CAB80-25 — Page 49

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46

July.

A preliminary full scale trial was conducted over the Rolls Royce Works, Derby. Aerial observation was carried out and tests were arranged to ascertain whether the smoke interfered with the operation of guns and searchlights. The results were considered to be successful in that (a) the R..F. observers reported that, although targets outside Derby were clearly visible in the moonlight the Rolls Royce Works could not be seen and accurate bombing would have been impossible and (b) the smoke did not interfere with the operation of ... guns and searchlights.

In view of the favourable reports on the full scale trial, smoke schemes were operated over the Rolls Royce Works and 21 other vital targets during the remainder of the moonlight period. Aerial observation was carried out over some of the targets in order to obtain data on the effectiveness of the smoke in impeding aimed bombing attacks.

The reports of the R..F. observers appeared to be uniformly unfavourable, their general effect being that (a) the smoke did not hide targets and (b) smoke "trails" downwind of the targets assisted the bomber crews in locating the target areas. In a report to the Deputy Chiefs of Staff Sub-Committee covering these observations the Ministry of Home Security pointed out that, as regards (a) the smoke cloud could be intensified by closer spacing of the generators; while as regards (b) the Air Staff took the view that the smoke might be a source of danger to the vital targets.

After reviewing the month's results and the Ministry of Home Security and ir Staff observations the Deputy Chiefs of Staff Sub-Committee decided * that (a) the contradiction between the reports on the preliminary trial at Derby and the subsequent operations left inconclusive the question whether smoke concealed vital targets; (b) further experimental work was required; (c) in the meantime no further operations over vital targets should be conducted; (a) in anticipation of the August experiments proving successful the Ministry of Home Security should explore and report on the operating personnel which would be required for the full operation of smoke schemes at vital points and (e) pending the outcome of the August experiments no further orders for generators should be placed.

August.

1

Experimental schemes were operated during the August moonlight period at:-

کھ

*

(1) The Schemical Defence Experimental Station, Porton,

Wilts.

(ii) Two non-vital points one near West Bromwich and

the other at Stewartby, Beds.

Paper No. D.C.0.S. (40) 97.

D.C.0.S.(40) 28th mtg. Minute 1.

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