Dynamic Testing
Engineers needed a detailed knowledge of the space vehicle's dynamic flight characteristics to design structural, guidance, and flight control systems. They initially used analytical data that had not been substantiated by test for design criteria. The Dynamic Test Vehicle test project determined the dynamic characteristics of the space vehicle and verified earlier analyses.
The objectives of the dynamic tests were to:
- Determine the space vehicle structural dynamic characteristics under conditions simulating flight configuration and environment insofar as practicable.
- Determine the optimum location for flight sensors and obtain experimental transfer functions for the control system.
- Determine the physical mating capability of stages and modules.
- Compare dynamic test results with subsequent flight test results for continuous development of dynamic test techniques and facilities to assure the highest possible degree of accuracy in the development of future vehicle structures prior to flight.
- Determine the space vehicle dynamic characteristics under conditions simulating transport from the Vehicle Assembly Building to the launch pad insofar as practicable.
— NASA, Saturn V Dynamic Test Vehicle Test Project Plan
Dynamic tests came in three configurations, one for each phase of Saturn V-powered flight. Configuration I focused on testing the entire stack, as if the vehicle had just launched. Configuration II exercised the stack as if the first stage had jettisoned and the second stage were firing, and configuration III tested just the third stage and Apollo spacecraft. Tests began with Configuration III in the Saturn IB Dynamic Test Facility, while the Saturn V Dynamic Test Stand, first, and second stages were still under construction. Configuration I testing followed in the Saturn V Dynamic Test Stand, then Configuration II in the same place.
Configuration III testing took place in late 1965.
Configuration I dynamic tests required the first stage of the Saturn V, which was loaded into the test stand January 13, 1966. Testing would have to wait for the last piece, the second stage, to arrive.
With all the components at MSFC as of November 10, 1966, the second stage was stacked atop the first inside the Dynamic Test Stand on November 23. The third stage was added to the stack November 30, and the Instrument Unit and boilerplate Apollo were installed in December. The rocket was stacked and ready for "Configuration One" testing.
Configuration One Testing ran from January through March. Testing produced "several minor irregularities indicating the need for possible engineering changes" which were addressed during March, 1967.
Configuration Two testing followed, in which the first stage was removed from the stack to simulate conditions after the first stage had jettisoned.
Dynamic testing examined "the vehicle's response to lateral, longitudinal, and torsional excitation, simulating those that would be experienced in flight. The vehicle was "mounted on a hydrodynamic support system made up of four hydraulic/pneumatic pedestals to permit a simulated unrestrained reaction." Engineers tested vibrations in one plane at a time with different amounts of ballast simulating "fuel load at critical time points in the flight trajectory."
NASA historian Mike Wright summarizes the testing:
| “ | Combined, the tests involved 450 hours of shaking to gather data from some 800 measuring points. A simulated Apollo capsule with the same weight and same center of gravity as the spacecraft being checked out for launch at Kennedy Space Center were placed on top of the rocket. Forces were applied to the tail of the rocket to simulate engine thrusting, and various other flight factors were fed to the vehicle to test reactions. During some of the shaking tests, the rocket moved as much as 6 inches at the top and up to 3 inches at the bottom. The tests were mandatory before the Center could certify that the guidance system would hold the rocket on course when it was launched. | ” |
On August 3, 1967, MSFC announced the successful completion of the dynamic test program, thereby declaring dynamics and structures of the Saturn V ready for its first launch later in the year. The dynamic testing resulted in "several slight modifications" to the final flight vehicle.
The first Saturn V launch came three months later, with Apollo 4. The dynamic test article LTA-2 was refurbished and flown on the next Saturn V launch, Apollo 6.
After dynamic testing, the second stage returned to KSC for a time for launchpad B checkout.
Read more about this topic: Saturn V Dynamic Test Vehicle
Famous quotes containing the words dynamic and/or testing:
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—William James (1842–1910)
“Bourbon’s the only drink. You can take all that champagne stuff and pour it down the English Channel. Well, why wait 80 years before you can drink the stuff? Great vineyards, huge barrels aging forever, poor little old monks running around testing it, just so some woman in Tulsa, Oklahoma can say it tickles her nose.”
—John Michael Hayes (b.1919)