Ever a subject of contention, confusion, speculation, and bar-room brawls, Waco's system of codifying its planes gets somewhat clarified courtesy of Jack Wilhelm, of the Waco Historical Society, Ray Brandly, author of the definitive Waco book, and Aerofiles' own Lennart Johnsson.

First letter = POWERPLANT (MOTOR CODES)

Second letter = AIRFRAME DESIGN
Indicated specific drawings or design changes,
varying considerably within individual models

Third letter = SERIES

Suffix = REMARKS
Dash number generally indicated first year of production

MOTOR CODES 1927-1929:

125 = 125hp Siemens-Halske

A = 220hp Wright J-5

B = 165hp Wright J-6-5

C = 225hp Wright J-6-7

D = 150/180hp Hisso A/E

G = 115hp Curtiss OX-5, 100hp OXX-6, 115hp Tank

J = 330hp Wright R-975

MOTOR CODES 1930-1942: A = 330hp Jacobs L-6MB

B = 175hp Wright R-540

C = 250hp Wright R-760

D = 285hp Wright R-760-E1

E = 350hp Wright R-760-E2

H = 300hp Lycoming R-680-E3

I = 125hp Kinner B-5

J = 365hp Wright R-975-E1

K = 100hp Kinner K-5

M = 125hp Menasco C-4

O = 210hp Kinner C-5

P = 170hp Jacobs LA-1

Q = 165hp Continental A-70

R = 125hp Warner Scarab

S = 420-450hp P&W Wasp Jr

U = 210hp Continental R-670, 225hp W-670-K, 220hp W-670-6

V = 240hp Continental W-670-M

W = 450hp Wright R-975-E3

Y = 225hp Jacobs L-4MB

Z = 285hp Jacobs L-5MB

Lycomings were not used until model E in 1940. Kinner C-5 was only on two planes, and the 160hp R-5 was never used.

BASIC AIRFRAME

A = Primary Glider

B = Open types, 1932 & 1933

C = 1931 open types with P & Q engines (LA-1 & A-70)

D = 1931 cabin types

E = 1932 cabin types

G = C series closed types as from 1937

H = All D series

I = 1933 cabin types

J = 1934 cabin model with Wright engine

K = 1934 cabin models with Continental & Jacobs engines and
    standard cabin models from 1935

L = 1933 (last) A series

M = 1934 open types

N = 1930 open types

O = 1935 custom cabin with Continental & Jacobs engines

P = All open types from 1936

Q = 1936 custom cabin types and 1930 National Air Tour Special

R = 1939 E series

S = Straightwing variants of basic model 10

T = Taperwing variants of basic model 10

U = 1935 custom cabin with Wright engines

V = All N series

Y = Version of the Taperwing with Wright R-975

X = Variant of the basic model 10 with OX-5 or OXX-6

SERIES

A = Two-place with side-by-side seating 1932 & 1933

C = All cabin models 1931-1935, and Custom cabin models from 1936

D = Military series 1934-1937

E = Variants of the basic model 10 with OX-5 or OXX-6 and
    "Executive" cabin models from 1939

F = Tandem cockpit 2 & 3-place open models 1930-1937

G = 1930 National Air Tour Special; two CRGs only, c/n 3349/3350

M = See second letter Y

N = Tricycle-gear cabin series 1937-1938

O = Open models 1927-1929

S = "Standard" cabin models 1936-1937

T = Model RPT; one only, c/n 6000

W = Postwar "Aristocraft"; one only, c/n 9600

Z = Primary glider

REMARKS

A = Armed variants of the D series

S = Used in 1935 to differentiate between the current versions of the
    earlier (or "standard") cabin series and the newly introduced
    "Custom" cabin series. Became third letter in 1936, i.e.: model YKS
    introduced in 1934, was YKC-S and YKS-6 in 1936 (all were built
    under the same ATC)

1,2,3 = Used in 1935 to identify higher-powered versions of the Wright
    R-760, Jacobs, and P&W Wasp Jr engines. See first letters C, S, Y,
    Z, and second designation of D and E (e.g.: S3HD-A, CUC-1, YOC-1)

6,7,8 = Used to indicate models introduced in 1936 thru 1938; e.g.:
    models UPF-7 and VKS-7, introduced in 1937, remained in production
    until the early '40s with the largest annual production of the
    UPF-7 being achieved in 1941.

WACOS BY YEARS OF PRODUCTION:

1923 = 6

1924 = 7; 8

1925 = 9

1926 = 9

1927 = 10; 125; 10-W/ASO; BSO; DSO

1928 = 10/GXE; 125; ASO; 10-T/ATO; BSO; CSO; CTO; DSO

1929 = ASO; ATO; BSO; CSO; CTO; DSO; GXE; JTO; JWM; JYM; KSO;
    LAJ; NAZ; RSO

1930 = BSO; CSO; CRG; CTO; HSO; HTO; INF; KNF; MNF; LAJ; NAZ;
    PSO; QSO; RNF

1931 = BSO; CSO; CTO; PCF-2; KNF; MNF; ODC; OSO; PDC; QDC; QCF;
    QCF-2; RNF

1932 = BBA; BDC; BEC; CSO; CTO; ENF; IBA; KBA; OBF; OEC; PBA;
    PCA; PBF; RBA; RCA; TBA; TBF; UBA; UBF; UBF-2; UEC

1933 = CHD; CMD; CSO; CTO; FGH*; JYO; PBF-2; PLA; UBF-2; UIC; ULA

1934 = CJC; S3HD; UKC; UMF-3; WHD-A; YKC; YKC-S; YKS-6; YMF-3; ZKS

1935 = CPF; CPF-6; CJC-S; CUC; CUC-1; CUC-2; S2HD; S3HD-A; UKC-S;
    UOC; UMF-5; YKC-S; YMF-5; YOC; YOC-1

1936 = AQC-6; CPF-6; CQC-6; DJC-S; DKS-6; DPF-6; DPF-7; DQC-6;
    EPF-6; EQC-6; SQC-6; UKS-6; UPF-6; VPF-6; YKC-6; YKS-6;
    YPF-6; YQC-6; ZKS-6; ZPF-6; ZQC-6

1937 = AGC-7; DGC-7; EGC-7; JHD-6; LPF-7; UGC-7; UKS-7; UQC-6;
    VGC-7; VKS-7; VPF-7; VQC-6; YGC-7; YGC-8; YKS-7; YPF-7;
1938 = AGC-8; AVN-8/N; EGC-8; JHD; UPF-7; VKS-7; VPF-7; WHD;
    YKS-7; YPF-7; YVN-8/N; ZGC-8; ZKS-7; ZPF-7; ZVN-7/N;
    ZVN-8/N

1939 = AGC-8; AVN-8/N; EGC-8; JHD; UPF-7; VKS-7; VPF-7; WHD;
    YKS-7; YPF-7; ZGC-8; ZKS-7; ZVN-8

1940 = ARE; HRE; RPT; SRE; UPF-7; VKS-7; WRE; YKS-7; ZKS-7

1941 = ARE; HRE; SRE; UPF-7; VKS-7; YKS-7; ZKS-7

1942 = SRE; UPF-7; VKS-7F

1947 = W

Unknown/unspecified years = ICA; KCA; QNF; SFB; TCA; UCA; UCF; UDC