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Air vs liquid cooled engines.


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#1 Flo

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Posted 20 March 2012 - 09:26 PM

What's the consensus? Is an air cooled power plant less susceptible to battle damage? And if it is, does that make for a more survivable aircraft?

A few thoughts.

Firstly, 'survived heavy damage' means, by definition, 'was hit'. If hit by ground fire, this would almost certainly be from the front. Radials offer a large target area. The ability to fly with a cylinder shot off is rather impressive, but if a liquid cooled engine, with it's smaller profile, would have avoided the damage completely it wouldn't have to worry about it's vulnerable cooling system in the first instance.

The placement of that cooling system is therefore a major concern to the designer. Buried in the wings, away from the point of aim, may offer some protection. Sticking it behind the propeller, where incoming fire would already have inflicted heavy damage on the fighter, is more fatalistic. Placing it deep in the fuselage, surrounded by armour, is almost certain to defend it from most ground fire.

The ability to armour the engine more effectively in a liquid cooled power plant cannot be ignored. The cost, in weight, must be considered, but liquid cooled engines tended to offer more power, compensating somewhat.

So the question can be answered as either 'the liquid cooled engine is delicate, therefore more vulnerable' or 'the air cooled engine is bigger, therefore more vulnerable'.

Thoughts, gentlemen?

Some stats, to help out. Area/hp for Merlin 1200sq in/1500hp; R-1830 1809sq in/1200hp; Napier Sabre 1840sq in/2400hp; R-2800 2190sq in/2100hp.

Between July 25 and August 7, 1944 the 9th AF lost 80 aircraft, the majority Thunderbolts. Over the whole of those two months the 2nd TAF lost 151 Typhoons. The majority of losses to both were to ground fire. Typhoons and Thunderbolts were operating under very similar conditions, the Hawkers in direct support, the P-47s in close support, with considerable cross over in roles. During the Normandy operations the 9th AF flew 2891 sorties, the 2nd TAF 9896. The 9th AF claimed 2654 vehicles destroyed, the 2nd TAF 3597. The 2nd TAF claimed 257 of the 391 tanks destroyed by Allied aircraft, reflecting the slight difference in tasking between the two forces.
It's the closest example of air vs liquid cooled propulsion I can think of. Typhoon losses ran at about twice those of Thunderbolt equipped units, but they mounted three times the sorties. Just as well, since they made one third of the claims per sortie. It's possible to cut the figures to demonstrate various points- I fully expect Duncan and Lightning to do just that! :D- but I think they're close enough to refute claims of any superiority of either power plant.

I haven't mentioned air to air losses for a reason. There are a multitude of factors beyond the survivability of a single aircraft component involved in the loss of an aircraft. For example, late war Japanese fighters were much better protected than earlier models, but they suffered far greater attrition.

The figures above are largely derived from this pamphlet: http://www.ibiblio.o...DDay/index.html
I was going to use a Brit source, but then I remembered I may have let slip that I'm a bit of a Hawker fan! ;) I'm pretty sure Richard Hallion holds that air cooled engines are tougher, amongst other things. Any primary documentation countering anything I've scrawled above will be gratefully received. Fire away, guys...

Edited by Flo, 21 March 2012 - 01:52 PM.
clarification


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#2 Ricky

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Posted 21 March 2012 - 08:25 AM

Between July 25 and August 7, 1944 the 9th AF lost 80 aircraft. Over the whole of those two months the 2nd TAF lost 151 Typhoons. The majority of losses to both were to ground fire. Typhoons and Thunderbolts were operating under very similar conditions, the Hawkers in direct support, the P-47s in close support, with considerable cross over in roles. During the Normandy operations the 9th AF flew 2891 sorties, the 2nd TAF 9896. The 9th AF claimed 2654 vehicles destroyed, the 2nd TAF 3597. The 2nd TAF claimed 257 of the 391 tanks destroyed by Allied aircraft, reflecting the slight difference in tasking between the two forces.
It's the closest example of air vs liquid cooled propulsion I can think of. Typhoon losses ran at about twice those of Thunderbolt equipped units, but they mounted three times the sorties. Just as well, since they made one third of the claims per sortie. It's possible to cut the figures to demonstrate various points- I fully expect Duncan and Lightning to do just that! :D- but I think they're close enough to refute claims of any superiority of either power plant.


Let me be the first to play with the numbers...

25th July - 5th August is 11 days
The whole of July and August is 61 days

Therefore:
7.3 P-47s were lost per day
2.5 Typhoons were lost per day

Given that the Typhoons were flying 3 times as many sorties, that further increases the gap - the ratio of loss rates per sortie is 7.3:0.8 in favour of the Typhoon! That makes for a ratio of more than 9:1

Now, obviously, the statisics are not directly comparable, making a mockery of my analysis. Anybody know the P-47 losses for the whole of July/August 1944?


[edit - to improve loss ratio]

Edited by Ricky, 23 March 2012 - 12:17 PM.


#3 Flo

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Posted 21 March 2012 - 01:49 PM

The 9th AF lost 80 aircraft of all types, not just P-47s. I should have made that a wee bit clearer, Ricky :o. The majority were Thunderbolts and the small number of medium bomber losses were all radials, too.

(Edited above, which might help.)

I gave two full months worth of Typhoon losses to offer a broad comparison of the circumstances- Augusts losses were 150% greater, so there's no clear way to differentiate between the two months without skewing the figures. Typhoon losses prosecuting forces in the Falaise Gap were high, but the results were worth it.

Without (hopefully) getting into a flame war, the reason for the Typhoons use at the pointy end and the Thunderbolt being preferred for hitting the enemies rear was probably an exaggerated opinion of the effectiveness of the British 3" UP/ RP-3 rocket.
Unlike its' American counterpart it fired from a launch rail, increasing accuracy, as well as being faster and harder hitting.
While it was more accurate and had the potential to kill any German tank, it wasn't nearly as lethal as believed at the time. 4% effectiveness is a number often bandied around today.
The real 'killer' was the shock and awe effect of massed fighter bomber attacks. Armour crews knew their chances of surviving a direct hit were effectively nil, and often bailed out as soon the attack began. In it's aftermath, with their retreat cut off by burning soft skinned vehicles and invigorated Allied troops advancing on their thoroughly disrupted attack they abandoned their vehicles and withdrew on foot.
I think this has been linked before? http://mr-home.staff...bies/rocket.txt
From some of the descriptions linked above (and elsewhere), it seems accurate targeting was difficult. '4%' may have been generous- that would imply one tank kill per 25 rockets fired, or a guaranteed hit for each pair of rocket Typhoons attacking armour!
Still, while the numbers are interesting, the horrific reality is that Normandy was carpeted with Axis dead and their devastated vehicles. No-one on the ground at the time challenged the fact that it was a direct result of allied air power. Thunderbolts and Typhoons were aptly named.

#4 Kutscha

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Posted 21 March 2012 - 04:37 PM

I think you will find Flo is that the 4% is for test conditions, not combat conditions. What I have seen for combat conditions is less than 1%. Even launched from rails the flight wasn't flat/straight.

I count 184 Typhoon losses to all causes for July and Aug. Flak is mentioned for the loss 31 times in July and 68 times in Aug.

#5 USSInidiana

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Posted 21 March 2012 - 05:11 PM

Wouldn't we also have to know the targets they were going against?
I mean different targets may mean heavier/less flak right?
How long was each sortie?
I mean the longer ranged the sortie the more time you might be exposed to flak along with having farther to fly back to base right?
Did each airforce use different target approach techniques? I mean by that did one AF fly low/low/low ,the other maybe say medium hieght then dropping down low alt in final approach.One may expose onesself to flak more but just my opinion.

#6 Edgar Brooks

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Posted 21 March 2012 - 06:48 PM

This is taken from a 2 TAF report on standard methods for fighter-bombers.
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#7 Flo

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Posted 21 March 2012 - 08:52 PM

:D I was starting to think no-one was interested!

Kutscha, have you heard of this? http://www.asavn.net/memorialGB.htm On my 'to do' list, possibly next year, with a few other sites in Northern France.

Edgar, have you anything on rocket attacks? (Their conduct, not accuracy.)

Indy, the reason I picked Normandy is because it's the one time I'm aware of that all your caveats were met. The aircraft were similar in size, weight and performance, the targets were within the same area, often getting hit consecutively by jugs and tiffys (real bad day at the office for Jerry! :eek:), the aircraft were operating out of bases near to, or even alongside each other when the first forward airbases were established.

The only major difference was Typhoons were the preferred option for direct support, but even that wasn't set in stone. Thunderbolts often hit enemy units in contact with Allied forces, while Typhoons were allowed to extend into the battlespace when no direct tasking was available.

The numbers available, for losses, claims and sorties flown will vary by source, but not, I'm willing to bet, significantly so.

As Ricky pointed out, based only on the numbers from that first link, if one airframe does appear to suffer proportionally higher losses, it's the Thunderbolt. But Kutschas already added a few Typhoons to our total. I'm still going to put my money on similar losses for both types, once we've got some solid numbers for Thunderbolts.

I'm interested to see what conclusions are drawn, though. Especially if we get some more posters on the thread...[where can I buy a devil smilie around here? ;)]

#8 Edgar Brooks

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Posted 21 March 2012 - 10:30 PM

I only have trials reports, and recommendations, nothing (yet) on what orders were actually issued to pilots on the front. Low level, and a shallow angle featured in the recommendations, but I don't know any more than that.

#9 ChrisMcD

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Posted 26 March 2012 - 04:12 PM

:D I was starting to think no-one was interested!

As Ricky pointed out, based only on the numbers from that first link, if one airframe does appear to suffer proportionally higher losses, it's the Thunderbolt. But Kutschas already added a few Typhoons to our total. I'm still going to put my money on similar losses for both types, once we've got some solid numbers for Thunderbolts.

I'm interested to see what conclusions are drawn, though. Especially if we get some more posters on the thread...[where can I buy a devil smilie around here? ;)]


Hi Flo,

To be honest, I am amazed!

I would have thought that the Sabre would be very vulnerable to battle damage with that dammed great radiator sticking out in front. The Thunderbolt was a very solid aircraft and I have never heard of the R-2800 being particularly vulnerable to battle damage.

While in no way doubting your statistics, I wonder whether some other tactical factor is having an effect? I doubt if it is size since they are both huge compared to most other fighters. Perhaps the Typhoon's rockets tended to lead to a pattern of attack that was harder for light flak (which I assume is the major culprit) to cope with.

Thanks for some thought provoking figures.

#10 Mostlyharmless

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Posted 28 March 2012 - 09:25 PM

One possibility is that after dropping bombs or rockets both aircraft used most of their ammunition for strafing. If they did, the Thunderbolt would spend slightly longer doing it as they had 300 rounds per gun v. 200 and their guns were only a little faster firing (800 rpm v. 600–700 rpm). If both fired while making their initial pass and firing rockets, perhaps only the Jugs would think that it was worth making a second attack.

#11 Flo

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Posted 02 April 2012 - 07:00 PM

It's certainly possible that some other factor, such as a willingness to make multiple passes at a target, resulted in increased Thunderbolt losses.

Is it possible that the design of the aircraft was that factor?

Put another way, if it was the Typhoon who suffered significantly greater losses, would you look for external factors, or attribute them to the Typhoons reputed weaknesses; its' compressibility issues and the liquid cooled Sabre?

#12 NeoConShooter

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Posted 13 April 2012 - 07:37 PM

What's the consensus? Is an air cooled power plant less susceptible to battle damage? And if it is, does that make for a more survivable aircraft?

A few thoughts.

Firstly, 'survived heavy damage' means, by definition, 'was hit'. If hit by ground fire, this would almost certainly be from the front. Radials offer a large target area. The ability to fly with a cylinder shot off is rather impressive, but if a liquid cooled engine, with it's smaller profile, would have avoided the damage completely it wouldn't have to worry about it's vulnerable cooling system in the first instance.

The placement of that cooling system is therefore a major concern to the designer. Buried in the wings, away from the point of aim, may offer some protection. Sticking it behind the propeller, where incoming fire would already have inflicted heavy damage on the fighter, is more fatalistic. Placing it deep in the fuselage, surrounded by armour, is almost certain to defend it from most ground fire.

The ability to armour the engine more effectively in a liquid cooled power plant cannot be ignored. The cost, in weight, must be considered, but liquid cooled engines tended to offer more power, compensating somewhat.

So the question can be answered as either 'the liquid cooled engine is delicate, therefore more vulnerable' or 'the air cooled engine is bigger, therefore more vulnerable'.

Thoughts, gentlemen?

Some stats, to help out. Area/hp for Merlin 1200sq in/1500hp; R-1830 1809sq in/1200hp; Napier Sabre 1840sq in/2400hp; R-2800 2190sq in/2100hp.

Between July 25 and August 7, 1944 the 9th AF lost 80 aircraft, the majority Thunderbolts. Over the whole of those two months the 2nd TAF lost 151 Typhoons. The majority of losses to both were to ground fire. Typhoons and Thunderbolts were operating under very similar conditions, the Hawkers in direct support, the P-47s in close support, with considerable cross over in roles. During the Normandy operations the 9th AF flew 2891 sorties, the 2nd TAF 9896. The 9th AF claimed 2654 vehicles destroyed, the 2nd TAF 3597. The 2nd TAF claimed 257 of the 391 tanks destroyed by Allied aircraft, reflecting the slight difference in tasking between the two forces.
It's the closest example of air vs liquid cooled propulsion I can think of. Typhoon losses ran at about twice those of Thunderbolt equipped units, but they mounted three times the sorties. Just as well, since they made one third of the claims per sortie. It's possible to cut the figures to demonstrate various points- I fully expect Duncan and Lightning to do just that! :D- but I think they're close enough to refute claims of any superiority of either power plant.

I haven't mentioned air to air losses for a reason. There are a multitude of factors beyond the survivability of a single aircraft component involved in the loss of an aircraft. For example, late war Japanese fighters were much better protected than earlier models, but they suffered far greater attrition.

The figures above are largely derived from this pamphlet: http://www.ibiblio.o...DDay/index.html
I was going to use a Brit source, but then I remembered I may have let slip that I'm a bit of a Hawker fan! ;) I'm pretty sure Richard Hallion holds that air cooled engines are tougher, amongst other things. Any primary documentation countering anything I've scrawled above will be gratefully received. Fire away, guys...


In that they do not include the cooling systems for LC engines. Once that is included, the vulnerable area to power ratio changes to favor air cooled engines. Also, the AC engine has a very much smaller vulnerable area in that any part of the LC engine that is hit by even a rifle caliber bullet will eventually down the plane. But radials require hits from powerful cannon to damage the engine and the resulting area is much smaller in that it either takes more than one/two hits to stop the engine and they must be in a much smaller location, IE the crank case as you point out, shooting even 3-4 of the 18 cylinders off of a R-2800 will not stop the engine, most times. In addition, RC bullets will not damage the heavy metal fins that are the cooling device on air cooled engines. A .22 LR will perforate the cooling jacket of any engine, or radiator, or hose, etc.

Your point about the location of auxiliary equipment is also fallacious in that the point of aim is the entire plane and dispersion of the bullets in the projectile stream mean that regardless of the exact point of aim, the very few hits that are made are truely random in nature. A RCMG will have a cone of fire between 2-3 1/2' per 100 M. A heavy MG with it's better mounting is ~40" / 500 M. About the same as a wing mounted cannon, but at least twice that of an engine mounted gun. A .50 caliber M2/3 HMG is 15" radius at 600 yards from a equivalent mount. A ground mounted, manually pointed cannon is lucky to keep 10% of it's shells with in 105' of the moving target at 1,000 M! Or 330' at 2000 M.

I know that these stats sound incredible, but they are best case examples! Because there are so many more RCMGs than there are HMGs and many times more HMGs than cannon, the smaller caliber weapons have a very deadly record. One ~8 MM slug in the radiator, oil cooler, water jacket, hose(s), pumps, holding tank(s), oil pan below the fill line and that engine WILL STOP running sooner than later! That is many square feet of vulnerable target area. The air cooled radial on the other hand does not have a pressurized coolant or oil cooler bathed in Prestone to kill it quick. The only point of vulnerability is the crank case below the fill line, the oil hoses and tank. Total target area about 1/3 to 1/4 that of the LC engine!

Instead of guessing about areas, why not take the two planes you mentioned and see what one random hit at a time would do to each plane in the same relative location. If you do that say ten times you should get an idea about the relative vulnerability of the two planes. Then you will see that the plane with the largest target area will be the most vulnerable!


#13 Wuzak

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Posted 14 April 2012 - 12:06 AM

Air cooled engines do need oil coolers, and they are bigger for an air-cooled engine with the same power as a liquid cooled engine.

Loss of a head or a hole in the crankcase will cuase the engine to lose oil, so it will sieze at some stage.

In the case of the R-2800 losing "3-4" of its cylinder heads the pilot will have been extremely lucky that the heads were taken off without causing damage to the pistons or cylinders, each of which could cause a catastrophic failure of the engine.

#14 Flo

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Posted 14 April 2012 - 10:15 AM

But you're largely speculating and applying what you perceive to be common sense in your rebuttal.

In that they do not include the cooling systems for LC engines. Once that is included, the vulnerable area to power ratio changes to favor air cooled engines. Also, the AC engine has a very much smaller vulnerable area in that any part of the LC engine that is hit by even a rifle caliber bullet will eventually down the plane. But radials require hits from powerful cannon to damage the engine and the resulting area is much smaller in that it either takes more than one/two hits to stop the engine and they must be in a much smaller location, IE the crank case as you point out, shooting even 3-4 of the 18 cylinders off of a R-2800 will not stop the engine, most times. In addition, RC bullets will not damage the heavy metal fins that are the cooling device on air cooled engines. A .22 LR will perforate the cooling jacket of any engine, or radiator, or hose, etc.

Your point about the location of auxiliary equipment is also fallacious in that the point of aim is the entire plane and dispersion of the bullets in the projectile stream mean that regardless of the exact point of aim, the very few hits that are made are truely random in nature. A RCMG will have a cone of fire between 2-3 1/2' per 100 M. A heavy MG with it's better mounting is ~40" / 500 M. About the same as a wing mounted cannon, but at least twice that of an engine mounted gun. A .50 caliber M2/3 HMG is 15" radius at 600 yards from a equivalent mount. A ground mounted, manually pointed cannon is lucky to keep 10% of it's shells with in 105' of the moving target at 1,000 M! Or 330' at 2000 M.

I know that these stats sound incredible, but they are best case examples! Because there are so many more RCMGs than there are HMGs and many times more HMGs than cannon, the smaller caliber weapons have a very deadly record. One ~8 MM slug in the radiator, oil cooler, water jacket, hose(s), pumps, holding tank(s), oil pan below the fill line and that engine WILL STOP running sooner than later! That is many square feet of vulnerable target area. The air cooled radial on the other hand does not have a pressurized coolant or oil cooler bathed in Prestone to kill it quick. The only point of vulnerability is the crank case below the fill line, the oil hoses and tank. Total target area about 1/3 to 1/4 that of the LC engine!

Instead of guessing about areas#, why not take the two planes you mentioned and see what one random hit at a time would do to each plane in the same relative location. If you do that say ten times you should get an idea about the relative vulnerability of the two planes. Then you will see that the plane with the largest target area(#2) will be the most vulnerable!


We've all heard survivor stories, but be wary of drawing broad conclusions from narrow results. As Wusak posted, not every cylinder hit is survivable. By the same token, not every hit to a cooling system is fatal. George Unwin recalls surviving machine gun hits to his Spitfire engine with little effect, that doesn't mean I'd be willing to claim that Merlins were particularly resilient to mg fire! ;)
Either way, as I posted above, there are different options for placement of cooling systems. But reguardless of whether I'm right or wrong in my assumptions, my question stands- does the choice of cooling system negatively effect the survival prospects of an aircraft? If you believe so, can you provide figures to back your proposition? Not common sense arguments, or thought experiments, but specific, real world instances?

#We've already done this in the UK. It was what persuaded us to develop rapid fire cannons in the first place. :D

#2 This is why I linked to a pro P-47, American written article, comparing aircraft of similar size, performance and role, operating alongside one another, for loss figures. The 9th and 2nd trained on the same bombing ranges, with the same staff, prior to D-Day, so even their aircrew training was directly comparable. I cannot think of a clearer example of where the only major difference between aircraft performing the same mission against the same foe was the type of engine employed.
That difference doesn't seem to have increased the survivability of the air cooled fighter.
Of course, my friend Ickysdad has a quite extensive library. I'm rather hoping he'll join us. Perhaps he can provide some more precise figures for the ninths P-47 losses. They might demonstrate the relationship you appear to favour. I'd take that as a definitive answer to my question, unless someone could post convincing evidence otherwise. Would you accept the most obvious conclusion if they do not?

Edited by Flo, 15 April 2012 - 12:44 AM.


#15 NeoConShooter

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Posted 19 April 2012 - 06:25 AM

Air cooled engines do need oil coolers, and they are bigger for an air-cooled engine with the same power as a liquid cooled engine.

Loss of a head or a hole in the crankcase will cuase the engine to lose oil, so it will sieze at some stage.

In the case of the R-2800 losing "3-4" of its cylinder heads the pilot will have been extremely lucky that the heads were taken off without causing damage to the pistons or cylinders, each of which could cause a catastrophic failure of the engine.

Do a Google search for T-Bolt pics with damage. There are literally dozens with several entire cylinders gone that flew back to england after getting hit.

#16 NeoConShooter

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Posted 19 April 2012 - 06:48 AM

But you're largely speculating and applying what you perceive to be common sense in your rebuttal.



We've all heard survivor stories, but be wary of drawing broad conclusions from narrow results. As Wusak posted, not every cylinder hit is survivable. By the same token, not every hit to a cooling system is fatal. George Unwin recalls surviving machine gun hits to his Spitfire engine with little effect, that doesn't mean I'd be willing to claim that Merlins were particularly resilient to mg fire! ;)
Either way, as I posted above, there are different options for placement of cooling systems. But reguardless of whether I'm right or wrong in my assumptions, my question stands- does the choice of cooling system negatively effect the survival prospects of an aircraft? If you believe so, can you provide figures to back your proposition? Not common sense arguments, or thought experiments, but specific, real world instances?

#We've already done this in the UK. It was what persuaded us to develop rapid fire cannons in the first place. :D

#2 This is why I linked to a pro P-47, American written article, comparing aircraft of similar size, performance and role, operating alongside one another, for loss figures. The 9th and 2nd trained on the same bombing ranges, with the same staff, prior to D-Day, so even their aircrew training was directly comparable. I cannot think of a clearer example of where the only major difference between aircraft performing the same mission against the same foe was the type of engine employed.
That difference doesn't seem to have increased the survivability of the air cooled fighter.
Of course, my friend Ickysdad has a quite extensive library. I'm rather hoping he'll join us. Perhaps he can provide some more precise figures for the ninths P-47 losses. They might demonstrate the relationship you appear to favour. I'd take that as a definitive answer to my question, unless someone could post convincing evidence otherwise. Would you accept the most obvious conclusion if they do not?


P-47
Total Sorties = 423,435
Bomb tonnage = 113,963
Lost in combat = 3,077
Enemy AC Kills = 3,082
Destroyed Grnd 3,202
Combat loss/Sortie 0.7%

Just some numbers to add fuel to the fire. I do not know the Typhoon numbers. If there is a significant differance between the two Plane's Mission loss and bomb tonnage rates, then I would say there might be something to this????

Just off of the top of my head... I think that when you look at the bomb tonnage per mission you will find that the T-Bolt was top of the heap in Ground Support? I will also go out on a limb and think the T-Bolt will have a lower total loss per mission ratio. I could be wrong because I really do not have a clue what the Typhoon's numbers are.
Cherry picking any small section of days might not yeild a true picture of the values?

#17 Ricky

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Posted 19 April 2012 - 10:25 AM

Just some numbers to add fuel to the fire. I do not know the Typhoon numbers. If there is a significant differance between the two Plane's Mission loss and bomb tonnage rates, then I would say there might be something to this????

Just off of the top of my head... I think that when you look at the bomb tonnage per mission you will find that the T-Bolt was top of the heap in Ground Support? I will also go out on a limb and think the T-Bolt will have a lower total loss per mission ratio. I could be wrong because I really do not have a clue what the Typhoon's numbers are.
Cherry picking any small section of days might not yeild a true picture of the values?


There will be a significant difference between bomb tonnage rates, because Typhoons used rockets more often than P-47s did (though both used both).
If you want the best tactical aircraft to be decided by bomb tonnage per sortie than the Lanc wins (they were used in a tactical role during Goodwood) followed by the B-17 or B-24 (whichever one was used in Cobra).

It is very hard to work out the effectiveness of ground-attack aircraft - claims are always massively inflated, and generally hard to substantiate, even when you do subsequently conquer the territory. And it is pointless dropping 15000 lbs of bombs (or firing 15000 rockets) if they all miss...

Loss rates are a better comparison, but even here there are differences. Mission profiles, ordnance used, theatre of operation, target types... all have an impact on loss rates. That was why Flo selected a very limited date and place range, because within that window you have P-47s and Typhoons flying the same mision type, against the same targets, from the same bases, using the same or similar tactics. Given that as many variables as possible have been removed, the total figures for that period should be our best bet for figuring out which plane was more vulnerable. All we need are the full P-47 figures.

#18 NeoConShooter

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Posted 05 June 2012 - 01:55 AM

But you're largely speculating and applying what you perceive to be common sense in your rebuttal.

Either way, as I posted above, there are different options for placement of cooling systems.It seems that the P-39 has something to say for this and the best L/sortie rate of all AC in WW-II? 0.4%/ sortie??? But reguardless of whether I'm right or wrong in my assumptions, my question stands- does the choice of cooling system negatively effect the survival prospects of an aircraft? If you believe so, can you provide figures to back your proposition? Not common sense arguments, or thought experiments, but specific, real world instances?

#We've already done this in the UK. It was what persuaded us to develop rapid fire cannons in the first place. :D

#2 This is why I linked to a pro P-47, American written article, comparing aircraft of similar size, performance and role, operating alongside one another, for loss figures. The 9th and 2nd trained on the same bombing ranges, with the same staff, prior to D-Day, so even their aircrew training was directly comparable. I cannot think of a clearer example of where the only major difference between aircraft performing the same mission against the same foe was the type of engine employed.
That difference doesn't seem to have increased the survivability of the air cooled fighter.
Of course, my friend Ickysdad has a quite extensive library. I'm rather hoping he'll join us. Perhaps he can provide some more precise figures for the ninths P-47 losses. They might demonstrate the relationship you appear to favour. I'd take that as a definitive answer to my question, unless someone could post convincing evidence otherwise. Would you accept the most obvious conclusion if they do not?


1. My uncle RTB'd twice with the P-47 shot all to hell and back, once with 22 20 mm, two 30 MM and >200 MG hits. I've never even heard of anything even remotely like that for any other plane.:eek:
2. From page 232 of American combat planes by Ray Wagner;
The P-47 flew 423,435 missions, dropped 113,963 tonnes of bombs, lost 3,077 in combat, shot down 3,082 and got 3,202 more on the ground and had a loss rate per Sortie of 0.7%.
P-51's numbers are; 213,873 sorties, 5,688 tonnes of bombs, 2,520 lost, 4,950-4,131 kills and losses per sortie of 1.2%.
The P-38 was; 129,849 sorties, 20,139 tonnes of bombs, 1,758 lost and 1,771 and 749 kills, for 1.4% lost/sortie.
The numbers for all other planes in US service Except the P-39 were not as good and they all flew a much lower %age of missions A2G.
I wonder what the other Allied and Axis planes mentioned here did for the entire war, instead of for a small percentage of the war? Say at least 50-100K sorties?

#19 NeoConShooter

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Posted 05 June 2012 - 02:01 AM

Loss rates are a better comparison, but even here there are differences. Mission profiles, ordnance used, theatre of operation, target types... all have an impact on loss rates. That was why Flo selected a very limited date and place range, because within that window you have P-47s and Typhoons flying the same mision type, against the same targets, from the same bases, using the same or similar tactics. Given that as many variables as possible have been removed, the total figures for that period should be our best bet for figuring out which plane was more vulnerable. All we need are the full P-47 figures.


I agree with all you said. It's just that bombs or rockets we used both at the same time sometimes tend to show how many times you were moving dirt. In the case of the P-47 that is about 1/4 of the time. If you are using bombs or rockets, you are probably not shooting things down??? So thses numbers would be veri indicative of who did what to whom?:rolleyes:

#20 Flo

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Posted 05 June 2012 - 11:08 AM

Is that any attempt to 'cut' your figures is likely to show variation based on a great many factors. To get to a figure set that only reveals the difference between one distinct factor-power plants, say- you have to discount as many of those other factors as possible. Simply lumping every mission ever flown into a set won't tell you a great deal about why an aircraft performed the way it did. Ask Kiwi or Wuzak to explain the difference between descriptive and inferential statistics or what constitutes a statistically viable sample, if my layman's understanding seems off.

"I wonder what the other Allied and Axis planes mentioned here did for the entire war, instead of for a small percentage of the war? Say at least 50-100K sorties?"
What they did was follow a completely different development cycle, adapting to completely different circumstances.
Your own figures demonstrate that. Note that the ground attack specialist (P-47) had far fewer aerial 'kills' than the escort fighter (P-51), but much more ordinance delivered.
Note too that using only those figures we could confidently demonstrate that ground attack was less hazardous than escort work...
In reality the figures only demonstrate that the aircraft were employed differently. More accurate conclusions would require more precise data.
One way would be selecting an equivalent sample of P-47s and P-51s performing the same mission, against the same opposition, at the same time. This approach would offer a far better insight into the capabilities of the two airframes than pointing at '50-100K sorties' and trying to distil some sense out of it.

Edited by Flo, 05 June 2012 - 11:47 AM.





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