"Best forward speed" approaches

(Ben Jackson) wrote in message news:qYx4b.238270$cF.77016@rwcrnsc53...

I haven't done the math, but it seems like if you float down half a 2
mile runway after zooming down the ILS you're not going to be clear any
sooner that if you'd flown the ILS more slowly but made the first turnoff.

Well, let's take a stab at the math. I like my approach speed (whatever
it will be) stabilized outside the FAF. Typical glideslope intercept is
4-5 nmiles. So if I'm slowing, I want to slow down about 6 nmiles out.
That's ~4.5 minutes to DH. OTOH, if I keep my speed to 120 kts, I
can do the same in 3 minutes.

So the question is, does it take me an extra 1.5 minutes to get off the
runway? I don't think so...I can throttle back when I break out and
slip a little bit to scrub speed so I can dump in the flaps. Maybe
an extra 1/2 minute?

But I can see where it *could* take at least an extra minute for
some planes which are slicker or if the pilot is unwilling to just
throttle back.

I also know pilots who want to slow up (if they're going to slow)
way earlier than I do, in which case the time differential is greater.

Cheers,
Sydney

But I can see where it *could* take at least an extra minute for
some planes which are slicker or if the pilot is unwilling to just
throttle back.

Yes, I call it the EDM effect. Once you buy a graphic engine analyiser
and see how fast your engine freezes when you pull power, you'll think
twice before pulling back too far when coming down.

-Robert

Well, I feel vindicated. I haven't changed my let down procedure as a
result of putting in an EDM700. The procedure I was using typically only
cools the engine by a few degrees/minute, about 1/10th the default limit
set on the unit. Basically, I leave the trim alone, which keeps airspeed
more or less constant, and drop about 4" of manifuld pressure without
touching the mixture. With the new engine I have been also reducing RPM
to keep from driving the engine with the prop, in which case I do see a
bit more of a temp drop, but still well under 20 deg/min. 4" gets me a
500 FPM descent without touching anything else, and then putting the power
back in I get back to level flight without ever messing with trim.

"Robert M. Gary" wrote:

But I can see where it *could* take at least an extra minute for
some planes which are slicker or if the pilot is unwilling to just
throttle back.

Yes, I call it the EDM effect. Once you buy a graphic engine analyiser
and see how fast your engine freezes when you pull power, you'll think
twice before pulling back too far when coming down.

-Robert

--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

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