Hiller UH-12 / H-23 / HTE-1
UH-12E
Stanley Hiller Jr designed the Model 360 which has enjoyed considerable commercial success since its first flight in 1948. It was derived from the UH-5 which had proved very unstable during trials and had subsequently been fitted with a new stability system patented as the Hiller 'Rotormatic'. It entailed fitting the two-blade rotor with two small paddles which acted as a control rotor and were also connected to a hanging stick. This servo 'paddle control' system tilts the rotor head and actuates the cyclic pitch control.
Known as the Hiller UH-12 as Hiller had become part of United Helicopters, the Hiller UH-12, incorporating a two-bladed main rotor and a two-bladed tail rotor on an upswept boom. The UH-12 had a framed 'bubble'-type cabin, no fuselage structure around the engine, skid undercarriage and a 175hp Franklin 6V4-178-B33 engine. Maximum takeoff weight was 1015kg.
In 1963 the US Army was buying 137 more Hiller OH-23 observation helicopters to meet its requirements until a five-way competition for a light helicopter was decided at Ft. Rucker, Alabama. In 1963 the British navy was adding seven UH-12E to the 14 bought in 1962. The Royal Navy used its 12E’s to train fleet pilots at Culdrose Naval Air Station in Cornwall. They were fitted for instrument flying. 12E were also in use with Canada’s army and air force, known as CH-112.
![]() UH-12C
A purely military version, the UH-12D / OH-12D, flew on 3 April 1956 and 483 went to the US Army. The Franklin engine had been replaced by the more powerful 320hp Lycoming VO-540, and the transmission had also been changed to increase the service life of the helicopter.
![]() Hiller UH-12E ZK-HFG
The UH-12EL was a UH-12E retro-fitted with Ham-Standard rotor stability augmentation system, stainless steel rotor blades and 1400kg TOGW.
The UH-12E4 featured inverted rear tail planes and lengthened cabin to accommodate pilot plus rear bench seat for 3 pax. All new helicopters now have these features and they can be retrofitted on Model 12Es. Designated UH-12E4T when fitted with Soloy conversion to 400shp Allison 250-C20B turboshaft. This engine conversion was jointly developed with Soloy Conversions of Chehalis, Washington who began work on it in 1976.
UH-12
Engine: 175hp Franklin 6V4-178-B33
TOGW: 1015kg
Undercarriage: skid
UH-12A
1950
Engine: 200hp Franklin 6V4-200-C33 or Franklin 6V-335-B, 210 hp
TOGW: 1082kg
UH-12B / HT Mk.1
Engine: 200hp Franklin 6V4-200-C33 or Franklin 6V-335-B, 210 hp
TOGW: 1128kg
HTE-2
Engine: 200 h.p. Franklin
Rotor dia.: 35 ft
Weight: 2,500 lb
Max. Speed: 84 mph
Seats: 3
UH-1C
Engine: 200hp Franklin 6V4-200-C33
UH-12D / OH-23D Raven
Engine: 241kW / 250hp Textron Lycoming VO-435-A1C
Main rotor diameter: 10.82m
Length: 8.53m
Height: 2.97m
Empty weight: 824kg
TOGW: 1240kg
Max speed: 153km/h
Cruising speed: 132km/h
Service ceiling: 4025m
Range: 330km
UH-12E / OH-23G
Engine: 305hp Textron Lycoming VO-540-A1A / Lycoming VO-540-C2A, 305 hp.
TBO: 1200 hrs.
Main rotor: 10.8 m / 35.3 ft.
Seats: 3.
Length: 40.7 ft.
Height: 10.1 ft.
Max ramp weight: 3100 lbs.
Max takeoff weight: 3100 lb / 1410 kg.
Standard empty weight: 1759 lbs.
Max useful load: 610 kg / 1341 lbs.
Max landing weight: 3100 lbs.
Max sling load: 1000 lbs.
Disc loading: 3.2 lbs/sq.ft.
Power loading: 10.2 lbs/hp.
Max usable fuel: 516 lbs.
Max rate of climb: 993 fpm.
Service ceiling: 15,000 ft.
Hover in ground effect: 10,400 ft.
Hover out of ground effect: 6800 ft.
Max speed: 83 kts.
Normal cruise @ 3000 ft: 51 kts.
Max cruise: 80 kts
Fuel flow @ normal cruise: 125 pph.
Endurance @ normal cruise: 3.9 hr.
Max range: 390 km.
Seats: 3.
UH-12EL
Engine: 305hp Textron Lycoming VO-540-A1A
TOGW: 1400 kg
UH-12E3
Seats: 3
UH12E Soloy
Engine: Allison 250-C20 turbine, 400 shp
UH-12E3T / UH-12ET
Seats: 3
UH-12EJ
Engine: Allison 250
UH-12ET
Engine: Soloy 400shp Allison 250-C20B turboshaft
Hiller 12E4
Engine: Lycoming VO-540-C2A, 305 hp.
Seats: 4.
Disc loading: 2.84 lb/sq.ft.
Pwr loading: 9.18 lb/hp.
Max TO wt: 2800 lb.
Empty wt: 1890 lb.
Equipped useful load: 886 lb.
Payload max fuel: 370 lb.
Range max fuel/ cruise: 274 nm/ 3.2 hr.
Range max fuel / range: 312 nm/ 4.7 hr.
Service ceiling: 16,200 ft.
Max cruise: 83 kt.
Max range cruise: 67 kt.
ROC: 1290 fpm.
HIGE: 10,800 ft.
HOGE: 7200 ft.
Max sling load: 1000 lb.
Fuel cap: 276/516 lb
Seats: 4
UH-12E4T
Engine:Soloy 400shp Allison 250-C20B turboshaft
UH-12E5
Engine: 340hp Textron Lycoming VO-540
Seats: 5
UH-12E-L3
Engine: Lycoming VO-540-C2B, 305 hp
Main rotor diameter: 35 ft 5 in / 10.80 m
Empty weight: 1759 lb / 798 kg
Normal TO weight: 2800 lb / 1270 kg
Max overload weight: 3100 lb / 1405 kg
Max cruise SL: 78 kt / 90 mph / 145 kph
Max ROC SL: 1290 fpm / 393 m/min
Service ceiling: 15,200 ft / 4630 m
Range w/aux fuel, 2800lb/1270kg: 379 nm / 437 mi / 703 km
Seats: 3
Baggage capacity: 125 lb / 57 kg
Cabin length: 5 ft 0 in / 1.52 m
Cabin width: 4 ft 11 in / 1.50 m
Cabin height: 4 ft 5 in / 1.35 m
UH-12SL
Engine: supercharged Textron Lycoming TIVO-540
UH-12L
Engine: Textron Lycoming VO-540 engine.
UH-12 L3
Engine: 305hp Lycoming VO-540-C2A
UH-12 SL3
Engine: supercharged 315hp TIVO-540-A2A
UH12E-SCL
Engine: Allison 250-C20 turbine, 305 shp.
Vne: 96 mph.
MAUW: 3100 lbs.
Empty wt: 1650 lbs.
Useful load: 1450 lbs.
Endurance(@ 90 mph, 22 gal/hr): 2:05 hr.
Range (@90mph): 188 sm.
Max ROC: 1706 fpm.
Max vertical ROC: 1463 fpm.
![]() OH-23
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