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'.
And yes, I do mean drag rises then falls slightly as speed increases! Does
anyone know the reason for sure? Pitch attitude higher at 110kts than 120kts
would be my guess.
Regards,
Jeremy
Jeremy Davey
Europa XS monowheel 537M
-----Original Message-----
From: owner-europa@post.aviators.net
Subject: RE: Speed Kit
Hi Martin,
I think this has been alluded to before, a few months back. See Europa
newsgroup exchanges re:'the step'.
Some say it is an illusion, others that it exists and has been documented !
FWIW, my guess is that it's illusiory.
I don't believe that ANY aircraft breaks the laws of aerodynamics, so if it
is a real phenomena, it'll be described
somewhere in the standard literature. Ask a boffin !!
Alan
-----Original Message-----
From: owner-europa@post.aviators.net
Subject: Speed Kit
Hi Folks,
One thing I noticed when I fly is if I level off at - say - 3,500 ft let the
speed build, throttle back to say 5,000 rpm I get around 115 kt indicated.
If I climb to 3,600 ft first then gently point the nose down to bring me
back down to 3,500 ft and let the airspeed gets up to around 125 kt
indicated, throttle back to 5,000 rpm the airplane settles back to 120 kt
indicated (where it stays). Don't know if its some weird aerodynamic thing
but it seems by pushing it over its normal cruise speed first then letting
it settle back to its own cruise speed, you get a few knots more than if you
were to let it make its own way up.
I haven't taken any scientific measurements just an observation of the ASI.
Anyone else found this? Any ideas?
Martin Tuck
N152MT
Wichita, Kansas
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