N1 and prop RPM connection

[dfournie]

Memory offset 0898 and 08C8 deal with Eng #1 N1% and prop RPM.

Memory offset 2000 also appears to contain N1% for Eng #1.

1) How does the value in 08C8 relate in the conversion required from N1 to prop RPM? What is actually in 08C8? N1 values are usually in the 30,000s, prop RPMs for a King Air are around 1700-2000 RPM.

2) Why is they also another offset at 2000 for Engine 1 N1%?

3) When 0898 is converted properly with 08C8 will it equal the value in 2000?

In the case of a turboprop, is the recip engine prop RPM offset also used for turboprop RPM?

[Pete Dowson]

1) How does the value in 08C8 relate in the conversion required from N1 to prop RPM? What is actually in 08C8? N1 values are usually in the 30,000s, prop RPMs for a King Air are around 1700-2000 RPM.

As it says, 08c* is a scaling value. Multiple the two values and divide by 65536 (i.e. shift down 16 bits). Isn't that clear? It says it right there in the document.

2) Why is they also another offset at 2000 for Engine 1 N1%?

The engine values in the low ranges are all FS98 compatible, and have been maintained specifically by FSUIPC for compatibility. The others (2000=) were discovered and verified later, some for FS2000, some FS2002 and so on.

3) When 0898 is converted properly with 08C8 will it equal the value in 2000?

It should do -- it is probably derived from the latter by FSUIPC in FS2004, maybe FS2002 also, I don't remember.

In the case of a turboprop, is the recip engine prop RPM offset also used for turboprop RPM?

Try it and see. Sorry, all I know is what is written in the document -- and a lot of that has been supplied by others. I am not aircraft expert I'm afraid.

You can easily watch these values live using FSUIPC's Monitor facilities.

Regards,

Pete