I have a question....

[davebender]

In other words they were on Me-109s produced from late 1940 onward.

 

[Shortround6]

In other words they were on Me-109s produced from late 1940 onward.

Sorry for my bad memory.

From "Messerschmitt Bf 109 F,G,&K series, An illustrated study" By Jochen Prien Peter Rodeike

Page 12-13
" One area of the Bf 109 extremely vulnerable to enemy fire was the cooling system. Even an insignificant hit could quickly lead to a complete loss of coolant and an inevitable engine seizure. This weakness was responsible for a large number of losses and led in 1941 to the introduction of radiator cutoff valves. These allowed the either wing radiator to be shut down in the event of a hit in the cooling system, so as to preserve the remaining coolant for the other, intact radiator and thus enable the the aircraft to return safely. These radiator cutoff valves were not installed on the production line, rather they were delivered to front line units as kits to be installed in the aircraft, at least this is known to have been the case with JG 51 and JG 52. Although the system performed satisfactorily in service, for some obscure reason the number of modification kits was very limited. Indeed, the crash or forced landing of a machine equipped the cutoff valves often led to a race between nearby units to recover the coveted valves for their own use. For some unexplained reason the retrofitting of the cutoff valves was restricted to the F-series; they were neither fitted to the following G-series during production nor were they made available as modification kits"

Any other sources would be welcome.

From this we can conclude that while the valves may have been a very good idea, the split radiator system on the 109 was not designed with the valves in mind, they don't show up until several years after the split radiator is adopted. Without another source to the contrary, the total number of 109s fitted with the valves was very small compared to the total number of 109s built.

 

[riacrato]

I thought I remembered Rodeike and Prien mentioning that these were standard replacement parts for the G (don't know how many kits were produced) and factory standard for K series 109s, but I'll have to check again. They are definetly available in the "replacement parts list" for the G series, so certainly existed for that type. I think the original reason for the underwing radiators was the requirement to mount a 250 kg bomb, though.

For what it's worth: This picture supposedly shows a captured G-6 of JG 77 (see http://www.kurfurst.org/Tactical_trials/Bf109G-6_US_EB102/109G-6_US_EB102.html) and the cutoff valves are visible.:

It maybe a case of luck, but I'd be careful speculating how many Bf 109s received the kit.

 

[renrich]

Plain and simple, radials are more reliable than liquid cooled engines. They also weigh less for the same displacement. The US Navy used radials because they valued reliability for over water use, not just for carrier AC but multi engine patrol craft. Read Shores' books about the campaigns in SE Asia and the CBI and notice the times that liquid cooled engined AC were out of the fight because of problems or damage with coolant systems in inline engines.

As far as the changing role of fighters, almost all fighters evolved into the fighter bomber role during WW2.

 

[Glider]

Maybe because I tend to look at things from a basic level, one reason why I thought radials were a better bet for a Naval aircraft is that they are shorter, and its easier to design a plane with a better view for landing.

 

[Shortround6]

I thought I remembered Rodeike and Prien mentioning that these were standard replacement parts for the G (don't know how many kits were produced) and factory standard for K series 109s, but I'll have to check again.

It maybe a case of luck, but I'd be careful with the number of many Bf 109s received the kit.

On further reading, on page 169 it says;

"In addition the K-4 was was built with radiator cutoff valves like those which had been retrofitted to limited numbers of of F-series aircraft in 1941."

I am not a mechanic but I can see no reason why a G-series could NOT have been refitted or even a batch done at one of the many factories manufacturing or re-manufacturing 109s.
But so far it is far from standard.

 

[Shortround6]

Plain and simple, radials are more reliable than liquid cooled engines. They also weigh less for the same displacement. The US Navy used radials because they valued reliability for over water use, not just for carrier AC but multi engine patrol craft.

Air cooled engines put out less power than liquid cooled engines of the same displacement. On a power per unit of weight basis (which is more important than power per unit of displacement) they often came out ahead of the liquid cooled engine and this WAS of importance to the navy. The lighter for the same power but less streamlined radial (early years) allowed for shorter take-off runs and faster climb out than an equivalent liquid cooled engine. they traded a little top speed for the better climb performance and take off/landing, got better reliability and no glycol storage once glycol came into use. The initial decision to go to air cooled was taken before glycol came into use as a coolant.

 

[renrich]

Good info, SR. There were probably other reasons but I feel sure that Lindberg chose a radial at least partly for reliability. Probably, the prevelance of air cooled engines in general aviation has some thing to do with reliability and simplicity also.

 

[riacrato]

On further reading, on page 169 it says;

"In addition the K-4 was was built with radiator cutoff valves like those which had been retrofitted to limited numbers of of F-series aircraft in 1941."

I am not a mechanic but I can see no reason why a G-series could NOT have been refitted or even a batch done at one of the many factories manufacturing or re-manufacturing 109s.
But so far it is far from standard.

I think the point was anyway if this was the intention behind the dual radiator and I am pretty sure it was not, eventhough it may have been a plus for retrofitted Fs Gs and the Ks.

 

[zoomar]

As others have said, I suspect it had as much to do with the "political" preference of the IJN and USN for radial engines, together with the more ready availability of suitable radial powerplants when the main wartime WW2 carrier planes (A6M, D3A, B5M, F4F, F6F, F4U, etc) were being designed. Radial engines were also presumed to be more reliable and easier to maintain than in-lines, which would be a positive factor for carrier-based planes.

 

[davebender]

Do you have historical data to support that claim?
Let's pick 1942 as it's the mid point for the European war.
DB601E Service Life ??
RR Merlin Service Life ??
R2600 Service Life??

These were all mature engines by mid 1942 so teething problems associated with new equipment aren't an issue. Otherwise I would have included the BMW801, DB605 and R2800.

 

[tail end charlie]

Plain and simple a watercooled engine is more reliable than an aircooled one, how many cars and motorcycles use water cooling today? However we are talking about a combat use and an aircooled engine is much less vulnerable both to enemy fire and the elements.

 

[Colin1]

Plain and simple a water-cooled engine is more reliable than an aircooled one, how many cars and motorcycles use water cooling today?

I'm not sure the analogy is sound
How many WWII fighters got caught in the rush hour?

 

[tail end charlie]

I'm not sure the analogy is sound
How many WWII fighters got caught in the rush hour?

On all engineering principles of reliability for an engine machining tolerances and control of thermal loads/expansion etc a watercooled engine comes out on top, reliability isnt the same as utility under fire. I raced motorcycles and even for a 5 lap blind race a water cooled engine produces more power and falls apart less often.

 

[tail end charlie]

I'm not sure the analogy is sound
How many WWII fighters got caught in the rush hour?

On all engineering principles of reliability for an engine machining tolerances and control of thermal loads/expansion etc a watercooled engine comes out on top, reliability isnt the same as utility under fire. I raced motorcycles and even for a 5 lap blind race a water cooled engine produces more power and falls apart less often.

 

[Shortround6]

Plain and simple a watercooled engine is more reliable than an aircooled one, how many cars and motorcycles use water cooling today? However we are talking about a combat use and an aircooled engine is much less vulnerable both to enemy fire and the elements.

Trying to use modern (last 20 years or so) car and motorcycle engines as an illustration doesn't work very well.
Too many other things cloud the issue.

For a given displacement the liquid cooled engine will usually have more power. Some countries tax on an engines size or displacement. Some countries (Japan for one) restrict motorcycle drivers to certain displacement limits. They do not tax/restrict on actual power.

It is easier to design for pollution control with a liquid cooled engines. A very important consideration in todays world.

Air cooled engines generally need a fan or forced cooling of some sort to deal with slow or vehicle stopped running conditions and getting good heaters with air cooled engines is more of a problem. Try using an air cooled car without a fan/blower in city traffic
The fan needs power to run at all speeds while a liquid cooled engine can use an electric fan or clutch fan at slow speeds (stopped) and turn it off when speeds are high enough (30mph or so).
Cars are now so heavy anyway (crash resistance and such) that any weight saving from an air cooled engine isn't going to be noticed.

There are other reasons.

 

[Colin1]

reliability isnt the same as utility under fire.

I raced motorcycles and even for a 5 lap blind race a water cooled engine produces more power and falls apart less often

No
but you quote reliability as the reason why the inline trumps the radial.

I believe you but I would still move away from the parallels you're drawing with automotive engines. If recip aircraft had tachographs they'd look completely different to their road-going equivalents. Radials, especially those developed or put into service during the war years, needed to be moving at flying speed to satisfy their cooling requirements, even just taxying could get hairy.
The stop-start nature of an automotive journey would demolish a radial within a very short space of time.

The radial had a deserved reputation for reliability - in its own environment.

 

[Shortround6]

On all engineering principles of reliability for an engine machining tolerances and control of thermal loads/expansion etc a watercooled engine comes out on top, reliability isnt the same as utility under fire. I raced motorcycles and even for a 5 lap blind race a water cooled engine produces more power and falls apart less often.

Were you racing in a displacement class?

If yes, case closed.

If you come up with a set of racing rules in which the weight of the engine, including cooling system, was the governing limit, you might see more air cooled engines.

 

[davebender]

Plain and simple a watercooled engine is more reliable than an aircooled one

I suspect that to be true. However we need historcal service life data to put this issue to rest.

 

[renrich]

It is not just reliability but survivability. The radial engine is much less liable to be put out of action by battle damage. A single rifle bullet in the wrong place can disable a liquid cooled engine. Much less likely with a radial.