D R compass drill



D R compass drill


Instructions for using D R compass before flight, in flight, after flight and supplementary notes. Handwritten notes in right margin with drills.




One page typewritten document


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[inserted] 745193 W/O ROSSER [/inserted]


[underlined] Before Flight. [/underlined]

1. On entering the aircraft note MASTER UNIT reading. Apply "A" error and check that all repeaters are correctly synchronised. The V.S.C. must be set to zero and repeaters corrected if necessary.
[inserted] (1) Note M.U. reading. Apply A error to repeaters. [/inserted]

2. When all the engines have been started and not before, put "SETTING – NORMAL" switch to SETTING", and switch "ON".
[inserted] (2) Start up. Switch to 'Setting' Switch ON. [/inserted]

3. After 3 or 4 minutes, or when the repeaters are oscillating gently either side of a mean heading put switch to "NORMAL" halfway between oscillating of needle.
[inserted] (3) When repeaters O.K. switch to Normal. [/inserted]

4. Set V.S.C. at zero. Check synchronisation of repeaters with the MASTER UNIT reading. Correct repeaters if necessary.
[inserted] (4) Set variation to zero. Check repeaters with M.U. and correct.

5. Set local Variation on the V.S.C.
[inserted] Set Variation. [/inserted]

[underlined] In Flight. [/underlined]

6. When the aircraft is airborne, flaps in, undercarriage retracted, and the aircraft trimmed for straight and level flight on initial course, check repeaters with MASTER UNIT reading. Adjust repeaters if necessary (M.U. [symbol] A Error [symbol] Local Variation. [symbol] Repeater Reading).
[inserted] (6) On [indecipherable word] check repeaters with M.U. and adjust. [/inserted]

7. In order to avoid wandering "Off Track" for any length of time repeat proceedure [sic] in Para. 6. every 20 minutes and make an entry to this effect in the Navigation Log. Constant comparison should be made between the repeaters and P.4. Compass.
[inserted] (7) Repeat every 20 mins (Bomb Aimer). Enter in Nav. Log. Compare repeater with P.4. [/inserted]

8. If the gyro topples put switch to "Setting" to hasten return of the repeater to the correct heading, then back to "Normal" and check synchronisation.
[inserted] (8) If gyro topples switch to Setting. When O.K. back to Normal. [/inserted]

8a. Change Variation midway between the [indecipherable word].

[underlined] After Flight. [/underlined]

9. Bring V.S.C. to zero.

10. The D.R. Compass must [underlined] NOT [/underlined] be switched "OFF" until the aircraft is stationed in dispersal.

[underlined] Notes. [/underlined]

(a). Ref. Para. 1. If synchronisation was carried out correctly when the aircraft was last swung, all repeaters will now read the same as the MASTER UNIT [symbol] "A" Correction.

(b). Ref. Para. 2. Engine starting may cause a serious drop in voltage i.e. if switched on would cause gyro to topple.

(c). Ref. Para. 6. If repeaters have become desynchronised the D.R. Compass is not necessarily U/S, and every effort must be made to re-synchronise.

(d). Ref. Para. 7. Any difference between the P.4. Compass and the repeater reading may be due to the bomb laod, [sic] but correct synchronisation of the repeaters must be checked with the M.U.

(e). Ref. Para. 8. A toppled gyro is usually indicated by the repeaters turning in one direction only, or by a sudden change in the repeater reading up tp [sic] 50 or so.
Usually caused by aircraft exceeding a bank of 75 and drop in voltage below 23 volts.

(f). Care must be exercised not to look at the course setting needle from an angle as parralax error up to 5 may occur.

(g). The pilot must not press too heavily on course setting knob; this may turn repeater card, and cause desynchronisation.

(h). Re. Para. 9. To return V.S.C. to zero, compass must be switched on otherwise V.S.C. knob free wheels.

(i). Re. Para. 1. A.Error – Should the A Error change this may be due to the gyro-spindle becoming magnetised.


“D R compass drill,” IBCC Digital Archive, accessed February 22, 2024, https://ibccdigitalarchive.lincoln.ac.uk/omeka/collections/document/36724.

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