Mike Williams
Senior Airman
- 572
- Oct 19, 2006
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Level speed charts showing the impact of increased boost with the P-51 D made possible by 150 grade fuel.
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Mike,
Do you have the limits around the Fw-190D-9 MW? How much was carried, when it could or could not be used, and limits (time or otherwise)?
Cheers,
Biff
I have a chart that shows FW190 A-9, D-0, and TA152 H-1, and on that chart it shows the D-9 with some better airspeed performance than your chart, e.g., SL speed shown on posted chart was about 375 mph whereas my chart has about 388 mph (most of it is similar). In any event, it appears to me that both of these aircraft were very similar in performance with maybe a slight advantage to the D-9 up to about 20k due to slightly better climb and the P-51D having a definite advantage above 25k due to better climb and significantly better airspeed. However, due to uncertainties of manufacturing tolerances in engines, engine tuning levels, propellers, streamlining, and error tolerances of test equipment, and test condition variations, we are really trying to make a precise cut with a dull axe.Level speed charts showing the impact of increased boost with the P-51 D made possible by 150 grade fuel.
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Hello Biff,
Dietmar Hermann wrote the following: "In October the number of Fw 190 D-9s on strength with the Gruppe rose to 68. Of these, 53 had been converted to 1,900 h.p. and one was delivered by Focke-Wulf with the MW 50 system. The remaining 14 were in the process of being converted and completion was imminent."
"In production aircraft it was planned that the MW 50 system could be used to draw fuel or methanol/water from the 115-liter tank. On account of delivery difficulties, however, it was decided to use the tank with methanol-water only, and this was dubbed the "Oldenburg System" (see III./JG 54). This system was installed in production aircraft beginning in November 1944."
"By the end of December 1944 there were 183 Fw 190's in operation with the increased performance modification, and 60 more had been delivered with the MW 50 system and were at the point of entering service."
I'm not sure of duration or limits yet, will check.
I have a chart that shows FW190 A-9, D-0, and TA152 H-1, and on that chart it shows the D-9 with some better airspeed performance than your chart, e.g., SL speed shown on posted chart was about 375 mph whereas my chart has about 388 mph (most of it is similar). In any event, it appears to me that both of these aircraft were very similar in performance with maybe a slight advantage to the D-9 up to about 20k due to slightly better climb and the P-51D having a definite advantage above 25k due to better climb and significantly better airspeed. However, due to uncertainties of manufacturing tolerances in engines, engine tuning levels, propellers, streamlining, and error tolerances of test equipment, and test condition variations, we are really trying to make a precise cut with a dull axe.
Mike,
Thanks! I remember reading somewhere exactly what you quoted. The reason I ask is the Fw-190D-9 had a little better performance than the P-51D in the 12-20k'ish block, and I'm wondering how much of that was due to the MW-50 / Oldenburg System (how much and just as importantly for how long). I also have read, as davparlr mentioned, that the seals around the firewall to cowling were very important as they added about 10 or so MPH (IIRC). Just trying to figure out what they Allies were going up against when they did meet the Long Nosed Fw's (between cowl seal, MW50, and fuel you could have a pretty good spread on your opponents top speed / power out.
Cheers,
Biff
Hello Biff, as noted above Flugbericht Fw 190 D-9/210002 Nr. 3 discussed trials of an aircraft with the engine seals and noted "During these flights the seals between engine and wings pulled out and then were torn off. It was also noticed that exhaust gases caused minor fire in spots. Therefore, an improvement of the sealing within this area is necessary."
To reiterate from Dietmar "D-9 production aircraft did not have the slit sealing (engine gap seal). I have the information from a document named "Lfd. Entwicklungsarbeiten Fw 190/Ta152" from 8.1.45 updated 20.3.45 with the handwritten statement "24.3. Rechlin lehnt ab!". "
My view of the condition representative of standard production Fw 190 D-9's during 1945 is as follows: Jumo 213A operating at 1.8 ata with B4 fuel & MW 50, equipped with ETC 504, main wheel fairing doors absent/fixed and engine gap not sealed. The curve best fitting the condition of a standard production Fw 190 D-9 is curve 4 of the Focke-Wulf Fw 190 D-9 chart dated 11.3.45 That's the curve I charted above.
My information shows the D-9 having a slightly better climb rate up to about 15k but my data may be off since I don't read German. Another advantage that the P-51D has is endurance. The P-51D has a combat fuel load of 184 gallons vs the D-9 of 138 gallons and since the D-9 did not go into production until August of '44, it's reasonable to assume forward European airfields were available for the P-51, so no long trip back to England and much more time over the battlefield.
My information shows the D-9 having a slightly better climb rate up to about 15k but my data may be off since I don't read German. Another advantage that the P-51D has is endurance. The P-51D has a combat fuel load of 184 gallons vs the D-9 of 138 gallons and since the D-9 did not go into production until August of '44, it's reasonable to assume forward European airfields were available for the P-51, so no long trip back to England and much more time over the battlefield.
I also recall reading that by late '44 and early '45, Luftwaffe aircraft often times didn't have a full loadout of fuel onboard due to logistics and supply issues.Also remember that the smaller the fuel load the smaller the perf hit. A lot of Bf-109 & FW-190 performance versus the P-51 came from the smaller airframes / fuel tanks designed for shorter duration flights.
Cheers,
Biff
Basically, most (?) European fighters were point defense fighters , after all almost everything is pretty close. The most impressive feature of the P-51 was that it could fly 600 miles, engage these lighter defensive fighters with full combat fuel and with formidable effect and then fly 600 miles home. This is a general statement and general statements are often dangerous, most flight test are performed at combat weight which usually means full internal fuel, except the P-51 which has an internal extended range tank. So, to really compare airframe vs airframe to the Fw 190 D-9, the P-51 would have to be tested at 138 gallons of fuel instead the normal tested 180 gallons, or about 250 lbs lighter. So, yes added fuel affects performance but these test include that effect.Also remember that the smaller the fuel load the smaller the perf hit. A lot of Bf-109 & FW-190 performance versus the P-51 came from the smaller airframes / fuel tanks designed for shorter duration flights.
Cheers,
Biff
Which certainly would improve performance but would also negatively affect combat time. Fuel on the ground is one of the most useless thing in flying like runway behind you and altitude above you.I also recall reading that by late '44 and early '45, Luftwaffe aircraft often times didn't have a full loadout of fuel onboard due to logistics and supply issues.
Basically, most (?) European fighters were point defense fighters , after all almost everything is pretty close. The most impressive feature of the P-51 was that it could fly 600 miles, engage these lighter defensive fighters with full combat fuel and with formidable effect and then fly 600 miles home. This is a general statement and general statements are often dangerous, most flight test are performed at combat weight which usually means full internal fuel, except the P-51 which has an internal extended range tank. So, to really compare airframe vs airframe to the Fw 190 D-9, the P-51 would have to be tested at 138 gallons of fuel instead the normal tested 180 gallons, or about 250 lbs lighter. So, yes added fuel affects performance but these test include that effect.
I think I'd start a graphical comparison with the data sets shown below and move on from there. One less than desirable issue is that the P-51 data derives from a USAAF test at Wright Field of an actual P-51D aircraft, serial number 44-15342, whereas the Fw 190D-9 data is from engineering estimates from Focke-Wulf Flugzeugbau's Abt.: Flugmechanik-L. Flight trials of Fw 190 D-9s can be found here and are useful, however, the data charted is insufficient to show performance at 1.8 ata throughout the full range of altitudes with level speed, climb rate and climb time. While it was concluded by the Power Plant Laboratory of Materiel Command's Engineering Division that the V-1650-7 engine would satisfactorily comply with a 75" Hg manifold war emergency rating with 150 grade fuel and P-51Ds are reported to have operated at 75" Hg., such as shown in this Encounter Report from Chuck Yeager, 72" Hg. appears to be the generally accepted limit in the 8th AF beginning in June 1944. An increase of boost from 67" hg. to 72" on the P-51D should increase power to about 1820 hp and increase speeds below full throttle height by around 7 mph. RAF Mustangs operated at 80" Hg. / +25 lb.sq. in. boost. A. & A.E.E. reported - "Use of +25 lb/sq.in. instead of +18 lb/sq.in. boost increased the True Air Speed below full throttle height 25 mph."
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Hi
One or two commenters say that the higher octance fuel with higher compression ratio would produce more power and faster climb rate but not greater horizontal speed. If someone could explain that I would appreciate it.
thanks