Originally Posted by
IO540
That's also true, but one could argue that the best advice for somebody flying a plane with no engine instruments is to leave the red lever fully forward during all climbs, and also to never climb more than say 6000ft which avoids the need to lean during high altitude climbs.
All in all, this makes a spamcan pretty useless
There is IMO nothing wrong with leaving the mixture full rich in the climb, other than you may waste a bit of fuel. I do not understand your comment about never flying above 6000 ft. I though I was clear in my earlier post. If the power being developed is less than 75%, a value which you can determine from the information in the POH, than obviously you can lean. As a rule of thumb the full throttle engine output in most light touring/trainers falls below 75% between 7000 and 8000 ft.
I have simplified the situation as there are cases when a more sophisticated
approach is required, like for example leaning for maximum power prior to takeoff at a high altitude airport, but given the fact that the original poster is obviously stuggling with very basic concepts I thought it more appropriate not to go into advanced concepts.
In any case my experience is the biggest problem new PPL's have is most were never taught how to properly lean in cruise flight and therefore all the book planning they do with respect to calculating fuel flows is utterly useless.