Help with B25 engine color

Travis

you can paint your fins and mount aluminum, such as Alclad, and then flow in a thick wash of black paint or black acrylic.  Let that dry and then buff off any that is on the high spots that you dont want.

I have seen radials  with aluminum fins, dark metallic grey fins and black fins.  The aluminum with black recesses would be the most visually appealing.

A quick google of R-2600 radial engine shows two restored engines, one with aluminum fins and another with black painted fins.  Black surfaces ( paint) are supposed to dissipate heat faster, while plain aluminum shows interfin cracks as a dark jagged line. 

HTH some

David

Whoops! got me on that one!

Radials leak oil constantly, it is thier nature, so a fine brown film is usually on well-used engines and sometimes  on the backside of blade roots. A leaking prop seal or mag seal will throw oil as well. Unless it has blown a jug or interclinder oil line it should NOT look like brown filth on a day to day basis. a small spot of oil under the exhuast is commonplace and now we catch that with a coffee can that hangs under the exhuast.

 Man I love going to work and smelling that smell!!!!!

 David

Actually, black paint retains heat better than other colors.  Lighter colors such as engine greys or silver do a much better job of disappating heat (and radial engines generate a lot of heat).  You have to remember that a/c cylinders are made in two parts and screwed together under heat & pressure, w/the upper 1/2 (the head) is made out of aluminum alloy, while the lower 1/2 (the barrel) is made out of steel. The head is rarely painted while the barrel is usually painted  w/grey or aluminum paint to prevent corrosion (rust).  (sometime late in the war, the Navy and P&W developed a method to spray a thin layer of molten aluminum over the exterior of a cylinder to aid in heat dissapation which made the cylinder appear silver overall)

Most of the black you do see on a radial cylinder is actually the baffeling which is bolted to the cylinder in order to direct and control airflow around the sides and top of the cylinder for cooling.  (they're soooo much fun to remove and replace during a cylinder change).  I usually paint 3/4 of the cylinder around the sides w/black and the top of the cylinder black to represent the baffling with a vertical silver stripe on the front 1/4 of the cylinder to represent the part of the actual cylinder that can be seen.  After that's dried a couple of days I apply a very thin wash of black to the silver area to accent the cooling fins (which are grossly over scale on most models).

As far as oil leakage goes, most of the stains will be aft of the engine where the airflow blows the oil in flightand on the lower part of the cowl and nacelle when the a/c is sitting on the ground.  Depending on the condition of the engine and the amount of maintenance performed, the oil stains can range to very light, to very heavy (I once saw an old DC-6 which had been sitting on the ground in Kansas City for two days - it had a puddle of oil under the #1 engine that was a good 12 feet in diameter, an inch deep and was still growing visibly from the oil leaking out of the cowling and off the wing - the crew came out, added about 15 gallons to the oil reservoir, cranked her up and took off!) 

Remember the basic rule of thumb of the radial - If it ain't leaking oil, it's out of oil 

I am looking for a more used wheathered look.  I am thinking that the aluminum base with the blackish/brown wash that was suggested might do that.  I have never used a wash before on my previous builds because I am relativily new to the hobby and this is the first time I have tried wheathering techniques.  

 I understand the wash can be made with black acrylic paint, water, and a couple drops of liquid dishwashing detergent to keep it from bonding to the plastic.  Is this accurate?

 Travis