D.N.C.’ s memorandum of the 14th July [Doc 194] is criticised as follows:

A. 3. Day flying will probably always be on a greater scale than night flying but the American roller blinds are apparently successful.

A. 4. It is considered that even in new construction British carriers, working conditions in closed hangars in the tropics will be intolerable.

A. 5. This is an unfair statement. No trouble has ever been experienced to our knowledge.

A. 6. Not agreed. The bollards and other ship’s gear are well outboard, and advantages far outweigh disadvantages of narrow hangars.

B. 4. Not agreed that the closed hangar wins in the case of the unarmoured carriers.

C. 5. Not agreed that the closed hangar wins in the case of unarmoured carriers.

D. 4. A suicide dive down a lift-well would presumably have the same results and be much more spectacular.

2. Since carriers with and without armoured flight decks present different constructional problems, the two types will be considered separately in summing up.

Open-sided Hangars.

3. The following are the main advantages:–

(a) Speed of Operation.
(1) Engines can be warmed up in the hangar and flown off immediately on ranging. This advantage loses some of its weight when applied to liquid cooled engines, which are liable to overheating if run for long periods.
(2) Three lifts can be fitted.

(b) Ventilation and Cooling. The openings provide excellent ventilation and cooling, an important point in hot weather. In Northern waters, the hangar can be kept warm by closing the shutters.

(c) Handling, maintenance and parking of aircraft. Considerable extra space is provided in the open-sided hangar.

(d) Testing Engines. Engines can be run up without risk of fire. This saves many man hours which would otherwise be wasted in ranging on to the flight deck.

(e) Light. With the shutters up, little artificial light is required and maintenance becomes easier.

4. A possible disadvantage of this system may be that washing down may be expected at hangar deck level with the movement of the ship. In this connection, officers who have taken passage in the U.S.S. WASP said that in very bad sea conditions the hangar kept perfectly dry but it should be noted that the freeboard in American carriers is normally considerably greater than in ours. Closed Hangar.

5. This type of hangar has the following advantages:–

(a) Aircraft fuel and hangar installations can be protected by armour both overhead and at the both sides.

(b) More aircraft can be stowed below since the construction allows of double hangar design. Fleet Carriers (armoured carriers with unarmoured flight decks).

6. The advantages of the open-side cannot be applied to this Class without losing its armoured characteristics.

7. The extra top weight causes more motion in this Class than in lighter ships with a consequent liability to wash down at hangar deck level. Light Fleets and Escorts.

8. All the advantages if the open side apply, while those of the closed hangar do not.


9. It is felt that open-sided hangars should not be contemplated for armoured Fleet Carriers.

10. It may be worth while, however, to consider building Light Fleets with open-sided hangars without necessarily providing for such large openings as those in U.S. carriers.