Hamilton Standard Super-Hydromatic Propellers
Part 3: Aircraft Applications
by Tom Fey
Published 11 Jun 2018; Revised 27 Oct 2023
Douglas B-23 Test Mule – Pratt & Whitney acquired a Douglas B-23 Dragon, AAF serial 39-32, to use as a test mule for various R-2800 engines, including an R-2800-S and R-2800-27 with a dual rotation nose case for testing Model 624060-1 Super-Hydromatic propellers. The date and photographs, as well as the -1 designation of the prop, indicates this is an early version of the dual rotation propeller (Fig. 23).
Chance Vought F4U-1A Corsair – A bird cage F4U-1A Corsair was fitted with an unspecified version of the R-2800 with a dual rotation nose case for testing of the Model 624060 Super-Hydromatic propeller. Cables can be seen running from the engine accessory compartment over the fuselage back into the cockpit area. It appears this aircraft tested the early version of the dual rotation Super-Hydromatic. Flight test dates are not known, but likely sometime in 1944 (Figs. 24, 25).
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| Fig. 23. Six blade Model 62460 Super-Hydromatic dual rotation propeller on the Douglas B-23 test ship. | Fig. 24. The Vought XF4U-1A with early Model 624060 Super-Hydromatic dual rotation propellers photographed at Rentschler Field, East Hartford, Connecticut. Date unknown. | Fig. 25. The Vought XF4U-1A with early Model 624060 Super-Hydromatic dual rotation propellers photographed at Rentschler Field, East Hartford, Connecticut. Date unknown. |
Douglas XTB2D-1 Skypirate – Two prototypes of the Douglas XTB2D experimental torpedo bomber were built, serial numbers 36933 and 36934. The maiden flight occurred March 13, 1945. The aircraft used the R-4360-8 engine of 3,000 horsepower with a 0.425:1 reduction ratio and SAE #60 and #80 propeller shafts. The propeller had dual four-blade hubs with the fore blades being Drawing Number 2C15 B1-12 of 14' 1" diameter and aft blades 2C15B2-12 of 14' 3" diameter. This aircraft used the "late" version of the Super-Hydromatic with the barrel-shaped pump bodies. Final disposition of the two aircraft is unknown, but there is a photograph taken 3-Dec-48 of the intact but propeller-less -934 being hoisted aboard a barge (Figs. 26, 27, 28).
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| Fig. 26. Douglas XTB2D-1 serial 36933 with R-4360-8 engine and Model 828060 Super-Hydromatic dual rotation propellers. The aircraft weighed 18,405 lb. empty. | Fig. 27. Head on view of the XTB2D-1 with Model 828060 Super-Hydromatic dual rotation propellers. Fore propeller was 14' 1" diameter, aft propeller was 14' 3" diameter. | Fig. 28. The only Super-Hydromatic propeller blades known to exist. Stenciling is consistent with blades used on the XTB2D-1, and note the three blades in the upper part of the photograph are the outboard, right-handed blades while the lower four blades are inboard, left handed blades. Photograph circa 2015. |
Northrop XB-35 – The maiden flight of the XB-35 took place on June 25, 1946. Only 19 flights total were undertaken with the Model 828060 dual rotation Super-Hydromatic propellers due to chronic problem with failure to govern, hunting around a specific setting, and severe vibrational issues. The engines, propellers, and gearboxes were Government Furnished Equipment and were never adequately tested together before installation in the airframe. Single rotation Hydromatic propellers of 15' 3" diameter were subsequently installed to allow flight testing to continue. The first prototype flew only 24 total hours, and second prototype three hours, over three years of testing. Super-Hydromatic fore propeller blades were Drawing Number 2C15-B2-Oa7 on a #80 spline hub with a diameter of 15' 3". Aft propeller blades were Drawing Number 2C15-B2-Oa8 on a #60 spline hub with a diameter of 15' 1" with capability for both feathering and reverse pitch operation. Photographs indicate both "early" and "late" type Super-Hydromatics were installed and that six blade units, very likely of fixed pitch (both props in the pair are devoid of pump bodies) were installed, at separate times, on the outboard #1 or #4 positions on the aircraft (Figs. 29, 30, 31).
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| Fig. 29. Northrop XB-35 in flight with the Super-Hydromatic propellers. Note the absence of spinners on all the units and the apparent absence of pump bodies on the outboard props on #2 and #3 engines. Signed by chief test and maiden flight pilot Max Stanley. Collection of Tom Fey. | Fig. 30. Late Model 828060 eight blade Super-Hydromatic dual rotation propeller on the XB-35. | Fig. 31. The XB-35 with Model 828060 eight-blade Super-Hydromatic dual rotation propeller on the #2 and #3 engines. If this six blade dual rotation propeller on #1 engine is indeed a Super-Hydromatic, it is lacking pump bodies on both propeller units and it is likely pitch locked in cruise position. |
Grumman F6F-5 and Chance Vought F4U-1 – Accelerated flight tests using a single rotation Model 4260-3 Super-Hydromatic propeller were underway on both aircraft before February 1946. Propeller performance was deemed "quite satisfactory", however recurrent hydraulic fluid loss from the propeller to the engine nose case was noted, stopping testing until a seal could be designed and installed.
P-47M 42-27386 – Flight testing of a four blade, single rotation Super-Hydromatic Model 4260-25 with blades Drawing Number Y2C15B3- 30R by Paul Burke commenced on Tuesday March 12 and was completed Friday March 15, 1946. The propeller accumulated 4 hours and 35 minutes of flight time and propeller performance was deemed "satisfactory…. with a decrease in vibration"
Hughes XF-11 – The first Hughes XF-11 (44-70155) experimental photo reconnaissance aircraft utilized two Pratt & Whitney R-4360-31 turbo supercharged engines of 3,000 horsepower with dual rotation Super-Hydromatic propellers of 15' 1" diameter for the fore propeller and 15' 3" for the aft propeller. Its first and last flight occurred on July 7, 1946 with Hughes at the controls. A faulty seal in the aft propeller on the starboard Super-Hydromatic allowed hydraulic fluid to escape from the aft pump body into the engine. The uncontrolled aft blade set went into flat pitch. The resulting extreme net drag and complete thrust loss of the starboard propellers, coupled with pilot error, resulted in a near fatal crash (Figs. 32, 33, 34).
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| Fig. 32. The elegant Hughes XF-11, prototype number 1, serial 44-470155, with Super-Hydromatic dual rotation propellers. Diameter is 15' 1" on the fore propellers, 15' 3" on the aft propellers. It appears maintenance or repair is being performed on the starboard engine as the cowl flaps and/or access panels are missing. | Fig. 33. Howard Hughes in his fedora, running up the 28 cylinder, 3,000 horsepower Pratt & Whitney R-4360-31 engines. | Fig. 34. Hughes aloft on the maiden flight of the XF-11 from Culver City, CA, on 7 Jul 1946. The aircraft crashed due to propeller failure and pilot error approximately 60 minutes after this photograph was taken. |
Curtiss XC-113 (maybe) – The XC-113 was a Curtiss C-46 Commando modified in 1945 and was used as a test bed for the General Electric TG-100 turboprop engine on the starboard wing. A ground accident prevented the aircraft from ever flying with the TG-100, and it is unknown if the XC-113 used the Super-Hydromatic propeller or not. Based on the XP-81, the TG-100 likely required a "self-contained" type (no oil lines in the bore of the prop shaft) propeller like the Aeroproducts or Hamilton Standard Super-Hydromatic type, however testing both a new engine and new propeller on the XC-113 would have carried significant risk (Fig. 35).
Kaiser Fleetwings XBTK-1 – The XBTK-1 was designed as a "Skyraider-light" single place dive bomber/scout aircraft intended to operate off the smaller CVE class aircraft carriers. First flown in April 1945 and powered by a Pratt & Whitney R-2800 with the Hamilton Standard Super-Hydromatic, it several novel airframe features. Problems with governing and surging of the 13’7” diameter Super-Hydromatic prop (with 2C15B1-16N blades) required retrofitting a Hamilton Standard Hydromatic of equivalent diameter to continue flight testing. Two prototypes were built and flown, and perhaps three additional airframes were produced, but the contract was terminated in September 1946 with both flying aircraft struck off inventory by April 1948.
Convair XP-81 – The second iteration of the dual powered XP-81 was the first American turboprop to fly using a 1,400 horsepower General Electric TG-100 (XT31) turboprop engine with a single rotation propeller in the nose and a 3,750 lb-thrust Allison J33-GE-35 jet engine in the aft fuselage. First flight of this power plant combination was December 21, 1945. The aircraft used a four blade Aeroproducts A542F-17 prop of 12’ 1” diameter on the early flights, however later test work on aircraft 44-91001 used a 12’ 6” diameter Hamilton Standard Super-Hydromatic with "… square tips and suffered vibration and oil leakage problems." The vibration was traced to a dynamic imbalance issue that was corrected by adding 98 inch-ounces of static imbalance to the propeller. Interestingly, the Super-Hydromatic’s 35 degree per second pitch change caused the propeller control system to overshoot the desired pitch setting, resulting in oscillatory hunting in pitch and wild excursions in torque horsepower. Ultimately a restrictor valve was put in the control system that reduced the pitch change rate to a more manageable 5 degrees per second.
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| Fig. 35. The XC-113, Curtiss C-46 modified with a General Electric TG-100 turboprop engine on the starboard side. While the TG-100 was destined to fly with Super-Hydromatic single rotation propeller, it is not known if a Super-Hydromatic was installed when this photo was taken. The XC-113 was damaged in a ground accident and never flew with the TG-100. | Fig. 35a. XTBK-1 with dive brakes extended both above and below the wing. The square tipped, uncuffed, nearly constant-chord blades and flat faced, single piece hub assembly are characteristic of the Super-Hydromatic propeller. | Fig. 35b. The XTBK-1 mixed the engine exhaust with the engine cooling air in an internal duct on both sides of the aircraft fuselage, which exited mid chord over the wing. This exhaust pump design was intended to reduce drag and improve engine cooling. It did neither, requiring retrofit with a more conventional system. |
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| Fig. 36. The Convair XP-81 dual powered experimental fighter with a 12' 6" Super-Hydromatic single rotation propeller. General Electric TG-100 turboprop in the nose, Allison J33 jet in the rear fuselage. The TG-100 never developed its intended power, inhibiting high speed flight testing and performance. | Fig. 37. XP-81 serial number 44-91001, while taxiing. |
Ryan XF2R-1 Dark Shark – The experimental, dual powered Ryan XF2R-1 was pulled by 1,760 horsepower General Electric TG-100 (T31) turboprop engine with a 11 foot diameter Super-Hydromatic single rotation propeller in the nose and pushed by a 1,650 lb. thrust General Electric I-16 jet engine in the aft fuselage. First flight was in November of 1946 and top speed neared 500 mph. Flight test involving flattening of prop pitch on approach and after landing to minimize landing runs were successfully performed (Figs. 38, 39, 40).
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| Fig. 38. Ryan XF2R-1 Dark Shark dual powered naval aircraft had a General Electric TG-100 turboprop in the nose and a GE I-16 turbojet in the rear fuselage. The Super-Hydromatic propeller was 11 feet in diameter and the aircraft reached nearly 500 mph with both power plants running. Experiments were conducted by commanding Super-Hydromatic to flat pitch on approach in an effort to reduce approach speed and landing runs, but reverse pitch in flight was not attempted. | Fig. 39. Ryan XF2R-1. The landing gear folded directly outward into the wing; note the landing gear door hanging down near midspan of the wing. | Fig. 40. Ryan XF2R-1. It boasted a 5,000 foot per minute climb rate and set a turboprop altitude record of 39,160 feet on 2 May 1947. |
Lockheed (L-1249) U.S. Navy R7V-2 and U.S. Air Force YC-121F – Both were powered by Pratt & Whitney T34 turboshaft engines of 5,500 horsepower each, which propelled the aircraft to a cruise speed of 430 mph. The propellers used on these aircraft were the three-blade, square-tipped, 15 foot diameter Hamilton Standard Model A-3470-5. The A-3470 was used exclusively on the turbine Constellations and sported a presumably steel blade with a 24 inch chord. The blade drawing number is "A4D15A3-24H CHG. M". Based on the similarity of Figure 41 to the "Turbo-Hydromatic" propeller mounted on a test cell T34 in the 1953 Hamilton Standard Family Day brochure (Part 1, Figs. 45 and 46), plus the service annotation that cracks were found in the pump bodies of the propellers while in service, leads me to believe that the A-3470-5 propeller is indeed of the Super-Hydromatic design. If this is true the A-3470 series Super-Hydromatic propellers flew approximately 4,500 hours in the USAF YC-121F aircraft in addition to whatever hours were flown in the two USN R7V-2 aircraft.
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| Fig. 41. Hamilton Standard A-3470 Propellers Mounted on the Pratt & Whitney T34 turboshaft engines of 5,500 horsepower that power the Lockheed R7V-2 for the U.S. Navy. Engine spacing limited the propeller diameter to 15 feet. | Fig. 42. Lockheed YC-121F on Approach to Landing. Note the tip tanks. | Fig. 43. Lockheed R7V-2 with Hamilton Standard A-3470 propellers. The R7V-2 could be distinguished from the YC-121F by the lack of wing tip tanks. | Fig. 44. The YC-121F was quite a performer and averaged a speed of 490 mph over the 2,340 mile flight from Long Beach CA to Andrews AFB in Maryland in January of 1957. This Lockheed ad takes advantage of that unofficial record flight, but no commercial T34 powered Constellations were ever built. The triangular finlets on the spinners between blades are interesting. |
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