All Lockheed L-1011 models used tapes for the Trailing Edge Flaps position indicator. Tapes are analog instruments that use a color marked tape to indicate values on a vertical scale. In the case of the TE Flaps instrument, the scale indicates the degrees of flaps extended on the outside and the maximum flaps extend speed in Knots on the inside. The instrument that I show you here is very similar to the instrument in use with the L-1011, however, it is from an Airbus A300. The L-1011 has a slightly different speed/flap range. However, the instrument is still good enough to illustrate the mechanics of the device.
By the way, the TE FLAPS indicator has great back illumination !
The instrument case is held in place by two screws on the backside of the instrument.
Once removed, the instrument casing slides right off and reveals the two discrete tape mechanisms for the right and the left hand side TE FLAPS tapes.
The top view shows the two Control Transformer synchros (CTs) with the blue end caps and the two DC torque motors.
The two sides are basically symmetrical - as can be seen in this right-hand-side view.
Bottom view
Left hand side view
The mechanical elements that drive the tapes are very similar to a tape cassette player (for those who still remember what that was). There is a take-up reel and the supply-reel. The gear that connects the CT also doubles as the supply-reel with the tape wound onto it and the send largest, spring loaded wheel, acts as the take-up reel.
The motor drive also links to a wheel that acts as a mechanical limiter and prevents the motor from over-torquing the tape and breaking it.
The next image shows the motor energized with 2.5V ... which will develop about enough torque to extend the tape out to 22º flaps extended. As you can see the motor on the left hand side of the instrument drives the tape on the right hand side on the instrument face.
I think that is on of the latest versions of the L-1011 Flaps Indicator that was used in the -500 and -250 versions, since you don't have the 27 and 42 positions ;) Nice work!
ReplyDeleteGood point. I'd be curious to research this a little further. From the trace on the instrument it appeared to come from an A300B, however, the trace could be wrong since the serial numbers don't perfectly match (well, actually they are partially missing).
ReplyDeleteIt really seems to be from an L-1011. You can see in this diagram:
ReplyDeletehttp://www.tristar500.net/cockpit/main_panel.jpg
The speeds and flaps range perfectly match. Initially the long body versions had 4, 10, 18, 22, 27, 33 and 42 positions. But due to LRS system reliability problems the 42 position was surpressed. With the L-1011-500 they added the 14 position and eliminated 27º.
The 2 iluminated signs on the bottom should say (SLAT) on the LH and (LE EXT) on the RH.
For the initial long body version you had the following flap settings:
ReplyDeleteFlap settings and respective speed limits are,
4 - 250 KIAS
10 - 230 KIAS
18 - 210 KIAS
22 - 205 KIAS
27 - 200 KIAS (not used)
33 - 170 KIAS
42 - 164 KIAS (blocked on most aircraft).
4, 10, 18, 22 are approved for takeoff, depending on the individual airline procedures.
4 and 10 are the most usual flap positions for take-off.
The slats deploy fully when the flap HANDLE moves beyond the 3 degree position.
DLC (Direct Lift Control) activates when the flap HANDLE is moved beyond the 33 degree position.
Wow .. nice job! Thank you so much for the information. I agree with you, this is in fact a late version TE FLAPS tape for a L1011! This is good to know. The unit itself has the SLATS and the TE move annunciators missing. So I am actually on the lookout for a better one. But this was very helpful.
ReplyDelete