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# Helicopter Test Tower (Building 1231A)

### Julia L. Bradshaw

Apr 05, 2022

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# **Quick Facts**

**Year Built:** 1946 **Historic Eligibility:** National Register Eligible**Important Tests:** Helicopter Blades, Helicopter Rotors **Year Demolished:** 2012

# History

Built in 1946, the Helicopter Test Tower, also known as the Helicopter Apparatus and Helicopter Rotor Test Facility, was a specialized test facility built for improving helicopter design. The facility was also used as a centrifugal G tester to support the testing of rocket payloads. The conical-shaped facility was 39-feet high, with a 16-foot-wide base that tapered to 3 feet in diameter at the top. An elevated safety net encircled the tower.  

The original facility design drawings are dated 1944 and 1945. The control room, located adjacent to the helicopter apparatus tower, was approximately 19-feet by 20-feet wide and occupied the area of the present Child Care Facility (B1231). An addition to the control room was added in 1971. The helicopter apparatus electrical power was obtained from Building 1235, the Frequency Converter Building, also known as the “6000-horsepower dynamometer.” The frequency converter station could provide power from two hertz to 118 hertz with a corresponding range of voltage. 

Richard Pappa worked on a helicopter noise study in 1975 with Wylie Laboratories prior to joining NASA. Part of his report reads, “The Helicopter Rotor Test Facility consists of a 30-foot-high conical steel structure that supports a single vertical rotor shaft, surrounded at its base by a 10-foot-high octagonal building which houses operating controls and data acquisition systems. Rotor blades under study are attached to a hub at the end of the rotor shaft, accessible from outside the cone structure along an overhanging catwalk. Slip rings at the hub allow blade pressure data from surface-mounted strain gauges to be obtained during operation of the rotor. Drive power is supplied by a 3000-horsepower induction motor located near the rear of the building.” 

The equipment in the test tower was removed in 1982 when the facility was decommissioned, altered and converted for use as an observatory by Langley’s Skywatchers Astronomy Club. The small support building located adjacent to the tower was converted to become Langley’s Child Development Center which went through several expansions through the 1990’s. In 2010, upgrades to the center included outdoor lighting which negatively impacted the use of the telescopes in the observatory.  

The facility was vacated in 2010 and demolished in 2012.  

# Related Materials

            - 1964 Facility Resume
            - 1965-1966 Real Property Record
            - 1966 Facility Resume
            - 1974 Facility Resume
            - 1980 Letter to Remove Tower Equipment  
            - Building 1231 Poster 
            - Helicopter Test Tower Description 
            - Phantom Drawing 

Examples of the kind of work done in this facility can be found on the NASA Technical Reports Server. Examples include: 
            - 1948 Effect of Wind Velocity on Performance of Helicopter Rotors
            - 1956 Investigation of Compressibility on a Rotor