Re: tip vortices *do* exist!

From:         sharpes@c-17igp
Date:         29 Mar 93 12:27:53 PST
References:   1
View raw article
  or MIME structure

> jonathan@hermes.chpc.utexas.edu (Jonathan Thornburg) writes:

>A final point:  We had some discussion in this newsgroup a few
>months ago on in-flight use of spoilers.  As I recall, the consensus
>seemed to be that they're used for roll control, but not usually for lift
>dumping as such.  

  The C-17 uses spoilers at least six ways, one of which is roll control,
another being, of course, ground spoilers.  Spoilers are symmterically
deflected with flaps in the cruise configuration for speedbrakes (an
average of 14 degrees spoilers and 8 degrees of flap at max deflection).
The outboard spoiler is coupled to the ailerons for precise speed control
while under the tanker (it's gonna be a sweet flyin' thing!).  During
landing approach, spoilers are coupled to the throttles to take out the
engine response time delay and, lastly, spoilers are used to enhance
ground effects (yes, enhance ground effects!  It's called SAGE - Spoiler
Enhanced Ground Effects).

  When the Globemaster III is making a steep approach (about 5 degrees
glidepath), the spoilers are uprigged nine degrees.  At the appropriate
height, the spoilers retract and the lift they dumped comes back to
reduce sink rate.

                      _____________
         Dan                |                 "Opinions expressed 
           Sharpes          |                  are mine alone, and
                           _|_                 not another's"