General Forums => Aircraft and Vehicles => Topic started by: Slade on February 21, 2017, 06:25:08 PM
Title: Radial vs. Inline
Post by: Slade on February 21, 2017, 06:25:08 PM
Guys,
This might be obvious but I'd still like your input. Which engine is better at surviving hits a radial (like in a P-47) or in-line engine (like in a Spit)?
Thanks for your thoughts on this. :salute
Title: Re: Radial vs. Inline
Post by: FLS on February 21, 2017, 06:40:11 PM
Radial. That's one reason the Navy liked them.
Title: Re: Radial vs. Inline
Post by: pembquist on February 21, 2017, 07:16:00 PM
Radial, also just because it has a round cowl doesn't always mean it is radial if it is german.
Title: Re: Radial vs. Inline
Post by: Vraciu on February 22, 2017, 01:12:50 AM
This might be obvious but I'd still like your input. Which engine is better at surviving hits a radial (like in a P-47) or in-line engine (like in a Spit)?
Thanks for your thoughts on this. :salute
Generally speaking an air-cooled radial is more durable. An in-line is tough as hell as long as it doesn't get too hot. That's the key. A .22 in the radiator of a liquid-cooled engine will cause way more havoc than that same bullet into just about anything on a radial.
In-lines have been known to go a LONG way without coolant. I remember reading a story about a Mustang driver who lost his radiator and made it halfway across Europe by pumping the fuel primer until his hand was bleeding. It's all about heat and friction.
Title: Re: Radial vs. Inline
Post by: USCH on March 03, 2017, 05:34:06 PM
In-lines have been known to go a LONG way without coolant. I remember reading a story about a Mustang driver who lost his radiator and made it halfway across Europe by pumping the fuel primer until his hand was bleeding. It's all about heat and friction.
I also read that story.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 03, 2017, 05:56:05 PM
I'm no expert on the P-51, but did it only have one radiator? Seems like a serious oversight in a long range escort fighter. Most other inline designs had two separate radiators like on the 109 and most Spitfires, or a single radiator made up of two or more sections with automatic cutoff valves (like on Ju 88, Fw 190D etc.) (109 had manual cutoff valves in the cockpit.)
Title: Re: Radial vs. Inline
Post by: DaveBB on March 03, 2017, 07:06:02 PM
It had an oil cooler too. Very small chin opening.
This information applies to the P-51H only. Had to fact check myself.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 03, 2017, 07:34:38 PM
I was talking about coolant radiators only, not oil coolers. And earlier P-51 models most certainly had oil coolers...
Title: Re: Radial vs. Inline
Post by: save on March 06, 2017, 09:09:45 AM
So the the 109s and spitfires had doubled radiator systems and P51 did not ?
I always wondered why I never see a P51 in AH with a radiator leak, with no redundancy. Is it harder to hit P51 coolant system than than 109's ? The 109s gets them if you sneeze at them, even though they have some sort of redundancy system.
Title: Re: Radial vs. Inline
Post by: Zimme83 on March 06, 2017, 09:36:38 AM
This also explains why water leaks are rare on the pony, the radiator is located mostly inside the fuselage, compare with for ex a 109: (http://109lair.hobbyvista.com/techref/systems/cooling/f_coolant.plan.jpg)
Title: Re: Radial vs. Inline
Post by: Zimme83 on March 06, 2017, 09:43:06 AM
The picture of the 109 reveals that it had only one cooling system so it had no redundancy either, a hit in one of the radiators would lead to a total loss of cooling water.
Title: Re: Radial vs. Inline
Post by: save on March 06, 2017, 03:11:33 PM
Where are the cutoff valves located ?
Title: Re: Radial vs. Inline
Post by: Zimme83 on March 06, 2017, 03:22:28 PM
The feed and supply routes were roughly the same as before; however, a feature not shown in the diagram below was the provision for fitting individual radiator shutoff valves in the feed tube to each radiator in order to shut one off in the event of combat damage. Somehow, this never became a standard factory fit and these became highly prized items in the field (for obvious reasons!).
The coolant system remained largely unchanged from the F on through the K models.
Not the best source but the best i could find.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 06, 2017, 06:43:15 PM
These are the valves on a 109G-2 in yellow.
(http://www.me-109.com/999999y.JPG)
They were moved closer to the firewall area in the later G-K models. Most if not all 109G-K had these valves mounted at the factories. Finnish ace Kyösti Karhila said in an interview by the Finnish Virtual Pilots Association that all their 109G-2s and G-6s had them.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 06, 2017, 07:08:30 PM
The valves actually are in the diagram Zimme posted. The feed valve is located jut left of where the "port feed line" arrow points to. The return valve is just left of where the "port return line" arrow points to.
Title: Re: Radial vs. Inline
Post by: Zimme83 on March 07, 2017, 06:10:38 AM
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.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 07, 2017, 12:23:38 PM
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.
Title: Re: Radial vs. Inline
Post by: mikeWe9a on March 07, 2017, 12:38:07 PM
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
Title: Re: Radial vs. Inline
Post by: mikeWe9a on March 07, 2017, 12:58:12 PM
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
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 07, 2017, 02:52:03 PM
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.
Title: Re: Radial vs. Inline
Post by: Dawger on March 07, 2017, 03:57:43 PM
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.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 08, 2017, 12:03:59 AM
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.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on March 08, 2017, 12:17:43 AM
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.
Title: Re: Radial vs. Inline
Post by: Dawger on March 08, 2017, 12:22:46 PM
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.
Title: Re: Radial vs. Inline
Post by: JVboob on May 21, 2017, 08:20:01 PM
radial sound way better and I hate radiator hits online
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 02:46:58 AM
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 05:19:22 AM
Go to 12:26 of the following video:-
Pay special attention to the outcome at 12:57.
Title: Re: Radial vs. Inline
Post by: PR3D4TOR on May 22, 2017, 06:50:40 AM
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.
The cylinder banks are cast and machined as separate parts, unlike in a typical car engine.
Yes thank you, I am familiar with the Merlin engine. Also motorcycle and car engines. Have rebuilt quite a few of those which I found to be of an identical architectural approach to the Merlin. Even at 22:10.
Perhaps if you consistently used accepted terminology we could all get a handle on the differences in production you are claiming. Are you under the illusion that the barrels and heads are typically one piece? Are you talking about cylinder liners versus Nikasil / Alusil, for example?
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 07:35:00 AM
Perhaps if you consistently used accepted terminology we could all get a handle on the differences in production you are claiming. Are you under the illusion that the barrels and heads are typically one piece? Are you talking about cylinder liners versus Nikasil / Alusil, for example?
No. Cylinders and heads are usually not in one piece (lol). Cylinders and crank case usually are.
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 07:53:30 AM
Are you doing ok Shida? Arguing over semantics in a two month old thread doesn't seem like you.
I didn't bump it :old:
I was just confused / intrigued by the 'unlike in car engines in inline aero engines the cylinders and crank case are not just drilled out of a block of metal' comment. Would love to have seen a car engine drilled out if a block of metal. In fact your picture came pretty close :rofl
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 07:55:27 AM
I think we'll have to agree to differ on the definition of usually. :salute
Title: Re: Radial vs. Inline
Post by: GScholz on May 22, 2017, 08:03:26 AM
The Americans have been making engines like that for the better part of a century. Heavy and inefficient, but bulletproof... Which is a good thing in America. :D
Title: Re: Radial vs. Inline
Post by: nrshida on May 22, 2017, 08:07:46 AM
The Americans have been making engines like that for the better part of a century. Heavy and inefficient, but bulletproof... Which is a good thing in America. :D
Doesn't driving very fast through bends also make you difficult to shoot? :banana:
Title: Re: Radial vs. Inline
Post by: MiloMorai on May 22, 2017, 08:15:37 AM
Stupid German engineers. How the hell do they think they're going to get the cylinder head gaskets in there? I just don't think they thought that through.
Title: Re: Radial vs. Inline
Post by: SIK1 on May 22, 2017, 10:34:31 PM
The fact is that radials were what the post war airliners used before the jet was introduced. They had the best weight to power ratio, they were reliable, and proven. After all it was a radial Lindbergh used on "The Spirit of St. Louis". And nothing sounds better than an R2800 from start up to full song. imho.
:salute Sik
Title: Re: Radial vs. Inline
Post by: GScholz on May 23, 2017, 06:55:12 PM
On reflection the lack of head gasket was obviously to prevent all the midi-chlorians from just leaking out (http://i1114.photobucket.com/albums/k526/rwrk2/detective2.gif)
I wonder if hydrolock was ever a problem with the DB series? Not really examined them closely.
Title: Re: Radial vs. Inline
Post by: RODBUSTR on May 26, 2017, 09:15:20 PM
I thought the USN's main use of radials were do to weight savings and less maintenance. they tested inline engine planes like the P51, but never found 1 that would pass the muster,