On 2010-08-20 4:18 PM, Linda Abrams wrote:
how level is "very nearly level?" How much of a bubble "off" is
still "level enough" for cross-wind purposes? (assuming I'm using a
large, good carpenter's level)
Linda,
I can't say how much of the bubble I'd want out of center.
We used to primarily talk about the "tail height" needing to be 75", the
original specification with the single fork nose gear and I forget which
tire. For single fork nose gear planes, we'd consider that 75" was
ideal, 74" inches would be OK, 73" is still sort-of OK (but was
sub-optimal in strong crosswinds), 72" should be fixed and anything
lower was getting dangerous. These numbers were not scientifically
arrived at but were derived from reports and experience.
How that translates to bubble diversion, I just don't know.
If the plane has a longer double fork nose gear (usually longer by 1.5")
then the tail would need to be 1.5" higher than the original standard to
keep that on-the-ground datum (the window sill) level and the angle of
attack of the wings at the specification.
More recently, we've been emphasizing that the window sill needs to be
level as that is the specification and applies to all models and all
landing gear modifications.
Unless we can get something more definitive, I'd suggest you measure
your tail height with a friend or two. Set the bubble level on the
window sill. Then have one friend lift the tail till the bubble is
showing level and determine how many inches difference there is between
level and its normal on-the-ground attitude.
If I were only 1"-2" low, I would probably wait will next year to put in
new donuts or add a spacer. If there were a 3" differential, I would do
landing gear maintenance.
If you do this, perhaps you can report back on how much the bubble was
off center on your bubble-level for each inch of droop from level.
Sorry I can't be more specific.
Ed
