oh cool, does this mean the spit pilot in AH should have either the current speed WITHOUT fireing or 5mph less AND the possibillity to shoot? But i already wrote topspeed is ok, i just wanted to point out that this spit was prepared.
2000-2200hp, definitly. I never said something different, though the power increase surprised me too. But the doc of the russian am-38 test convinced me that supercharger take indeed a lot of power.
But itīs useless, you ll write in 2 weeks again that this spit used a serial engine in several BB, nevertheless i try again to explain it.
Spit had in 2nd gear of the supercharger in the middle 1700PS (see atachment, oh and compare critical altitude of 1st gear to the boscomb spit again...)
Weight of the spit14: 3800kg.
Climbrate in 2nd gear: 3600ft/min = 18.4 m/s
Climbrate in 1st gear: 5100ft/min = 26m/s
DIFFERENCE: 7.6m/s
To lift 3800kg with 7.6m/s you need: 3800*9.81*7.6 = 283kW
or 283/0.735 = 385PS
This is no niklas trick, this is basic, essential physics. The spit must have had in 1st gear 385PS more than in 2nd gear for the gain in climbrate. So 1700+385 = 2085PS
But wait, we didnīt take prop efficiency into account. In this case we have to divide it, because 385PS refer to the power of the propeller. But we are interested in the engine power. Letīs assume an excellent(!) efficiency for climbs: 0.85
385/0.85 = 450PS
So the boscomb spit-14 had at least 1700+450 = 2150PS.
And this with an excellent efficiency, which on the other hand compensates for the little gain in climb angle. 2000-2200PS, definitly, tendency toward 2100-2200PS.
PERIOD
Next problem, the mach number. Looks like the unique "the elliptical wing explains all" argument there comes another one, "the thinner wing explains everything". Unfortunatly not true. Mach effects show already up at Mach0.4- 0.5 in certain areas. What pulls you down in a dive? Weight. Does the spit has a high wingloading? NO. Does it have, looking at the topspeed/power ratio, an excellent aerodynamics? NO. Alone the "bags" (cooler), the standing engine, and so on.
We donīt talk about slight differences. We talk about Mach 0.89-0.91 claims compared to Mach 0.8 of aircraft like P39 or P51, 109, or even Metors.
You know how that "the spit is the fasted aircraf in the world" hype began? The Aeroplane, Nr. 1495, 19.1.40. A spit pilot claimed that he exceeded 600mph in a dive. How? He became unconscious, when recovering he was in a vertical climb at 400mph. Someone assumed that he must have been faster than 600mph in the dive....
This is how the story of the "fastest fighter in the world" began. Even the english author raises doubts, aerodynamically, and physically, because a pilot who recovers from a blackout canīt read exact speeds and altitudes.
But what happened? The newspapers picked up this story and made a big propaganda story out of it, speaking from the "fastest fighter of the world". Based on such a unscientific proof. But well, propaganda is made to give people a good feeling, especially for those who donīt have enough brain to judge whether somehting makes sense or not.
Later they tried to backup those fastest fighter story with a pityful test, you just have to watch the initial acceleration (what is higher than a spit near ground at best level acceleration, substracting the 1G away for gravity) to know that the whole test is a farce. Heck according to the instruments theyīd broken through the barrier of sound lol. But ok, iīm really not surprised that it was an army test. I doubt that a scientific research institute like the naca would have come to the same result....
Again, believe what you want. Those stories are made to be believed (...). Feel happy, if it suits your dreams and fits to your numerous colourful posters and pictures you probably have of the spit.
Substantial lower critical mach number? Sorry, 12 to 14-15% isnīt substantial.
You want a comparison of critical mach numbers? Check
http://naca.larc.nasa.gov/reports/1945/naca-report-824/index.cgi?page114.gifAs you can see in the following pages for the 24xx series or 230 series ( the closest airfoils to common ww2 airfoils), the difference is very very small between 15 and 12%. Having the biggest point already at 20%, the spit airfoil is probably a bit worse than the 24xx. And actually at zero lift the 15% 230 airfoil is better (cl = 0) .... (2R1 is basically an early 230xx)
And again, the wing is only a part of an aircraft. Cooler, engine-wing mounting, nose shape etc - this is all very important. And the spit showed already at normal speeds that it wasnīt the best design for really high speeds. And it didnīt had a high wingloading. But of course, it outclassed all other high speed design by 0.01 Mach - oh no, 0.02? nono 0.05? nonononon 0.08-0.10 Mach !!!! LOL. What a joke.
niklas
