The Experiments

The HSR Program Office assigned the six Phase I and one Phase II flight experiments reference numbers.

All six Phase I experiments were continued in Phase II and were iden­tified in their Phase II form by the letter "A” following the number. Only experiment 1.5 changed in nature in Phase II. All of the experiments
were assigned Tupolev principal investigator counterparts. The experiments and principal NASA-Boeing investigators are listed below:

• 1.2 Surface/Structure Equilibrium Temperature Verification: Craig Stephens (NASA Dryden).

• 1.5 Propulsion System Thermal Environment: Warren Beaulieu (Boeing).

• 1.5A Fuel System Thermal Database: Warren Beaulieu (Boeing).

• 1.6 Slender Wing Ground Effects: Robert Curry (NASA Dryden).

• 2.1 Structure/Cabin Noise: Stephen Rizzi (NASA Langley) and Robert Rackl (Boeing).

• 2.4 Handling Qualities Assessment: Norman Princen (Boeing).

• 3.3 Cp, Cf, and Boundary Layer Measurement and CFD Comparisons: Paul Vijgen (Boeing).

• 4.1 In-Flight Wing Deflection Measurements: Robert Watzlavick (Boeing).[1486]

Because the HSR program was the primary funding source for the Tu-144LL flight experiment, it followed that the relevant HSR Integrated Technology Development (ITD) teams would be the primary customers. Subsequent to Phase I, however, it became apparent that some of the exper­iments did not have the ITD teams’ complete support. The experimenters believed that data analysis would be accomplished by the interested ITD teams, but the ITD teams who had little or no input in the planning and selection of the experiments had no plans to use the data. This was com­plicated by the cancellation of the HSR program by NASA in April 1999.[1487] In retrospect, it appeared that the experiment selection process did not properly consider the ultimate needs of the logical customers in all cases. In deference to the HSR program, however, it should be noted that the joint U. S.-Russian Tu-144 project had political aspects that had to be considered and inputs for data from Tupolev that may not have fit neatly into HSR requirements. Fortunately, the bulk of the raw data from all of

the experiments, except Langley’s 2.1 and 2.1A, is maintained at NASA Dryden.[1488] The data from 2.1 were fully analyzed and reported in several NASA and Boeing reports.[1489]

The data from all but experiment 2.1, Structure/Cabin Noise, were collected by the Damien DAS and were for the most part managed in Zhukovsky by Tupolev engineers. Experiment 2.1 had a dedicated DAS and experienced none of the data acquisition problems suffered at times by the other experiments. NASA Dryden’s Glenn A. Bever was the NASA onsite engineer and instrumentation engineer for the dura­tion of the program. In this capacity, he supported all of the experi­ments, except Langley’s experiment 2.1, which had its own engineers and technicians. From 1995 to 1999, Bever made 19 trips to Zhukovsky, "a total of 8 months in Russia all told hitting every month of the year at least once.”[1490] Because Dryden had responsibility for instrumentation, Bever worked with Tupolev instrumentation engineers and technicians directly to ensure that all of the experiments’ data other than 2.1 were properly captured. Often, he was the only American in Zhukovsky and found himself the point of contact for all aspects of the project. He "wrote Summaries of Discussion at the end of each trip which tended, we discovered, to act like contracts to direct what work was to happen next and document deliverables and actions.”[1491] Bever utilized a rather new concept at the time, when he transmitted all of the collected data from the experiments under his purview to Dryden via the Internet. He translated the instrumentation calibration information files into English calibration files, wrote the programs that reduced the data to a manip­ulative format, applied the calibrations, formatted the data for storage, and archived the data on Dryden’s flight data computer and on CDs. One of his final accomplishments was to design the air data sensor sys­tem that collected altitude and airspeed information from the Phase II flights flown by the NASA pilots.[1492] Langley’s instrumentation technician,

Donna Amole, and Dryden’s Project Manager, Russ Barber, attested to the significant efforts Bever contributed to the project.

Experiment 1.2/1.2A, Surface/Structure Equilibrium Temperature, consisted of 250 thermocouples and 18 heat flux gauges installed on pre­determined locations on the left wing, fuselage, and engine nacelles, which measured temperatures from takeoff through landing on Mach 1.6 and 2 test flights.[1493] High noise levels and significant zero offsets resulted in poor quality data for the Phase I flights. This was due to problems with the French-built Damien DAS. For Phase II, a Russian-designed Gamma DAS was used, with higher-quality data being recorded. Unfortunately, the HSR program did not analyze the data, because the relevant ITD team did not believe this experiment was justified, based on prior work and preexisting prediction capability at these Mach numbers. The initial poor data quality also did not suggest that further analysis was warranted.[1494]

Experiment 1.5, Propulsion System Thermal Environment, sampled temperatures in the engine compartment and inlet and measured acces­sory section maximum temperatures, engine compartment cooling airflow, and engine temperatures after shutdown. Thirty-two thermocouples on the engine, 35 on the firewall, and 10 on the outboard shield recorded the temperature data.[1495] The data provided valuable information on thermal lag during deceleration from Mach 2 flight and on the temperature profiles in the engine compartment after shutdown. Experiment 1.5A in Phase II developed a Thermal Database on the aircraft fuel system using 42 resis­tance temperature devices and 4 fuel flow meters to collect temperature and fuel flow time histories on engines 1 and 2 and heat rejection data on the engine oil system during deceleration from supersonic speeds. HSR engineers did not fully analyze these data before program cancellation.[1496]

Experiments 1.6/1.6A, Slender Wing Ground Effects, demonstrated no evidence of dynamic ground effects on the Tu-144LL. This correlated
with wind tunnel data and NASA evaluation pilot comments.[1497] Effects were determined on lift, drag, and pitching moment with the canard, both retracted and extended. Forty-eight parameters were measured in flight, including inertial parameters, control surface positions, height above the ground, airspeed, and angle of attack. From these, aerodynamic forces and moments were derived, and weight and thrust were computed postflight. A NASA Differential Global Positioning System (DGPS) provided highly pre­cise airspeed and angle-of-attack data and repeatable heights above run­way accurate to less than 0.5 feet. Getting this essential DGPS equipment into Russia had been difficult because of Russian import restrictions. In Phase I, 10 good maneuvers from the 19 flights were accomplished, eval­uating a range of weights, sink rates, and canard positions. The data qual­ity was excellent, and the results indicated that there is still much to be learned regarding dynamic ground effects for slender, swept wing aircraft.[1498]

Langley’s Structure/Cabin Noise, experiment 2.1, was unique among the seven flight experiments, in that it used its own Langley-built DAS and had on site its own support personnel for all flights on which data were collected. Another unique feature of this experiment was its direct tie to a specific customer, the HSR structural acoustics ITD team. The two principal investigators, Stephen Rizzi and Robert Rackl, were members of the team, and Rizzi was the team lead. This arrangement allowed the structure of the experiment to be designed directly to meet team require­ments.[1499] Several datasets, including boundary layer fluctuating pressure measurements, fuselage sidewall vibration and interior noise data, jet noise data, and inlet noise data, were used to update or validate various acoustic models, such as a boundary layer noise source model, a cou­pled boundary layer/structural interaction model, a near-field jet noise model, and an inlet noise model.[1500] The size of the dataset and sampling rates was staggering. The required rate was 40,000 samples per second for each of 32 channels. The Damien DAS was not capable of sampling at these rates, thus necessitating the Langley DAS. Langley, as a result, provided personnel on site to support experiment 2.1. These included

Rizzi, Rackl, and several instrumentation technicians from Langley’s Flight Instrumentation Branch, including Vernie Knight, Keith Harris, and Donna Amole, the only onsite American female on the project. Amole spent about 5 months in Zhukovsky during 8 trips. Her first trip was chal­lenging, to say the least. The Tupolev personnel were not eager to have an American woman working with them. Whether because of supersti­tion (Amole initially was told she could not enter the airplane on flight days), cultural differences, or perhaps a misunderstood fear of poten­tial American sexual harassment issues, Amole for the first 2 weeks was essentially ignored by her Tupolev counterparts. She would not be deterred, however, and won the respect and friendship of her Russian colleagues. Glenn Bever and Stephen Rizzi provided essential support, but many times, she was, like Bever, the only American on site.[1501]

Experiment 2.4, Handling Qualities Assessment, suffered in Phase I from poor data quality, which predicted a very poor flying aircraft. The aircraft response to control deflections indicated a 0.25-second delay between control movement and aircraft response. Furthermore, angle-of – attack, angle-of-sideslip, heading, altitude, and airspeed data all were of suspect quality at times.[1502] These data issues contributed to the HSR pro­gram’s desire for U. S. pilots to fly the airplane to evaluate the handling qualities, because access to the Tupolev pilots was limited. Additionally, in Phase II, a new air data sensor from NASA Dryden corrected the nag­ging air data errors. This experiment will be covered in more detail in the following section on the Tu-144LL Handling Qualities Assessment.

Experiments 3.3/3.3A—Cp, Cf, and Boundary Layer Measurements— collected data on surface pressures, local skin friction coefficients, and boundary layer profiles on the wing and fuselage using 76 static pressure orifices, 16 skin friction gauges consisting of 10 electromechanical bal­ances and 6 hot film sensors, 3 boundary layer rakes, 3 reference probes, 5 full chord external pressure belts consisting of 3 on the wing upper sur­face and 2 on the lower surface, and angle-of-attack and angle-of-sideslip vanes. Measurements from the 250 thermocouples from experiment 1.2 were used in the aerodynamic data analysis.[1503] Data were collected at Mach

0. 9, 1.6, and 2 and included over 80 minutes of stabilized supersonic flight. Data quality was good, although some calibration problems with the pressure transducers and mechanical skin friction balances arose. On flight 10, the lower wing surface midspan pressure belt detached and was lost, and 4 tubes on the upper midspan belt debonded. Fortunately, the failures occurred after the minimum data requirements had been met. In Phase II, Preston tubes and optical-mechanical sensors devel­oped at Russia’s Central Institute of Aerohydromechanics (TsAGI) were implemented for additional skin friction measurements. The HSR pro­gram did not fully analyze these data, believing that prior XB-70 data already filled these requirements.[1504]

Experiment 4.1A, In-Flight Wing Deflection Measurements, pro­vided a limited verification of the wing geometry under in-flight loads. These data are needed for validating the aeroelastic prediction meth­odology and providing the in-flight geometry needed in computational fluid dynamics analysis. Boeing’s Optitrak active target photogrammetry system was used, and Boeing managed the experiment. The installed system incorporated 24 infrared reflectors mounted on the upper sur­face of the right wing, each pulsed in sequence. Two cameras captured the reflected signals in order to provide precise x, y, and z coordinates.[1505] The system was used on Langley’s Boeing 737 in the early 1990s high lift experiment, designed to quantify the precise effect of high-lift devices.

Not listed among the formal experiments was a Phase II indepen­dent "piggyback” experiment leveraging off the data collected from experiment 2.4, Handling Qualities Assessment, flown by the NASA research pilots. This involved a new longitudinal, lateral, and direc­tional closed-loop Low-Order Equivalent System (LOES) method of air­craft parameter identification using an equation-error method in the frequency domain. Because the data were accumulated by pilot-in-the – loop frequency sweep and multistep maneuvers, these were added to the test cards for the first four Phase II flights.[1506] Langley’s Dr. Eugene A. Morrelli requested theses datasets and developed the pilot maneuvers necessary to acquire them. This was a unique example of a researcher taking advantage of his colleagues’ work on a once-in-a-lifetime
experiment and of the spirit of cooperation among NASA researchers that allowed this opportunity develop.