......the power curve explanation is a good one.....but one also must
look at the manifold pressure indicator before noting the differences in
speed, a rpm setting alone under these circumstances will exagerate the
difference in speed....
Regards,
Alex
-------- Original Message --------
Subject: RE: Speed Kit
Date: Sun, 16 Dec 2001 20:37:11 -0000
From: "Jeremy Davey"
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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