P-38 or Mosquito?

AlexS said:

Using these rules, for example, show's that the Sherman tank was a very much more effective tank than the Tiger could ever be, check out the Sherman firefly as a really good reply to the Tiger

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While the Sherman was a more effective war machine than the Tiger on a cost basis the Firefly gets a bit of an overblown reputation. Yes the 17pdr was a very good gun, however ergonomics and size of the ammo are rarely taken into account in many quicky evaluations. Rate of fire is about 1/2 the rate of fire of 76mm Sherman and the 42 rounds of ammo it carried was only possible by putting an ammo rack where the bow gunner used to sit. Further slowing down the rate of fire when the ammo in the turret was exhausted.
Firefly's weren't much good for anything except anti-tank work and many a Sherman went through Europe without ever seeing a German tank.

AlexS said:

It was easier to fly (took forever to open up the engines of a P38 in a hurry), it was easier to maintain (Merlins were used everywhere)

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That's not true - Compare the engine controls on the Mosquito to the P-38 and you're going to have many similarities if not identical processes to power up rapidly. Where it gets a little complicated is if you have to drop auxiliary tanks and transfer fuel. Eventually pilots trained for this. What is your basis to say engine maintenance was easier? Well known fact the P-38 had issues in the ETO but is your assumption based on that or operations in the Pacific?

The Mosquito had a tail wheel, any tail wheel aircraft is much harder to fly than one with a nose gear. Lastly wood is horrible to maintain and repair, especially in adverse climates.

Shortround6 said:

While the Sherman was a more effective war machine than the Tiger on a cost basis the Firefly gets a bit of an overblown reputation. Yes the 17pdr was a very good gun, however ergonomics and size of the ammo are rarely taken into account in many quicky evaluations. Rate of fire is about 1/2 the rate of fire of 76mm Sherman and the 42 rounds of ammo it carried was only possible by putting an ammo rack where the bow gunner used to sit. Further slowing down the rate of fire when the ammo in the turret was exhausted.
Firefly's weren't much good for anything except anti-tank work and many a Sherman went through Europe without ever seeing a German tank.

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Good points - especially about the Firefly only being good for anti-tank work - on the other hand that is what it was made for.
The worst example of a tank only being good for anti-tank work was the Panther. This vehicle was said to be the one that was
the basis for the MBT's that came later. It was only an example of how not to make an MBT.

As to the Lightning and the Mossie - I'm sure the Axis would have loved to have had either as both were bloody good aircraft.

AlexS said:

Apart from that many keep mentioning the P38's a better long range fighter (or in my opinion just not as bad as the mosquito as a daylight fighter). Someone even mentioned that even if they weren't knocking down many enemy fighters, while the while the enemy fighters were on them, they weren't on the bombers, hmmm a little gem from Paton comes to mind, "the idea is not to die for your country, but the make the other guy die for his". Fighter aircraft performed only one of many purposes that aircraft were used for during ww2 and there is more than one way to skin a cat, for instance the English bombed at night. If you could only produce one or the other, the mosquito wins every time, purely because of it's versatility. It was easier to fly (took forever to open up the engines of a P38 in a hurry), it was easier to maintain (Merlins were used everywhere), it wasn't as expensive and used resources that were not as in demand so while some have bought up that there wasn't a shortage of aluminum it certainly cost more. As I've mentioned before having a navigator also expanded possible uses, night fighting, or check out the "Operation Jericho" raid as what it could do with daylight bombing. If they had guns, they carried at least 4X20mm cannon as a minimum, up to a full blown 57mm cannon. The list goes on and on. The effectiveness of any war machine i comes from a combination of ease of operation; ease of production; range of uses (versatility), cost, and performance. Using these rules, for example, show's that the Sherman tank was a very much more effective tank than the Tiger could ever be, check out the Sherman firefly as a really good reply to the Tiger.

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When the USA entered the war it was the ONLY long range high altitude fighter the allies had.
In terms of bomber escort and fighter aircraft the only Merlins that mattered were the two stage supercharger versions mattered. Every extra Mosquito you make is 2 less Spitfire IX or P-51 B/C D.
During big week, in round numbers there were 100 P-51s 100 P-38s and 800 P-47s. There were many fighter versions of the Mosquito in service but none were used because it couldnt do the job. Mosquito's were used in Big Week and later doing what it did best, assisting RAF bomber command on their night raids and attacking ground targets like airfields during the day.


Versatility is one thing, but you have to be able to do the day job. The Mosquito was unusual in that it was the best night fighter, the best recon aircraft, and the best path finder/ precision bomber also an excellent heavy strike aircraft. It couldnt take on s/e fighters and couldnt act as a bomber escort. The thing is the combined offensive and all US strategy was based on long range bombing, you cannot compare a whole strategy to a few raids like Operation Jericho. Without the P-38 the whole US strategy would have to be changed and or delayed, meaning the LW would still be a major threat at D-Day. The Halifax and Stirling were much more versatile than the Lancaster, they could carry more people and cargo, they were just no where near as good at the day job of dropping bombs especially very big bombs on places a long way away.

If you could only produce one or the other you need the USA to start producing Mosquitos before it was designed, when it isnt even involved in a war, waiting for Merlins to be shipped from UK during the BoB and later when everyone in UK also wanted Merlins.

The job of an escort is to stop bombers being shot down. This is done mainly by being there, the LW would try to find bomber boxes or formations which didnt have cover. After that they prevented the LW attacking as they wanted. Without escorts the LW could "work over" a bomber formation from the speeds and directions they chose.

The "English" didnt bomb at night the RAF did, their crews came from all over the world. Of the airfields close to where I live most were Canadian but also French and Polish squadrons with individual service men from literally all ower't place.

Shortround6 said:

While the Sherman was a more effective war machine than the Tiger on a cost basis the Firefly gets a bit of an overblown reputation. Yes the 17pdr was a very good gun, however ergonomics and size of the ammo are rarely taken into account in many quicky evaluations. Rate of fire is about 1/2 the rate of fire of 76mm Sherman and the 42 rounds of ammo it carried was only possible by putting an ammo rack where the bow gunner used to sit. Further slowing down the rate of fire when the ammo in the turret was exhausted.
Firefly's weren't much good for anything except anti-tank work and many a Sherman went through Europe without ever seeing a German tank.

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In fact Firefly carried 77 17 pdr rounds, 63 in the turret crew area and 14 in the bin where the bow gunner used to sit.
While it was primarily an anti-tank weapon it could fire HE rounds and while its HE Mk I round was anemic, the Mk II was much better, even if not as good as the HE round M48 of the 75mm M3 gun. And it still had its turret mg.

Shortround6 said:

While the Sherman was a more effective war machine than the Tiger on a cost basis the Firefly gets a bit of an overblown reputation. Yes the 17pdr was a very good gun, however ergonomics and size of the ammo are rarely taken into account in many quicky evaluations. Rate of fire is about 1/2 the rate of fire of 76mm Sherman and the 42 rounds of ammo it carried was only possible by putting an ammo rack where the bow gunner used to sit. Further slowing down the rate of fire when the ammo in the turret was exhausted.
Firefly's weren't much good for anything except anti-tank work and many a Sherman went through Europe without ever seeing a German tank.

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Except the 'overblown' Firefly could handily defeat even the much vaunted Tiger at normal battle ranges, and could open up MkIV's, still the backbone of the Heer, at any range.

P-38

Mosquito had some vicious handling characteristics and killed plenty of aircrew.
Weather killed as many Mosquitos as enemy action - rot and delamination never end well in an airplane

Macandy said:

P-38

Mosquito had some vicious handling characteristics and killed plenty of aircrew.
Weather killed as many Mosquitos as enemy action - rot and delimitation never end well in an airplane

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Name me a WW2 combat aircraft that, under certain conditions, didn't have problematic handling? These were high-performance aircraft which means some compromises had to be made to achieve that performance.

Weather didn't kill a single Mosquito because a Mosquito is an inanimate object. It may have killed the crew but how is bad weather the fault of the aircraft? Across the board, as many aircrew died in training accidents as did combat operations, regardless of nation or type of aircraft flown.

By "delimitation" I presume you mean delamination? Do you have specific numbers of aircrew killed due to this problem to compare against combat losses?

As to the P-38, it was far from problem-free:

The P-38 performed usefully but suffered from a number of problems. Its Allison engines consistently threw rods, swallowed valves and fouled plugs, while their intercoolers often ruptured under sustained high boost and turbocharger regulators froze, sometimes causing catastrophic failures.

Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat.

The P-38's General Electric turbo-supercharger sometimes got stuck in over-boosted or under-boosted mode. This occurred mainly when the fighter was flown in the freezing cold at altitudes approaching 30,000 feet, which was the standard situation in the European air war. Another difficulty was that early P-38 versions had only one generator, and losing the associated engine meant the pilot had to rely on battery power.

In an article on ausairpower.net, Carlo Kopp noted that in their early days in the European theater, "Many of the P-38s assigned to escort missions were forced to abort and return to base. Most of the aborts were related to engines coming apart in flight….[due to] intercoolers that chilled the fuel/air mixture too much. Radiators that lowered engine temps below normal operating minimums. Oil coolers that could congeal the oil to sludge. These problems could have been fixed at the squadron level. Yet, they were not."

Eighth Air Force historian Roger Freeman described how bravery plus the P-38 was not enough during a mission on November 13, 1943, "an unlucky day for the 55th. In typical English November weather, damp and overcast, forty-eight P-38s set out to escort bombers on the target leg of a mission to Bremen; one turned back before the enemy coast was crossed and two more aborted later. At 26,000 feet over Germany, pilots shivered in bitterly cold cockpits, flying conditions were unusually bad, and the probability of mechanical troubles at that temperature did not help. Again outnumbered, the 55th was heavily engaged near the target as it strove to defend the bombers, for which it paid dearly. Seven P-38s fell, five to enemy fighters and the others to unknown causes." Another 16 Lightnings limped home with battle damage.

Things got better. The arrival of the improved P-38J-25 and P-38L models, modified on the production line based on lessons learned in Europe, helped, but problems remained. Lightning pilot 2nd Lt. Jim Kunkle of the 370th Fighter Group remembered: "The critical problem with us was we didn't have much heat in the cockpit. On high altitude missions it was very cold. And we didn't have the engine in front of us to help keep us warm. Bomber guys had those heated blue union suits that they wore but we tried heated clothing and it didn't work for us."

The only source of heat in the cockpit was warm air ducted from the engines, and it was little help. Lightning pilots suffered terribly. "Their hands and feet became numb with cold and in some instances frost-bitten; not infrequently a pilot was so weakened by conditions that he had to be assisted out of the cockpit upon return," wrote Freeman.

buffnut453 said:

Name me a WW2 combat aircraft that, under certain conditions, didn't have problematic handling? These were high-performance aircraft which means some compromises had to be made to achieve that performance.

Weather didn't kill a single Mosquito because a Mosquito is an inanimate object. It may have killed the crew but how is bad weather the fault of the aircraft? Across the board, as many aircrew died in training accidents as did combat operations, regardless of nation or type of aircraft flown.

By "delimitation" I presume you mean delamination? Do you have specific numbers of aircrew killed due to this problem to compare against combat losses?

As to the P-38, it was far from problem-free:

The P-38 performed usefully but suffered from a number of problems. Its Allison engines consistently threw rods, swallowed valves and fouled plugs, while their intercoolers often ruptured under sustained high boost and turbocharger regulators froze, sometimes causing catastrophic failures.

Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat.



The only source of heat in the cockpit was warm air ducted from the engines, and it was little help. Lightning pilots suffered terribly. "Their hands and feet became numb with cold and in some instances frost-bitten; not infrequently a pilot was so weakened by conditions that he had to be assisted out of the cockpit upon return," wrote Freeman.

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Was there any reason why pilots werent given electrically headed gloves or suits as issued to bomber crews? I remember reading how to make your own heated gloves to ride motorcycles, basically just a length of resistance wire sewn onto a piece of thin canvas and then sewn inside the glove, motorcycles only run off 12 V supply.

On the criticisms of the P-38

buffnut453 said:

The P-38 performed usefully but suffered from a number of problems. Its Allison engines consistently threw rods, swallowed valves and fouled plugs, while their intercoolers often ruptured under sustained high boost and turbocharger regulators froze, sometimes causing catastrophic failures.

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Number of rods thrown?
early turbo regulators froze, later ones were much better but not perfect.

buffnut453 said:

Arrival of the newer P-38J to fill in behind the P-38H was supposed to help, but did not help enough. The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. This could cause detonation and rapid engine failure, especially at the high power settings demanded for combat.

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ALL P-38s used the same radiators. Later P-38s got bigger housings/ducts and moved the radiators a bit further out into the air stream. Also added boundary layer splitters.
The British fuel furphy has been addressed many times. Yes anti-knock compounds precipitated out of the fuel, they were heavy aromatic compounds, not lead compounds.

buffnut453 said:

In an article on ausairpower.net, Carlo Kopp noted that in their early days in the European theater, "Many of the P-38s assigned to escort missions were forced to abort and return to base. Most of the aborts were related to engines coming apart in flight….[due to] intercoolers that chilled the fuel/air mixture too much. Radiators that lowered engine temps below normal operating minimums. Oil coolers that could congeal the oil to sludge. These problems could have been fixed at the squadron level. Yet, they were not."

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The bolded part is large part of the problem. Fixing the problems at squadron level simply required the USAAF pilots to fly the P-38 as both Allison and Lockheed advised.
NOT as USAAF instructors or hanger know-it-alls advised.
P-38s in Europe (and other places) were routinely being flown at high rpm and low boost in cruise conditions in the mistaken belief that this would allow more rapid availability of military or combat power. This also resulted in less range as it used more fuel for the same power to the propellers.
A low rpm, higher boost, cruise setting with the turbos spinning faster would have meant higher intake mixture temperatures which would go a long way to solving many of the too cold engine problems. Increase the intake mixture temp by 100 degrees and the peak temperature inside the cylinder goes up 100 degrees and the temperature of the exhaust gas goes up 100 degrees as an example.
It also requires less fuel for the same power to props as you are not running at the higher rpm so you have less friction in the engine.
So a large part of fixing the engine problems doesn't even require a wrench or screw driver.

This would do nothing for the pilot being too cold, but it would do away with many of the engine complaints.

As far as getting bounced and having to go to full power goes, having the turbos spinning several thousand rpm faster to begin with may be more of an advantage the engine spinning faster but turbos idling.

Are we going to blame the aircraft for poor training and procedures?
British were using the low RPM/high boost method of cruise in 1942 with Spitfire MK Vs and other aircraft.

Further to Shortrounds comments I would add several items. Callum would do a better job of this but here goes.

The first is that the forces, and therefore fuel, required to accelerate and decelerate the pistons and con-rods is significant and increases with the square of the rpm so increasing the rpm significantly increases the internal loads. Using mythical rpm figures if the engine is cruised at 3000 rpm it will use four times the fuel to overcome these acceleration/deceleration forces that it would at 1500 rpm.

Another consequence of the high rpm/low boost operations is that the engine is designed for the supercharger(s) to force air into the cylinders at high rpm. When the boost is reduced the piston has to suck the air in. This means that the bearings that are designed to operate under constant load are now unloaded during 1/4 of a cycle which allows the crankshaft to "flop around" inside the bearing during the induction stroke. Soon after the compression stroke starts the crankshaft is then slammed back onto the bearing. This jackhammer effect will eventually damage/destroy the bearing which will result in debris from the bearing entering the oil gallery's downstream of the failing/failed bearing and starving bearings downstream. It will also reduce oil pressure to the rest of the engine as oil flows freely from the failed bearing instead of having the back-pressure that the bearing is designed to provide.

The exact same thing will happen on a Merlin or Griffin as Rolls Royce used Allison bearing made under licence.

A third consequence is that the bearings downstream of the failed bearing may seize on the crankshaft causing a connecting rod failure. I think this would be a rather rare result but Callum will possibly correct me on that.

A fourth consequence is that the small ends of the con-rods would suffer reduced lubrication and if one of those seizes that will definitely break a rod.

From the earlier comment on Allison's breaking rods in Europe some may conclude that the Allison con-rods were structurally unsound. I counter that with the fact that many air race Merlins use Allison con-rods.

MiTasol said:

From the earlier comment on Allison's breaking rods in Europe some may conclude that the Allison con-rods were structurally unsound. I counter that with the fact that many air race Merlins use Allison con-rods.

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Late/post war Allison rods from the G-series V-1710.

Allisson con rods may have been slightly stronger than Merlin con rods, but the late war Merlins were rated for 2000+ BHP in service. Con rods dont break because they are weak, they break because something goes wrong, no conrod will survive a breakdown in big or small end lubrication or a piston seizure, but the conrod flying out of the crankcase is what is seen. In my racing days, no one ever blamed a holed piston on weak pistons.

pbehn said:

Allisson con rods may have been slightly stronger than Merlin con rods, but the late war Merlins were rated for 2000+ BHP in service. Con rods dont break because they are weak, they break because something goes wrong, no conrod will survive a breakdown in big or small end lubrication or a piston seizure, but the conrod flying out of the crankcase is what is seen. In my racing days, no one ever blamed a holed piston on weak pistons.

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I totally agree with you which is why I covered the two most likely causes of rod failure - crankshaft (big) end or small end lube failures so that those who have no mechanical knowledge do not assume that the rod failures were a design failure.

They were caused by improper operation of the engine.

MiTasol said:

I totally agree with you which is why I covered the two most likely causes of rod failure - crankshaft (big) end or small end lube failures.

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My post wasnt directed at you, it is a topic that often comes up.

MiTasol said:

Another consequence of the high rpm/low boost operations is that the engine is designed for the supercharger(s) to force air into the cylinders at high rpm. When the boost is reduced the piston has to suck the air in. This means that the bearings that are designed to operate under constant load are now unloaded during 1/4 of a cycle which allows the crankshaft to "flop around" inside the bearing during the induction stroke. Soon after the compression stroke starts the crankshaft is then slammed back onto the bearing. This jackhammer effect will eventually damage/destroy the bearing which will result in debris from the bearing entering the oil gallery's downstream of the failing/failed bearing and starving bearings downstream. It will also reduce oil pressure to the rest of the engine as oil flows freely from the failed bearing instead of having the back-pressure that the bearing is designed to provide.

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Given the speeds of the engines involved, the pistons in the engine are always reducing the pressure below that of the intake manifold, so "boost" in never pushing piston down.
The highest load on rods/bearings is just after TDC on intake stroke when the crank is changing direction from pushing the piston up to pulling it down, while the piston is creating a low pressure to induce the intake air into the cylinder. That's where your rods/rod bolts/bearings/wrist pins fail - normally at high rpm.

Bearings better not ever be allowed to "flop around" and as the crankshaft is turning perfect circles (well within the constraints of actual materials), there is no jackhammer effect during normal operation.

There can be "jackhammer" effect from detonation, but detonation causes issues to pistons, rings, valves, spark plugs and bearings.

There aren't any oil galleries downstream from rod bearings - the oil from rods flows out to pan where the big debris is screen off before it goes into the scavenge oil pump and through the filter before it goes back into engine. And a damaged bearing will allows "leak" more oil than good one, so very little debris even goes to the next rod over on same crank throw.

All the engines I've blown up via rod bearing failure have been so catastrophic that little ends didn't have enough time to failure from lack of lubrication. (I have have rods fail from lack of little end lubrication, but that was cause, not consequence).

Hey Shortround6,

re "Yes anti-knock compounds precipitated out of the fuel, they were heavy aromatic compounds, not lead compounds."

Did you mean "evaporated"? The aromatics (along with alkylates) are in solution with the other gasoline components, and will not precipitate out of solution.


edit: Hey buffnut453,

re "The J model's enlarged radiators were trouble-prone. Improperly blended British fuel exacerbated the problems:Improperly blended British fuel exacerbated the problems: Anti-knock lead compounds literally seethed out and became separated in the Allison's induction system at extreme low temperatures. . ."

Freeman did not know what he was saying. I assume that he was quoting someone, but whoever he was quoting was incorrect.


Hey anyone else,

re precipitation of TEL and/or British Avgas being the cause of the V-1710 problems

TEL (tetraethyl lead) goes into solution when added to gasoline and will not precipitate out, and it remains stable in a gasoline solution for at least 6 months. The reason lead is combined with tetraethyl (making it a liquid compound) is to allow it to go into solution.

The idea that TEL could precipitate out of the charge while traveling through the turbocharger (or supercharger) and degrading the running of the V-1710 is false. The stories of lead build-up being found in the intercooler system are false, at least if they are attributed to TEL precipitation. Regardless of the V-1710 apologist's myth to the contrary, TEL will not precipitate out on the way to the combustion chamber.

The lead in the TEL compound prevents/inhibits the ignition of gasoline by raising the temperature at which charge mixtures will combust. TEL is a liquid, and at the temperatures found in the intercooler system the TEL will not combust and leave atomic or molecular lead oxide - this is the gray or gray-yellow residue found on some components of the engine after combustion (ie valves, spark plugs, interior of the exhaust manifold) - and sometimes on the interior of the intake manifold (due to blowback and preignition through the intake valves).

The main source for degradation of WWII aviation gasoline was the break down over time, due to oxidation of the alkylates and aromatics (particularly if there is a fresh air source) and/or exposure to actinic* light. The proper sealing of the fuel storage units was a partial solution to the oxidation problem - but only partial due to various chemical processes that go on in the gasoline even without a fresh air source. The removal of optical sight glasses for the fuel levels was the primary way of preventing the breakdown due to actinic* light.

*actinic light is generally defined as in the blue frequency range and higher (ie into the ultraviolet range)

Also, I thought that it had been shown (on this website) that the P-38 never ran on "British gasoline" except for (possibly) a very limited period by the British A&AEE/RAE/AFDU when it (the P-38) was first tested by the Brits - and was actually operated by the USAAF using US made Avgas at least 99% of the time.

My, I seem to have started something of a kerfuffle...which was not my intent. I was simply responding to a 2-line post that made a lot of claims without any facts. The stuff I posted in italics was gleaned from a website simply to illustrate that the P-38 wasn't problem-free. It was not meant to be a treatise or the final word on the topic. If someone's going to claim that an aircraft killed as many crews due to its poor handling characteristics as were lost in combat operations, I'd like to see some evidence of that...that's all.

buffnut453 said:

My, I seem to have started something of a kerfuffle...which was not my intent. I was simply responding to a 2-line post that made a lot of claims without any facts. The stuff I posted in italics was gleaned from a website simply to illustrate that the P-38 wasn't problem-free. It was not meant to be a treatise or the final word on the topic. If someone's going to claim that an aircraft killed as many crews due to its poor handling characteristics as were lost in combat operations, I'd like to see some evidence of that...that's all.

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You got me going for a second there, as to which type you were referring to. The P-38 and Mosquito were both very effective, versatile and the allies as a whole would have been knackered without them for all sorts of reasons, but they both attract "knockers" like a pot of honey attracts wasps.

Mosquito, lose an engine near the ground and you died… simple as that.

Most were pushed onto the fire dump when the weather delaminated them.