“Northern Arizona” aka “Static Test”
A tremendous field of yellow and a dot in the distance. The concrete and welded steel test stand was surrounded by mainly graduates milling like ants around the large cylindrical object at its center.
The motor casing was a truncated Aluminum-Lithium pipe a good 40 inches in diameter and towering over them at ten feet high; it was a large rocket motor. With all the care and busied reverence priests might have exercised in antiquity over an idol of ancient Moloch did these priests gingerly erect their flare. A small crane lifted the Ammonium Perchlorate – R45 – Aluminum grains over the top of the casing and lowered them into the crucible.
Underneath, the upper bulkhead with its radial heat sinks impressed some of the newer initiates with its appearance. Powder-coated white to test the heats effect on paint it gave some idea of the suborbital vehicle that a considerably longer version of the motor would be attached. The sun was intolerable even in the Arizona highlands.
Wiping the sweat from his brow, John Smith was preparing the lower bulkhead, its ablative nozzle and the closing assembly (a series of heavy lead weights and plywood). The grains were almost loaded and he was almost finished himself. Ted Henry, out of the University of Illinois, were checking the thermocouple attachments and copper tubing that would provide the desired mass of temperature and pressure information that they were seeking in this test.
The motor was too large, too powerful for a load cell to measure the actual thrust but previous tests with somewhat smaller motors proved that their computer modeling was sufficiently accurate that they could, from the other measurements, calculate its total impulse.
A grad turned to the supervisor and asked “Are you sure this test fixture can take the load?”
“100%,” replied the super, “The motor was truncated to a point where we have a factor of 2 safety margin on the stand. To increase the margin, we’re operating the motor at a lower operating pressure further reducing the thrust. We’re good.”
The test stand had been host to several designs but this was the largest motor they would fire from it. It would hold. Since the thrust was downward, they firing the solid-propellant motor upside down, something you can do with solid rocket motors, the only danger was busting the thing in two. A very efficient design, very Spacenix.
However the design for the motor was the intellectual property of Daedalus PSC LLC, a sister company to Spacenix. They were building the “Cessna of space” that would allow one or two intrepid souls to fly to the edge of space or 330,000 feet for the cost of one million dollars. Reusable with water recovery, it looked in the demos like a wingless, vertical Lear Jet.
But today only the first full-scale test of its propulsion module was on the agenda. Heywood Aerospace Systems, the parent company, hard spun off Daedalus a few years back and finally had all the necessary subcomponents with which to build and sell their elegant space birds.
Ted tightened the lengths of bent copper tubing to the ports on the bulkhead and bulled firmly but carefully on the thermocouple and stress sensor leads. Unraveling a long length of multiconductor white he measured off a length and with a “rat belt” secured it together to be connected to the data acquisition equipment housed within the test stand itself.
The hi-rel ignition system was already buried within the motor with a bright orange lead carefully strung though the grains and, as soon as the they affixed the lower bulkhead on the top of the inverted motor, would string it though the nozzle as well. Connecting it to the test stand’s electrical ignition system, they would be able to fire the motor at a safe distance.
John exclaimed loudly to the rest of the team, “Ted and I are finished. Where are the grain loaders at?”
They informed him that they were finished about 20 minutes before them. John was glad to hear this and they swung the crane over to the completed contraption and started to bring it over the top of the motor. Lowering it, it taking several grads on step ladders some coaxing to get the O-Rings to settle into the casing correctly, it finally entered the top of the tube and then seated with a satisfying thud. They started to remove the closing assembly in parts, lowering them to their comrades beneath.
Ted over the next hour with John verifying his work,and holding the manuals managed to get all the wiring hooked up. The supervisor reminded them that they had a good ten thousand dollars worth of propellant on the line so they had better be sure to get the data the company needed in this test.
Strangely absent was the few reporters that would occasionally show up. Spacenix was careful to inform the local media about these tests and even the local TV station showed up for a smaller test a few months before. But no love today. Spacenix’s company cameras would be the only ones watching today with about 20,000 viewers on YouTube once they released their footage there.
Ted did a quick once over and informed the team that he was done. They retreated to their vehicles and started driving out towards the small observation point about a mile west of the stand. John brought his pick-up around waiting for Ted to flip the primary ignition breaker, and hop into the truck to rejoin the main group.
After Ted and John made it to safe distance, the team started arming their switches. Systems checks were quickly done and finally the supervisor lifted the cover on the firing switch and toggled it to the ON position.
After about a second, a small whiff of smoke appeared above the motor and very shortly after the motor came up to full power. Like an angry, loud volcano, fire shot into the sky even casting shadows at a distance of one mile. God, these things are loud, exclaimed one of the engineers.
They watched the timer display the passing seconds and continued to watch the vulcanian display. Ten seconds…twenty…thirty….
“How’s the stand holding up?” asked the super. This was going to be the largest motor they would be firing on it.
“Everything is nominal on the stand, Chief” responded one of the grads in front of a laptop. Budget only allowed a remote connection with the stand’s sensors; they would have to wait on the treasure trove of motor data when they fetched the memories from the stand after the test.
“How’s the motor doing?” the super asked over the distant roar.
The grad on the telescope monitor reported “Everything is A-OK, err, nominal, sir. Vibration looks good.”
It was noticeable that the motor was getting louder, a characteristic of solid-propellant motors. Its ablative nozzle helped compensate for this effect but the increase in thrust was obvious even to the casual observer.
Under the time displace, someone had affixed a smaller display labeled “altitude in miles”. This really fueled the imagination as you could picture the flying craft in your mind. Everybody was excited, terrified but excited. Rocket motors really were like long-burning, non-exploding bombs.
They watched the timer counting. The burn was projected to last 160 seconds, about two and a half minutes. At the two minute mark the supervisor commented that this was where the astronauts would be feeling the maximum acceleration at about 2.5 G’s.
At 163 seconds the motor abruptly cut out and burned down to nothing shortly thereafter. A successful test! Relieved hoots and hollers were the response and afterward they opened two bottles of champagne to celebrate.
They had a winner! Floyd would be overjoyed.