Keith Willshaw wrote:
"Eunometic" wrote in message
ups.com...
A higher flying Airbus or B747-400 at 44,000ft might have glided nearly
30 minutes. This suggests that a fighter plane with its lower glide
ratio probably only needs half the amount of time (10 minutes) which
suggests that a thermal battery is possibly more efficient or at least
adaquet whereas an airliner may need twice as much.

What seems extraordinary is that both airbus and boeing designers have
provided insufficient RAT power to opperate all systems: spoilers,
flaps, undercarriage seem to be neglected. This makes an emegency
landing much harder. In both the airbus A330-200 azores and boeing 767
gimli fuel out landing case the lack of spoilers added a great deal of
risk as pilots manouvered agressively to loose altitude and speed for
runway lineup.


If you add more power to the RAT you increase drag and reduce the
glide distance, the record suggests they made the right trade offs.

Apparently in the the lockheed L.1011 Tristar The RAT pressurises a
hydraulic system that can be connected through to the undercarriage,
flaps, spoilers although the system becomes quite sluggish in this mode
and one would expect the pilots to time this opperation carefully.

I would like to see some sort of one shot Emergency Power System EPS
such as a thermal battery to provide supplementary power to allow full
flight control opperation for final 5-7 minutes of flight. There may
be safety issues related to chemical power sources (eg hot thermal
batteries with very high current output or hydrazine gas generators in
a crash) Clearly in fighter aircraft the intention is to allow the
aircraft to get into an ejection zone.

Poor L.1011: a fine piece of advanced engineering that was a commercial
failure (due to delays on the RB.211 engine I think)






(an excellent aircraft in engineering terms that was a commercial
failure)



Keith