HN39.
Thanks for the LF/AoA graph. Thought you would rise to the small challenge!
Fascinating discussion on
HF antennae and propagation, chaps... Yes,
Graybeard, think the VC10 also achieved whole-airframe antenna from its fin-mounted thingy. Whereas the B707 just had the antenna sticking forward from top of fin. Aft reception could be difficult in my experience on some aeroplanes, but can't remember which ones of VC10, B707, A310, or DC10. Pretty sure the VC10 is better than B707 in that respect. Aerial-tuners also used to be a problem sometimes, leaving you with the inability to transmit. Changing freq sometimes solved the problem.
Re
VHF-AM in static, I'd just like to point out that ear-splitting static often accompanies St Elmo's fire.
Re Airbus's
proposal of using GS as a way of checking the veracity of sudden indicated-airspeed changes, the
Flightglobal report quotes Airbus as saying:
"While airspeed and ground speed can not be compared directly, Airbus notes that over a "very short period", normally significant factors like windspeed, changes in altitude, air temperature and angle of attack will be negligible, allowing for a direct comparison of changes in speed rather than speed itself."
I wonder what "very short period" they have in mind. By definition, large aircraft never experience rapid changes in GS. IAS/CAS, on the other hand, changes very rapidly in gusts. In the different situation of entering a jetstream from the side, the tailwind-component (for example) can increase by 100 kts in two or three minutes. This leads to a steady loss of IAS, which has to be recovered by climb thrust to build kinetic energy until the GS has been increased by the 100 kts.
On walk-rounds, I sometimes pondered on the positioning of the three probes. #1 & #2 are usually symmetrically positioned; #3 usually near #1. All seem equally susceptible to icing. But is it only the shape of the probe itself that matters?
Another point: can't someone invent an even more powerful heater that could kick-in as soon as a sensor/camera shows the beginning of ice formation? On the VC10, we had an ice-probe visible under the captain's DV window. It had a light which enabled the captain to inspect it with mark-1 eyeball, and a heater to de-ice it. (If it was icing up, we would put the airframe anti-ice on.)
Wouldn't it be nice if pilots could actually SEE their pitot tubes?