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1. 07:21 AM - Re: Flying "On the Step" (William J Hamilton)
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Subject: | Flying "On the Step" |
Folks,
Any number of text books on the basics of aerodynamics will explain. My
favourite is Mechanics of Flight, A.C.Kermode.
It should not be "controversial", being a matter of settled physics of
flight. All that varies between aircraft is the shape of the curve --- for
"older" aircraft there is a pronounced peak, for jet aircraft the curve is
quite flat, as has been previously mentioned, and as I noted, there is
another factor at work with a jet --- Mach. No. and boundary layer adhesion
---- but the practical flying techniques are the same ---- descend on the
cruise level, or decelerate to the steady speed at the desired power
setting.
Doing as John V. does is as good as any way of staying on the front side of
the lift / drag curve.
"On the step" is a bit misleading, hailing from flying boat days, but serves
a purpose, but what is really happening, as I mentioned in a previous post,
is that there are (except right on the peak of the curve, a speed unstable
place to try and stay) two speeds for the same power/thrust ---- either side
of the peak --- what John V. describes is the most common way to make
certain you are on the "fast" side of the peak.
Cheers,
Bill Hamilton
From: owner-commander-list-server@matronics.com
[mailto:owner-commander-list-server@matronics.com] On Behalf Of John
Vormbaum
Sent: Wednesday, August 24, 2011 2:33 PM
Subject: RE: Commander-List: Flying "On the Step"
Andrew,
This is purely an empirical observation, but in my 500B I've found that the
wing seems to become most efficient at an IAS of ~135kts+. There are huge
arguments for & against the 'step', but the benefit I've found is quicker
trimming.
Those smarter than me might be correct about flying it to the altitude, and
trimming from that point being no less efficient than overflying your
altitude by a couple hundred feet and dropping back down, but in my 500B it
seems to trim up much quicker, and at a higher airspeed sooner, if I fly it
a little higher and get on the step. If I DON'T do that, there are numerous
power/pitch/trim changes that need to be made before the airplane wants to
settle down. Think 15 minutes.
If I fly it onto the step, when I'm ~200ft above my target altitude, I can
point her downhill, close cowl flaps, pull the props back, set power, and do
the first big mixture grab. At that point the airplane is at its target
altitude and I only need about 60 seconds to get the trim where I want it.
Then I can focus on setting LOP and/or turbo boost, and the airplane will
stay rock-steady at the altitude. A slight trim adjustment over the next
minute or two is usually all it takes after that, and then I can settle in
for my hours of boredom at cruise.
Again, just anecdotal, but I sure seem to mess with the trim wheel a lot
less this way.
/J
From: owner-commander-list-server@matronics.com
[mailto:owner-commander-list-server@matronics.com] On Behalf Of Andrew &
Bridget Watson
Sent: Tuesday, August 23, 2011 1:03 PM
Subject: Commander-List: Flying "On the Step"
Hello everybody,
I read the earlier emails--some questions on "Flying on the Step".
Out on the Internet there appears to be violent disagreement on whether such
a thing exists or not. Note: I'm not trying to brew up a storm, just trying
to understand.
My father taught me there was such a thing. I believed and still believe
there is; that flying on the step is not a myth. The way I rationalised it
then is as below, I appreciate folks setting me straight, either on-list or
off-list.
1. There are 4 forces that act upon an aircraft:
1. Thrust, which is directly forward
2. Drag, which is directly rearward
3. Weight, which is vertical down
4. Lift, which is perpendicular to the aircraft wings, 'upward".
2. As speed increases, so does lift.
3. If the aircraft is in a nose down attitude, speed will increase
because:
1. it is in a shallow dive
2. lift, being perpendicular to the wings, will be assisting in drawing
the aircraft forward
4. Altitude "lost" in the nose down attitude will be compensated by the
increased lift associated with the increased speed.
Is this simple logic valid or should I go and hide my head in shame
somewhere? <grin>
Thanks all in advance for your help in my understanding of this.
Andrew
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