Fokker, the problem with even that approach is at some times that is fine at others it is not, so when is and when isn't is not a judgement call you can make without really knowing stuff.
Often the scenario is fine, but is it the optimal solution.
Maybe your engine maintenance bill is fine, but as Aussie Bob showed us earlier, what he thought was a good run was actually far from optimal.
I am sure in a Boeing jet there are infinite numbers of ways to get from Sydney to Melbourne, and I could walk up and let her rip and arrive, but when a pilot who really knows his stuff does it, the fuel bill is going to be way less, and a whole heap of other stuff is going to be far oops...closer to optimal.
That help?
Last edited by Jabawocky; 9th Sep 2012 at 08:37.
Reason: changing far from to closer to
but when a pilot who really knows his stuff does it, the fuel bill is going to be way less, and a whole heap of other stuff is going to be far from optimal.
????
Jaba, does that statement actually make sense to you?
Here's some more ForkWisdom for you to tear your hair out over!
For those you don't have an all cyclinder engine monitor and tuned gammis etc:
1) if in doubt leave it full rich in the climb or lean it only to keep it running smoothly 2) alternatetively, look at the EGT reading on TO and only lean to that during the climb 3) in the cruise, if you are confident that your power setting/ altitude has you below 75% HP, lean till it just starts to run rough then richen just till running smoothly
Dr
Last edited by ForkTailedDrKiller; 9th Sep 2012 at 07:15.
Trent: These young guys and gals you are talking about will one day fly something for someone that is really nice. If they stay in GA it may just be something simple like a 182 that the owner is fastidious about, an owner who will listen. I meet lots of these folk, they let me fly their aeroplanes and they listen and are open to new stuff ....
In the interim, just follow the good Doctors advice back at #123
Quote: but when a pilot who really knows his stuff does it, the fuel bill is going to be way less, and a whole heap of other stuff is going to be far from optimal.
????
Jaba, does that statement actually make sense to you?
ooops I just fixed that......too many distractions
Yeah Forkie that will work fine, but it is sub optimal And in aviation we always strive for excellence don't we.
No hair removal required.
Hey when is that TN, IO550, tip tanked FTDK going to be a reality?
For better or worse you are obliged to set what your boss asked you to set. SOP's do have merit.
However, a good one size fits all might be something like 75 ROP a power setting of 65% and the smoothest RPM that is within the parameters. Not grossly under or over square.
Treat your engines gently, typically maintenance and owners don’t
However, a good one size fits all might be something like 75 ROP a power setting of 65% and the smoothest RPM that is within the parameters. Not grossly under or over square.
Why would that be a good one size fits all? The very reason a one size fits all in a cook book like a POH is the very reason half this thread exists.
And if I run my engine at 980mb and 251 rad/s is that over square? I am sure there has been enough education on this forum already. Ohh and I do that about 60-80F LOP too.
And if I run my engine at 980mb and 251 rad/s is that over square?
HA! Trick Question! The only time the mighty RV-10 could make 29in/2400rpm is below 1000 feet amsl (on an average day) and running 60 - 80 LoP at that stage is just showing off.
Last edited by Trent 972; 10th Sep 2012 at 08:39.
Reason: because I could
The reason why it is a one size fits all is simply because it is.
Even John Deakin points this out in his writings.
65% power is not so high as to put you above some TCM recommendations on leaning and not so low as to result in low ICP leading to ring float and poor sealing. It also gets you from A to B at a reasonable speed in a naturally aspirated twin, and this is usually of financial benefit as maintenance costs out way fuel burn costs.
At 65% you can’t hurt anything.
75 ROP moves you away from the hot CHT values of ~40 ROP and as you are not striving for all out speed at 75% power, then little reason to run the richer mixture of 100 – 125 ROP best power mixture setting. So 75 ROP is a reasonable compromise mixture setting.
RPM set to wherever the engine runs smoothest. That should be a no brainer. Grossly under square can lead to the first point and is inefficient. Grossly over square will frighten the boss and when ROP the effective timing is too advanced.
Your bite on the metric v US instrumentation values is as meaningless as the OWT that states one shouldn’t run over square. The reality is all reading this understand what is meant by under or over square, it is a handy measuring tool. Having spent some time flying behind metric instrumented 1820 radials I find it not as intuitive as the US system.
There are not too many aircraft I know of particularly in reference to Trent 972’s question that will not be perfectly happy to run with this type of power setting. Sure there is better but that was not the question.
You won’t convert me to the APS way of running an engine, I was already there 14 years ago. As you convert to your new (?) religion try not to become too rabid and one eyed. WOT LOP is a great thing in the right place with a correctly set up aircraft, instrumentation and properly educated pilot. Remove one of these elements and you’re better off back with something like the one size fits all set up.
Jabba #149 – "My point is if you know what you are doing".
Now, there is the rub. Jabba, half don't understand (and won't admit to) suck, push, bang, blow; and, are not remotely interested. Bit like my Pa's beer analogy – he says - the young 'uns, never tasted good beer, so they will drink whatever; crook or not. Because they think it' a good beer, they know no better.
Those with the 'nowse', savvy or basic interest will come; there will always be those who slam car doors or simply wish to be seen as experts. Then of course, there is the dreaded 'legal eagle' angle. Take care mate, take good care and tailwinds.
Obidiah: Maestro; mea culpa. I have read and appreciated (even agreed). Speaking as 'old school ' one who has operated (the engineers), normal, round, super charged and turbo charged engines (hell even the odd jet), without anything more than a couple of crook plugs, stuck valve and one (secret and private) fright.
The real issue (IMO) is that engineers are 'qualified' people, pilots ain't. The exponential increase in arrogance, is only matched by a lack of knowledge, i.e. the modern (non interested pilots) cannot and will not talk to the "Ginger beers'. Sad, but very true. It takes a lot more folk than a half educated pilot to get from 'push – to squeeze'.
Otto - over and out.
Last edited by Kharon; 11th Sep 2012 at 10:20.
Reason: Stuffed it up
And in aviation we always strive for excellence don't we. 
