Radial vs. Inline

[Zimme83]

Seems that most 109:s from the F and onward had the valves even if it wasn't always mounted from the factory. The problem would be to implement it in the game. While it give the 109 the ability to limp home with a radiator leak it would probably not be enough cooling effect left to run the engine on full power without risk of overheating it. In the event of a radiator leak the options would be continue the fight and suffer an engine failure eventually or disengage and limp home on reduced power. I guess the best way would be to let the 109 have a bit longer time before the engine fails from overheating.

[PR3D4TOR]

At low and medium altitudes half the radiator surface would be more than enough to cool the engine at cruising speed or even on WEP at high speed. Maximum cooling capacity was only really needed during full power climbing at best climb speed (i.e. slow), or at very high altitudes where the air is very thin. So getting home on one radiator would be no problem at all in a 109 or Spitfire or other multi-radiator designs.

[mikeWe9a]

It had an oil cooler too.  Very small chin opening.

This information applies to the P-51H only. Had to fact check myself.

While the P-51H oil cooler is located in the nose, the air inlet is for the carburetor.  The P-51 oil cooler was a heat exchanger, transfering heat into the aftercooler coolant, which was then plumbed to the main radiator under the belly.  Earlier P-51 models had a separate oil cooler that was located in the belly as well.

Mike

[mikeWe9a]

At low and medium altitudes half the radiator surface would be more than enough to cool the engine at cruising speed or even on WEP at high speed. Maximum cooling capacity was only really needed during full power climbing at best climb speed (i.e. slow), or at very high altitudes where the air is very thin. So getting home on one radiator would be no problem at all in a 109 or Spitfire or other multi-radiator designs.

Something that is not really modeled here, in actual combat an aircraft might well not have the GAS to get home at a reduced altitude.  Doing so would also be risky, as the lower altitude and true airspeed would make the aircraft more liable to interception and more vulnerable to ground fire.

Mike

[PR3D4TOR]

I really doubt a P-51 at 30k uses more than half its cooling capacity on cruise setting. Full throttle on the other hand is more debatable at that alt...

Less of an issue for Spits and 109s since they rarely operated very far from friendly bases.

[Dawger]

I split a jug on a radial (head separated from the barrel) and I only had to shut it down because the oil lines between cylinders were old and one broke. It took about 50 minutes to pump 8 gallons of oil out the 3/8 inch line and the pressure to get below 20 PSI.

I also had an exhaust valve break (radial engine) and bounce around inside the head for 15 minutes causing a significant vibration before it punched a hole. The engine started streaming black smoke at that point. I landed about 20 minutes later and the engine was still producing about 50% power. The piston was very hot and the friction was the main cause of power loss.

Radials are more fragile (air cooled cylinders are hanging in the breeze by necessity) but tend to keep running with damage.


An inline is a big chunk of metal but basically won't run with significant damage.

With both if you lose the means to keep it all cool, it is going to quit eventually.

[PR3D4TOR]

Hate to disagree with you there Dawger, but unlike in car engines in inline aero engines the cylinders and crank case are not just drilled out of a block of metal. The construction methods of both radials and inlines were very much the same. The better compactness of an inline is the result of liquid cooling sleves being more compact than air cooling fins, so you can stack the "pots" closer together.

Here's a Merlin being rebuilt, with all its pots off.

[PR3D4TOR]

The "pots" on an inline were of course not single units, but usually cast or machined into one piece to save weight and increase compactness, but I wouldn't say they were stronger than the cylinders on a radial.

[Dawger]

The "pots" on an inline were of course not single units, but usually cast or machined into one piece to save weight and increase compactness, but I wouldn't say they were stronger than the cylinders on a radial.

With an inline the cylinders are protected by the rest of the engine in a significant fashion. On a radial the cylinders are protecting the rest of the engine.

You are correct that the construction is fairly similar but the arrangement provides a difference in what attracts the most hits.

Outside of combat damage, my experience is radials break more often but keep running where other types break less but are more likely to fail completely when they do.

[JVboob]

radial sound way better and I hate radiator hits online

[nrshida]

unlike in car engines in inline aero engines the cylinders and crank case are not just drilled out of a block of metal.

  what?

Here's a Merlin being rebuilt, with all its pots off.

They just glued all the 'pots' together for convenience of removal. 

[PR3D4TOR]

what?


They just glued all the 'pots' together for convenience of removal. 

Typical car engine block. Cast and machined as a single piece. Unlike typical aero-engines (and motorcycle engines).

[nrshida]

Go to 12:26 of the following video:-



Pay special attention to the outcome at 12:57.

[PR3D4TOR]

That is just the crank case, like in the picture I've already posted. The cylinder banks are cast and machined as separate parts, unlike in a typical car engine.


This is a Merlin with its cylinders removed. Cylinder blocks (missing in picture), crank case, reduction gear housing all being separate parts bolted together. This method makes it easier to cast each part with minimal use of metal wich saves weight.





This is a Chevrolet LS engine block where everything is cast and machined as one part. Faster and less labor intensive. Saves $$$.

[PR3D4TOR]

Go to 22:10.