Defiants and Battles deployed overseas, any merit in that?

RCAFson said:

The Merlin II/III could do somewhat better with 100 octane fuel and was rated for 12lb boost at TO for about 1200hp.
The Merlin VIII was rated at 1275hp with 100 octane. The Merlin XXX (1360hp) was also a good candidate.

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You do NOT want to be using the 12lb boost rating for take-off on a regular basis with an early Merlin. EACH and EVERY use of the boost override switch had to noted in the log book for the engineering officer to determine any extra maintenance procedures (changing plugs and oil inspections) and shortened time between overhauls.
If you had to use it on an existing airplane under bad conditions that is one thing, PLANNING to use it on a routine basis on a NEW variant of aircraft is poor planing.

1200hp is also a bit optimistic for take-off.

The R.M.S. 2 specification ( none produced ) called for 1000hp at 3000rpm at 8 1/4lbs boost with 100 octane using the same supercharger gear as the Merlin III.

Please note that there was a bit of strengthening going on even with some of the Merlins that came right after the MK III, VIII and X. The Early Merlins were still restricted to 2600 rpm amd 4-6 lbs for climb while the slightly later ones were allowed to use 2850 rpm and 9 lbs boost for climb.

The Merlin VIII was good for 1080hp at 5 3/4 lbs for take-off on 87 octane.

The Merlin XII was rated at 1175hp for take off at 12 1/2 lbs boost. at some point in their production both the VIII and the XII got stiffened side panels to the crankcases, longer cylinder stud bosses, longer cylinder studs, the cylinder spigots were made slightly longer amongest a few other modifications.

Blenheims were used by both the RAF and Hellenic Air Force against the Italians in the Greco Italian war and were found to be vulnerable against Italian CR42's. The Greeks at this time had in their small air force a squadron of Fairey Battles but only used them on targets where fighter opposition was not expected to be present. The Greeks realised that if the Blenheim was vulnerable to CR42's then the Battle had no chance, and so even as desperate as the Greeks were for aircraft they still didn't resort to using the Battle against defended targets. The Fairey Battle was used in the Italian East African Campaign along with a number of other obsolete types but again it was not risked against fighters. So if you ask me using the Battle against a Japanese fleet sounds like a recipe for disaster, look at what happened to the Devastator and remember the lack of success gained by the Italians when they attempted using small bombs against ships, even if the Battle was able to get through the fighters and massive AA barrage then it still wouldn't have caused much damage.
As for the Defiant, well the Defiant was just a bad idea. Fighters attack other fighters from behind not by getting alongside of them and to add to this in a single seat fighter the pilot is the gunner and not his chauffeur and so uses the whole aircraft to aim his guns without relying on instruction. The success of the Defiant as a day fighter was only due to Me 109 pilots attacking them from behind after mistaking them for Spitfires and Hurricanes, as soon as the Luftwaffe realised this mistake they only had to attack them head on to shoot them all down. As a night fighter four rifle calibre machine guns was not really enough against large aircraft such as German bombers and again you didn't really want to have get along side them to shoot at them, especially close enough to use 33 cals.

Shortround6 said:

You do NOT want to be using the 12lb boost rating for take-off on a regular basis with an early Merlin. EACH and EVERY use of the boost override switch had to noted in the log book for the engineering officer to determine any extra maintenance procedures (changing plugs and oil inspections) and shortened time between overhauls.
If you had to use it on an existing airplane under bad conditions that is one thing, PLANNING to use it on a routine basis on a NEW variant of aircraft is poor planing.

1200hp is also a bit optimistic for take-off.

The R.M.S. 2 specification ( none produced ) called for 1000hp at 3000rpm at 8 1/4lbs boost with 100 octane using the same supercharger gear as the Merlin III.

Please note that there was a bit of strengthening going on even with some of the Merlins that came right after the MK III, VIII and X. The Early Merlins were still restricted to 2600 rpm amd 4-6 lbs for climb while the slightly later ones were allowed to use 2850 rpm and 9 lbs boost for climb.

The Merlin VIII was good for 1080hp at 5 3/4 lbs for take-off on 87 octane.

The Merlin XII was rated at 1175hp for take off at 12 1/2 lbs boost. at some point in their production both the VIII and the XII got stiffened side panels to the crankcases, longer cylinder stud bosses, longer cylinder studs, the cylinder spigots were made slightly longer amongest a few other modifications.

Click to expand...

The Fulmar pilot's notes states that with 100 octane fuel 9 lb boost could be used for TO using the Merlin VIII. In a separate paragraph it states that use of the boost cut-out may be used at low altitude for more power, but on those occasions it must be logged.

Harvey-Bailey gives 1275hp at SL with 9lb boost with 100 octane. He also states that the R.M.4.M was the 100 octane version of the Merlin VIII, but was otherwise identical, and that it had a 1300hp TO rating at 9.75lb boost and became redundent when the VIII was cleared for 100 octane.