Navalized P-38/39/40: pros cons
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rank amateur
Airman 1st Class
Would a P38 be able to take off on such short a distance as an aircraftcarriers' deck?
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T Bolt
Colonel
I think coming up with an aresting hook that would work with the twin boom design of the P-38 might be difficult
There are several big issues:
- the relatively large wing span adversely impacts the ability to maximize the storage of aircraft on a carrier. A significant difference would still exist even if a folding wing mechanism were fitted.
- the liquid cooled engines would complicate maintenance - you would be introducing a type of engine that is both different from and more complex than the air cooled engines used by all other deployed aircraft deployed on a carrier
- the throttle response of the turbocharged engines is an issue, particularly on landing (this is presumably one of the reasons why the US Navy completely avoided the use of turbochargers). Conversely, the operational requirements of the time emphasized low and medium altitude performance where the turbochargers were of little or no benefit.
- the wing loading is relatively high and would be increased by the addition of naval equipment
- an engine failure would have serious consequences on either take-off or landing (this is a situation where you are probably better off with one very reliable engine rather than two engines of lower reliability and/or greater vulnerability to combat damage.)
- the cost is almost certainly considerably higher
I would submit that the US Navy was well served by The F6F and F4U and had no reason to change things.
Robert
- the relatively large wing span adversely impacts the ability to maximize the storage of aircraft on a carrier. A significant difference would still exist even if a folding wing mechanism were fitted.
- the liquid cooled engines would complicate maintenance - you would be introducing a type of engine that is both different from and more complex than the air cooled engines used by all other deployed aircraft deployed on a carrier
- the throttle response of the turbocharged engines is an issue, particularly on landing (this is presumably one of the reasons why the US Navy completely avoided the use of turbochargers). Conversely, the operational requirements of the time emphasized low and medium altitude performance where the turbochargers were of little or no benefit.
- the wing loading is relatively high and would be increased by the addition of naval equipment
- an engine failure would have serious consequences on either take-off or landing (this is a situation where you are probably better off with one very reliable engine rather than two engines of lower reliability and/or greater vulnerability to combat damage.)
- the cost is almost certainly considerably higher
I would submit that the US Navy was well served by The F6F and F4U and had no reason to change things.
Robert
soulezoo
Senior Airman
This...^^^^
P-40 or even P-39 vs F4F maybe you can make an argument. Would the differences and any advantages really outweigh what was done historically. I really don't think so.
FLYBOYJ
"THE GREAT GAZOO"
Stores Chiefs would hate to have a bilge made just to store glycol!
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
Not sure why we're comparing early AAC/AAF aircraft to mid-war USN aircraft...
In any case, the P-40 and P-39 did not have the range of the F4F (845 miles): P-40 - 650 miles, P-39 - 525 miles and while the P-38 had an impressive range of 1,300 miles, the P-38 is simply not suitable for carrier ops.
The P-40 and P-39 also would have needed some structural modifications, like stronger main gear for landings, tail structure mods for allowing the shock of the arresting proceedure and of course, modifications for folding wings, which would complicate things, as the fuel tanks and armament may need to be re-arranged for that.
In any case, the P-40 and P-39 did not have the range of the F4F (845 miles): P-40 - 650 miles, P-39 - 525 miles and while the P-38 had an impressive range of 1,300 miles, the P-38 is simply not suitable for carrier ops.
The P-40 and P-39 also would have needed some structural modifications, like stronger main gear for landings, tail structure mods for allowing the shock of the arresting proceedure and of course, modifications for folding wings, which would complicate things, as the fuel tanks and armament may need to be re-arranged for that.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
The U.S. Navy had 4 F-5Bs (FO-1), used exclusivly from land bases.Lockheed didn't seem to agree
Regarding Lockheed's model 822 proposal, the U.S. Navy didn't want such a large aircraft, regardless of Lockheed's proposal for folding wings, strengthened tail structure tailhook, so the model 822 never left the drawing board.
Keep in mind that with liquid-cooled engines or radial engines, the model 822 would present several problems. First of which, is the "handed" engine requirement. If an engine is damaged on the 822, it can't be swapped for any engine, it has to be either a right-hand engine or a left-hand engine, so this increases the need for more engine reserves and nessecary parts specific to each engine. Also, the Navy did not want to dedicate additional room on already cramped carriers, for ethylene glycol storage. Also, the 822 would also take up more space on the deck as well as below, reducing the available number of fighters the carrier needed to have on hand.
The Navy also felt that the 822 may be problematic for launches and was too heavy for safe recovery, as the P-38 was over 7,000 pounds heavier than the F4F, 3,000 pounds heavier than the F6F.
GregP
Major
The stall speed wasn't really near Naval requirments, either. It could have been made to meet the requirments, but the wings would have gotten bigger.
Power off, the P-38J stalled at 99 mph with gear and flaps up. Power on it stalled at 78 mph with gear and flaps down. Power on it stalled at 53 mph with gear and flaps down. The 53 mph SEEMS OK until you realize it was at 54" MAP and 3,000 rpm ... hardly an approach configuration. The F6F Hellcats typically stalled in Landing Configuration at 78.5 knots or 90 mph, but also they weighed a LOT less than a P-38. Getting s a plane more than 5,000 pounds heavier stopped in the cat stroke mikght have been interesting from the point of vbiew of where the stress from the hook would be distributed in the P-38 airframe.
From an energy standpoint, the P-38 has some 41 more mass and only takes about 6% more energy to stop, but the stress has to be collected somewhere in the airframe or the hook pulls out. By comparison with the P-38, the Hellcat was cheaper by far, available, MUCH easier to produce, and would result in more aircraft stored in the same space and burn less fuel for a slight drop in performance in top speed and climb, but an advantage in turn ability and stall resistance. The advantage was all Hellcat in gasoline usage, and the P -38 also used Glycol coolant. The P-38 had good centerline arramanet. The F6F Hellcats six 50's were't too far behind, and all the F6F guns had the same trajectories. The cannon in the P-38 had different ballistic chraracteristics than the MG armament did, so if one was hitting, the other was missing except at short range.
I love the Allison but, if given a choice for flight off a carrier, I'd opt for the Hellcat any day of the week.
Power off, the P-38J stalled at 99 mph with gear and flaps up. Power on it stalled at 78 mph with gear and flaps down. Power on it stalled at 53 mph with gear and flaps down. The 53 mph SEEMS OK until you realize it was at 54" MAP and 3,000 rpm ... hardly an approach configuration. The F6F Hellcats typically stalled in Landing Configuration at 78.5 knots or 90 mph, but also they weighed a LOT less than a P-38. Getting s a plane more than 5,000 pounds heavier stopped in the cat stroke mikght have been interesting from the point of vbiew of where the stress from the hook would be distributed in the P-38 airframe.
From an energy standpoint, the P-38 has some 41 more mass and only takes about 6% more energy to stop, but the stress has to be collected somewhere in the airframe or the hook pulls out. By comparison with the P-38, the Hellcat was cheaper by far, available, MUCH easier to produce, and would result in more aircraft stored in the same space and burn less fuel for a slight drop in performance in top speed and climb, but an advantage in turn ability and stall resistance. The advantage was all Hellcat in gasoline usage, and the P -38 also used Glycol coolant. The P-38 had good centerline arramanet. The F6F Hellcats six 50's were't too far behind, and all the F6F guns had the same trajectories. The cannon in the P-38 had different ballistic chraracteristics than the MG armament did, so if one was hitting, the other was missing except at short range.
I love the Allison but, if given a choice for flight off a carrier, I'd opt for the Hellcat any day of the week.
Why? Take a look at the physical properties of ethylene glycol. It is a benign chemical, not particularly toxic, with a flash point of 111 degrees Celsius (compared with around -45 for petrol/gasoline). It freezes at -13 degrees Celsius and heating coils maybe installed in outside tanks exposed to very low ambient temperatures! It is most often stored in regular mild steel drums.
I keep seeing the difficult/dangerous to store argument against the storage of glycol on board aircraft carriers, but it is entirely spurious.
Cheers
Steve (putting on his rather old chemist's hat)
Take a look at the difficulties of extinguishing it once it is ignited:
(from the CDC website)
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
I think people are under the misconception that "coolant" is a hazard, and that's actually not the case, as the only thing hazardous about coolant, is that it will kill you if you try and drink it (even if it's strained through a loaf of french bread).
The Navy's argument against bringing liquid-cooled aircraft into the inventory, was that creating storage space for ethylene glycol would rob them of precious storage space for hydraulic fluid, oil, gasoline and other liquids necessary to keep the aircraft committed to battle.
Having one or so liquid-cooled aircraft aboard may not seem like such a big deal, but if your entire compliment were all liquid-cooled, you'd need to have a great deal of storage for coolant. For example: a P-51D has a total coolant capacity of 21.5 gallons (16.5 - engine/5.0 - After Cooling System), a P-38 has a much greater capacity.
You could say the same thing about a lot of materials on an aircraft carrier. Glycol can be diluted with water to a non combustible liquid, something you can't say for petrol or oils. You can't generally spray water on to an oil/petrol fire either, you'll just spread it. Special nozzles were eventually developed that did enable water to be used, but it took the loss of the USS Lexington (to re-ignited gasoline fires) before the 'Rockwell nozzle' became generally available. The above is not an argument against storing glycol. The space issue may be a valid argument, but not the hazard. Gasoline and other oils present a far greater hazard and the navy was obliged to store them if it wanted to operate any aircraft.
Cheers
Steve
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GregP
Major
There is not much of a problem storing glycol. All it takes is a tank. Add one anywhere when the carrier is built and you have it.
But glycol means you need the glycol itself, a radiator cap, a water pump and, at minimum, 3 or more hose connections to the engine to make it flow. So you have 6 hose ends minimum, a cap, a radiator and a pump to fail, adding maybe 20 more ways to fail. Each hose could fail due to a hose clamp on either end or the hose itself, the pump can leak at either connection, lose a blade or blades or lobe if positive displacement type, or a bearing, the radiator cap can either leak or fail pressure, the radiator can leak at the in and out connections or in any of the cores, and it can also get plugged up in mmany more than one place and cause issues as a result. The coolant can always fail over time and simply not cool well enough. The entire system can be fine and still suffedr battle damage rendering the cooling system inoperable.
I've always thought the Navy wanted air-cooled radials mainly to cut down on possible failure modes in piston engine cooling systems.
But glycol means you need the glycol itself, a radiator cap, a water pump and, at minimum, 3 or more hose connections to the engine to make it flow. So you have 6 hose ends minimum, a cap, a radiator and a pump to fail, adding maybe 20 more ways to fail. Each hose could fail due to a hose clamp on either end or the hose itself, the pump can leak at either connection, lose a blade or blades or lobe if positive displacement type, or a bearing, the radiator cap can either leak or fail pressure, the radiator can leak at the in and out connections or in any of the cores, and it can also get plugged up in mmany more than one place and cause issues as a result. The coolant can always fail over time and simply not cool well enough. The entire system can be fine and still suffedr battle damage rendering the cooling system inoperable.
I've always thought the Navy wanted air-cooled radials mainly to cut down on possible failure modes in piston engine cooling systems.
GrauGeist
Generalfeldmarschall zur Luftschiff Abteilung
I recall reading an overview of the Navy's decision to keep radials as the primary power source for thier aircraft because they didn't want to convert existing carrier storage and didn't intend to modify current designs for carriers being planned/built.
There was also mention of the "old school" train of thought that the radial was more reliable and while I disagree about reliability over extended hours on the engine, I will agree that the radial is far more tolerant to battle damage (as seen with both Army and Navy radials)
There was also an interesting point made, that the coolant lines were considered weak points and subject to a potential failure with the violent landings.
This is not to say that the Navy didn't consider liquid-cooled fighter aircraft, for example, the Navy had evaluated several P-51 aircraft over the years, starting with "Project Seahorse" and a P-51 [41-37426], then a P-51D (ETF-51D) [44-14017] and even later, with a pair of P-51Hs [44-64420/44-64700], leading North American to propose the NAA-133 project.
There was also mention of the "old school" train of thought that the radial was more reliable and while I disagree about reliability over extended hours on the engine, I will agree that the radial is far more tolerant to battle damage (as seen with both Army and Navy radials)
There was also an interesting point made, that the coolant lines were considered weak points and subject to a potential failure with the violent landings.
This is not to say that the Navy didn't consider liquid-cooled fighter aircraft, for example, the Navy had evaluated several P-51 aircraft over the years, starting with "Project Seahorse" and a P-51 [41-37426], then a P-51D (ETF-51D) [44-14017] and even later, with a pair of P-51Hs [44-64420/44-64700], leading North American to propose the NAA-133 project.
Conslaw
Senior Airman
I recognize all these difficulties in adapting the P-38 for naval service, still I can imagine small quantities of naval P-38s being used for special strike missions, Fast bombers to go after high value, defended targets. Imagine if you will, a Doolittle II type strike.
