Hello Aleatorylamp,
Here is why I think when I post a reply, you interpret it strangely and you go off on yet another weird direction:
I am really not sure how you arrived at that solution but one day later you are back to doing something else.Originally Posted by Aleatorylamp
Originally Posted by Aleatorylamp
This is also a strange sequence to choose to do things.
How did you select 12,500 feet as the Critical Altitude?
I am not saying this is correct or incorrect because I don't really know, but if you are finding the Manifold Pressure to be too low at 12,500 feet and need to raise it, then either you really raising the Sea Level Manifold Pressure.... Or you are raising the Critical Altitude so the 12,500 feet value you have listed is just a particular test altitude and not really the Critical Altitude.
You mention a certificate which I do not know about. If it is a modern Type Certificate, just keep in mind that modern operating conditions are not the same as they were during war time.
Why did you choose to reference a report on a P-39D-1 which does not have the same version engine as the one you are building? Why did you pick a report on an engine with an experimental intake manifold? Power outputs, Manifold Pressures and even Critical Altitudes would be pretty useless information for a standard production aircraft. You are wasting your time with this report unless you are just trying to get some extra historical perspective and you would have to come to your own conclusion as to how this report is useful.Originally Posted by Aleatorylamp
I believe it is entertaining but not useful.
This is a more useful report but still not representative of a service configuration P-39D.Originally Posted by Aleatorylamp
From your summary of a summary, it appears things do not make sense, but if you read the actual report, the numbers make perfect sense.
Read the last line of the "Purpose" section of this report.
It says "Individual intake port backfire screens not installed in engine."
Now you would have to ask: What does this mean and does it alter the data I am looking for?
Simple answer is yes. It significantly changes the numbers and was probably the reason for conducting this test.
If it is specifically listed then it probably was not the normal configuration of this engine.
It would also be the removal of an obstruction from the intake system and without the obstruction, it makes sense that there would be better air flow and Critical Altitude would increase.
Now if you look at the table for Critical Altitude for Normal Power and Military Power, you will see that Normal Power is 2600 RPM while Military Power is achieved with 3000 RPM.
THAT was the difference, so it all makes sense if you read the information in the report.
- Ivan.
Bookmarks