Re: Power for Take-Off

Date:         17 Sep 97 02:49:23 
From:         lstone_no_spam@wwa.com (Larry Stone)
References:   1 2 3
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In article <airliners.1997.2164@ohare.Chicago.COM>, mayerp1@nevada.edu
(PAUL G MAYER) wrote:

>Not quite.  It's true that FAR 25 aircraft must meet minimum one-engine
>out climb criteria in order to be certified.  However, "light piston
>twins" are certified under FAR 23 which has no such requirement.

>3. After rotation, accelerate to Vyse (best single engine climb speed).
>   Leave gear down.  If power fails here (below Vyse), ABORT back onto the
>   runway.  Most light twins will not fly (let alone climb) in this
>   configuration at typical takeoff gross weight unless at or near sea level.
>   The old saw here is it's better to go through the fence at 50 than into
>   the trees at 100.

I've flown light-twins, particularly the Beech Duchess, out of airports
like Palo Alto and San Carlos, CA which have 2,500' and 2,600' runways
respectively. For the Duchess, the book accelerate-stop distance (distance
to accelerate to decision speed (same as rotation speed for most
light-twins), then abort), at sea level and standard temperature (15C), is
2,450'. However, until I get the gear up, continuing is not an option.
Meaning if I lose an engine after roatation but before the gear is up,
I've got to put it back down even though I know I'm going off the end. At
this point, flying a twin is just like a single except things are twice as
likely to go wrong. In those conditions, I flew every take-off as a
short-field takeoff - tight turn onto the very end of the runway, brakes
set, engines full, release brakes, and let her rip.

Another problem with light-twins is the single-engine landing. With the
gear and flaps down, a go-around is not an option. With full power on the
operative engine, you're still descending. So you want to aim for the
runway such that you don't end up short. But at these short runways like
Palo Alto and San Carlos, you don't want to end up long either as you need
to get it down fairly close to the arrival end of the runway. Long ago at
San Carlos, I decided if I ever lost an engine right after take-off (but
with the gear up so continued flight was acheived) with a west departures,
I'd just continue straight 8 miles to that 10,000+ foot runway at SFO.
That way, I could plan to land a couple of thousand feet down the runway
but if I did end up short, I'd still be on runway and if I ended up long,
I still had plenty of stopping room. Frankly, I think my life is a little
more important than any delays it might cause to air traffic at SFO.

--
-- Larry Stone --- lstone@wwa.com
   http://www.wwa.com/~lstone/
   Belmont, CA, USA
   My opinions, not United's.