On Mon, 28 Apr 2008 04:20:30 GMT, Eric Greenwell
wrote in igcRj.6716$r12.4153@trndny03:

Larry Dighera wrote:

...
Interesting. Thanks for the information.

How do you think it might affect a sailplane's L/D?

Well, if the sailplane skin is transparent to radar a big reflector
could be mounted inside, they don't weigh much. On the other hand a
cylinder type reflector could be made quite aerodynamic and even
incorporated into (say) the wing tips?

Cheers

That sounds like a very simple, inexpensive and effective solution to
the issue. Best of all, the pilot can't turn it off. :-)

Locally, approach radar has no trouble finding our transponderless
gliders (when we call them), tracking them, and warning/diverting other
traffic. We generally do this within 15-20 miles of our towered
airports. It works well for us, given the altitudes we fly at.


Thank you for this information.

Would the gliders you mention be of glass-fiber, aluminum, or
carbon-fiber composite construction? I would expect a glass ship with
few metal parts to be rather transparent to radar.

I don't know that a corner reflector would improve on the situation, or
if they would detect the gliders without the radio call. While the pilot
can't turn it off, it may be the controller doesn't notice it without
the radio call, and may not be able to see it because of other clutter,
or perhaps the display filter settings.

I would guess the controller would need to adjust his scope from it's
usual setting to see primary targets, so a radio call may be
necessary. While a corner reflector would doubtless increase the
radar energy returned to the radar antenna and provide a brighter
primary target, I doubt that would be sufficient to cause the glider
so equipped to become visible on ATC's scopes without reconfiguring
them to display slow-moving primary targets.


It's worth contacting ATC in your area to see if they are willing and
able to do the same for you. It's not practical everywhere, but it's
cheap and easy if it is.


I'm not so much concerned about my personal situation as I am about
the FAA rescinding the glider exemption from FARs that require
transponder use. If we can give the FAA some guidance on this issue,
the outcome will likely be more acceptable, than if the draft their
NPRM without pilot input, IMO.

A problem the reflector can not solve is TCAS will still not detect the
glider. This might be deal-breaker for the FAA/NTSB people.

I agree. But rescinding the glider exemption from FARs requiring
transponder use won't address that issue with powered aircraft that
lack an electrical system either. It looks like the FAA's response to
this NTSB recommendation is destined to be a compromise at best.
Hopefully it won't result in all gliders and aircraft without
electrical systems being grounded until they have transponders
installed and signed off.