The A2A Simulations Community

In one of the interviews, I think FSBreak, Scott said he was a musician for awhile.

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© 2011 Peter J. Carlson, All Rights Reserved
"O! for a horse with wings!" -William Shakespeare

He still is. His qualifications as a sound engineer are outstanding, and I have learned a significant amount from him in the years we have worked together. Who do you think does all the sound for Accu-Sim?

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Oh wow, I won!
Mmm, but with the wrong explanation...better study a bit more..

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Interesting discussion. If the pilot were to leave the throttle exactly where it is when the engine kicks into high supercharger, would the following happen(?): Engine briefly surges from 54" to 67" and then goes back down again to 54" as the pressure regulator catches up? So if the pilot didn't manually move the throttle back up to the-now-possible 67", he would actually start to slow down...because 54" inches in low blower delivers more power than 54" in high blower. Right? Or am I totally misunderstanding how the man. pressure regulator works?

Congrats jcblom, btw!

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1)i7 980x 4.35 ghz, gtx 470s SLI, Matrox th2go, Creative x-fi
2)i7 2600k, Gigabyte z68x, gtx 285s sli

54" manifold pressure is the same regardless of high or low blower. Man pressure is an indication of power. So if there is no change in the man pressure then there is no change in power. As Scott was saying when you kick the supercharger into high gear it takes more power to turn. So any increase you get in lower altitudes is taken away by the large increase in drag it puts on the motor.

I am not sure how the regulator works though, so not even going to guess. Best I can tell though it just stops you from going over 67" manifold pressure.

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S Jordan
Milviz Staff Member
AM; United States Navy
FSX Hours: 2000 and counting

Yes, the manifold pressure regulator adjusts the engine internal throttle to maintain a certain pressure, based on the cockpit throttle position.

However you are doing a WEP climb (the throttle would be wide opened), the pressure will continue to drop as you climb over 10,000 feet. Once the supercharger switches into high gear, the manifold pressure rapidly advances to 67".

Now let's say you are in a cruise at 40", at 8000 feet, on LOW blower, then manually switched to HIGH blower, you just get a momentary surge of pressure (not more than a few inches of manifold pressure) and a little vibration in the airframe.

Scott.

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A2A Simulations Inc.

The best way to visualize this is that as you pass the critical altitude for the low blower the regulator stays set at whatever power setting you are using. From that point on as you gain altitude you begin losing MP. Keep in mind that the engine is now developing a SPREAD between the set on the regulator and what the engine is now producing in power which is LESS than the regulator setting.
Now the ram pressure is approaching that needed to trigger the switch to high blower. When that point it reached, the blower switches speed into it's higher ratio. At that instant the regulator which has been "cheated" by the low blower speed not being able to provide what it's asking for, suddenly sees the power it wants. It "grabs" that power and rushes the engine on up to where the regulator is set. WALLA! Manifold pressure surge!!!!
It's simply "adjusting" things back to where they were.
So the MP surge can be correctly defined as the difference between the regulator setting and whatever beneath that setting the MP happens to be as the ram pressure at the carb triggers the charger switch.

Dudley Henriques

Ah..right, duh, we're firewalled to begin with, so of course its going to jump up and stay there . Makes sense:oops:

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1)i7 980x 4.35 ghz, gtx 470s SLI, Matrox th2go, Creative x-fi
2)i7 2600k, Gigabyte z68x, gtx 285s sli