IMHO this is a major breakthrough in cutting the work required
... snip ...
This is a brilliant idea on whoever thought it up.
Good thinking outside of the box. Literally :)
Brilliant! brilliant! Brilliant!
IMHO this will become the cooling system of choice.
Paul Lamar
This would also appear to do away with the need for cowl flaps -
can use
cowl flap lever to adjust radiator angle. Perhaps just have a rod
connected
... snip ...
Certainly looks interesting and simple, who will be the first to try
it ??
Ed Anderson
Good idea Ed.
BTW I am really jazzed on this rad location. This removes many of the
objections to liquid cooling systems. Simple cheap and easy to make
and install.
Again: The rad IS the scoop, the duct and the diffuser.
Paul Lamar
Wow. I thought you were joking at first, Paul. After all, you DO throw
some sarcasm out there from time to time...
Well, maybe we should discuss some pros & cons.
Others have already brought up some of the Pros:
- light weight
- simple construction
- can be pivoted to control "scoop size"
- - increase angle for more cooling, more drag
- - decrease angle (towards airframe) for less cooling, less drag
- obviates the need for cowl flaps
- frees up cowl space
Here's some of the Cons:
- that looks like A LOT of drag - is it?
- MINIMUM drag is the radiators's rectangular edge-on area, PLUS the
rough radiator core area
- God, it's ugly
- debris has direct, unimpeded access to damage your radiator (this is a
big one)
- to coerce air THROUGH the rad, some upstream "baffling" (box?) will
need to be implemented; otherwise most air may simply go around the rad
- we aren't dealing with speed-reduced (pressure increased) airflow
here; this will be top-speed (lower pressure) airflow.
And here's a question to clear things up for the group: Is this a
"wedge", or "ramp" design?
- WEDGE: A wedge traps air against the aircraft belly, forcing it
through the rad core out into the slipstream. Larger angles will scoop
more air.
- RAMP: A ramp impinges on the slipstream, forcing air through the rad
core, where it exits alongside the airframe. A ramp would be like a
real thick, porous cowl flap. Larger ramp angles increasingly impact
the slipstream.
- Each have their pros & cons: At high AOA, wedge becomes less
effective, and ramp becomes more effective (assuming belly mounting).
I know the idea of freeing up cowl space is alluring, but what is
keeping this arrangement from being moved up to the cowl belly vs. the
aircraft belly? At the cowl area we can do some fancy fiberglass work
to make this look attractive, plus we'll have that big fan helping out
(in tractors).
Let the flames begin ...
- Vince Orton
I addressed most of these issues already. If the rad has a square
header tank you can always streamline it with gup.
Prop efficiency would be better with it further back.
It is a free country. Put it anywhere or do anything you want :)
I am going to run with it because I have been struggling with the
cooling system problem for five years. Nobody has built anything that
is totally satisfactory under all possible ambient conditions.
I have already built a test rig and ran it on top of the Van so I
know it will work and I can get a larger rad down there than will
fit under the cowl. Just in case I need it.
Perry Mick has essentially the same thing and he has the smallest
rad of anybody flying with a rotary. Admittedly he is not making as
much power as some other people.
I expect our rad sizes to come down in the future using this system.
Paul Lamar
Isn't the fact that there is boundary layer between the fuselage
belly and the top of the rad an advantage? You want to slow the
airspeed down entering the rad and that would be slow air in the
boundary layer. But thinking farther, I guess you are loosing the
energy factor - of converting high speed air to low speed high
pressure air.
Perry
Boundary layer is slow moving air. What you want is fast moving air
to build as much pressure and flow across the rad as possible.
BTW I want to explain why cooling is our largest problem. Perry and I
spent a few miserable days out in hot Palm Springs CA trying to figure out
why his engine was over heating. Perry would land with an over heated
engine, we would try something and Perry would make another test flight.
There is nothing more frustrating than having your engine overheat over
and over again before you reach pattern altitude. I think Perry will
agree with that.
As it turned out the overheating had nothing to do with the size,
location or installation of Perry's rads. It was an internal leak due
to a broken tension bolt.
In many other cases people work on the airplane for five or ten years
under estimate the cooling problem and then have it overheat on climb out.
Your first and highest priority should be to make certain your engine is going to cool.
If a particular approach allows the possibility of designing a cooling system that
is obviously over kill you should go for it. This super simple rad under the
fuselage is such a system as you can easily accommodate almost any size rad.
Use a big one. After you are sure it is going to cool then and only then should
you worry about drag. At that point you can start cutting down on the size
and angle of the rad to reduce the drag.
When it is where you want it you can then improve the cosmetics.
Paul Lamar
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