Craft crew help with weather encounter testing
By Bradley Hicks, AEDC/PA
/ Published September 04, 2018
ARNOLD AIR FORCE BASE, Tenn. -- The craftsmen at the AEDC Hypervelocity Ballistic Range are supporting efforts to improve a long-standing “weather encounter” capability by making sure all the elements are in place for upcoming tests.
During these tests, projectiles at high velocities will pass through simulated weather as they travel down the range. Afterwards, the impact of these weather conditions on the projectiles will be assessed.
The range Craft crew at is responsible for the construction of the mechanisms that will create the weather conditions necessary for the tests. According to Carson McAfee, a craft supervisor for the Test Operations and Sustainment contract at Arnold AFB, the craftsmen have proven more than capable.
“This is a great crew,” McAfee said. “They work well together; they work hard; and they know what they’re doing.”
TOS Test Operations Engineer Mark Brown said the weather conditions to be manufactured for the tests are rain, snow and ice crystals, and other weather effects. A different system is needed to create each type of weather condition, and each system must be carefully installed along the range, which is contained within a large tank running the length of the facility.
Brown said engineers at the range are working with the Craft crew to design and build improved versions of these weather simulation systems. The engineers are receiving input from the craftsmen on their ideas and taking recommendations on ways to improve the designs to make the devices more effective.
“It’s very common for them to come up with good suggestions,” Brown said. “We’ll have a drawing and they’ll suggest ways to improve its fabrication.”
“You can give them an idea and they can run with it and create some things that you maybe did or didn’t think about,” McAfee added. “They’re very capable.”
While no weather encounter testing has been performed with the new systems, Brown said some of the hardware used to create the weather conditions have been completed and installed above the intended path of the projectile.
A single “rain dripper” station has been constructed and partially installed. This unit, which creates the rain effects, is based on a similar rain system design from the 1970s but never used. Water flow can be controlled to create effects ranging from light mist to streams.
The system used to create snow and ice conditions is different than the one used to create the rain effects.
Images of the projectiles will be captured as they travel down the range. This will allow test engineers to see the cumulative effect of weather encounter as the projectiles pass through the weather field.
Brown said once a weather encounter system is built, engineers and craftsmen will work together to “tune it” to make sure the test conditions are repeatable.
Brown said the customers have developed computer models showing how they expect the projectiles to behave, and the weather tests serve to confirm the accuracy of these models.
“It’s just like in a wind tunnel, you’re validating your Computational Fluid Dynamics,” he said. “Here, we’re validating the erosion model.”
Instrument technicians will assist with data collection, as they have been working with engineers on cameras and optics to improve the images generated during testing.
Improved weather encounter testing is set to begin at the end of the current fiscal year and continue into future years. Launcher validation was performed late last year.
Brown said the ability to successfully fire a projectile was a prerequisite to the weather testing. Several checkout launches have already been performed with only one checkout remaining.
The craft crew, which is made up in part of instrument technicians, outside machinists, an electrician, a boilermaker, is performing these launches.
The outside machinists and the boilermaker inspect and repair range systems. The machinists, along with the instrument technicians and electrician set up the weather systems, while the machinists and boilermaker close the range tanks and set up the launcher, including loading the projectile, after the machinists and boilermaker have set up the quick-operating valves.
Machinists and the electrician set up the powder and the ignition circuit.
Instrument technicians are responsible for setting up the imaging systems, which include the high-speed and infrared cameras, X-rays and laser flash. The technicians also arrange the detection and triggering systems for the launches, while the outside machinists operate the launcher and recovery tube gas and vacuum systems.
It is up to the instrument technicians to run the sequencer and the high-speed data collection system.
Pipefitters are installing systems necessary to generate rain and snow.
A laborer is on hand to help with the post-launch cleanup.
McAfee said the young craftsmen are relying on the experience and knowledge of Lead Outside Machinist Mark Carson, who has worked at the range for more than 30 years.
“He’s really the only one who’s ever seen these type of shots done and, in some cases, seen a shot done at all,” McAfee said. “We’ve got a new crew, fairly young crew, so he’s having to do a lot of teaching and training each shot. Between each checkout, he’s having to lead and direct.”
McAfee said when previous weather testing dropped off, the craft crew there diminished. The crew has grown in the years since as the demand for testing has again risen, and McAfee said the assistance provided by the craftsmen is proving vital to testing.
“Just since I’ve been here in the last year, we’ve built this crew back up,” McAfee said. “They started prior to me coming, but this crew has gotten built back up, so not only are we doing things we haven’t done in several years, we’ve got a crew that has never seen this stuff. We’re learning as we’re doing it. It’s on-the-job training.
“We don’t test for hours and days in a row. You have to take advantage of every opportunity, and they are.”