The Waco S Series is a family of

American American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...

cabin biplanes produced by the

Waco Aircraft Company The Waco Aircraft Company (WACO) was an aircraft manufacturer located in Troy, Ohio, United States. Between 1920 and 1947, the company produced a wide range of civilian biplanes. The company initially started under the name Weaver Aircraft C ...

starting in 1935.

Development and designations

The Waco closed cabin biplanes, initially known as the C (for Cabin) series were all unequal span, staggered single bay biplanes. They were fabric covered, the wings having a wooden structure and the control surfaces and fuselage constructed from metal frames. The wings were braced with outward splayed ''N'' form interplane struts plus a strut connecting the centre section rear spar to the bottom of the forward interplane strut, following Waco's standard practice. They had a fixed tailwheel undercarriage, which could be partially or completely faired. There was seating for 4/5 including the pilot. Most were powered by 7 cylinder radial engines of different makes. When

Waco Waco ( ) is the county seat of McLennan County, Texas, United States. It is situated along the Brazos River and I-35, halfway between Dallas and Austin. The city had a 2020 population of 138,486, making it the 22nd-most populous city in the st ...

released its slightly larger custom cabin series, those original Cabin series aircraft it continued to produce were redesignated as 'Waco Standard Cabin series', with the final designation letter changing from C to C-S to S. For instance in 1935 the YKC became the YKC-S, then the YKS-6 in 1936. All three were indistinguishable from each other. Waco used numeric suffixes like -7 to indicate a subvariant ''introduced'' in 1937 and so on. The standard cabin can be subdivided again into three groups, early examples having a boat-tail skylight (QDC, OEC & UEC), mid series aircraft with a faired skylight (CJC, UIC, UKC, YKC) or late examples with no skylight (DJC-S, HKS, ZKS, UKC-S UKS-7, VKS-7, YKC-S, YKS-6 & 7, ZKS-6 & 7). All of the types built under the C-S and S designators lacked a skylight though the skylight could be faired over on earlier aircraft. Later types were also slightly longer than earlier models. From about 1937, all S series aircraft had wings lacking leading and trailing edge cutouts. Externally, the S series differed from the Custom or later C series in continuing with early C series features such as ailerons on both wings, linked by a prominent strut, and square edged rear side windows. Like most Waco aircraft, the S series were available with many different engines (identified by the first letter of the type designation).

Operational history

The S series proved to be popular with both commercial and private pilots and over 50 were still airworthy in 2001, including examples of the CPTP VKS-7F version. During the

Second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

several S series aircraft were impressed by the

USAAF The United States Army Air Forces (USAAF or AAF) was the major land-based aerial warfare service component of the United States Army and ''de facto'' aerial warfare service branch of the United States during and immediately after World War II ...

as the UC-72K or UC-72M and used as

Liaison Liaison means communication between two or more groups, or co-operation or working together. Liaison or liaisons may refer to: General usage * Affair, an unfaithful sexual relationship * Collaboration * Co-operation Arts and entertainment * Li ...

, executive light transport and instrument refresher training aircraft.Simpson, 2001, p. 575 Only a handful remain airworthy in this century.

Variants

(per Simpson, 2001, p. 575 and Green, 1965, p. 307) ;DKS-6 : ;HKS-7 :

Lycoming R-680-13 The Lycoming R-680 is a nine-cylinder air-cooled radial engine, the first aero engine produced by Lycoming. The engine was produced in two types, the E and B series; both are essentially the same. The B4E was available in a trainer version wit ...

;UKS-6 : Continental W-670-K ;UKS-7 : Continental W-670-K ;VKS-7 : Continental W-670-M The -7F model was used in the CPTP program, F indicating that flaps were fitted. ;VKS-7F : Continental W-670-M The -7F model was used in the CPTP program, F indicating that flaps were fitted. WacoYKS-6

;YKS-6 :

Jacobs L-4 The Jacobs R-755 (company designation L-4) is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States by the Jacobs Aircraft Engine Company. Design and development The R-755 was first run in 1933 and was stil ...

; YKS-7 :

;ZKS-6 :

Jacobs L-5 The Jacobs R-830 or L-5 is a seven-cylinder, air-cooled, radial engine for aircraft manufactured in the United States, production started in 1935.Gunston 1989, p.85. Design and development The R-830 was effectively an enlargement of the R-755 ...

;ZKS-7 :

;HKS-7 :

Lycoming R-680 The Lycoming R-680 is a nine-cylinder air-cooled radial engine, the first aero engine produced by Lycoming. The engine was produced in two types, the E and B series; both are essentially the same. The B4E was available in a trainer version wit ...

-13

Specifications (VKS-7F)

References

Notes

Bibliography

* * * *

External links

Technical and model data on Waco aircraft
{{WACO 1930s United States civil utility aircraft

S series S series or Series-S or ''variation'', may refer to: Transportation * Bedford S series, trucks * Chevrolet S-series, pickup trucks * GMC S-Series, school bus * International S series, trucks * International S series (bus chassis) * S series (T ...

Biplanes Single-engined tractor aircraft Aircraft first flown in 1935