REFLECTOR:Props

Tue, 6 Apr 2004 11:40:52 -0400

I am a bit familiar with the Global prop.  I don't think they are working
on the prop right now.  They had done work under the AGATE SBIR and
produced some prototype props.  They were working to develop a production
prop, but did not have funding to get there.  They also were discussing
providing blades for a hub vendor.  The quasi-constant concept was that
through building a composite structure they could change pitch in response
to air loads.  It produced better that fixed pitch general performance (as
we know fixed is best for a single flight phase), and less general
performance than CV (with less hardware and complexity).  So the end goal
was to give near CV takeoff-climb-cruise with the cost and complexity of a
fixed. They had success at the concept, but did not seem to be able to get
to a production prop because of the ramp up costs.

I have maintained contact (meet each year at OSH) with one of the
engineers.  I hounded him to build a pusher, but needless to say, that was
not on their priority list.  They did build a non-quasi for a Glasair
(owned by one of the principals) that was a new design but not quasi.  It
was a big improvement over any of the fixed that they tried. They also
built a three blade on an RV.  The other advancement of the design was
noise levels.  They were able to provide a significant decrease in the prop
noise.  As a side note, they claimed that a big chunk of A/C noise was
actually cowling noise from the pressure pulses hitting the large
oil-canning surface.  So maybe a pusher is better in that area.  They also
thought that pushers should have an advantage available if they could find
a way to exit exhaust and cooling air though the spinner.

That's is about all that I know.

-jerry

                      "Andy Millin"                                                                                                     
                      <amillin@sbcgloba        To:       <reflector@tvbf.org>                                                           
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                      04/06/2004 08:49                                                                                                  
                      AM                                                                                                                
                      Please respond to                                                                                                 
                      reflector                                                                                                         

I was looking around the net at composite props again.

I found Whirlwind http://www.whirlwindpropellers.com has a prop that would
be good for the XL.  I don't know that they make it in the pusher
configuration.  At $12.5K for the prop and $1,275 for the governor it ain't
cheap.  After hearing the maintenance and downtime woes, any option that
would be more robust than the MT sounds like it would be a better value.

Also found several references to a Quasi Constant Speed prop being
developed.  Unfortunately, all of the information seems to have been posted
between 1998 and 2000.  The website for Global Aircraft Corporation
(http://www.globalaircraft.net/) doesn't work anymore.  The NASA SBIR site
says the prop went into production in 2001.  Does anyone know anything more
about the status?

Andy
Working on the sump tank

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