Category And Colors

TI-2094, Add. No. 2, dated March 3, 1945, initiated action for the application of standard camouflage (olive drab and light gray) to all A – 20, A-26, and B-25 aircraft destined for use by the Far East Air Force, at the request of their CG. This required a waiver from Mil. Req. Policy No. 15, dated November 19, 1943. (Note – these aircraft would be finished in Olive Drab ANA No, 613 and Sea Gray ANA No. 603, not the earlier Dark Olive Drab No. 41 and Neutral Gray No. 43.)

Since the war had ended, Procurement Division (WF), in a letter to HQ AAF, dated October 24, 1945, questioned whether camouflage was now required on gliders, liaison aircraft, troop carriers and helicopters, because this required the stocking of camouflage materials. The Production Division (Washington, DC) granted a waiver dated November 14, 1945, stating that those types of aircraft no longer required camouflage, pending revision of Mil. Req, Policy No. 15,

Supplement to T. O. 07-1-1 adds new identification markings for all aircraft operating within the continental United States, November 1945.

The war was now completely over and huge numbers of aircraft were being returned to the US. It would seem that the number of low – flying aircraft incidents was on the rise and as a result, the AAF issued directions in T. О. 07-1-1B, November 6, 1945, for new identifi­cation numbers to be painted on all aircraft (except helicopters and lighter-than-air). These have become popularly known as “Buzz Numbers.” The applicable portions of the supplement read as follows:

NOTE The work directed in paragraphs 17.b. and 17.c. will be accomplished prior to oral (he next 100-hour inspec­tion by all activities within the continental limits of the United States having permanently assigned aircraft.

1. Paragraph 17.b. of T. O. No. 07-1-1, dated 20 July 1945, is hereby revised to read as follows:

b. IDENTIFICATION MARKINGS.

(1) On all aircraft, except helicopters and lighter-than-air, operating solely within the continental limits of the United States, an identification marking will be placed on the lower surface of the left wing, and each side of the fuselage if space permits without relocation of the insignia. These identification markings will consist of two letters and three numerals determined as outlined below. Letters and numerals will be of uniform size, with the letters separated from the numerals by a dash.

(2) The wing markings will be centrally placed on single-engine aircraft and will be placed outboard of engine nacelles on other aircraft, with the top of the letters and numerals forward. The letters and numerals will be of the same height as the wing insignia, with the width at least two-thirds of the height, and the width of each stroke at least onc-sixth of the height.

(3) The exact location and size of the fuselage markings will depend upon the fuselage surface available therefor. Normally, they will be of such size as to cover approximately three-fourths of the surface on which they are placed, but the height of the letter and numerals need not exceed 48 inches. The proportion of the width of the letters and numerals and the width of the stroke to the height will be the same as that of the wing markings in so far as practicable.

(4) The identification markings will be yellow on camouflaged surfaces and black on aluminized surfaces and of either gloss or lusterless enamel or lacquer.

(5) The first letter of the identification marking will identify the type of aircraft, the second letter will be an equivalent for the model number, and the numerals will be the last three numerals of the radio call number. The letters to be used for the various types and models, together with an example of the identification marking of a specific aircraft of each type, are set forth below:

LETTER DESIGNATION LETTER EQUIVALENT

FOR TYPE MODEL FOR MODEL

Attack Aircraft

2. Paragraph 17.c. of T. 0. 07-1-1, dated 20 July 1945, is hereby revised to read as follows:

c, Radio call numbers are not required on primary trainers which do not have radio equipment and which bear field identifying numbers; however, identification markings required by paragraph 17.b. are applicable to primary trainers.

On April 9, 1942, tests were run at Halifax, Nova Scotia, to check the visibility of PBY aircraft used for anti-submarine patrol low over water. One PBY was painted flat white, the second was unpainted and the third was in blue-gray finish. It was reported that the test proved unquestionably the effectiveness of white paint on aircraft used for anti-submarine work on sunny days.

As a result, HQ, 1st Bomber Command recommended that camouflage specs, should be changed to provide for the painting of the undersurfaces of anti-submarine aircraft with oyster white lacquer. The necessary materials should be provided to Bomber Command. This recommendation was supported by both the British and American submarine officers.

Further tests were run on April 21, 1942, and it was concluded that a glossy paint might improve the effectiveness, and that de-icer (boots) along wing and tail surfaces also needed to be white. (Note: the request for a white anti-submarine camouflage led to a long, foot­dragging, contest and caused a lot of hard feelings. Not until June 1943, did Materia! Command issue a final report on further tests of the white finish. By that time, it was immaterial, as responsibility for anti-submarine coastal patrols had been handed over to the US Navy. Full details of this can be found in the following pages).

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Martin B-26B-1-MA, 41-17707, aircraft number 76, was the 164th B-26B of 1,883 built. It is seen painted in the final Sea Search scheme of neutral gray upper surfaces and white lower surfaces. Note the white leading edges of all surfaces. This scheme was developed at Eglin Field. (USAF)

North American XB-28-NA, 40-3056, was developed to replace the B-25, but it was not adopted. It made its first flight in April 1942. The pre­war.’AAF markings are shown on the rudder, together with a very polished natural metal finish. (March AFB Museum)

The Director of Bombardment sent a memo to the CG., Anti-submarine Group, on November 19,1942, stating that extensive tests at the Air Force Proving Ground (Eglin Field) had shown that the best type of camouflage for anti-submarine aircraft was:

Ail undersurfaces and surface of airplane that was in shadow should be painted with Insignia White, No. 46, and all other surfaces Neutral Gray No. 43. A picture was enclosed showing the manner in which the two colors should be applied.

He requested that a study should be made as to the suitability of this type of camouflage for use in the Anti-submarine Command. If they had developed a more effective type of camouflage, he requested that they should forward the information as to the type of paint used and a diagram of the scheme used.

On November 23, 1942, HQ., Anti-submarine Command replied stating that extensive testing had been made on camouflage for submarine search, and a report had been submitted on August 31, 1942, to the Commmanding General, Air Forces Eastern Defense Command. The results obtained were varied, but in general the conclusions reached were generally the same as those reached by the Proving Ground. They felt, therefore, that adequate tests had been made, that the camouflage recommended by the Proving Ground be adopted without delay, and that a technical Order be expedited for the camouflage of all Anti-submarine Command aircraft.

On November 30, 1942, the Commanding Officers of the 25th and 26th Anti-submarine Wings were informed that the Dir. of Mil. Req. had issued authority to camouflage all tactical antisubmarine aircraft as follows:

Under Surfaces – Insignia White No. 4 Upper surfaces – Dark O. D. (no change)

They were also informed that a Technical Order would be published in the near future.

a. Organization insignia will be placed on each side of each lighter-than-air aircraft. The location for observation balloons will be on each side, halfway between the greatest diameterand the leading edges of the horizontal lobes. The locations for spherical balloons will be at points in line with and three feet from each end of the wording “U. S. ARMY.”

b. In no instance will the size of lighter-than-air insignia exceed 9 square feet. The insignia placed on each craft assigned to an organization will be uniform in size. However, this does not require that insignia of different organizations be of the same size.

c. The insignia for alt lighter-than-air aircraft will be painted on two-ply envelope fabric, code No. 101, and securely attached to the envelope with rubber cement. Each sheet of fabric will be neatly trimmed to the minimum size required, and, to insure adhesion, corresponding areas of the aluminum finish will be carefully removed from the envelopes with suitable wire brushes.

This version of the T. O. was the first to be typeset and printed in color. It included a complete set of the colors from Bulletin No. 41, including the addition of Sand, Shade No. 49. There were two further pages, covering the types of materials to be used for applying the camouflage markings and insignia (these have been omitted from this work as being too technical and of limited use). The great improve­ment over the previous versions showed the extent of its use within the AAF, and the industry that supplied the aircraft at this crucial point in the war. All subsequent issues reverted to being in only black and white.

Only two days later, a later version, T. 0.07-1-1A, had to be issued to correct the titles of Figures 1 and 2. These were now amended to read:

Figure 1 – Operation over Predominately Green Terrain Figure 2 – Basic Camouflage.

All references to Figures 1 and 2 in the first section of the T. O. were to be changed to agree with the amended titles (this was obviously a paste-up error in the production of the document).

Tests show that the newly standardized JAC olive drab did not meet the reflectance requirements. Testing continued to correct the problem. June 25,1943.

Numerous tests had been made by Eglin Field to determine the reflection factor of the standard dark olive drab camouflage paint, and they advised Mat. Com. (WF) on June 5, 1943, of the results. Eng. Div. (WF) used these test as a basis and found that the original Dark Olive Drab Shade No. 41 had a reflectance of 7.8, but that the new Olive Drab standardized by the JAC (without Mat. Com. (WF) assistance), had a reflectance of 9.4. This exceeded the recommended 8.0%, and testing was under way to reduce it to the required value.

Material Command Report on camouflaging of Anti-Submarine Aircraft, June 23,1943.

Report No. ENG-56-M-4531, dated June 23, 1943, was issued to report on the results of tests of various color arrangements of camou­flage paint on airplanes in flight, conducted at Langley Field, VA, between January 8-21,1943. It contained the following data:

The 1st Sea Search Attack Group provided five B-18 aircraft, with serial numbers 37-464,

37-465,37-561,37-574, and 37-621. Three of the B-18s were painted over their existing finish, while the other two were left in their existing colors. The test color schemes for each of these aircraft followed the paint boundaries shown in Figure 1, and were as follows:

(1) B-18 no. 37-464 was painted on all underneath surfaces (area “A”) in Shade No. 46 Insignia White camouflage enamel. Side and top areas (areas “B” and “C”) were finished in Flight Camouflage white enamel white (haze paint) applied in a pattern of graduated light reflectance values, over black camouflage enamel, to produce a bluish “haze” effect.

(2) B-18 no. 37-468 was painted over all exterior surfaces (areas “A, B, and C”) in flight camouflage white enamel (haze paint) applied in a pattern of graduated light reflectance values, over black camouflage enamel, to produce a bluish “haze” effect.

(3) B-18 no. 37-621 was painted on all underneath surfaces (area “A”) in Shade No. 46 Insignia White camouflage enamel, with the vertical control surfaces and side of the fuselage (area “B”) painted with Shade No. 43 Neutral Gray camou­flage lacquer. The top surfaces (area “C”) were left in the original Dark Olive Drab color.

(4) B-18 no. 37-561 was left in its original camouflage colors of Dark Olive Drab above and on the sides surfaces (areas “B and C”), with the lower surfaces in Neutral Gray (area “A").

(5) B-18 no. 37-574 was left in its original finish of Shade No. 47 Insignia White all over.

All of the test flights were made on days with unlimited ceiling, with normal haze conditions for the area and with widely scattered or no clouds. Aircraft were viewed from the ground while they were flying at altitudes of 2,000, 4,000, 6,000. and 10,000 feet, both directly overhead and at a distance of approximately one mile from the viewing point while flying in E-W and N-S directions. The relative effectiveness of the camouflage was observed on both approach and departure runs.

Conclusions: it was found that the most effective combination of camouflage schemes under all conditions was as follows:

a. Underneath surfaces, leading edges and “front view” areas – Shade No. 47 Insignia White.

b. Side (essentially vertical) surfaces – Shade No. 43 Neutral Gray.

c. Top surfaces – Shade No. 41 Dark Olive Drab.

The exact shade of gray used on the vertical surfaces was not critical, but it was recommended that very bright or very dark grays should not be used. Tests were also run by flying a B-17E, at 6,000 and 10,000 feet, above the camouflaged B-18s flying at 2,000 and

4.000 feet. It was found that none of the different camouflage schemes were best under all of the test conditions. It was also found that the haze painted airplanes did not have any camouflage characteristics which were better than at least one of the other schemes. The report finally recommended that the Anti-Submarine Command should paint its aircraft in the scheme described in the conclusions above.

A major revision of T. 0.07-1-1 was issued on December 26,1943. It started by stating that painting of the exterior metal surface of AAF aircraft was discontinued, except as directed for aircraft destined for foreign agencies. This was a major revision of the requirements and the document is reproduced below:

Martin Baltimore Mk 1, FA204, prior to delivery to the RAF, in Dark Earth and Middlestone over Azure Blue finish. These were the standard RAF desert colors for North Africa. (USAF via Gerry R. Markgraf)

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Douglas C-53-DO, 41-20062, as seen at Lubbock Field, Texas, in late 1943. It has the identification yellow nose and rear fuselage bands ordered for transports flying within the continental USA. (Nick Williams)

TECHNICAL ORDER No. 07-1-1 December 26, 1943

DOPES, PAINTS AND RELATED MATERIALS
GENERAL—AIRCRAFT CAMOUFLAGE, M ARKINGS AND INSIGNIA

This Technical Order replaces T. O. Nos. 07-1-1, dated June 15,1943; 07-1-IC, dated July 3, 1943; and 07-1-ID, dated September 24,1943.

a. DAY CAMOUFLAGE. – Standard day camouflage for liaison aircraft, helicopters, and gliders consists of upper surfaces olive drab, shade No, 41, Bulletin 41 or AN Bulletin 613; and lower surfaces neutral gray, shade No. 43, Bulletin 41 or Army-Navy sea gray, No. 603. (See AN Bulletin 157A.)

b. NIGHT CAMOUFLAGE.

(1) GENERAL. – Special black camouflage paints, color designation, “Jet No. 622,” have been developed for use in minimizing visibility of airplanes at night. The estimated quantities of materials required will be found in table 1.

(2) PREPARATION OF SURFACES.

(a) Metal surfaces which are painted with dull camouflage finish should preferably be stripped to bare metal in accordance with T. O. No. 07-1-7, and the metal cleaned and primed in order to save weight. However, if weight is not critical, Jet No. 622 camouflage enamel may be applied directly over the dull finish, after thorough cleaning and careful smoothing with No. 320 or finer waterproof sandpaper and water to minimize porosity and roughness.

NOTE Application of lacquer over enamel may cause lifting of the enamel. If, upon trial, trouble is encountered in application of lacquer over the old finish, the finish must be removed or Jet No. 622 enamel used. Prior to application of Jet No. 622 camouflaged enamel, unpaintcd metal surfaces will be cleaned in accordance with Specification No. 98-20007 (or phosphoric acid alcohol cleaner in accordance with T, O. No. 01-1-1) and then primed with one smooth coat of zinc chromate primer, Specification No. AN-TT-P-656.

(b) Wood surfaces painted with dull camouflage or aluminized finish will be cleaned and then smoothed out by sanding with No. 320 or finer waterproof sandpaper and water, prior to application of the Jet No. 622 camouflage enamel. Unfinished wood sur faces will be prepared in accordance with Specification No. AN-C – 83, to produce a surface as smooth and free from irregulari­ties as possible, prior to application of the Jet No. 622 camouflage enamel. Surfacer, Specification No. 14116, may be used in direct-on-wood finishes, provided the film is sanded as thin as possible commensurate with the desired smoothness and “hold­out” or fullness of gloss of the final finish.

TABLE 1

METAL SURFACES FABRIC SURFACES

North American P-51D-5-NA, 44-13550, aircraft A9-M of the 380th FS, 363rd FG, seen at strip A-8 on August 10,1944. Note how the invasion stripes have been painted out above the top of the fuselage and insignia, with dark olive drab. The same was dune to the stripes above the wings. Squadron color on the spinner is blue. (William L. Swisher)

(3) APPLICATION. – Application of Jet No. 622 camouflage will be by spraying, which presents no unusual problems. How­ever, because of the need to produce a black finish having as near mirror-like an appearance as possible, it is necessary to take extra precautions to avoid dust during painting and drying. Dust which becomes adhered to the paint, especially on the bottom and side surfaces, will result in reduced effectiveness of the camouflage.

NOTE Lacquer, being faster drying, is preferred for Jet No. 622 finish for this reason.

Lockheed P-38H-5-LO, 42-66923; P-51A-10-NA, 43-6246: and P-47D-23-RA, 42-27798, From the AAF School of Applied Tactics, at Orlando Army Air Base, FI. Note the white ellipse markings of the school aircraft on the nose. The last three digits of the serial number were painted black on the ellipse. The school was under control of the AAF Board, who reported to the Dir. of Mil. Req. in Washington. (USAF via Gerry R. Markgraf)

Jet No. 622 lacquer will be applied to the properly prepared surfaces of metal {and wood) by spraying not less than two full coats; Jet No. 622 enamel, one mist coat and one hiding coat. Application of the camouflage material will be controlled so as to produce a finish of uniform hiding and blackness and very high gloss.

NOTE In the event that a rough finish is applied in the field, it may be smoothed by rubbing lightly with 320 or 400 waterproof abrasive paper after which a light, but wet, coat of camouflage material should be applied,

(4) FABRIC SURFACES. – Fabric doped with dull camouflage finish which has not become brittle, may be converted to jet camouflage by the following procedure: Remove all grease and dirt, then wash with soft soap and water, rinse with clean water, and allow the surfaces to dry. Apply two wet spray coats of thinner, Specification No, AN-TT-T-256, to soften up the old finish, and allow to dry not more than 30 minutes. Apply three spray coats of gloss black pigmented dope, the last of which is cut with an equal portion of clear dope, Specification No. AN-TT-D-514, before thinning to impart added gloss. If fabric is new, dope in accordance with Specification No. 98-24100, using a minimum of two brush and two spray coats of AN-TT-D-514 dope. Follow with one spray coat of sanding guide dope (3 ounce pigment, aluminum per gallon of AN-TT-D-514 dope). Sand (dry) moderately with No. 280 (or finer) sandpaper to minimize weave effects.

NOTE Ground parts when sanding.

Finish with three spray coats of gloss black pigmented dope, Specification No. AN-TT-D-554, the last coat of which is cut with an equal portion of (clear), Specification No. AN-TT-D-514 dope, before thinning, to impart added gloss.

(5) MAINTENANCE OF JET NO. 622 FINISH.

(a) The effectiveness of night camouflage is reduced by accumulations of mud, dust, oil, gun blast, or exhaust gas residues, and chalking of the paint film, particularly on sides and under surfaces, of aircraft. Excessively widespread scratches, and es­pecially bare metal exposed by scratches, also have a deleterious effect. Therefore, cleaning and maintenance operations on the airplane should be so conducted as to avoid scratching the finish and to minimize exposure of bare metal. Before engaging in night operation, mud, dust, muzzle blast or exhaust gas residues and oil should be removed and all bare metal areas re-touched with Jet No. 622 camouflage material, especially on sides and under surfaces. At least once a week, and oftener, if necessitated by ground or atmospheric conditions, the airplane shall be washed and then polished with aircraft polish, stock No. 7300755000. The use of wax is discouraged because it will interfere, subsequently, with the drying of paint where retouching is necessary and because satisfactory results are obtainable through the use of polish. THE CLOSER THIS TYPE OF CAMOUFLAGE AP­PROACHES THE APPEARANCE OF A BLACK MIRROR, THE MORE EFFECTIVE IT BECOMES.

(6) REJUVENATION. – If, on extended exposure, a surface haze appears on the paint, which cannot be removed with polish, wash with soap and water and rinse with clean water then wipe surface thoroughly with clean cloths wet with naphtha or solvent, Specification No. P-S-661. The cloths should be wet by pouring solvent on them and should not be dipped into the solvent. Spray one light coat of Jet No. 622 camouflage enamel, Specification No. AN-E-3, or lacquer, Specification No. AN-TT-L-51. Clean doped surfaces in the same manner, but apply only glossblack dope, Specification No. AN-TT-D-554, cut with clear dope, Specification No. AN-TT-D-514.

C A U1′ 1 О N DO NOT APPLY LACQUER ON JET 622 ENAMEL, AS IT WILL INJURE ENAMEL FILM. CHECK THF STENCILED MARKING FOR APPLICABLE SPECIFICATION OR TEST WITH LACQUER SOLVENT.

Northrop P-61A-1U-NO, serial unknown, named “Lucky Lady” on the nose and “Doris” on the right hand engine cowl, seen at strip A-8 on August IS, 1944. (William L. Swisher)

Republic P-47D, of the 375th FS, 361st FG, running up at Langley Field, Virginia, in the USA, prior to the unit embarking for Bottisham, England, in July 1943. This was the last P-47 Group to be assigned to the Eighth Air Force. Note the fancy nose cowl red marking with white trim; these markings were not used in England. Serial number not visible. (USAF via Gerry R. Markgraf)

Republic P-47D-25-RE, 42-26418, aircraft HV-A, flown by Lt. Col. Francis Gabreski, of the 61st FS, 56th FG, having its guns rearmed, Note the colors of the gun hay: zinc chromate primer and Dark Olive Drab on the wing rib top faces. Aircraft was painted in dark green and ocean gray, courtesy of the RAF, with front half of the cowl and the rudder in red. Full invasion stripes were above and below this aircraft. Col. Gabreski was shot down over Germany in this aircraft on July 20,1944. (USAF via Gerry R. Markgraf)

c. METAL CORROSION PREVENTION. – The exterior of alclad metal fuselages and metal airfoils does not ordinarily require paint as a protection against corrosion. (Refer to T. O. No. 01- 1-2.) However, where it is necessary to provide additional pro­tective finish on any parts not made from aluminum coated aluminum alloy, any such unprotected parts will be cleaned with phosphoric acid alcohol cleaner, finished with one coat of zinc chromate primer, Specification No. AN-TT-P-656, and two coats of aluminized lacquer. Aluminized lacquer consists of lacquer, cellulose nitrate, clear, Specification No. AN-TT-L-51, pig­mented with 12 ounces per gallon of paste, aluminum pigment, Specification No. TT-A-468.

d. ANTIGLARE. – Antiglare camouflage olive drab or dull dark green paint is authorized where necessary, to be applied to top of the fuselage in front of the cockpit and on the inside upper one-fourth of the engine nacelle forward of the leading edge of the wing.

e. WOOD SURFACES. – Exterior plywood surfaces will be finished with two coats of sealer, Specification No, AN-S-17, or on open grained woods, one coat of sealer followed by one coal of surfacer, Specification No. 14115, sanded down, before the final two coats of aluminized varnish. Use 18 to 20 ounces of pigment, aluminum paste, Specification No. TT-A-468, in each gallon of varnish. Specification No. AN-TT-V-116.

f. WOOD – FABRIC. – Exterior wood surfaces (fabric covered) will have a minimum of one brush coat of sealer, Specification No, AN-S-17, and two brush or spray coats of clear tautening dope. Specification No, AN-TT-D-514, prior to attachment of fabric. The fabric may be cemented in place with the second coat of clear dope, or may be laid on the dried second coat

with cementing effected by wetting the fabric with thinner or thinned dope. The finish over the fabric shall consist of a minimum of one brushed (first) coat and two sprayed coats of clear tautening dope followed by the necessary spray coats of pigmented dope.

g. FABRIC.

(1) Exterior fabric parts will have a minimum of two brush and two spray coats of clear nitrate dope, Specification No. AN-TT – D-514 (aluminized dope vehicle, Specification No, AN-TT-D – 551, is not a suitable substitute, as it does not have the tautening qualities of Specification No. AN-TT-D-514). This will be followed by two or more coats of aluminized dope prepared by adding 8 ounces per gallon pigment, aluminum paste, Specification No. TT-A-468, to dope, cellulose nitrate, dear, Specifica­tion No. AN-TT-D-551, before thinning. Patching will be accomplished with clear dope, Specification No. AN-TT-D-614, applied in same manner as semipigmented dope previously used.

(2) For emergency rejuvenation of old fabric, add 1 fluid ounce each of tricresyl phosphate and castor oil to 1 gallon of two to one mix of clear dope, Specification No. AN-TT-D-514, and blush retarding thinner, Specification No. AN-TT-T-258. Apply one coat by brush to clean surface, followed by one spray coat. After several hours drying, spray one coat of aluminized dope, prepared as specified in paragraph 2.g.(l).

North American P-51B-15-NA, 42-106950, aircraft WR-P “Iowa Beaut” of the 354th FS, 355th FG, 65th FVV, 2nd Air Div, Eighth Air Force in summer 1944. Note how the invasion stripes have been painted out with smooth finish paint. This may be RAF Smooth Dark Green, rather than Dark Olive Drab, as it is slightly richer in color. Note white nose cowl and yellow tab, denoting the 354th FS. (LISAF)

North American P-51D – 5-NA, 44-13357, aircraft B7-R “T1KAIV” of the 374th FS, 361st FG, 65th FW, 2nd Air Div, with underneath invasion stripes only, after October 1944. Note 6 kills under canopy. Aircraft has the unit yellow spinner and nose. (USAF)

3. MARKINGS.

Only such markings and identifying insignia as outlined herein will be used on AAF aircraft except as specifically authorized by the Commanding General, AAF.

a. PARTS. – Each part and assembly will be permanently and legibly marked the same number as the drawing number in such location that it can be read after assembly in the unit. (See Specification No. 98-24105.)

b. DETAIL. – Various detail and code markings for the cockpit, fuselage, oil lines, etc., as required in Specification No. 98­24105, will be maintained. In addition, Jet No. 622 finishes (on metal and wood) surfaces will be stenciled in yellow on an upper surface with the code number of the approved gloss black of the paint manufacturer under the two applicable specifications (Bulletin 102 for lacquer, and 148 for enamel), two dashes, followed by the symbol for the material as “L-51” or “E-3.” Ex­ample: 6005—L-51.

c. RADIO CALL NUMBERS

(1) Radio call numbers of not less than four numerals will be maintained on all AAF aircraft except as stated in paragraph 3.c.(3), utilizing both sides or each outboard side, as applicable, of the vertical stabilizer and rudder assembly. These call number^, or designators, will be of a size discernible at a distance of 150 yards. They will be derived by deletion of the first numeral of the serial number (4) and the hyphen (-), and the combination of the remaining four or more numerals. In case of serial numbers of type 41-7, use zero as necessary to make four numerals, as 1007. Decalcomauia may be used where avail­able.

(2) On all airplanes operating solely within the continental limits of the United States, the radio call numbers will also be placed, with the top forward, on the lower surfaces of wings, except asstated in paragraph 3.c,(3). The size of the number to be painted on aircraft and the matter of whether the numbers will be painted on the left wing only or both wings will be determined by the local using agency in accordance with the space available and the desired usage,

(3) Radio call numbers in neither location are required, however, on primary trainers not equipped with radio and which bear field identifying numbers.

d. PROPELLER MARK1NGS. – American propeller blades, design Nos. A-272U07 and C-3821306, used in sets in Aeroproducts and Curtiss propellers, respectively, will be identified by a yellow stripe, 3/8 inch in width and 3/8 inch inboard of the yellow tip section. A. O. Smith propeller blades used in sets in Curtiss propellers will be identified by two 3/8-inch yellow stripes, one 3/8 inch inboard of the yellow tip section and the other stripe 3/8 inch inboard from the first. These stripes will extend completely around the blade section. The stenciled markings between the 18- and 24-inch stations on the cambered side of the propeller blades will be retained. When the exact location of the blade reference station is known, a stripe of yellow paint 1/8 inch wide, 2 inches long and spaced equally distant between the leading and trailing edge of the blade, will be placed on the thrust face at the reference station.

CAUTION Unless the exact location of the reference station on the blade is known no attempt will be made to identify this location by the afore-mentioned stripe.

A conference was held at Mat. Lab. (WF), between February 23 and 27, 1945, to discuss the unsatisfactory condition of the Jet No. 622 finish on P-61 aircraft being received at overseas bases. It was decided that the problem was probably due to non-conformance to requirements and the use of unapproved enamel. Tests had shown that the enamel finish was definitely improved by use over a zinc chromate primer.

Mat. Lab. recommended that the Procurement Section (WF) should provide Northrop Aircraft with the latest list of approved specs, and that Northrop be requested to use a coat of zinc chromate primer before applying two coats of Jet No. 622 Lacquer to the P-61. They also recommended that the materials being used by Northrop be checked for conformance to spec, requirements.

Douglas A-26B-35-DL, 41-39456, aircraft E3-K of the 732nd BS, 453rd BG, Ninth Air Force. The A-26 had a very protracted development and did not start replacing the A-20s until lute 1944, despite the 1941 serial number. (March AFB Museum)

Large number of AAF aircraft seen on Iwo Jima on March 6,1945, includes twenty P-51s, four P-61sof the 548th NFS, two C-47s and one C-46, plus one Navy TBF, Mount Suribachi is prominent in the background. The P-61s are in gloss black, the P-51s arc in natural metal and the transports camouflaged. (USAF)

Curtiss C-46D-I0-CU, 44-77658, aircraft N5-D of the 313rd TCG, Ninth Air Force. It was seen at strip Y-32, Ophnven, Belgium, on March 24, 1945. It had just made an emergency landing after being hit by two 88mm shells while dropping US Army paratroopers over the Rhine at Wesel, Germany, during Operation VARSITY. (William L. Swisher)

A minor revision of Spec.98-24105-S, Amendment No. 2, was issued on March 18, 1946. However, all of the changes related to other spec, number changes except for further changes to the aircraft dope code markings (see Appendix В on aircraft maintenance markings.).

Revised version of ANA Bulletin No. 166, Gloss Colors, issued, June 1946.

A minor revision, ANA Bulletin No. 166a, was issued on June 6, 1946, which informed users that the earlier porcelain enamel panels were no longer available for distribution and that only cardboard enamel panels were now available. No changes were made to any of the standard gloss colors, which had been introduced in 1938.

New edition of T. O, 07-1-1 issued, June 1946.

A new edition of T, 0.07-1-1 was issued on June 7,1946, and became the last version to be produced by the AAF. It also introduced the long-lasting (still in use) method of indicating revisions by black vertical revision lines alongside the new or revised information. We will take advantage of this new feature by only printing information so marked. First was the preliminary note stating when the work was to be accomplished. This now read:

NOTE The work required herein (except paragraph 17.b.) will be accomplished as soon as practicable by all activities having the affected aircraft. The work directed in paragraph 17,b. will be accomplished prior to or at the next 100-hour inspection period by all activities within the continental limits of the United States having permanently assigned aircraft.

Consolidated XB-36-CF, 42-13570, made its first flight on August 8, 1946, and ultimately beat the XB-35 as the replacement for the B-29. Powered by six P & W R-4360 engines, it was also natural metal finish all over. (USAF)