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However at about 16k ft, the Fw-190D-9 engine starts losing significant power, while the P-51 engine is into its second wind. This starts to show up around 20k where the P-51 gains significant improvement of airspeed over the Fw.
Airspeed
P-51B 442 mph
Fw-190D-9 426 mph
Significant advantage P-51
KrazyKraut said:We had this a couple of times now and there is no "truth" in neither what you or Soren say, because it's all just seculation.
Well, I admit that "the truth" was in my opinion only. However, I still think my premise is correct.
I'll bet that if there was a critical need, the production problem would be solved quickly.Besides that, the Tempest II never seeing any action was due to a pretty messed up production planning not because it wasn't needed.
It also makes more sense to evaluate the Dora vs. the P-51 D because the transition had progressed well when the Dora arrived in numbers and I highly doubt the USAAF would've ever switched back because of the B's small performance advantage.
The fact that there were a number of P-51Bs flying at wars end has been established.
But here are some comparisons with the P-51D. There is a strange note here. The climb rates have been modified to 75" Hg, however, I have not determined a factor for updating airspeed to 75" Hg yet, so the airspeed numbers below for the P-51D is at 67" Hg. I expect the 75" Hg numbers to be closer to the P-51B numbers but a bit less. P-51B airspeed at 75" Hg numbers are in parenthesis.
20k
A/S
Fw-190D-9 426 mph
P-51D 421 mph (442 mph)
Climb
Fw-190D-9 2992 ft/min
P-51D 3080 ft/min
Note: I made an error in the previous entry in the P-51B climb at 20k, rate should be 3480 ft/min, not 2940 ft/min.
25k
A/S
Fw-190D-9 417 mph
P-51D 440 mph (440 mph)
Climb
Fw-190D-9 2158 ft/min
P-51D 2350 ft/min
And, with a better dive, I think you can see that even the P-51D would be quite a handful for the Fw-190D-9 at 20k ft. and above.
Kool kitty89 said:Inless you're talking about the P-51 at 75" boost (with 100/150 grade fuel) that's much too fast.
By the time the Fw-190D-9 arrived, 75" boost had been approved,
http://www.wwiiaircraftperformance.org/mustang/75inch-clearance-v-1650-7.jpg
and used.
http://www.spitfireperformance.com/mustang/combat-reports/357-yeager-6nov44.jpg
Of course I used 75" boost.
Are up implying that Spitfire Performance alters government test documents to reflect a bias?P-51 Mustang Performance (which tends to be a bit biased toward allied a/c anyway)
I don't think the Mustang had a significant speed advantage over the Dora until ~23,000 ft.
I think you will find that test results at 75" boost does not support this comment (see my data.)
Soren said:The P-51B didn't climb at 4,700 ft/min Davparlr, not even at 75" MAP where at at the most reached 4,380 ft/min.
The test report you refer to has a test weight of 9680 lbs for the P-51B which is about the fighter weight of the P-51D (according to "America's Hundred Thousand"). The fighter weight of the P-51B is about 9070 lbs. I think if you calculate climb performance with 600 lbs less, you will be pretty close to the 4700 ft/min rate at SL.
I don't know too much about the Tempest V, but according to some accounts I read from German pilots they found the Dora to be about as or slightly slower than the Tempest at low altitude but found its climb and maneouverability to be better. These are subjective assessments of course and also depend on fit and finish of the respective pilot's aircraft. For every aircraft mentioned here there is a wide range of different performance graphs available that's why I won't jump on the figure posting wagon. If I find the time I'll try to research some representative stats and draw my conclusions then. So far I'll go by the wording of the books I have which all pretty much say that these aircraft were about even, with the Dora's performance dropping off rather sharply above critical altitude.Hello KrazyKraut
Later Tempest Vs with Sabre IIB were faster than 190D-9 at sea level and up to appr 9500ft and then again from 19500ft upwards, early Tempest Vs with Sabre IIA were faster than 190 D-9 between appr. 1,000 - 10,000 ft and then again from 19500ft upwards.
Juha
Didn't the P-51 have a problem with the 100/150 grade fuel due to the merlin's tendency for spark plugs to foul rather heavily and rapidly when using it. (compared to the R-2800 and V-1710 which were deemed satifactory in terms of fouling using 100/150 grade)
All I know is what is on the internet. Apparently higher maintenance was required but production was high and there were several reports of 70+boost being used. Maybe someone else has knowledge of its usage.
Plug fouling was a problem with the 150 octane fuel and the crew chiefs basically changed the plugs every two missions. Speculation was that a very high percentage of engine failures resulting in a lost Mustang in late 1944 through the end of the war were in fact due to the fuel/plug issues.
The 1650-9 which came out in the P-51H, and retrofitted in post war P-51D's apparently were more reliable with the 150 octane.
9,300 lbs seems to be the fighter weight of the P-51B davparlr, not 9,080 lbs.
Data from "America's Hundred Thousand"
P-51B
Basic weight 7325
Pilot 200 (from P-51D data)
Useable Oil 94 (from P-51D data)
Cal. 50AMMO 378 (from P-51A data, four machine guns)
Internal Fuel 1080 (from P-51D data)
Gross weight 9077
P-51D
Basic weight 7673
Pilot 200
Useable Oil 94
Cal. 50AMMO 564 (six machine guns)
Internal Fuel 1080
Gross weight 9611
Basic weight is empty weight plus trapped fuel, machine guns, and pyrotechnics.
A detailed breakdown of Empty Weight and Basic Weight of the P-51B is in the book, too.
According to wright field it is 9,300 lbs for the P-51B and 9,700 lbs for he P-51D.
you couldnt get very far with only half a tank of fuel.....
so need to think that luftwaffe interceptors can fly with only half fuel