Hello Davita, BEagle and Saintsman,
Thanks for your anecdotes. Thought I'd better look at my pilot's conversion-course notes (Gatwick Bee-Hive, 1971). They are a mixture of my handwritten notes and diagrams of our Pete Horscroft's lectures on the subject, a few diagrams from the maintenance manual, and extracts from the ARB Flight Manual (Doc.No.VS.5.2). The latter document may be specific to the Type 1103/1109, but it seems unlikely that the stall protection would have varied from other types.
I was immediately struck by how sophisticated the system is, and reminded of the 13-point checklist that the copilot had to perform on it during the pre-flight checks at the beginning of a crew's stint. We and the F/Es certainly had it tough in those advanced, but BITE-less aeroplanes...
Had forgotten that the duplicated system means there are actually 2 AoA probes per side (one very close above the other, No 1 system probes being on the left). What I remembered well was that each heated probe is small, and its vane is hidden inside a slim conical cover which admits the air through slits in its leading edge. This is unlike the BAC 1-11 (despite the systems being otherwise similar), or any other a/c I flew subsequently - all of which have larger, uncovered vanes.
You may recall better than I that:
the L/H-side probes are nominated #1 system, and the R/H-side #2;
the
lower probes signal the "AUTO-IGNITION", e.g., #1 (left) actuating the #1 igniter system in each engine;
each
upper probe signals only its "WARNING" (stick-shaker & knocker) system - #1 (left) actuating the L/H control-column
and arming the #1 "IDENT" system, and #2 (right) actuating the R/H control-column
and arming the #2 "IDENT";
each
lower probe's second task is to signal the "IDENT" part of its system - each system having its own horn, but either system able to actuate the pusher, fitted only on the L/H control-column.
The AUTO-IGNITION mode has no phase-advance, apparently, unlike the warning and ident modes. That contradicts a comment in my previous post (re the clean-up phase hot/high/heavy)
*. According to my handwritten diagram and notes, it looks for an AoA which is modified only by Slats angle and Mach.
The WARNING mode looks for an AoA which is modified by:
rate of AoA
**, Slats angle, and Flaps angle, but not Mach (?). This is further modified by an LRM (lift-rate modifier) for normal accelerations > 1G.
The IDENT mode obviously looks for a higher AoA than the warning mode, but uses the same parameters of modification, including the LRM one.
Davita,
I cannot find a figure for the pilot force necessary to overcome the push, but I thought it was a high 2-digit number in pounds?
BEagle,
You seem to have been keen on slatless approaches, so guess you were a base-trainer? Recommended approach speed slatless with full flap is VAT +20 on our 1103s/9, so I presume the VAT +10 was trainee error?
Yes, out of Nairobi or even Entebbe for London, we used to fly absolutely level (if not a tad downhill, although that was frowned upon) for the clean-up, and some F/Es would gratuitously offer us full throttle in anticipation of the auto-ignition lights coming on. As you say, there was quite a lot of pushing to be done on the TPI levers (but nothing like as much as a G/A on a jet with underslung engines). Flap-limiting speed was 229, and V2 +60 about 224.
Added by edit (2014-02-23)
* So, when the F/E reported the auto-ignition coming on, it was caused by the actual AoA reaching the auto-ignition threshold - not a phase-advanced engagement (combination of high AoA-rate and AoA, as in turbulence).
** (sometimes referred to as "phase advance")