Thighsolator Wrote:that is some interesting stuff vanir, so if i understand you... to keep the manifold pressure low enough to prevent detonation, with the supercharger in gear and MW50 spraying, you have to lower the throttle... right? full throttle with supercharger in first gear and low altitude and MW50 should considerably raise the manifold pressure and cause detonation, if i understand correctly. This will result in higher horsepower and eventually engine damage, but as altitude goes up, atmospheric pressure decreases and you can't maintain the manifold pressure. How many stages did the DB603 and Jumo 213 superchargers have? GM1 was used at high altitude because of better oxygen supply that it provided, and that would be why the H models came with both boost systems
Not exactly what I mean. But keep in mind I'm not an aeronautical engineer.
Firstly the idea of any water injection system is to prevent predetonation by cooling the supercharger exhaust into the cylinders. Even raising the normal maximum manifold pressure by a very small amount can cause engine damage quickly because the act of compressing the air intake (ie. supercharging) heats up the intake, so you've got this effect as well as you're trying to use a higher pressure than normally rated...engine ping, cylinders burn, valves pop, block cracks, heads warp. So never a good idea to raise normal maximum supercharger pressure even a little bit or even for a short time.
But water injection lets you do it, so long as the engine can handle the extra power. It takes away the problems associated with predetonation due to supercharger exhaust temperature. Intercooling does the same thing, but is not as effective and can be a bulky fitment (but intercooling has unlimited use).
So water-injection or intercooling = higher pressure than without
can be used but isn't caused dramatically by itself because the supercharger exhaust is being cooled (after being heated by supercharging) before going into the cylinders. Water injection or effective inter/aftercooling does tend to raise static manifold pressure
marginally and it increases volumetric efficiency a little just by itself, but it is other mechanics we achieve dramatic hp increases with, it just lets us use them (just to complicate matters you get a similar effect simply by raising the octane rating of your regular fuel, allowing higher pressures without predetonation).
Talking about an engine which has no boost system. The maximum manifold pressure is rated at full throttle height for the engine (and has a 5 or 10min limit before cool down to reduce oil temp and keep oil pressure up). Below this height applying full throttle in the same supercharger gear will raise manifold pressure above this figure. In other words you get maximum rated manifold pressure at part throttle. There are a few ways to handle this:
-Install a gate stop system on the throttle selector with multiple gates for use at different altitudes, pilot controlled.
-Fit a complicated mechanical valve system to automatically adjust throttle selection with appropriate actual throttle response to engine management.
-Tap a pressure release valve to the supercharger casing limiting maximum boost.
We'll need an actual aircraft mechanic who is personally familiar with these aircraft types to tell us which system was used on which, if any (meaning by default the pilot would simply have to govern his own use of the throttle below FTH).
Nevertheless I've looked at German boost system blueprints and aircraft mechanic descriptions and they also have an adjustor linkage to a supercharger boost governer of some sort, mostly likely a pressure release valve. They are obviously designed specifically for combat performance enhancement all the way to the engine rated altitude and are very dramatic boost systems.
Generally speaking traditional water-injection is for boosting take off performance, just for load carrying and rough field performance. It was designed to be used under 1000m and in the low supercharger gear, but it was adapted for fighter engines to give a wider altitude range of boost (which is about 200hp for the R2800 for example), usable in multiple supercharger gears. I don't think it is quite the same or as dramatic as the German boost systems, often working in conjunction with existing intercoolers and usable only at fairly low altitude regardless of engine rated altitude.
Now I might be corrected on some of my points here by a qualified aircraft mechanic...
Oh, edit to add, the Jumo 213E and F had three-speeds and two stages of supercharging, controlled by the Focke Wulf/BMW developed kommandogerat.
The DB-603LA has a hydraulic variable-speed supercharger barometricly controlled, with two stages.
Both use MW-50 instead of intercooling. The Jumo in the Ta-152H uses GM-1 instead of a third supercharger stage.
The 603LA wasn't actually the production engine for the Ta-152C. This was the 603L and was fitted an intercooler (I read that it was to solve overheating issues with the LA motor, besides MW-50 doesn't actually do much for the 603 which is such a powerhouse to start with). An air intake for the intercooler would have to be fitted, but it could've been placed inside the outboard wings to keep drag low (like a MkII Tempest but outboard of the guns), or under the fuselage like a Mustang radiator (not quite as large obviously).
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For the thread posting itself I'm editing to add, I fully support new slot Ta-152C modelling on the basis not only for an improved historical simulation, but simply because the Ta-152C is the single most important Luftwaffe fighter type in any realistic 1946 scenario.
All this flying coathanger crap and stretched 109s really annoy me when historically it was the Ta-152C which was going to replace the Fw-190D and take on the zerst
....![[Image: lol16no.jpg]](http://img316.imageshack.us/img316/5771/lol16no.jpg)
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hock: did he swallow a bunch of breast implants?![[Image: ta152perf.jpg]](http://i40.photobucket.com/albums/e215/zulu64/ta152perf.jpg)