To Fred and all you other speed-freeks...
On all the aircraft I have flown, there is a net gain in speed when you fly
it "on the step". The results are more pronounced with "cleaner" aircraft.
In the old days when we flew DC-6, C-46 and so forth - although not
standard operating procedure - we used to climb slightly higher (100-200ft.)
than cleared FL, maintaining climb power throughout until cruise speeds
where achieved, then slowly descending to correct altitude while reducing to
cruise power. A net gain of 5-6 kts where achieved. (NB: This was before
Mode C times - not at all tolerable today!!)
On the B 737 -200 we used to maintain climb thrust to a slightly higher
speed than chart values - after which cruise EPR was set. Speed gain: Mach
0.005 to M 0.01 with fuel flow about the same as best economy (M.0.72). The
interesting thing is that fuel used was thus lower throughout while cruising
a wee bit faster than best economy. Sheer magic!
On the -400 and -500, - aircraft with approximately similar drag curves,
the Flight Management Computer found out just the same: Best economy speed
turned out to be M 0.73/M 0.74 - instead of the more "draggy" 0.72. (Of
course the picture is quite complicated with all the various inputs to the
computer, of which Cost Index plays a major part).
The lessons learned from this is that of Body Angle while in the cruise. The
faster you go - the less is your angle of attack. Which again spells less
down pull on the stabilizer (less drag from stabilizer "lift") and less
wetted area from aircraft structure. As others have pointed out, a more
rearward placement of C of G also plays a major part in obtaining the
flattest - or optimum - angle. For the pure reason of easing off the load on
the Stabilizer. All this is of value to the Europa with its all flying tail.
Its really a little Boeing!!
With Christmas greetings to you all!
Hans.
----- Original Message -----
From: "Fred Fillinger" <fillinger@ameritech.net>
Subject: Re: Speed Kit
> I thought the reason is it that, as you approach cruise speed for any
> given trim, it takes a long time to finally get there, so I can
> 'demonstrate' it too. The S-Tec (autopilot) web site contains an
> article debunking it. Otherwise, aerodynamics texts and NASA research
> would document the phenomenon. They don't, and a credible answer as
> to why not will bring me into the faith, honest. Like conspiratorial
> holdover from the Cold War, 'cuz the Russians never caught on. :-)
>
> Regards,
> Fred F.
>
> > It is real! Check out a PA28 manual - the Warrior I learned in would
settle at 110kts
> > (if I remember right) or so at 2300rpm when throttling back from full
power on reaching
> > 100kts or so, or 120kts at 2300rpm if you throttled back from full power
on reaching
> > that higher speed. I remember clearly my instructor demonstrating it to
me and my
> > flight-test examiner doing the same when I throttled back early on the
climb out from
> > a PFL.
>
> > The reason is the shape of the drag curve. The drag is the same at both
speeds, and
> > equals the thrust from the engine+prop at 2300rpm. To get the higher
speed you have to
> > get the plane over the higher drag in between those speeds by using more
power or
> > diving. My instructor/examiner both talked about 'getting onto the back
of the drag
> > curve'.
>
>
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