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Approximate Inlet/scoop size for an internal 582 radiator?

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Posted

Hi.  I'm moving my Catalina's prominent radiator inside.     Does anyone have a faired/cowled 582 radiator setup that they're happy with?  What's your approximate inlet area?   I'm having a hoot reading NASA CR3405 and other resources, but I'd like to also see what has worked for other similar planes.  I assume most of our planes would have similar climb speed, cooling needs, and radiator area, so I'm guessing other people's experience would be directly applicable.  

I have lots of room to play with, so I can make the inlet/outlet almost any size I need, but a starting point would be helpful. 

Thanks!

Jim

 

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Posted

Hi.  I'm moving my Catalina's prominent radiator inside.     Does anyone have a faired/cowled 582 radiator setup that they're happy with?  What's your approximate inlet area?   I'm having a hoot reading NASA CR3405 and other resources, but I'd like to also see what has worked for other similar planes.  I assume most of our planes would have similar climb speed, cooling needs, and radiator area, so I'm guessing other people's experience would be directly applicable.  

I have lots of room to play with, so I can make the inlet/outlet almost any size I need, but a starting point would be helpful. 

Thanks!

Jim

 

Jim,  This is just from reading in the past, and my memory is not doing well:  I believe they said the inlet area should be about 1/5 the size of the outlet area, but there has to be an area between inlet and rad for the air to expand and slow down - I don't know what that distance should be.  Post up some findings - Might help someone.  Cheers,  EDMO

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Posted

I have a somewhat post about my journey replacing my cowl to the radial style. I refused to have a belly radiator and made mine work inside.

Hi.  I'm moving my Catalina's prominent radiator inside.     Does anyone have a faired/cowled 582 radiator setup that they're happy with?  What's your approximate inlet area?   I'm having a hoot reading NASA CR3405 and other resources, but I'd like to also see what has worked for other similar planes.  I assume most of our planes would have similar climb speed, cooling needs, and radiator area, so I'm guessing other people's experience would be directly applicable.  

I have lots of room to play with, so I can make the inlet/outlet almost any size I need, but a starting point would be helpful. 

Thanks!

Jim

 

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Posted

Hey Jim, another cat owner took a different approach installing the radiator onto the rear fuselage.....unfortunately it seems it was destroyed in an accident

Screenshot_20160808-082610.png

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Posted

I don't think I would want my radiator right there putting really dirty air over / around the elevator and rudder.  Seems like just asking for issues that close to both of them.

:BC:

 

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Posted

You do have a point there......

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Posted (edited)

Here's where I'm at so far.  (continued below pic) 

aX8bAwd.jpg

With some effort, I was able to place a Kawasaki EX500 radiator in the turtledeck area, low enough to clear the folding wings/flaperons.   I mocked up the ducting and plenum with plywood, cardboard and hot glue, solidly enough for a static run.    

The radiator core is slightly small for the calculations, but I'd hoped to overcome any cooling system shortcomings with

1) a massive adjustable barn-door cowl flap that would create a low-pressure area in the slipstream and propeller inflow, and would draw huge amounts of cooling air through the radiator.  I was so hopeful about this design that I began to believe that just the propeller inflow over the cowl flap would provide enough cooling for 3000RPM downwind displacement taxi.   The cowl flap is shown mocked up in the full-open position.   In cruise, I pictured that it would be nearly fully closed.    

2) Electric cooling fans in the form of a couple cheap 70mm EDF motors adding air from the cabin into the radiator plenum.   I didn't want to depend on these for anything except ground idle and maybe taxiing downwind.   Definitely not to be depended on for flight operations.  

Well, I instrumented everything pretty well and did some static ground runs.   #2 was a good success.  The cooling fans can hold the coolant temp within limits on a 90 degree day, facing downind, up to about 3000RPM.   #1 was a miserable failure.   Even with nephews with leaf blowers simulating fairly generous airflow into the intake duct, and simulating slipstream over the cowl flap, the engine was not adequately cooled at any RPM.   :(  If it had shown any promise at all, I would have made the mockup more solid and proceeded with step-taxi tests, but I think it was bad enough where I'm back to the drawing board. 

 

 

Edited by cowlove
move picture

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Posted

I'm still a little sad and disappointed that the cowl flap idea didn't work.   I was under the impression that a cowl flap providing suction was even more effective per unit area for developing air flow than ram air into an intake scoop.   

1) Maybe the cowl flap size is overkill?   The airflow separates?   I should have had an adjustable flap rather than the fixed mockup.  

2) Propeller inflow isn't as high-velocity as I pictured it being?   That close to the blades, it has to be a pretty good percentage of the outflow speed, right? 

3) A leaf blower simulating the slipstream isn't accurate?  Maybe the flow over the cowl flap needs to be several feet "deep" to really generate the aerodynamic effects, not just a narrow splash of air from the leaf blower? 

 

 

 

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Posted

Hey Cowlove...maybe a useful info I can give you regarding airflow around your cowl flap area thanks to a mistake I made the other day.....

Doing my prop blade adjustments and synchronizing on my renewed 912 at  I forgot the aluminum tool to set the degrees on my blades exactly along the fairing where you would have your cowl flap, about 1 1/2 inches behind my prop  . This tool is very light, made out of aluminum tubing and a couple of sliding plates riveted to the tubing. 

I started the engine, run it at idle, at 4000rpm and at full power (5400rpm..)-----believe it or not , the tool after I shut down was still there where I forgot it. Just lying there....not wedged in any way!!!!!!!!!!!!  I just could not believe my eyes.

Anyhow, since that experience I have the feeling that the whole cowl area behind the rear windows is a "no airflow" area....can't come up with another explanation. There might be a problem getting the air sucked through your rad because of this??!!

P.s my cat is ripping through the air again...just had a flight today. Report will be posted soon.

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Posted

Interesting.  Was the tool down on the turtledeck?   Or up higher, actually within the circumference of the prop?   I could see that the airflow falls off very quickly outside the propeller disc- in fact, there should be tip vortices and the air just outside the propeller disc should be moving forward, at least in blade pulses.     A good part of the exhaust cowl flap is within the propeller circumference, so I was hoping it would pull good airflow past it.    At least based on my cartoon-level understanding of propeller theory.

I will draw a sketch of PLAN B and post it.    

That is excellent you're in the air again!   How do the extra horses feel?    

 

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