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The fuel limited the amount of boost that could be used, but was not the source of the high altitude issues.
All of the German engines that saw widespread service had single stage superchargers. With a single stage supercharger the pressure ratio that can be achieved is limited. At high altitudes their superchargers couldn't give enough boost to maintain power. There were several projects for 2 stage superchargers and turbocharged engines, but I don'tthink many, if any, saw service.
The major German engines: BMW 801 and Jumo 211 had two speed superchargers by the time the war started while the Merlin, Allison had only one.
The DB600 series was not so dependant on its supercharger: this engine used a compression ratio of up to 8.5:1 compared to levels below 6.4:1 for the Merlin.
High compression ratios provide for high power, high efficiencies. This means the engine needs less boost and so a single stage supercharger will provide sufficient altitude compensation.
The major German engines: BMW 801 and Jumo 211 had two speed superchargers by the time the war started while the Merlin, Allison had only one.
The DB600 series was not so dependant on its supercharger: this engine used a compression ratio of up to 8.5:1 compared to levels below 6.4:1 for the Merlin.
High compression ratios provide for high power, high efficiencies. This means the engine needs less boost and so a single stage supercharger will provide sufficient altitude compensation.
Part of the reason the DB600 series was able to do "so well" at altitude was the fact that the 109 was one of the lighter fighter aircraft of WW II. Trying to use a DB600 series (not including the 603) in an 8-9,000lb fighter would have soon shown that it's altitude performance was wanting, at least up until the very last 605s.
That was one reason for the GM 1 equipment. Supplemental oxygen for the engine becaseu the supercharger wasn't good enough.
The major German engines: BMW 801 and Jumo 211 had two speed superchargers by the time the war started while the Merlin, Allison had only one.
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1. BMW-801 was in use 2 years after war started
2. If we really want to list down non-fighter, two-speed engines, than the R-1820, -1830, -2600 all were two-speed ones, with R-1830 even offering two-stage variant, unlike German engines
3. Merlin X is already covered by SR6
lso I think because no supercharger was so good as GM 1.. and GM 1 was simply, easy added device to any aircraft where such performance was desire. Idea was to produce one engine tuned for generic altitudes, and add GM to these few planes requiring for more. Easier production, mainatiance.
1. BMW-801 was in use 2 years after war started
2. If we really want to list down non-fighter, two-speed engines, than the R-1820, -1830, -2600 all were two-speed ones, with R-1830 even offering two-stage variant, unlike German engines
3. Merlin X is already covered by SR6
He 177 was certainly no light but it is difficult to see how altitude performance was 'wanting'.
I think you see thing from other side completely, you see, Bf 109 was one of the lighter fighter aircraft of WW II exact because DB 600 series was itself very light and compact.. the whole package. Good fuel consumption means less fuel needs carried for same range, and lack of two stage supercharger means no bulky intercooler, intercooler radiator needed, coolant requirement is less so small radiator will do. No wonder it was light.
There is decreasing dividients with increasing power via supercharge. More power is developed, yes, but more and more power is lost: cooling installation drag greater, weight is greater etc.
Its easy to see costs of such system. For example Spitfire Mark type V and Mark Type IX are really same aircraft, save engine: Mark type IX has two stage supercharged engine, larger prop, intercooler, needs intercooler radiator, larger oil cooler, larger coolant cooler. Otherwise all same. Now V weights about 6500 lbs, IX about 7400 lbs. So you add 900 lbs or about 400 kg for to install two stage system. Probably closer to 1100 lbs if you consider that range was down by about 20 % too, so to sompensate you need to carry about 200 lbs more fuel, fuel installation.. Now two stage system makes much more power, butmuch of that power goes into nullify that 900 (1100) lbs extra weight.
Also I think because no supercharger was so good as GM 1.. and GM 1 was simply, easy added device to any aircraft where such performance was desire. Idea was to produce one engine tuned for generic altitudes, and add GM to these few planes requiring for more. Easier production, mainatiance.
Obviously it didn't, otherwise they would not have played with GM-1 and such like.
The high compression ratio means that at a given altitude the supercharger needs a lower pressure ratio to provide the air to the engine, but at higher alltitudes the pressure ratio will be beyond the supercharger's comfort zone, and it will take a lot more hp to drive than a 2 stage supercharger would.
As we have seen before, 2 speed supercharging does not in itself provide higher altitude performance. It may mean that there has to be less compromise in the supercharger settings, giving a higher altitude rating. But we do know that the BMW struggled for performance at altitude.
People of course had different tastes, I'd not like to have an unprotected tank of highly explosive liquid in my fighter plane. Juha
It wasn't so bad, earlier versions were compressed NOX. Latter cryogenic versions were rendered combat safe (relatively speaking) by various methods.
Used in GM-1 was NO2.. also known "Haha" gas. Completely harmless and non-flammable. Juha is simply complete wrong, and I am not sure why he would have problem with 100 liters of lets say "highly explosive" (which is not) gm1 if he has no problem with on other hand 1000 liters of highly explosive aviation fuel... regular carried of course by all plane.
I would disagree with a fiar bit of what you've state about the DB600, Improvements in DB605 performance (aside from tuned scavenging and spark plugs) came about as a result of improvements in piston compression ratio and compressor fluid dynmamics, latter on still the supercharger was increased in size in the D and AS series engines but still remained a single stage. 1.98 ata boost, the maximum used by the 2000hp DB605DCM at CR of 8.5 is only 14 psig or 59 inches of mercury. To achieve somewhat lower power levels the Merlin needed 25psig (about 2.8 ata boost) for the same wieght and worse fuel consumption. Two stage compressors are not more efficient than single stage, they may draw less shaft power but this comes at the expense of intercooling which is basically throwing away energy into the intercooler for disposal by a bulky radiator of some kind.
Note I didn't say the DB605 with a single stage supercharger was better than engines with a two stage unit, I said it was far dependant on high supercharger compression ratios and provided sufficient performance; it clearly still faded away slightly earlier but not at all by much especially the latter englarged supercharger versions. The Merlin used its supercharger not to compensate for altitude but to overboost its engine while the DB605 did less so and it seems gained considerable fuel economy.
The DB605 was eventually developed as the DB605L (with two stage supercharger for the Me 109K-14) and also the bigger DB603L and LA of the Ta 152C, however these engines didn't use intercoolers and hardly gained weight.
As far as the BMW 801 was converned, it used CR of around 6.5:1 as did allied engines, the aircraft did quite well at altitude besting Sabre Typhoons and Griffon XII Spitfires and P-40's. its supercharger was improved and so it could remained competitive to 25,000ft which met most needs.
The BMW 801 also was developed as a turbo version, the BMW801T and Q which had outstanding performance, while there was also a BMW 801F with apparently a two stage three speed supercharger for the BMW 801F (for Fw 190A-10),
However I would argue that the DB605 didn't need a two stage supercharger due to a minimal gain in performance.
GM-1 was used for very specialised reconaisance missions and Mosquito intercepts, some USAAF P-51s also used NOX in an attempt to chase Me 262.
For various reasons the Germans fell behined in engine power throughout 1943 but caught up in 1944, however lack of two stage superchargers is a not the cause of this lag.
Hello Tante Ju
Maybe you should read more, first of all it os N20, 2 really should be ½ line lower, and if you read instructions of its use as narcotic, smoking is absolutely forbidden in the spaces it is used, guess why, and why the N2O cylinders must be absolutely clean before filling.
You might also look on page 100 in Fernández-Sommerau's Messerschmitt Bf 109 Recognition Manual,
or simply think why fertillers with high Nitrogen component are good base material for IEDs. And all burning needs oxygen.
Fuel tanks in 41-45 were usually self-sealing, that's why they were not so dangerous than high pressure tank with potentially explosive liquid gas which could self-ignite when got in contact with oil, grease, rubber etc.
Because medical tanks actually contain a mix of N2O and 50-70% oxigene? Its oxigine that is flammable. Also please read sign:
Nitrogen dioxide, NO2 on other hand is flammable, but it is not what is in GM-1. Perhaps this is root of confusion.
I do not have book. What does it say?
Chemistry simply does not work this way.. Compund has different properties than individual element. Nitrogen in fertilzer is good for explosive. Hydrogene is explosive, oxygene needs for burning. By logic it follows that if I mix fertilizer with water (H2O) I get some highly explosive stuff, right..? No, I actually don't.. I get just a stinky goo.
Nitrous oxide (N2O) is not potentially explosive, its completely non-flammable especially not in liqued form. Second you seem to mix it bit: "high pressure tank with potentially explosive liquid gas" - no such thing was ever used by German..
There was (i believe, steel) high pressure bottles, which I believe stored Nitrous oxide (GM-1) in gas form, similiar to oxygene bottles that were on any and every plane.
Then there was low pressure, insulated tank, this was simple aluminium I believe. It stored cooled Nitrous oxide gas that because of relative low temperature in liquid form, so no pressurization needed.
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Nitrous oxide (N2O) is not potentially explosive, its completely non-flammable especially not in liqued form. Second you seem to mix it bit: "high pressure tank with potentially explosive liquid gas" - no such thing was ever used by German..
Fuel tanks in 41-45 were usually self-sealing, that's why they were not so dangerous than high pressure tank with potentially explosive liquid gas which could self-ignite when got in contact with oil, grease, rubber etc. Juha