Best German fighter for the Eastern Front
- Thread starter wiking85
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And yet it was far from being aerodynamically as efficient as some of its contemporaries. It was a good job that it was small and had very powerful motors bolted on the front
http://www.wwiiaircraftperformance.org/me109/Hoerner-Me_109.pdf
Steve
Why does everybody also use the G-6 as a reference.. plenty of other 109's during 1944. G-14/AS, G-10, K-4.
DB 605 DC/ASC without MW for base-setting 1,98ata and 1,8ata
K-4 = 3400kg (7480lbs)
720km/h (448mph) @ 7200 meters (23,622ft)
590km/h (367mph) @ sea level
640km/h (398mph) @ 12000 meters (39,370ft)
That can't be all attributated to the engine alone.
DB 605 DC/ASC without MW for base-setting 1,98ata and 1,8ata
K-4 = 3400kg (7480lbs)
720km/h (448mph) @ 7200 meters (23,622ft)
590km/h (367mph) @ sea level
640km/h (398mph) @ 12000 meters (39,370ft)
That can't be all attributated to the engine alone.
Shortround6
Major General
I think we have been over this before and a MK V Spit uses just about the same amount of fuel to cruise as a 109F. At some altitudes and speed the the 109F comes out ahead and at some altitudes and speeds the Spitfire MK V does and they are usually within 2-3 percent of each other. IF the DB engine is more efficient that doesn't say much for the airframe.
Small does not mean efficient, it means small. A small but less efficient aircraft can have the same drag (speed for power) as a larger but more efficient aircraft.
Yes but your thesis was wrong, is wrong still... comparing apples to oranges does not help it. A comparison of airframe effiency is basically: power used, speed achieved, fuel consumed (if range efficiency is measured). You basically compared random powers at different speeds, i.e. not nearly the same or comparable conditions.
And vica versa - big does not mean more efficient, it just means big. If a small aircraft is capable of fullfilling the same duties its just means more efficient IMO.
In this case however the small aircraft mentioned had less drag than the larger but also less efficient aircraft, and had the same or better capabilities. Comparisons of power available / speed / range achieved reveals this. There is well known example of DB experiement with DB powered Spit vs same DB powered 109.
Civettone
Tech Sergeant
To come back to the original topic ... I believe tuning the engine to low altitude performance would be a massive advantage on the Eastern front. I know the Russians and British had engines which were tuned for low altitude, but I have never heard of such a thing for German engines, except for some 1945 prototypes.
Copied this from a post by Vanir:
Of course, the Germans started using methanol injection, but only in 1944. It seems they could have gotten some advantage out of producing a version, optimized for low altitude.
Kris
Copied this from a post by Vanir:
Of course, the Germans started using methanol injection, but only in 1944. It seems they could have gotten some advantage out of producing a version, optimized for low altitude.
Kris
MW was for low altitude use (below FTH). GM1 was for high altitude power boost (above FTH).
While the RR has deliberately designing some Merlins to perform better at low altitudes, the only Soviet engine tuned specifically for such a work might be the Mikulin AM-38, used on Sturmoviks. The Klimov engines were, as good/bad they were, were still equipped with single stage superchargers, while turning low RPM - thus expecting good high altitude performance would be too much. The full throttle height for the M-105P, second gear, was at 4000m, making ~1050 PS there, ie. in the ballpark with DB-601A series. Late versions were beefed up (150-200 kg weight gain), in order to use more boost, of course at lower altitudes. The VK-105PF was managing ~1180 PS at 2500m, the VK-105PF-2 making ~1240 PS at 2200m.
Later Klimov engines (106, 107, 108 ) were to use greater RPM (up to 3000 rpm), were feturing better high altitude performance, but it took plenty of time to get the VK-107 in production and use, other two never used in service?
edit: stating that Klimovs should have higher FTH than DBs, while implying that Klimovs have had more supercharger gears is misleading, DB's supercharger have had infinite number of supercharger drive ratios. Ie. it was not featuring the single-speed supercharger, like many V-1710s and Mikulins have had.
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Shortround6
Major General
The two speed supercharger is one way the Russians got more power out of the M-105 compared to the Hispano. There were a couple of Hispano engines with low geared superchargers that changed the FTH ( critical altitude) from around 3600 meters down to 1250 meters, they picked up around 100hp at low altitudes. Less power to the supercharger, less heating of the intake charge. Same reason the AM-38 picked up some power compared to teh AM-35. The Russian two speed drive allowed them to do this and still keep around 1050hp at 4000 meters (looking at your chart). It was not the only improvement but a single speed drive would have hurt them at one height or the other.
A lot of Wright engines had an upper FTH of 3100-4000 meters and used "low" gear for extra take-off/low altitude power rather than high altitude performance. (Merlin X and XX engines did the same thing, thats why they were primarily bomber engines)
A lot of Wright engines had an upper FTH of 3100-4000 meters and used "low" gear for extra take-off/low altitude power rather than high altitude performance. (Merlin X and XX engines did the same thing, thats why they were primarily bomber engines)
The Soviets also beefed up the M-100 (licence produced Hispano 12Y engine), from circa 450 kg to 570 (M-105, some weight was due to 2-speed supercharger drive, some for counter-balanced crankshaft), and then to 620 with the VK-105PF variant. That allowed increase in RMP, from 2400 to 2600, later to 2700. More RPM means more power at all altitudes, and, unlike the Mikulins or bread-and-butter V-1710s, the two speed supercharger was installed in time.
The AM-38, in the AM-38F version, was making ~1450 HP at 1000m, vs. 1150 for the AM-35/35M. Too bad neither AM-37 nor AM-39 were never introduced. 1st one featuring intercooler (and other improvements?), 1400 HP between 4-5000 m, second one being two speed (and two stage?? help!) development, capable for 1650 HP at 1000m, and 1500 HP at almost 6000m.
The AM-38, in the AM-38F version, was making ~1450 HP at 1000m, vs. 1150 for the AM-35/35M. Too bad neither AM-37 nor AM-39 were never introduced. 1st one featuring intercooler (and other improvements?), 1400 HP between 4-5000 m, second one being two speed (and two stage?? help!) development, capable for 1650 HP at 1000m, and 1500 HP at almost 6000m.
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Civettone
Tech Sergeant
Is that also what powered the Spitfire's LF versions?
Again, I am left with the question why this would not have been possible with the DB 601 and 605. Or was the DB centrifugal supercharger so different?
Kris
Shortround6
Major General
The DB engines used a hydraulic drive to the supercharger. At low altitude it 'slipped' and drove the impeller at about 7 times crankshaft speed and as the plane the gained altitude it tightened up until, at the full throttle height ( or critical altitude) the impeller was turning at about 10 times the crankshaft speed. The power needed to drive a centrifugal supercharger goes up with the square of the speed of the impeller. The DB engine was using about 1/2 the power at sea level or low altitude to drive the supercharger as it was at 5700 meters (DB605A). looking at the power curve chart for the DB 605A it goes from 1475hp (or PS, I know they are not quite the same) to about 1550 at just over 2000 meters (throttle fully open but supercharger at slow speed) and then drops to 1355 at 5700 meters ( supercharger at full speed). The Supercharger drive was 'saving' for the propeller about 200 PS (?) at low altitude.
The low altitude Spitfires used a high altitude gear ratio but cropped ( cut down) the impeller diameter to lower the tip speed and cut the power requirement that way. Since they were single speed superchargers they worked well at low altitude but LOST the ability to make large power at 5-6000 meters.
This may be OK if you have enough fighters so that you can use different ones at different altitudes but would have been unnecessary if the Spitfire had been fitted with a 2 speed Merlin like the XX.
Since the DB series engines already had a supercharger drive that freed up a fair amount of power at low altitude designing and fitting them with an even smaller supercharger or lower gear wouldn't have picked up a lot of power. ( French Hispano engines had a FTL of 3600-4000 meters or where using a "high" gear just like the early American Allison with it's FTH of 15000ft with 1040hp (P-40C).
The DB 605 may not have been able to use anymore power at low altitude. The curve shows the power rising from sea level to 2100 meters. Engines were often restricted at low altitudes to prevent over boosting and wrecking the engine. I don't know if the DB 605A was restricted at low altitude because of fuel limits ( detonation if boosted over 1.42 ata), cooling problems ( radiator can't cope with the extra heat of making more power) or if higher pressures in the cylinder would lead to exceeding the strength limits of certain parts.
Please note that by changing the gear ratio or speed of the supercharger impeller the total power made by the engine in the cylinders doesn't change (much) it just gets redistributed.
Most, if not all of the single speed supercharged engines could make way more boost at low altitude than they could survive.
The low altitude Spitfires used a high altitude gear ratio but cropped ( cut down) the impeller diameter to lower the tip speed and cut the power requirement that way. Since they were single speed superchargers they worked well at low altitude but LOST the ability to make large power at 5-6000 meters.
This may be OK if you have enough fighters so that you can use different ones at different altitudes but would have been unnecessary if the Spitfire had been fitted with a 2 speed Merlin like the XX.
Since the DB series engines already had a supercharger drive that freed up a fair amount of power at low altitude designing and fitting them with an even smaller supercharger or lower gear wouldn't have picked up a lot of power. ( French Hispano engines had a FTL of 3600-4000 meters or where using a "high" gear just like the early American Allison with it's FTH of 15000ft with 1040hp (P-40C).
The DB 605 may not have been able to use anymore power at low altitude. The curve shows the power rising from sea level to 2100 meters. Engines were often restricted at low altitudes to prevent over boosting and wrecking the engine. I don't know if the DB 605A was restricted at low altitude because of fuel limits ( detonation if boosted over 1.42 ata), cooling problems ( radiator can't cope with the extra heat of making more power) or if higher pressures in the cylinder would lead to exceeding the strength limits of certain parts.
Please note that by changing the gear ratio or speed of the supercharger impeller the total power made by the engine in the cylinders doesn't change (much) it just gets redistributed.
Most, if not all of the single speed supercharged engines could make way more boost at low altitude than they could survive.
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