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Doesn't matter what the boost is at various times of year, the control unit has a temperature sensor which is always at work anyway because temp at high altitude might be minus 30 C or worse. A far bigger change on every flight than between summer and winter. The density will be maintained and thus power will be unchanged.Could the Jumo-213 reach it's full boost pressure 1.8 ata in cold winter months? I can't read technical German (or any German at all!) so it is very difficult for me to understand the operation and boost pressure of this motor and it's unique mass air flow regulator.
Since the engine had a mass flow regulator and you have greater air density in cold/winter months - does this limit the motor to something like 1.6 ata? Flight tests are showing 1.8ata in chart dated Dec. 15, 1944:
View attachment 692595
Doesn't matter what the boost is at various times of year, the control unit has a temperature sensor which is always at work anyway because temp at high altitude might be minus 30 C or worse. A far bigger change on every flight than between summer and winter. The density will be maintained and thus power will be unchanged.
I have the Jumo213 control unit operational description in English, I will try to upload it to my website one day, but the diagrams need a lot of image processing to make clear so it will take me a while.Thank you. I just finished your book by the way...outstanding!
I was confused and stuck on the lower ata and wrongly thought it meant lower power. That regulator then is quite fascinating.
Calum,Doesn't matter what the boost is at various times of year, the control unit has a temperature sensor which is always at work anyway because temp at high altitude might be minus 30 C or worse. A far bigger change on every flight than between summer and winter. The density will be maintained and thus power will be unchanged.
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Simple formula is saying that for each 6°C decrease from standard altitude temp. you need to ad 1% hp and subtract 1% hp for each 6°C increase from standard altitude temperature.
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It can be found on various power charts, for example here (top left corner) - http://www.wwiiaircraftperformance.org/mustang/V-1650-7-High-Blower-power-chart.jpgI would expect more impact. Where did you find that simple formula?
It can be found on various power charts, for example here (top left corner) - http://www.wwiiaircraftperformance.org/mustang/V-1650-7-High-Blower-power-chart.jpg
Little bit hard to read, so here is detail from another source -
View attachment 692998
And nobody catch that error? Very unlikely.That makes no sense to me.
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Maybe the original rule of thumb was that 6 degrees (meaning degrees Fahrenheit) has an impact of 1 % on power, but somebody else assumed that degrees meant degrees Celsius and published that, which then started a life of its own.
You are right, you get more power in winter than in summer temperatures.
Simple formula is saying that for each 6°C decrease from standard altitude temp. you need to ad 1% hp and subtract 1% hp for each 6°C increase from standard altitude temperature.
So for example - power of Jumo 213A at S.L. on 1.8 ata is 2 100 PS in standard temperature (15°C). Same engine will give you in -15°C on 1.8 ata 2 205 PS.
The 213 controller knows how much fuel to inject, for given temperatures etc. The boost pressure itself is not actually very relevant.Could the Jumo-213A be adjusted to develop 1.8ata in cold winter months, or was this not done?
Would the top speed of the D-9 suffer in comparison to say a Mustang since the Mustang get's a % boost in winter, but the Dora-9 stays the same? The Mustang adds say 85 (?) hp in winter, how much additional speed would it get from that?
Sorry if these are dumb questions, I am but a simple layman.
It might be a lot more useful if you explain what exactly the underlying question IS you`re trying to get at ?