Radial too hot

Daddio · 10-15-2007, 04:56 PM

How can I cool this ol' girl down?
I operate a Pratt & Whitney R-2800 CB-3 as a wind generator at our test lab. She runs very well, but gets a little warm in the Fresno summer sun. The test runs are usually between 15 and 25 minutes long, including a warm-up to operating temperature before the test. I'm using 100LL in the tank and Aeroshell W120 in the reservoir.
Running stationary, obviously I don't have the kind of airflow across the cylinders or the oil cooler she was designed for. I am told removal of the cowling results in warmer running temperatures. The cowl flaps were remvoed long ago. Would replacing them and running with the flaps open result in better air cooling of the cylinders? I thought with those flaps sticking out into the wind it might draw air through the cowling better.
Any other stationary cool-running tips?
Thank you!
D²

Micdrow · 10-15-2007, 06:42 PM

Interesting use of a Pratt & Whitney. Im not sure there is a cure. Maybe some one else will have more info.

comiso90 · 10-15-2007, 06:45 PM

If I may ask, what test lab is that?... I'm Fresno too..

.

mad_max · 10-15-2007, 07:04 PM

Does the prop have blade-cuffs? Thinking maybe the prop was rebuilt and the blade-cuffs
weren't replaced. Radials like these cuffs as they push air into the cowling better.

Don't really know if replacing the cowl flaps and having them full open would make much
if any difference. Maybe google up an engine rebuilder that specializes in radials and
ask them how they keep them cool while testing and breaking them in before shipping.

FWIW

FLYBOYJ · 10-15-2007, 07:14 PM

You need to get baffling around the engine. Put the cowling back on and try to install the original baffling. Keeping the cowl flaps open won't help unless the cowl and baffling is properly installed. Also run as rich as possible. You'll burn more gas but it will also keep your engine cooler.

mad_max · 10-16-2007, 07:59 PM

Here's a link with names and websites of rebuilders. I'm sure one of them may be
of help if you'd email them a nice letter.

de_links_33

Daddio · 10-22-2007, 04:59 PM

(huh? I thought I posted a reply already. Theme to Twilight Zone...)
Great tips - thanks all around!
mad max: Do you know where I can get blade cuffs? I pictured that a year ago, but didn't know they existed.
flyboyj: To clarify - this engine does have the cowling installed, but I don't know if all the "baffling" is installed. (I heard this came from the #2 spot on a "C-6", but I think it must have been a "DC-6". This was years ago.) What baffling are you talking about?
D²

FLYBOYJ · 10-22-2007, 08:50 PM

Quote:

Originally Posted by Daddio

flyboyj: To clarify - this engine does have the cowling installed, but I don't know if all the "baffling" is installed. (I heard this came from the #2 spot on a "C-6", but I think it must have been a "DC-6". This was years ago.) What baffling are you talking about?
D²

There should be some shrouds or plates between the cylinders, especially at the first bank of cylinder heads. Sometimes the spark plug wires will be going through them. I found this on line and circled some examples.

mad_max · 10-23-2007, 06:01 PM

I'm not saying prop cuffs will stop your overheating problem, but could help.
Try here.

RSW PRODUCTS, INC. - HAMILTON STANDARD PROPELLER PARTS

GADGET · 10-24-2007, 12:43 AM

Try to enrich mixture a little bit.

FLYBOYJ · 10-24-2007, 06:31 AM

And not to burst Mad Max's bubble, but those blade cuffs are STC'd. They are going to be pretty expensive and personally i don't think they are going to help much. Make your own if you want to try that...

mad_max · 10-24-2007, 09:12 AM

Not bursting my bubble. I'm no AP..just trying to give suggestions.

No pain
here flyboy.

Running it rich is a good idea. Maybe even run it with water injection from an unlimited
supply of water like the stationary test when they pulled 3000+ HP from it.

FLYBOYJ · 10-24-2007, 09:43 AM

Quote:

Originally Posted by mad_max

Not bursting my bubble. I'm no AP..just trying to give suggestions.

No pain
here flyboy.

Running it rich is a good idea. Maybe even run it with water injection from an unlimited
supply of water like the stationary test when they pulled 3000+ HP from it.

All good Mad Max! Now the water injection sounds like an idea....

Daddio · 10-27-2007, 05:40 PM

It dawned on me that actual numbers really should be used here. Whoever set up this instrument panel marked an acceptable CHT range with green lines, but based on what - not sure. Furthermore, it was set up for running in the northeastern US.
What really is "too hot" for her?

I'm also wondering how to find out what sort of bird she used to pull.
There are now some shot in my album.
(Does that link work? e-greenhorn here)

FLYBOYJ · 10-27-2007, 06:26 PM

An R-2800 CB3 is a civilian engine. That looks like a DC-6 QEC without cowl flaps. Check this out...