On 6/13/2012 12:45 PM, Andy wrote:
On Jun 13, 6:31 am, John
wrote:
Needless to say, making sure the ballast is sloshed so the wings are
balanced, the upwind wing is held a little low, and the wing runner is
an olympic sprinter helps too. I recently couldn't persuade a wing
runner to hold the upwind wing low with predictable consequences.

John,

Do you always takeoff with full ballast? In my ASW19 I always had full
water or no water so a wing low cross wind takeoff was normal. With
the 28 I'm never full and I'd rather be ballanced and stay ballanced
than have the wing low.

If the wing runner really understood what was going on then holding
the wings level until start of the roll and then lowering slightly may
work but I'm usually happy to find a wing runner that understands the
need for balance and a fast run.

What do other do for cross wind takeoffs with partial ballast?

Andy

Zuni experience, ~48 gallons max (more than I could ever effectively use),
integral tanks with internal baffles, tailwheel, nose hook, negative
flaps...my experience with (any, mostly partial) ballast was inertia was your
friend in every case/situation...hence my vote in that ship was for max
wingtip clearances. In every case, beginning the run with negative flaps, I
obtained aileron control before any wingtip dropped.

I always instructed my wingrunners to level the wings, remove their hands to
*show* me wing weights were really equalized, and give me the longest run they
could without holding back on the tip. (Once the water was equally
distributed, I preferred to have them rest the wing bottom surface on the flat
of their palm, & explicitly said I did NOT want them wrapping their fingers
around the leading edge...simply run/sprint until the tug outsped their best
effort. Obviously, gusty crosswinds dictated some degree of non-level-ness,
but "close enough to level for practical purposes" was always the goal.)

No connecting of rope until the glider was perfectly aligned with the runway.

Elaborating briefly on the "never had any aileron control issues" claim, that
was true even behind a 180 HP Super Cub at 5300' msl from a 4,400' strip. I
*did* swear off any more fully ballasted T.O.'s from the strip behind that tug
after my only fully ballasted takeoff there...non-existent fully-ballasted
PTTT options prior to being able to execute a downwind return, and WAY too
long 'in the crash zone' below return height.

I should note my ship had the original stalky gear, which put a LOT of weight
on the tailwheel (relative to many 15-meter ships), further making the ship
less prone to weathervane in any event.

YMMV,

Bob W.