Testing your glide. Are people doing this?

"Paul Sengupta" writes:

On my IMC (instrument flying) rating renewal last year, I took off
(not in my plane, but a rented PA28)... when I got to cruising
altitude I levelled out, brought the throttle back then leaned the
mixture. The examiner said "There's a man who owns his own
plane."...he was referring to leaning the mixture, something I'd
always been taught to do from day one of my training. He said a lot
of renters fly around with mixture fully rich all the time. Even a
pilot friend of mine commented that he never leans the mixture
because he "never flies above 2000ft".

That's an interesting observation. On my first solo cross-country in
a rented 172 during my PPL training, I decided to rent the plane dry.
I made sure the tanks were topped off, leaned properly, filled up
again at my destination (even though I'd used only a few gallons --
school policy for student pilots), then flew back and fueled up again
on landing.

When I arrived back there was some consternation, since it turned out
that the club didn't rent dry to student pilots. They ended up
reimbursing me for the fuel I'd paid for and charging me the wet fee
for the plane. The manager tried to convince me that the wet fee was
a great deal, until I handed him the fuel tickets to show how little
fuel I'd burned on my trip. He asked me how I did it, and I smiled
and answered that I'd discovered a little red knob on the panel. Note
that at that time I would not even have thought of running lean of
peak -- I simply leaned to best power and enriched a bit, like my
instructor had taught me.

I wasn't going to make a big snit, but clearly the club assumes that
renters will always fly full rich. Nowadays, in my own Warrior, I
push the throttle to full for takeoff and don't touch it again until
I'm ready to land; in-between, I set power by adjusting the mixture
only, as recommended by the POH for best economy. I figure that if I
can make my engine run cooler, produce practically no carbon monoxide
(a major issue in a Canadian winter), avoid fouling plugs, *and* save
gas, what's not to love about running LOP WOT?


All the best,


David

"David Megginson" wrote in

renters will always fly full rich. Nowadays, in my own Warrior, I
push the throttle to full for takeoff and don't touch it again until
I'm ready to land; in-between, I set power by adjusting the mixture
only, as recommended by the POH for best economy. I figure that if I
can make my engine run cooler, produce practically no carbon monoxide
(a major issue in a Canadian winter), avoid fouling plugs, *and* save
gas, what's not to love about running LOP WOT?

That's one great thing about owning. Lots of time to fool with mixture and
MP and prop settings. I save about 2 - 3 GPH over common "squared" power
and ROP settings. Also, when you fly a rented plane slower, and more
efficiently, you are penalized. The same style in your own plane costs less
while maximizing your PIC time. Dunno about the CO being a major issue
though.

le moo

"Happy Dog" wrote in message .. .


That's one great thing about owning. Lots of time to fool with mixture and
MP and prop settings. I save about 2 - 3 GPH over common "squared" power
and ROP settings. Also, when you fly a rented plane slower, and more
efficiently, you are penalized. The same style in your own plane costs less
while maximizing your PIC time. Dunno about the CO being a major issue
though.

I'm not sure that MP has much measurable affect on glide, but playing with
the prop control sure does.

I tried this technique in my Bulldog (IO-360, CS prop). It
shuddered and shook so much I went back to the "normal"
method after 2 or 3 seconds!

Paul

"David Megginson" wrote in message
...
Nowadays, in my own Warrior, I
push the throttle to full for takeoff and don't touch it again until
I'm ready to land; in-between, I set power by adjusting the mixture
only, as recommended by the POH for best economy.

"Paul Sengupta" writes:

I tried this technique in my Bulldog (IO-360, CS prop). It shuddered
and shook so much I went back to the "normal" method after 2 or 3
seconds!

It sounds like lBad fuel/air distribution among the cylinders. I've
heard from a few other people with carbureted four-bangers who seem to
have some success, though I haven't heard from *anyone* with a
carbureted six-cylinder engine who has managed to fly LOP WOT (anyone
reading?). Perhaps it's because the O-320 (and O-360?) is able to
have all four cylinders equidistant from the carb.

I don't know why things are so bad on your fuel-injected IO-360, but
on the bright side, you have the option of trying Gamijectors if you
want.


All the best,


David

Well, normally at low-ish throttle settings I can lean pretty
aggressively and then I start getting power reductions as I
lean further (though the MP and RPM seem to stay the same
so I guess all that changes is the power produced and the
prop pitch). This all happens smoothly. But at wide open
throttle I didn't want to try it for too long or for too much
in case I damaged something. Didn't seem to like it though.
Couldn't swear to it but it seems that fuel distribution is quite
good normally.

Don't think I can use Gamis here in the UK.

Paul

"David Megginson" wrote in message
...
It sounds like bad fuel/air distribution among the cylinders.

"Paul Sengupta" writes:

Don't think I can use Gamis here in the UK.

In Canada, I think, U.S. approvals (STC, TSO, etc.) are acceptable for
U.S.-certificated planes. Is that not the case in the U.K.?

Uneven fuel distribution is the only reason I can think of that you
would get the shudder during leaning. In an ideal engine with perfect
fuel distribution, as you lean, the engine would simply produce more
power, then less power, then quietly shut off. The shuddering is from
different cylinders being at different parts of that progression
instead of all in sync.


All the best,


David

David Megginson wrote:

Perhaps it's because the O-320 (and O-360?) is able to
have all four cylinders equidistant from the carb.

Doubt it. The carb on *my* O-320 is located behind the engine. No way all four
cylinders are equidistant from the carb. I doubt that Lycoming has set up a
tuned induction system either, but it's possible.

George Patterson
You can dress a hog in a tuxedo, but he still wants to roll in the mud.

"G.R. Patterson III" wrote in message ...
David Megginson wrote:

Perhaps it's because the O-320 (and O-360?) is able to
have all four cylinders equidistant from the carb.

Doubt it. The carb on *my* O-320 is located behind the engine. No way all four
cylinders are equidistant from the carb. I doubt that Lycoming has set up a
tuned induction system either, but it's possible.


It seems to vary from one installation to the next. My carburated
O-360 will not run LOP. Well, it runs, but not very smoothly. My
flight manual lists a procedure for LOP (called economy cruise), but
my engine goes rough approximately 10 degrees LOP.

John Galban=====N4BQ (PA28-180)

"G.R. Patterson III" writes:

Doubt it. The carb on *my* O-320 is located behind the engine. No way all four
cylinders are equidistant from the carb. I doubt that Lycoming has set up a
tuned induction system either, but it's possible.

Is that a Continental O-320 (if such a thing exists)? The Lycoming
O-320 operator's manual suggests that all Lycoming O-320's have the
carb underneath:

Avco Lycoming O-320 series engines are equipped with a float type
carburetor. Particularly good distribution of the fuel-air mixture
to each cylinder is obtained through the center zone induction
system, which is integral with the oil sump and is submerged in oil,
insuring a more uniform vaporization of fuel and aiding in cooling
the oil in the sump. From the riser the fuel-air mixture is
distributed to each cylinder by their individual intake pipes.

Putting the carb back by the accessory drive would probably mess up
the distribution quite a bit. How well does your engine run lean of
peak?


All the best,


David