Ref P38 radiators. No. All models had radiators moundted on the sides of the tail booms. None were leading edge. The improved ones on the 'J' and 'L' were due to reshaping. The NACA had been doing a lot of work on boundry layer air movement that was applied to the problem. You may have been thinking of the supercharger air cooling system that ran through the wing leading edges in all versions prior to the 'J'. This was one of those really great ideas that proved a lot less great in practice. The ducting was damaged concussion if the enine backfired, maintainance was a bear, repair was worse (they were very prone to battle damage) and the actual degree of cooling and the back pressure both probably contributed to the engine failure problems in the UK. This was replace by a core cooling system that gave the cowlings of the 'J' and 'L' their 'beard' look. There was some drag increase from that, but the reduction in drag from the radiators aft was at least great enough to balance that out. The beard type actually could reduce drag compared to an external radiator. The drag resulting form air going thru the unit was unavoidable, but the externals had surface drag from the outer casing. The beard type used the outer casing as part of the streamlined skin of the a/c, presenting fewer corners and less total surface area.

In the P51, the drag effects of the ducting was largely cancelled by the 'jet exhaust' effect from discharging the heated air aft. The down side to enclosed radiators was that there were almost always cooling and/or streamlining issues to be worked out during flight testing. The externals were much more predictable within the level of aerodynamic knowledge of the period. Problem with leading edge radiators was the same, only worse. Goes back to limited understanding of boundry layer effects. Also, maintainence was usually easier for the beard type or externals than on leading edge types. They could be worked on standing flat on the ground rather than up on ladders as was needed for the Mosquito, for example.

Not knowing anything about "SuperFlexit" it's hard to argue this one. I do know that the rear fuselage tank in the Mustang was a standard feature and wasn't seen as a particular hazzard. Seems pretty odd, as simply preventing leaks means very little. Normal self sealing system for the day was a soft rubber bladder inside a light metal shell. This also made it much easier to draw fuel from the tank during maneuvers in which the fuel would otherwise be sloshing around in a partly filled tank, leaving the fuel feed dry at least part of the time. The reason they weren't used by the Japanese in the Zero was the fact that they reduced the fuel capacity of the tank.

Self sealing seems to imply to me that stopping leaks was the primary goal. I know that in some planes later in the war exhaust gas was pumped into the fuel tank to try and prevent a suitible fuel air mixture for an explosion developing. Perhaps the reason why the tank on the Mustang wasn't considered a fire hazard was because it was a neccesity for the long range required. In situations where long range wasn't required such as bomber interception the tank may have been looked apon less favourably, the effects on handling would have had something to do with this as well.

Your right about the P-38. Got a bit mixed up there. About the maintenance on the wing leading edge radiators. The mossie was a much bigger aircraft than a P-40 or spit they would have had to stand on something to get at the radiators regardless of position. Wing leading edge radiators on a single seater might actually be easier to get at compared with other locations as it's not below the wing or engine so you don't have to get under or around anything to work on it.

"Even if the rear tank was self sealing, it was still vulnerable to tracer or incendairy rounds or cannon shells until they were completely empty as it wasn't behind any armour." A point to note is that aircraft fuel tanks invariably have a proportion of unusable fuel, so the rear-tank would never be completely empty unless it was not filled in the first place. A round travelling through the fuel vapor floating off the residual would most likely cause the tank to explode.

I only read your post about gas fumes after writing my own and agree that an empty tank is more dangerous than full. However, I'm curious about this post. "The point of the self sealing bladder was to prevent the mixture of gas fumes and air. Unless the bladder is ripped seriously open, no fire or explosion." As a tank empties, air is bought into it to replace the space the fuel was occupying. In the case of the self-sealing bladder, is it the case that the air enters the newly formed space outside the bladder, with the bladder shrinking as the fuel is consumed?

You just answered my question from my previous post.

"The Tempest I which wasn't produced due to problems with engine reliability had wing leading edge radiators and was much faster than the Tempest V with the beard radiator. Tempest I reached 466 mph in february 1943 compared to the 426 mph the Tempest V reached in it's initial build." According to this(really good, IMHO) site, it was less a reliability(in the sense of a design fault) problem, than that the Sabre IV powering the Tempest Mk 1 was still needing a lot of development work. Apparently the Chief of the RAF at the time didn't want to split up the resources being used for engine development and also didn't trust the Mk 1's wing radiators(he thought they were prone to battle damage), so canned it and opted for the Mk 5 and a proven engine, at the expense of the superior speed of the Mk 1. A bit of a shame, but irrespective of whether it was a Mk 1 or a Mk 5, the Tempest Rocked! It would have to be my first equal favourite late-WW2 design, along with the Corsair. http://www.hawkertempest.se/mark.htm

Yes, the bladder collapsed as it emptied, keeping fuel vapors and air separated. The system was first used in the French Salmson2 of 1918 in a crude but fairly workable form. A ferry tank or drop tank didn't matter. An internal ferry tank would be purged with CO2 gas after use, before the a/c went into combat, and of course, drop tanks were just disposed of.