I have a question....

[davebender]

radial engine is much less liable to be put out of action by battle damage

I hate to sound like a broken record but....
Do we have historical data to support that statement? For instance:
?? x .50cal bullet hits required on average to down a Fw-190A
?? x .50cal bullet hits required on average to down a Me-109G.

 

[looney]

When an oil line is ruptured on a radial engine it will seize also. Only difference is coolant fluids.
In short it's not the engine itself only the coolants. Main reason for the preference of choosing an engine is political.

 

[renrich]

I don't have any statistics to support the issue as whether a radial is less prone to sustain disabling battle damage but I don't believe that the lack of stats invalidates that position. Frankly, I am not a big stats guy. I usually look at stats with a jaundiced eye. I think there is a certain amount of truth in the old adage, "there are lies, damn lies and then statistics.

If one looks at a cutaway of a WW2 fighter it seems to me that it is intuitive to understand that there are a lot more vulnerable areas in a liquid cooled engine fighter. That fighter has all the vulnerable areas of a radial engine plus all the vulnerable areas of the liquid cooling system. If it has more areas which can be damaged in battle then it seems to me that the likelihood of disabling battle damage goes up. I don't need to have a statistician prove to me that a car with four tires is more likely to suffer a flat tire than a motorcycle with two tires.

Page 99, Dean's "America's Hundred Thousand,"-- "During a 1944 fighter conference at Pautuxent River, Md. a large group of service and company test pilots was asked to name the power plant inspiring the most confidence." "The R2800 was by far the favored engine with 79% voting for it." 17% voted for the Merlin and 1% for the V-1710. "There is no question pilots worried about vulnerability of cooling systems in liquid cooled engines, especially in the face of heavy fire directed at them during ground attack missions."

As far as politics determining engine choice on that same page: " The US Navy, many years before the war, made a firm decision to use radial air cooled engines in their fighters (as well as all other types of Navy planes), and never deviated on any production aircraft." Seems pretty obvious to me!

Another issue with liquid cooled engine fighters that was of importance to the Navy was that most of that type of fighter were not well suited to ditching in the water, for obvious reasons.

 

[davebender]

Not if the liquid cooled engine fighter is smaller in size and therefore a smaller target. For example:
P-47D wing area = 300 sq ft
Me-109G wing area = 173 sq ft. 58% as large as P-47 wing.

Hit that huge P-47 wing with a Mk108 3cm mine shell and it makes little difference if the R-2800 air cooled engine still runs perfectly.

 

[vikingBerserker]

I believe the radials are faster and easier to swap out and I would assume a ship could carry more radial engines then water cooled. I would also the Navy's slow to change mentality probably came into play as well.

 

[Shortround6]

Not if the liquid cooled engine fighter is smaller in size and therefore a smaller target. For example:
P-47D wing area = 300 sq ft
Me-109G wing area = 173 sq ft. 58% as large as P-47 wing.

Hit that huge P-47 wing with a Mk108 3cm mine shell and it makes little difference if the R-2800 air cooled engine still runs perfectly.

Apples and oranges isn't?

The P-47 is carrying a heavier weight of armament and the P-47 is carrying more internal fuel for a greater range without drop tanks and the P-47 has the bulky turbocharger that allows it to fight at higher altitudes. 3 factors that make the entire plane bigger that have nothing to do with type of engine used and the vulnerability of the engine and it's systems.

 

[Matt308]

Perhaps it wasn't an empirical conclusion. Rather perhaps it was a "pilot/user" perspective that influenced strategic decisions. I have read numerous books about the Korean war wherein the seasoned WWII pilots who entered the war were forced into P-51s. Many wanted into jet operations, but more P-51 slots existed, so instead of waiting for an F-80/F-84 slot, they opted to fly. And the P-51 was the most prolific airplane available.

I recall reading that many pilots expressed real concern with the P-51's use for any sort of low level operations because of its cooling system vulnerability. Many of those pilots who expressed these concerns were ex-P-47 drivers. It is interesting to note that many of these same citings of concern with the Mustang were later renounced as unnecessarily stated and the foundation was not supported by Korean operations.

Just something to think about.

 

[billswagger]

I hate to sound like a broken record but....
Do we have historical data to support that statement? For instance:
?? x .50cal bullet hits required on average to down a Fw-190A
?? x .50cal bullet hits required on average to down a Me-109G.

Looking at bullets required to actually what's vulnerable probably isn't going to reveal itself in statistics.
Most combat reports look to require similar amounts of bullets, partly because of aim and the conditions of the combat.
I do know the 109 had radiators at the wing roots and while getting hit their isn't likely to bring the engine to an immediate stop it probably gave the pilot a limited time to react to the damage.

A hit in the engine block will have the same effect for either engine, probably killing a cylinder or two. V engines would then also leak coolant into other parts of the engine as a consequence of a cracked block. It would make for ruff running if still managed to run at all. I don't think a radial had to deal with that issue, because excess oil would just burn off but the oil would leak out just the same on both engines. You probably had more time with an oil leak than a coolant leak, particularly in the engine block.
The plane would be doomed either way, but if getting back to base was a goal, then radial had a better chance.
V engines also have headers and cam shafts that if hit could drop a whole row of cylinders, and that would kill the engine instantly.
The way the radial is engineered each cylinder is isolated which probably adds to its durability aside from a lack of cooling system.

As for performance that just depends on displacement.
Reliability probably also went to the radial, just less parts to worry about. I know the R-2800 was used as an aero engine well into the 70's for this reason.
When i was reading up on the Allison and Merlin, i stumbled on a racing boat site that mentioned there use. There was a lot of surpluss engines during the 1950s and 60s, which many boat racers used. They'd also run them at 4000-5000 rpm. and the Allison was said to be better for that than the Merlin. I'm not sure you could even attempt that with a radial so there is probably more flexibility with V engine so long as what ever it was going on had room for a cooling system.

 

[drgondog]

I hate to sound like a broken record but....
Do we have historical data to support that statement? For instance:
?? x .50cal bullet hits required on average to down a Fw-190A
?? x .50cal bullet hits required on average to down a Me-109G.

It would be impossible to a.) get the data, b.) normalize to strip out pilot skill deviations, c.) aggregate on range.

One item to consider in the ETO. It was rare for a German pilot to shoot down three US fighters down in a single mission, extremely rare to non-existant to find four or more.

Conversely it is easy to find many examples of 3 109s or 190s shot down in single mission by a US pilot, and while rarer, examples of four or more of either or both.

You can't draw any statistical inferences for the same reasons stated above - but you can say that a normal ammo load for the Mustang (including 4 gun P-51B) was adequate to take out up to five German fighters in one sortie.

While it is interesting to speculate how much more effective a 4x20 configured P-38/47/51 MAY have been against 109s and 190s, you have to ask two questions?

1. Would that have resulted in more e/a destroyed in aggragate?
2. Would more multiple scores of e/a destroyed in single sorties have been achieved.

I suspect not but have no basis for comparison other than the very small sample size of 3-4 kill sorties by Fw 190 with much heavier firepower (and less rounds per gun) over US fighters in the ETO and MTO.

 

[drgondog]

I hate to sound like a broken record but....
Do we have historical data to support that statement? For instance:
?? x .50cal bullet hits required on average to down a Fw-190A
?? x .50cal bullet hits required on average to down a Me-109G.

Duplicate

 

[davebender]

Making the engine less vulnerable does little good if you make the airframe more vulnerable (i.e. easier to hit) at the same time.

 

[riacrato]

It would be impossible to a.) get the data, b.) normalize to strip out pilot skill deviations, c.) aggregate on range.

One item to consider in the ETO. It was rare for a German pilot to shoot down three US fighters down in a single mission, extremely rare to non-existant to find four or more.

Conversely it is easy to find many examples of 3 109s or 190s shot down in single mission by a US pilot, and while rarer, examples of four or more of either or both.

You can't draw any statistical inferences for the same reasons stated above - but you can say that a normal ammo load for the Mustang (including 4 gun P-51B) was adequate to take out up to five German fighters in one sortie.

While it is interesting to speculate how much more effective a 4x20 configured P-38/47/51 MAY have been against 109s and 190s, you have to ask two questions?

1. Would that have resulted in more e/a destroyed in aggragate?
2. Would more multiple scores of e/a destroyed in single sorties have been achieved.

I suspect not but have no basis for comparison other than the very small sample size of 3-4 kill sorties by Fw 190 with much heavier firepower (and less rounds per gun) over US fighters in the ETO and MTO.

I find such a statement strange coming from you. There are certainly examples of three to four Russian fighters or armored attack aircraft like the IL-2 killed by the same pilot in one mission, very likely more even. And that is with such rather inadequatly armed fighters as the Bf 109 F. There are probably examples of two 4-engined-bombers downed by the same pilot on the same mission in fighters such as the Fw 190.

That argument doesn't lead anywhere, in the end aircraft have many delicate spots and since (imo) armaments progressed faster than armor, by '42 any mainstay fighter was able to kill the enemies equivalent several times over. If the pilot hits that is. If you force an F-16 to fly in a straight line at 200mph I'm pretty sure a Bf 109 G could shoot it down within seconds.

 

[billswagger]

I suspect not but have no basis for comparison other than the very small sample size of 3-4 kill sorties by Fw 190 with much heavier firepower (and less rounds per gun) over US fighters in the ETO and MTO.

That could also be a product of the air targets involved. Fw190s went for bombers and low level strikes.
Statistically thats gonna show up differently than if the Fw or the 109 were strictly pursuit aircraft and flew a majority of escort rolls.
You'd be comparing one plane that went after nothing but fighter aircraft, while the other went after bombers.
I would think it would be rare to find any accounts of P-47s or P-51s shooting down more than one bomber.
I think you could probably find several depictions of Fws downing two bombers.
Sort of makes a point.
Although, people who think the Fw or the 109 went around hunting fighters with mk108s lack an understanding of the weapon's deficiencies and its intended purpose.

 

[billswagger]

duplicate

it must be in season.

 

[Shortround6]

Making the engine less vulnerable does little good if you make the airframe more vulnerable (i.e. easier to hit) at the same time.

Kind of missed the point didn't you?

If you are trying to compare an air-cooled engine to a liquid cooled engine to see which is more vulnerable you have to compare like aircraft. Not ones with different armament weights, different ranges and different altitude requirements and then claim that the radial forces the the plane to be larger.

Try comparing the 109 to the Bloch 152, the Saab J 22, the Romanian I.A.R. 80, the Japanese KI 44 or the Russian LA-5.
Then tell me about how using a radial engine makes the plane so much bigger and turns it into a large target compared to the 109.

 

[renrich]

Oh well, the question posed was why the USN used radials rather than liquid cooled engines. It is apparent that the the USN chose radials long before WW2. In Dean, it is apparent that the pilots felt most confident with a radial over a liquid cooled. I have read somewhere that the F51s suffered a lot of losses in Korea because of the vulnerability of the cooling system but I am not going to look it up. It seems obvious to me that a radial is less damage prone and there are many stories of radials coming home with substantial damage to engines and many stories of liquid cooled engines either having glycol leaks or battle damage and losing the engine but that is all anecdotal so I guess intuitive reasoning does not get the job done. I am left with the fact that the Navy picked radials and must have had good reasons for doing so and the pilots thought the radial was the most survivable which is good enough for me.

In the good old days when I was driving clunkers all around Texas, I had a lot of engine problems due to radiators being leaky because of old age and corrosion. Used to have to fill the radiator with water more often than the gas tank with gasoline.

 

[renrich]

Oh well, the question posed was why the USN used radials rather than liquid cooled engines. It is apparent that the the USN chose radials long before WW2. In Dean, it is apparent that the pilots felt most confident with a radial over a liquid cooled. I have read somewhere that the F51s suffered a lot of losses in Korea because of the vulnerability of the cooling system but I am not going to look it up. It seems obvious to me that a radial is less damage prone and there are many stories of radials coming home with substantial damage to engines and many stories of liquid cooled engines either having glycol leaks or battle damage and losing the engine but that is all anecdotal so I guess intuitive reasoning does not get the job done. I am left with the fact that the Navy picked radials and must have had good reasons for doing so and the pilots thought the radial was the most survivable which is good enough for me.

In the good old days when I was driving clunkers all around Texas, I had a lot of engine problems due to radiators being leaky because of old age and corrosion. Used to have to fill the radiator with water more often than the gas tank with gasoline.

 

[renrich]

Oh well, the question posed was why the USN used radials rather than liquid cooled engines. It is apparent that the the USN chose radials long before WW2. In Dean, it is apparent that the pilots felt most confident with a radial over a liquid cooled. I have read somewhere that the F51s suffered a lot of losses in Korea because of the vulnerability of the cooling system but I am not going to look it up. It seems obvious to me that a radial is less damage prone and there are many stories of radials coming home with substantial damage to engines and many stories of liquid cooled engines either having glycol leaks or battle damage and losing the engine but that is all anecdotal so I guess intuitive reasoning does not get the job done. I am left with the fact that the Navy picked radials and must have had good reasons for doing so and the pilots thought the radial was the most survivable which is good enough for me.

In the good old days when I was driving clunkers all around Texas, I had a lot of engine problems due to radiators being leaky because of old age and corrosion. Used to have to fill the radiator with water more often than the gas tank with gasoline.

 

[drgondog]

I find such a statement strange coming from you. There are certainly examples of three to four Russian fighters or armored attack aircraft like the IL-2 killed by the same pilot in one mission, very likely more even. And that is with such rather inadequatly armed fighters as the Bf 109 F. There are probably examples of two 4-engined-bombers downed by the same pilot on the same mission in fighters such as the Fw 190.

I very carefully limited my comments to ETO and MTO for a reason. The documentation of claims to losses is easire to come by between LW and USAAF. So far the highest LW Claim and subsequent award (which closely matches actual losses) was by Egon Mayer with four. I have no real research data on VVS/LW to make any such comments re Ost front.

That argument doesn't lead anywhere, in the end aircraft have many delicate spots and since (imo) armaments progressed faster than armor, by '42 any mainstay fighter was able to kill the enemies equivalent several times over. If the pilot hits that is. If you force an F-16 to fly in a straight line at 200mph I'm pretty sure a Bf 109 G could shoot it down within seconds.

Final note - the comment wasn't about 'examples' but many examples of at least three German fighters shot down, with a significant population of four and 10+ for more than four in just the 8th AF. The comment was only to illustrate that maybe 280-400 rounds of .50 cal ammo per gun was more than adequate to take down 5 or six Me 109s - that it didn't take 20mm to do the job... and that perhaps the 2x quantity of ammo f sufficiently heavy API was more effective against enemy fighters than 125 rpg of 20mm?

I am not claiming superiority for USAAF fighters, only stating that it was not only 'adequate' but also sufficient to kill 109s with as few as 60-80 rounds per gun.

I would like to have seen the results of 4x20mm Mustangs and Thunderbolts, not only for air combat but also for destroying a/c on the ground.

 

[tail end charlie]

I don't know if I would go that far. Italy and France also lagged behind in V12 development. Britain and Germany were far ahead of everyone else for some reason.

Germany had the opposite problem. They lagged behind in air cooled radial engine development. Consequently aircraft designed for operation from KM Graf Zeppelin all used liquid cooled V12 engines.

In the early days of the schneider trophy the italians had reat in line engines but stopped development due to politics