By Timothy Raneyâ€¦Bald Engineer Guy with Glasses
This summary covers one of our monthly launch days conducted by the Heart of Virginia Association of Rocketry (HOVAR). HOVAR is a chartered and insured section (#704) of the National Association of Rocketry (NAR). We are a group of rocket enthusiasts who meet each month to fly low, mid and high power rockets from a beautiful farm in Prince Edward County. Our regularly scheduled launches are open to the public. Anyone is welcome to join us, though any guests must follow all NAR safety rules and regulations.
On this particular September day, I was the designated launch control officer. This job includes ensuring the rockets are safe to fly and the motor igniters are connected properly to the launch controller prior to launch. I normally fly rockets and function as the launch control officer as needed. Unfortunately, I didnâ€™t fly Experimental Rocket-09, â€œBarracudaâ€ since the wind speeds were too high. With the G79 motors on-hand, the projected altitude was about 2300-feet. So, the probability of losing the rocket was high since it could drift out-of-sight and well away from the launch area. Itâ€™s happened before and this time too.
We launched the rockets from the Boswell Farm's west field. During the afternoon, we launched â€“ B to G106 motors. We had perhaps 15 or more launches with some beautiful flights with rockets soaring above 1000-feet. As usual, we had a Federal Aviation Administration (FAA) approval for flights up to 6,000 feet above ground level (AGL). We call the FAA during launch site set-up. Unfortunately, the best flights of the day ended with some lost rockets. For example, we lost one rocket with an â€œFâ€ motor â€“ it landed on power lines in the farm yard. Estimated altitude was 1100-feet. Another rocket, a nice HV ARCAS scale model sounding rocket landed in the tallest oak tree next to the farm yard â€“ not far from the other one. We also had our first catastrophic failure in several years when an â€œEâ€ motor exploded in a rocket on the pad. When this type of incident occurs, it is not a safety issue since we stay 100-feet from the launch rack â€“ an important safety rule we always observe.
Our post failure analysis (largely subjective) indicated the black powder propellant grain likely cracked, allowing exhaust gasses to ignite the recovery parachute expulsion charge almost immediately. In this case, the flame front would have propagated rapidly along the crack from the ignition point to the expulsion charge. In contrast, the propellant normally burns at a controlled rate for a specific period in a properly functioning motor. Apparently, this particular motor was about 10 years old and stored under uncertain conditions. Thereâ€™s a lesson here â€“ store motors in sealed containers, preferably in a temperature controlled environment. No rough handling either.
Another incident occurred later. A rocket with an â€œFâ€ motor failed soon after leaving the launch rod. Its failure analysis was inconclusive. Though the symptoms were similar to the first failure. We also had several â€œCâ€ motors that failed to ignite. However, discussion afterwards indicated these motors were stored unsealed in a tackle box in a shed - less than ideal conditions. It is important to note these events are rare. The quality control and consistent reliability in this industry is excellent. Though once bought by the end-user, proper rocket motor storage and handling is their responsibility. Lastly, we had a rocket flying with a reloadable Cesseroni motor â€“ it ejected the motor casing when the expulsion charge ignited. Searching the probable impact area for at least an hour failed to find the motor casing.
Iâ€™d be remiss if I didnâ€™t mention the weather for an activity of this nature. We always keep our eye on the weather. Weâ€™ll check the local aviation forecast before the final â€œgo decisionâ€ for a given launch day. Of particular concern is any severe weather in the forecast, high winds or low cloud ceiling. With severe weather, we donâ€™t want to stand in a pasture as the highest points in the area. Itâ€™s great to be â€œoutstanding in your field,â€ but not when thereâ€™s lightning. As mentioned above, winds are another concern â€“ they either blow the rocket out of the launch area or can cause erratic flights. No one likes an erratic rocket. When we have clouds, the high ones are fine, but if the cloud ceiling is too low, we canâ€™t fly â€“ the rockets vanish in the clouds. When that happens, you often have no idea where the rocket landed. On this day, the weather conditions were sunny, clear with some high clouds (L1 cumulus) late in the day; wind speeds from 5-15mph measured with a La CrosseÂ® anemometer. Winds were predominantly from the southwest. The ambient temperature was ~85F. Very nice conditions, except for the wind.
Lastly, we had a good turnout â€“ 12 attendees â€“ Dr. Kevin Dunn, me and 10 quests represented by guys in their 50â€™s down to kids in high school and elementary school with their parents. So, we had a wide range of age groups. Rocketry is not just the models you had as a kid. We have video cameras, digital altimeters and electronically timed parachute ejection now â€“ very cool. Though this was an atypical launch day with its various incidents, I hope it gives you an idea of the fun and challenges we experience in in amateur rocketry. And I only use the term â€œamateurâ€ in its most positive context - "somebody who loves or is greatly interested in something" and we don't get paid to do it. Lastly, to answer the inevitable question â€“ No. We are not rocket scientists, but we could play them on TV.