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British were advising using 1800 rpm for Cruising In a Spit V with a Merlin 45. Depending on the boost used at 1800rpm this could give the same speed as 2650rpm at a lower boost.You don't suppose there's a relationship between this and the fact that Allisons could handle oversquare (high MP, low RPM) much more smoothly than Merlins, thus giving them superior long range cruise efficiency? (Guadalcanal->Yamamoto->Gaudalcanal)
Try that in a Spit.
This was specifically stated in the quoted report in the thread, detailing RAF experience with the Mustang Mk I.Does anyone have any actual official test/comparison data for the idea that the Allison could run at lower rpm significantly more satisfactorily than the Merlin - hopefully something that explains the problem/difference. The reason I ask is that I have not been able find any officially stated reasons for any significant difference, only anecdotal statements and suppositions.
As far as I know, based on what I know about engines and have been able to find out about the Allison and Merlin, the only reasons that might have made a difference are the type of spark plug used and the compression ratio.
1. Some spark plugs are more prone to fouling than others.
2. Engines with higher compression ratios are generally less prone to fouling of the spark plugs.
No.1 is ~solved by changing the type of spark plug (which was done a few times for various reasons - on both makes of engine). I can not imagine that the various responsible agencies did not think of this and implement a change if needed.
No.2 is ~solved by opening up the throttles to higher rpm and boost periodically during the flight (which is listed in the flight manuals for both makes of engines, although it does seem that it is mentioned less frequently re the Allison.). The higher compression ratio of the Allison would have slowed down/decreased (to a small but possibly significant degree) the fouling process caused by the high TEL content fuels used at the time.
I realize the above is somewhat general, but it should apply regardless of engine type.
Otherwise, I have read in most of the manuals for Merlin powered AC that it was often problematic when running below 1800 rpm, but this was due to the generator not being able to charge the batteries at lower rpm. I have read of this problem with Allison installations as well, although not as often.
I confused.+ + + =
Does anyone have any actual official test/comparison data for the idea that the Allison could run at lower rpm significantly more satisfactorily than the Merlin -
The whole airship thing (or most of it) was funding.Probably camshaft valve timing, eg. the Merlin had more of a high rpm racing heritage whereas the Allison came from an engine for dirigible airships (AFAIK).
The zero was indeed a formidable platform that had superior performance to its adversaries. But, as the RAF found in the battle of france and the BoB, in the hands of a quick thinking pilot with a bit of experience tactics could be out to good use in order to outwit and ultimately defeat a superior platform. The 109 once put into a steep dive could not pull out, so RAF pilots would attempt to orchestrate a dogfight to get a 109 into such a situation. 109 pilots would attempt to avoid this, thereby straight away putting them at a tactical disadvantage even in a superior performing platform. The Hurricane and Spitfire could out turn a 109, so again RAF pilots would hold the 109 in a horizontal fight. Again the 109 pilot attempting to avoid this also put them at a tactical disadvantage, thereby putting your adversary on the defensive.How good was Zero against famous Spitfire or German FW 190?
Can a Zero beat them any chance at all?
At the expense of 200mph+ maneuverability, ruggedness, protection, communication and any hope of pilot survival. A Spitfire could have been made to the A6M's spec and totally outclassed it in speed, climb, turn and range but the Allied nations never compromised pilot safety and protection for performance.The zero was indeed a formidable platform that had superior performance to its adversaries
The zero was indeed a formidable platform that had superior performance to its adversaries.
JayDawg,similarly in the Pacific area of operations, the Wildcat was far inferior and outclassed by the zero. But with tactics such as the 'Thatch Weave' manoeuvre by two wildcats it brought the fight to a level plane.
Today the USN FWS aka 'Top Gun' still utilise the thatch weave. I think it is accepted that as good and rugged a platform the F18 is in its different guises, it is outperformed and outclassed on many fronts by any potential adversaries. So the USN teaches its pilots to rely on tactics and manoeuvres. The F18 and stop on its tail and use its aerodynamics to bring the fight to its own terms against a faster and more ag platform.
In essence, the ability of a platform is only a part of the equation, in the hands of a well trained pilot that knows his platform inside out and knows the capabilities and vulnerability of his adversaries platform, that's what will decide the outcome of a duel in the skies..
JH
The F-18 is outclassed by any potential adversaries?I think it is accepted that as good and rugged a platform the F18 is in its different guises, it is outperformed and outclassed on many fronts by any potential adversaries.
I don't think flying within VR in today's world you're going to have the ability to do a "Thatch Weave" so please provide your reference for that. Top Gun will teach energy maneuvers when the fight is within VR, but in today's world if you're fighting completely VR, you pissed away several million dollars worth of technology.Today the USN FWS aka 'Top Gun' still utilise the thatch weave.
The F-18 is outclassed by any potential adversaries?
Surely that's not an F/A-18 we're talking about, is it?
Because they can do the "Thatch" Weave?If it so outclassed, why is my company still building them, and why do we still have customers wanting it?
Because they can do the Thatch Weave?