When Waco released its slightly larger custom cabin series, those original Cabin series aircraft it continued to produce were re-designated 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 sub-variant 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.
Waco ZKS-6
Probably only one DKS-6 was built, in 1936.
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).
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 several S series aircraft were impressed by the USAAF as the UC-72K or UC-72M and used as Liaison, executive light transport and instrument refresher training aircraft. Two VKS-7 became UC-72D, one YKS-7 became UC-72K, and two ZKS-7 became UC-72M, in 1942.
1936 Waco YKS-6
The 29 ZKS-6 & 7 built were re-designated from ZKC-S in 1936.
Waco YKS-6
65 YKS-6 built and 21 ZKS-7 1937(ATC 626) built at $5,695, one was converted to HKS-7 (300 HP Lycoming R-680-13 in 1947).
Waco YKS-7 NC19371
One YKS-7 was impressed by the USAAF as UC-72K in 1942 (NC19353) and one to the USN (09784).
Waco HKS-7 NC50662
The HKS-7 and HPF-7 of 1948 were not Waco production, but UKS (HKS-7) and UPF (HPF-7) modified with 300hp Lycomings (hence the “H”) and issued an STC. Two were reported as converted, NC29998 and NC32065, the latter reregistered NC50662.
Waco HPF-7 NC32065
Two of the 1937 UKS-7(ATC 648) were built, NC17721 and a CF- registered example, priced at $5,980.
Waco UKS-7 NC17721
Eighteen 1937 VKS-7 (ATC 648) were built at $5,980, of which two were impressed by USAAF as UC-72D (NC2307 and NC20955. Twenty-one VKS-7F cross-country trainers with controllable-pitch propeller went to the CPTP, with some repowered with 250hp W-670.
Waco VKS-7F NX31658
Six 1934 ZKS/ZKS-6 (ATC 533) were built; NC49, NC14050, NC17456, NC17460, CF-BDK, CF-BBQ, the ZKS-6 appearing in 1936. Redesignated ZKC-S Standard in 1935.
Waco ZKS-6 NC330TC
Eighty-six YKS-7/ZKS-7 were built, of which two ZKS-7 were impressed by the USAAF as UC-72M (NC2628, NC20954) and two as UC-72P (NC20909, NC20950). The 1937 ZKS-7 (ATC 626) was priced at $6,435.
VKS-7 Date: Jun 1937 Engine: Continental W-670M, 240 hp (179 kW) Length OA: 25’3″(7.70m) Span (upper): 33’3″(10.13m) Span (lower): 28’3″(8.61m) Empty weight: 1,917 lb (870 kg) Max gross weight: 3,250 lb (1,474 kg) Maximum load: 1,333 lb (605 kg) Maximum Speed: 149 mph (240 km/h) Cruise speed: 133 mph Stall: 50 mph Range: 530 mi Seats: 4-5 Price: $5,890 18 built
VKS-7 Date: 1938 Engine: Continental W-670M, 240 hp (179 kW) Length OA: 25’3″(7.70m) Span (upper): 33’3″(10.13m) Span (lower): 28’3″(8.61m) Maximum Speed: 145 mph (233 km/h) Empty weight: 1,960 lb (889 kg) Max gross weight: 3,250 lb (1,474 kg) Maximum load: 1,290 lb (585 kg) Price: $7,770 18 built
VKS-7F Date: Jun 1937 Engine: Continental W-670M, 240 hp (179 kW) Length OA: 25’3″(7.70m) Span (upper): 33’3″(10.13m) Span (lower): 28’3″(8.61m) Height: 8 ft 6 in (2.59 m) Wing area: 244 ft2 (22.69 m2) Empty weight: 2,256 lb (1,023 kg) Max gross weight: 3,250 lb (1,474 kg) Maximum load: 994 lb (451 kg) Maximum Speed: 145 mph (233 km/h) Cruise speed: 127 mph (204 km/h) Range: 518 miles (833 km) Service ceiling: 13,000 ft (3,962 m) Rate of climb: 850 ft/min (4.3 m/s) Crew: 1 Capacity: 3 or 4 passengers Price: $12,500 Built for Civilian Pilot Training Program as navigational trainer F designates use of flaps 21 built
YKS-6 Date: 1936 Engine: Jacobs L-4, 225 hp (168 kW) Length OA: 25’4″(7.72m) Span (upper): 33’3″(10.13m) Span (lower): 28’3″(8.61m) Maximum Speed: 144 mph (232 km/h) Empty weight: 1,809 lb (821 kg) Max gross weight: 3,250 lb (1,474 kg) Maximum load: 1,441 lb (654 kg) Price: $4,995
YKS-7 Date: Feb 1937 Engine: Jacobs L-4M/MB, 225 hp (168 kW) Length OA: 25’3″(7.70m) Span (upper): 33’3″(10.13m) Span (lower): 28’3″(8.61m) Empty weight: 1,882 lb (854 kg) Max gross weight: 3,250 lb (1,474 kg) Maximum load: 1,368 lb (621 kg) Maximum Speed: 146 mph (235 km/h) Cruise speed: 130 mph Stall: 50 mph Range: 590 mi Seats: 4-5 Price: $5,695
The 1931 Waco Model C “QDC” four place cabin biplane marked the entry of Waco in the field of cabin aircraft to compete with such established manufacturers as Bellanca and Stinson. The ship was powered with a Continental 165 hp engine and equipped with a metal propeller, cowl ring, electric starter, dual controls, brakes and tail wheel. The control wheel is on a jointed column, so that the ship can be piloted from the right or left, and the rudder pedals are dual.
The QDC was slightly shorter that the UOC and was 500 lb lighter. WACO replaced the QDC in 1933 with its most successful cabin design, the UIC.
The four place ODC of 1931 was priced at $5,885, and was modified to QDC.
Waco ODC NX11250
Two 1931 PDC (ATC 2-388) were specially modified three seat cabin biplanes built on special order.
WACO delivered 83 UICs before replacing the model with the UKC/YKC/CJC series of standard cabin aircraft in 1934. These trendy airplanes became a favourite of aviators like Jacqueline Cochran and corporate magnates such as Henry Dupont.
Forty 1934 UKC (ATC 528) were built selling for $6,285, redesignated UKC-S Standard in 1935, and UKS-6 in 1936.
Waco replaced the QDC in 1933 with its most successful cabin design, the UIC. Powered by a 210-horsepower Continental radial engine, the UIC was a four-person biplane with a conventional fixed tail wheel landing gear. The well-appointed cabin was accessed by automobile-style doors on each side, with a pair of individual front seats and a roomy rear bench seat for another two passengers.
The UIC’s fabric-covered fuselage was constructed from welded steel tubing, shaped with wooden formers and stringers while the wings were fabricated with spruce spars, spruce and wooden ribs, and aluminium edges. Ailerons on both wings were covered in aluminium and connected with push-pull struts that operated them in pairs. The UIC’s stable handling characteristics were considered to be forgiving, with good performance. Delivered with a full set of flight controls and instrumentation, the UIC was priced at a modest $6,000, well within the reach of smaller corporations and airlines.
WACO delivered 83 UICs (ATC 499), including prototype NC13061, selling for $5,985 before replacing the model with the UKC/YKC/CJC series of cabin aircraft in 1934.
More than fifty 1935 YOC at $6,895-7,295, and YOC-1 at $7,995 (ATC 569) were built.
Waco YOC NC15234
One YOC-1 was impressed by the USAAF as UC-72N (NC14683 or NC15248). South African Air Force impressed at least ten Wacos of different types (CUC and YOC).
Four 1935 UOC (ATC 568) were built, priced at $6,850-7,375. Two civil UOC were NC500/NC303E and NX14631.
Waco UOC ZK-ALA
The Royal New Zealand Air Force impressed one UOC (ZK-AEL/AEA). The Argentine Navy operated EQC-6 and one UOC.
All Aero 