Any excess will just flow around the inlet and
possibly increase drag. We don't know if our setup is optimum, but it
helps. Other homebuilters I've talked to report similar results. Oh,
for a wind tunnel and a lot of money.

Denny
Team Tango

Thanks, Denny. I thought if anyone would extract the last bit gain it
would be someone with a home built.

"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

"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 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?

"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

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

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.

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

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