BPF
The engine should be leaned anytime the aircraft is in cruise. I don't think it is well understood that excessively rich mixtures can be just as bad for the engine as too lean a mixture.
Well said!
The500man
Has anyone completed that APS online course?
Absolutely, and it has been my recommendation they make it a requirement to complete that prior to attending the live course. The online one fills the bucket of knowledge with rocks, the live course ours in a heap more sand, then adds a little water. When the masters course comes out this should almost fill the bucket with water!
I usually find that the only folk who ever knock the course, have never actually attended.
500 man and DAR
Some history and it is brief, so dont go getting carried away due lack of details.
Lycoming and TCM (CMI now) have written many manuals, then the aircraft manufacturers incorporated them and modified them to suit specific agenda's at the time. Why did we get the 75% power performance comparisons? To sell aeroplanes! Magazine test articles. So how do you get the best from your plane at 75% or more power? Run at 75-80 ROP of course.
Engineers say hang on a minute, we don't want that, we want more like 150-00 ROP, but that does not satisfy the economy and speed comparisons. So a tug of war begins.
In the old days, operating on the Lean side of Peak was well known and widely practised. The problem TCM and Lycoming had was their carby engines and later the injected engines were so poor in F/A ratio that running LOP was not easy, nor was the instrumentation good either. In one Lycoming publication they basically said pilots were not smart enough to do it!
So.....Factory can't produce a good reliable LOP performer without rough (scary) running engines, so lets just remove the whole LOP side of the graph...Don't Go There! Next problem is without accurate gauges and pilot training the Rich side of Peak is far more dangerous to engine health if mishandled, so lets go full rich until TOC even though we know its full of deposit causing excess fuel, it is just easier. So hence we got the manuals we did.
Next problem is so many manuals contradict each other. I do not have time nore space in this thread to post them all, but believe me, I have them, and its weird
As for LOP operations, well they are coming around full circle....and DAR's quote about Lycoming does not recommend....... well that just depends on which publication you read.
Poor or bad? - Well they are FAA approved, perhaps you should apply for an STC to change them if you know better....
Poor or bad? On second thoughts BOTH!! Yes they may be FAA approved, but check out the FAA A&P exams
And why would I want an STC for a manual?
I am interested in the sensors you used for detonation testing, were they precise pressure sensors with a data capture rate well over 20kHz or even up to 1mHz buried in the heads or were you using a Delta T method on CHT? Accoustics can work of course but in an aero engine not so well. Just curious, as I like to learn anything I can, and this is certainly interesting.