Milt said:
Incidently FBW and artificial stability will be a way we can design for a zero tail load or even an up load on the tail for cruising flight..It's happening with military aircraft and close for non-military using artificial stability. But the elevators will then have a very busy time preventing runaway in pitch.
Just curious about how an inherently unstable aircraft such as the F117 reacts to icing? Since it relies on multiple computers to fly at all, does icing make any difference (short of blocking the engine intakes and freezing the controls in place). Does it have de-icing equipment?
This web-site "http://www.grc.nasa.gov/WWW/RT1998/5000/5840ratvasky.html" describes a NASA/FAA Tailplane Icing Program (TIP), and mentions that it was initiated because of at least 16 accidents resulting in 139 fatalities attributed to such stalls. The objectives of this program were to improve understanding of iced tailplane aeroperformance and aircraft aerodynamics and to develop training aids and design tools to expand the awareness of ice-contaminated tailplane stall (ICTS). A 23-min video, "Tailplane Icing", was produced.
FAA Advisory Circular AC No: 23.143-1 "Ice Contaminated Tailplane Stall (ICTS) Date: 12/20/01" contains several warnings about the hazards of testing aircraft with stalled tailplanes, e.g.
WARNING
Some hazard is associated with ICTS flight testing. It is important that the applicant take appropriate precautions in the conduct of these tests and the flight test crew very carefully considers risk mitigation that includes defining minimum altitudes, conducting tests in a build-up manner, and providing emergency escape and parachute provisions.
Cheers,
