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Old November 18th 04, 03:26 PM
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Roy Page wrote:
: So the question is.
: How long is a "short field" for a PA28-181 ? And for that matter how does
: that relate to a PA28-140 with 30 less horses.

I fly a Hershey-bar PA28-140 with a 180hp engine, so it's probably somewhere
between the two. If your POH is anything like mine, I understand your apprehension
about what the "true numbers" are. Piper was particularly awful in the older books
WRT some things. For instance, I routinely fly my plane on grass strips with
3000-4000' DA, but I have no guidance from the POH on grass. I would also like
partial loading characteristics, since I almost never fly at gross (for a -180).
Neither of these are present.

I think that the poster who suggesting adding the takeoff (w/ or w/o obstacle
clearance) + the landing distance ground roll makes a very reasonable, yet not overly
conservative estimate. For mine at 3000' DA, that'd be 2200+600 over a 50' obstacle
from a paved runway. Given the safety factor of generally being under gross by
200-300 lbs, that's a very reasonable number.

WRT 1 notch or two, the decision is clear. You're either doing short field
by the book or you're not. While adding 1 notch may help some, you have no
substantive reason to know how much... thus, I wouldn't do it where I wasn't
comfortable with a normal takeoff.

All that said, from what I've gathered by looking through a number of POH's
(not Pipers') and other references, I've come up with the following "rules of thumb"
to keep from being overly aggressive/conservative:

"good" grass: adds 10-20%
"bad" grass: adds 20-30% - not yet tried...
10% under gross: decreases 10%
nonstandard DA: By the book

YMMV
-Cory


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************************************************** ***********************
* Cory Papenfuss *
* Electrical Engineering candidate Ph.D. graduate student *
* Virginia Polytechnic Institute and State University *
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