Over Square?
G'day,
The other day I was on a check ride with an instructor in a C206 and in the cruise I set up 24 Map and 23 RPM. He was not happy about the fact that I was flying "over square" even though I told him that I had got the cruise setting out of the POH. I se2424 and the flight continued as advertised. When I got back I checked the POH and it is allowed, in fact you can set 25/22 if you want but thats only about 50% horse power.
For me 24/23 gives the best comprimise between horse power/ TAS/ fuel consumtion and a quiet ride.(from looking at the book,not experience)
I have also been told that a lower rpm for a given horse power results in greater range because the fuel consumtion drop is greater proportionally than the loss of airspeed due to less internal loading on the engine.????Is that right?
I am sure that it is ok to use these settings as it is in the manual but why is there such widespread fear of going "over square"? I have not flown turbo-charged planes so maybe thats where my knowledge is deficient.
Any thoughts from those with some time up;
a) to confirm that the power settings I am using are ok
b) to explain exactly how flying "over square" damages the engine, on what planes this occurs etc, and
c)any other comments you care to make
Cheers, cjam