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Post by mrcapitalism on Nov 4, 2019 20:45:52 GMT -5
Which is interesting, because the CalClassic B377 Handling notes actually don't follow that convention. Minimum MAP is 23.5" @ 1700 RPM on descent. The reason given is "Shock Cooling." And yet, when I attempt a descent in my A2A B-377 COTS, I find that running the engines "square" on descent actually results in insufficient exhaust flow to spin the turbos. Since cabin pressure in that addon is bled from the engine turbos, this caused a loss of cabin pressure! Thus, my minimum MAP in that bird is dictated by minimum Bleed pressure, not minimum Manifold pressure! Worked out to about 23" MAP if I recall
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Post by Tom/CalClassic on Nov 4, 2019 23:29:05 GMT -5
The rule is that the MAP must be at least 10% of the RPM, not that they always remain square. So if you are at 1700 RPM on descent, that simply means you should not go below 17" MAP. It doesn't mean you can't go higher than that (as you do). And as you found, in some aircraft (in fact in many aircraft) the MAP will generally remain above square for the entire flight.
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Post by Erik on Nov 5, 2019 3:36:54 GMT -5
Yes, I should of course have typed 'not running undersquare'. Thanks again!
Erik
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