Saturn 1B and the RockeTiltometer™
I first met Steve Eves at LDRS 28 at Potter, NY, in July of 2009. I had flown out from my home in San Diego to see just how the east coast guys did things at a major launch. Steve had his Saturn 5 project which flew earlier that year on static display.
I was aware of the project and how successful it had been. Having fairly recently achieved my L3 and knowing all that went into my projects, I was truly impressed with what Steve and his crew had achieved with the Saturn 5. Particularly impressive were the techniques he had used on a 1600 pound rocket for deployment separation, which included inter-locking cams, pre-tensioners, vehicle air bags and the like. Things worked so well he even stuck the booster section landing!
So, when Bob Utley of Rockets Magazine contacted me regarding a new project Steve was working on, I was immediately interested. Steve had asked Bob if he was aware of anything available that would help him with his flight safety preparations. Bob remembered that I had been working on a device to measure the tilt attitude of a rocket’s flight path. In the event of an adverse attitude, such a tilt meter could be used to abort an air-started motor. Bob was aware that I had successfully test flown just such a device.
I had used my RockeTiltometer™ (roc'-e-til-tom'-e-ter, or RTOM) at LDRS 29 and at BALLS 19. In those cases it had prevented my staged motors from firing due to such adverse-attitude flight conditions. Fortunately, I later had a more successful flight at Plaster Blaster in 2010 using the RTOM. At the Plaster City, CA site, my H8 rocket flew well and this time the RTOM allowed ignition of the sustainer motor, resulting in a flight of over 22K’.
I told Bob I would be happy to furnish an RTOM for Steve to use in the Saturn 1B project he planned to fly at MDRA’s Price, MD site in early April of 2011. Steve realized the added safety such a device could provide, and considered avoiding the cost of losing the motor and all the work that had gone into the rocket, should it have problems during the flight.
I sent Bob a unit for some pre-testing and he eventually forwarded it on the Steve to incorporate into his overall deployment and ignition control systems. Steve utilized several timers, flight computers, and a GPS unit along with the RTOM in his scheme in order to assure the best chance for a successful, safe flight.
The flight was scheduled to occur on Saturday, April 16. I flew out the prior Thursday evening and headed out to the site Friday mid-day to see if I could help with any final preparations. Upon arrival, I came upon the ever-quipping Utley who steered me over to Steve’s Saturn 1B prep area where I instantly remembered Steve. He was a charming as ever – I figured he would be a bit uptight getting so close to launch time, but he proved to be very relaxed and totally in charge of the goings on. Steve took the time to show me the rocket and all the systems he had incorporated into the project. I was extremely impressed.
Steve then introduced me to his right-hand man, Tom Erb, who was preforming a multitude of system checks and final preparations with Steve. The idea was to have the rocket fully prepped and virtually ready to launch by the end of Friday so that Saturday morning would be more relaxed and afford everyone the time to fully embrace the flight and all the emotions such a huge 2-year project can impart. We discussed the RTOM features and went over its role in his setup. Steve had fully redundant systems and the RTOM was the last link in an ignition chain – the intent being to abort ignition if the staged section should exceed a tilt angle of 25 degrees from vertical at the time ignition was called for by a Xavien timer.
We made a couple of minor changes to the layout to be sure that Steve would be safe while precariously perched tending to the final system arming once things got under way, and then packed it in for the night - storing the rocket in an out-building since a weather system was headed our way.
Late Friday night, Bob, and Neil McGilvray, also of Rockets Magazine, the launch sponsor, decided to postpone the launch to Sunday, which promised clearer, though windy weather.
Sunday was bright and clear, and as expected a bit windy, with gusts to 25 knots. Due to some mis-fortune, the rocket was not ready-to-go until around 2 PM that afternoon – the good part was that the wind was calming down a bit and the lulls were getting more pronounced. The countdown finally commenced and at “…0”, ignition was applied to the collection of Loki motors and the Saturn 1B lifted off beautifully under full pressure.
Immediately, the rocket wandered a bit off vertical, but soared majestically under the first few seconds of boost, all-the-while falling over ever so slowly off of vertical. About 6 seconds into flight booster-burnout occurred and the separation charges fired. The systems unlocked as designed and the air bag inflated and pushed the sections apart – unfortunately the sustainer continued to head over pretty hard. At 6.75 seconds it was at an angle of 19 degrees (data coming from the logger on the recovered RTOM).
At 7.00 seconds, the Xavien called for ignition. However, the sustainer had rapidly moved off to a tilt of 27 at that moment and ignition to the staged motor was aborted by the RTOM. The critical angle had been pre-set for 25 degrees, so the movement from 19 to 27 degrees in that last quarter-second caused the RTOM to shut the systems down. Data from the logger later showed that the sustainer was becoming increasingly unstable at that point.
Thanks to Steve and the team’s foresight, great engineering and construction prowess, the sustainer was aborted but was still able to safely deploy its recovery chutes and made a nice landing about a half-mile away in pretty strong winds.
I felt good that the RockeTiltometer did its job and worked successfully that day. I hope to have one aboard the next Eves project!