RV6A down in Seattle area

"Morgans" wrote in message
...

"Peter Dohm" wrote

I could probably squirm out by saying that it hadn't actually seem it,
which is true, but the fact is that I simply forgot and I stand
corrected. Tracy Crook, and his work are quite famous (especially in the
RV community) and I would really like to take a look at his installation
to see just how much radiator he needed in a tractor installation with
plenty of ram air--a good look with the pilot/builder present is sure to
be informative and I would like to hear his opinion of other
installations.

His installation that I saw (he has since put a newer engine in) used two
GM air conditioner condensers as radiator, and strangely enough, that is a
pretty popular choice. I don't know if he started that trend, or if he
got the idea from someone else. I have also seen Ford 3.8's and Chevy
4.3's in airplanes with the same setup.

As I recall, he used them parallel in the cooling line, and had them
placed directly behind the standard cowl twin inlets.

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year. The layout
that you mention is very similar to one that I have seen used successfully
on a Subaru conversion in a KR2--although I don't know who may have done it
first.


The other popular radator placements I have seen use the radiator back at
the firewall, with the top of the engine baffled off from the bottom, and
had the cooling air go past the top of the engine, through the radiator,
then into the engine compartment, then out the normal lower outlet.

I would be especially curious what he thinks about pushers with ducted
intakes because consistent cooling has been somewhat elusive in southern
Florida.

Indeed. Use of NACA type of inlets have usually failed, badly. The type
of scoop that works the best is a P-51 type of scoop, mounted above or
below the engine.

The key is to have the air flow through the radiator first, then past the
engine, (or directly out into the air) because if the air picks up engine
heat then goes through the radiator, it is sure to fail.

I think that you are essentially correct, although I don't know how much of
the problem is engine compartment heating and how much is poorly organized
airflow if the air must flow past the engine.


The other key to this type of arrangement is getting the outlet into a
good low pressure area. I have seen some that looked like the twin round
inlets, only they are the outlets. They are indeed tricky to get right,
it seems.

Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!

--
Jim in NC

Peter

"Peter Dohm" wrote

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year.

No, I'm pretty sure they were AC condensors.

The layout that you mention is very similar to one that I have seen used
successfully on a Subaru conversion in a KR2--although I don't know who
may have done it first.


Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!

I have never understood why a person would not include an electric fan to
pull air through the radiator, when necessary ground runs do not provide
enough air flow.

That would be 5 pounds well spent, I would think. I will include one if my
installation ever takes place, unless someone could come up with a reason
not to include it.
--
Jim in NC

"Morgans" wrote in message
...

"Peter Dohm" wrote

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year.

No, I'm pretty sure they were AC condensors.

The layout that you mention is very similar to one that I have seen used
successfully on a Subaru conversion in a KR2--although I don't know who
may have done it first.


Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!

I have never understood why a person would not include an electric fan to
pull air through the radiator, when necessary ground runs do not provide
enough air flow.

That would be 5 pounds well spent, I would think. I will include one if
my installation ever takes place, unless someone could come up with a
reason not to include it.
--
Jim in NC

I have wondered about the exact same thing, and am leaning toward the same
solution.

Peter

Peter Dohm wrote:
"Morgans" wrote in message
...
"Peter Dohm" wrote

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year.
No, I'm pretty sure they were AC condensors.

The layout that you mention is very similar to one that I have seen used
successfully on a Subaru conversion in a KR2--although I don't know who
may have done it first.
Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!
I have never understood why a person would not include an electric fan to
pull air through the radiator, when necessary ground runs do not provide
enough air flow.

That would be 5 pounds well spent, I would think. I will include one if
my installation ever takes place, unless someone could come up with a
reason not to include it.
--
Jim in NC

I have wondered about the exact same thing, and am leaning toward the same
solution.

Peter


I would guess because the fan is a liability to flow at speeds over
thirty or forty mph and because a twelve inch 1/8 hp fan has little to
offer over a 54 inch 40hp fan.

Charles

On Feb 21, 12:10*am, Charles Vincent wrote:
Peter Dohm wrote:
"Morgans" wrote in message
...
"Peter Dohm" wrote

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year.
No, I'm pretty sure they were AC condensors.

The layout that you mention is very similar to one that I have seen used
successfully on a Subaru conversion in a KR2--although I don't know who
may have done it first.
Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!
I have never understood why a person would not include an electric fan to
pull air through the radiator, when necessary ground runs do not provide
enough air flow.

That would be 5 pounds well spent, I would think. *I will include one if
my installation ever takes place, unless someone could come up with a
reason not to include it.
--
Jim in NC

I have wondered about the exact same thing, and am leaning toward the same
solution.

Peter

I would guess because the fan is a liability to flow at speeds over
thirty or forty mph and because a twelve inch 1/8 hp fan has little to
offer over a 54 inch 40hp fan.

Charles- Hide quoted text -

- Show quoted text -

That would be my guess, and next I would wonder why people don't
install louvers controlled from inside the cabin to let the heat just
rise out of the engine compartment. I think some military planes of
WWII era had them.

Wil

"Charles Vincent" wrote I would guess because the fan
is a liability to flow at speeds over
thirty or forty mph and because a twelve inch 1/8 hp fan has little to
offer over a 54 inch 40hp fan.

But that big fan is trying to blow air into a couple 3 inch round holes, and
then diffuse that speed of airflow to many times the square inches of
radiator. What you end up with is no airflow past the radiator, and
overheating.

Instead, you put a fan right next to the radiator pulling air directly past
the radiator at a decent speed, with no diffusion losses.

It works. That's why cars have them. That's why water cooled airplanes
overheat if they tai for more than a few minutes.
--
Jim in NC

Peter Dohm wrote:
"Morgans" wrote in message
...
"Peter Dohm" wrote

I could probably squirm out by saying that it hadn't actually seem it,
which is true, but the fact is that I simply forgot and I stand
corrected. Tracy Crook, and his work are quite famous (especially in the
RV community) and I would really like to take a look at his installation
to see just how much radiator he needed in a tractor installation with
plenty of ram air--a good look with the pilot/builder present is sure to
be informative and I would like to hear his opinion of other
installations.
His installation that I saw (he has since put a newer engine in) used two
GM air conditioner condensers as radiator, and strangely enough, that is a
pretty popular choice. I don't know if he started that trend, or if he
got the idea from someone else. I have also seen Ford 3.8's and Chevy
4.3's in airplanes with the same setup.

As I recall, he used them parallel in the cooling line, and had them
placed directly behind the standard cowl twin inlets.

I think that you may mean heater cores, which would have a larger water
passage, but I am hoping for a look if I go to SnF this year. The layout
that you mention is very similar to one that I have seen used successfully
on a Subaru conversion in a KR2--although I don't know who may have done it
first.

The other popular radator placements I have seen use the radiator back at
the firewall, with the top of the engine baffled off from the bottom, and
had the cooling air go past the top of the engine, through the radiator,
then into the engine compartment, then out the normal lower outlet.

I would be especially curious what he thinks about pushers with ducted
intakes because consistent cooling has been somewhat elusive in southern
Florida.
Indeed. Use of NACA type of inlets have usually failed, badly. The type
of scoop that works the best is a P-51 type of scoop, mounted above or
below the engine.

The key is to have the air flow through the radiator first, then past the
engine, (or directly out into the air) because if the air picks up engine
heat then goes through the radiator, it is sure to fail.

I think that you are essentially correct, although I don't know how much of
the problem is engine compartment heating and how much is poorly organized
airflow if the air must flow past the engine.

The other key to this type of arrangement is getting the outlet into a
good low pressure area. I have seen some that looked like the twin round
inlets, only they are the outlets. They are indeed tricky to get right,
it seems.

Tricky seems to be an understatement, especially when using airports that
demand an estended ground run!

--
Jim in NC

Peter


Actually, they are GM *evaporator* cores, the heat exchanger that's
mounted in the dash to cool the air.

I've seen his installation on average about once a year for the last 10
years, & watched it evolve over the years from carbs to injection & from
the original 13B to the Renesis engine core. I think that if you ask
him, he'd tell you that they were 1. available, 2. affordable, 3. fit in
the stock cowl, 4. actually turn out to be fairly close to the right
thickness for a relatively high speed homebuilt like an RV-x.

His work is sublime pragmatism. A marketing exec would go into cardiac
arrest just looking at it, but everything is carefully engineered to be
good enough with nothing extra. For instance, the intake plenum is a
fiberglas covered plywood box. But inside the box are details (which he
openly describes to anyone who will listen) that almost everyone ignores
when they build an intake system (and almost no one else achieves his
performance). Which brings us back to my earlier posts about too many
people not doing their homework before doing a conversion project.

Charlie

"Charlie" wrote

Actually, they are GM *evaporator* cores, the heat exchanger that's
mounted in the dash to cool the air.


Yep, I knew that about 2 minutes after sending the post. Condensor would
be the little radiator out next to the car radiator. Oh well, at least
someone knew what I meant! g

I've seen his installation on average about once a year for the last 10
years, & watched it evolve over the years from carbs to injection & from
the original 13B to the Renesis engine core. I think that if you ask him,
he'd tell you that they were 1. available, 2. affordable, 3. fit in the
stock cowl, 4. actually turn out to be fairly close to the right thickness
for a relatively high speed homebuilt like an RV-x.

All true, but he plain likes rotary engines, too. Maybe goes past like a
littke bit, even!

His work is sublime pragmatism. A marketing exec would go into cardiac
arrest just looking at it, but everything is carefully engineered to be
good enough with nothing extra.

Yep. Kinda' like the JB Weld around the fitting for the cooling fluid into
the _evaporator_ cores.
I definitely has a sound to it, screaming by on a low pass, though!
--
Jim in NC