Launch Report February 24, 2013

The weather was the big story this weekend! It was a monument to the changeability of weather on the coast of North Carolina.? On Saturday, I drove down to Bayboro and pulled the trailer to the field in fairly heavy rain.? Jim Livingston joined me around 11:30 and we backed the trailer onto the slippery mud at the field entrance and parked it.? We then spent several hours making a map of the eastern and southeastern edges of the field, with special reference to routes of access to each portion of the field and how those areas can be accessed, both in dry weather and when the dirt roads are slimy and treacherous.? I will have copies of this map available in the future, for the guidance of people who drop rockets over on the eastern edge of our launch site.

Sunday started out looking a lot like Saturday.? From the window of our hotel in New Bern at 7:00 AM, all we could see was clouds, trees bending in the wind, and lots of deep puddles.? By 9 the rain had stopped completely, the wind was light and out of the northwest, and the temperature was warming up.? By the time we got all of the launch equipment set up, there were patches of blue sky visible as the clouds thinned and the ceiling rose.? But the salient feature at that time and for the rest of the day was the mud:? the ground was soggy and the puddles were deep and cold.

Even with this inauspicious beginning, Sunday turned out to be a great day for rocket flying, and a lot of people turned out to enjoy it.? Let?s have a look at the motor use summary, and then I?ll fill in some details.

There were several groups of students on hand, working on their final SLI projects and other scientific exercises.? The two groups I talked with were from the North Carolina School of Science and Mathematics, in Durham, and I think there may have been at least one more group on hand. ?The DART (Durham Area Rocketry Team) group from the NCSSM was responsible for two of the four K motor flights this weekend:? They flew their No Bull twice on the Aerotech K828FJ motor to very close to the 1 mile altitude target.? Dave Morey reports that the first flight made 5415? and the second flight, with a small HD camera taped on the side, reached 4875?.? As I recall, the recoveries of both flights went exactly as planned.? The last flight of No Bull was also the last flight of the day, occurring at exactly 5:45 as the sun was almost to the treetops in the west.? The winds on the ground had died away to nothing by that time, and the smoke from the fast Blackjack propellant just hung in the air and clung to the ground until long after we had all of the launch equipment packed away in the trailer.? Dave Morey flew his Starfire on a K560W and Chuck Hall had an almost-perfect flight with his new Patriot? on the Aerotech K695R.

Joe LoBuglio brought an engineering class from NCSSM who were all involved in a fascinating project.? This group flew eight rockets of the same weight, using the same motor (a C6-5), but with systematic variations in fin shape, fint cant (spiral or not spiral), fin cross-sectional profile, number of fins, rocket length, ogive or round nose cone, or a rough or smooth finish, varied in such a way that no 2 rockets were the same.? Just so you get the picture ? 4 rockets had long fins, 4 rockets had wide fins; 4 had straight fins, 4 had canted fins; 4 had 3 fins, 4 had 4 fins;? 4 had a round nose, 4 had a tangent ogive nose, etc., etc., but each parameter was distributed to each rocket in a different way, determined by a method called the Taguchi matrix.? Using eight observations to estimate the relative contribution of 7 variables is a statistically bold sort of endeavor, to say the least, but the results were quite clear:? The cross-sectional profile of the fins, whether they were rounded on the edges or left square, was the only variable that made a statistically significant difference in altitude attained, as reported by the little ?peanut? altimeter.? Fascinating!? And it suggests a statistical approach to a problem I have been working on at work for almost a year.? I?m psyched!!

For some reason, we had an unusual number of CATO?s this weekend.? Estes A3 and C6 motors destroyed the rockets they were flown in, an Aerotech G64W burned up a large portion of another, and Ray Bryant and Ken Stroud were testing a Dextrose/KNO3 L motor on Ken?s static test apparatus when it CATO?ed in one of the most impressive displays of flying burning propellant and damaged metal that I have ever seen.?? This CATO was almost as spectacular as the one that Mike McBurnett and Ed Rowe perpetrated with the sparky O motor in Potter, NY, at LDRS 28.? If anybody was taking video or still photos at that time and would be willing to share those shots, PLEASE forward them to Tanner or myself so that we can put them or a link to them on the website.

Favorite rocket name of the month:? Andrew Billin?s Mildew Sky Hook.? Back in the fall, flew this rocket with the fantastic little Cesaroni E75 motor in the little 24mm case.? The rocket was lost in the soybeans and Andrew went home without it.? It lay among the beans getting rained on for a few months and then someone found it while searching for something else.? Then it sat in the trailer for a while and grew a small crop of mold on the body tube before Andrew finally retrieved it and took it home.? The body tube was structurally sound, and after a little refinish and repaint work, he brought it back this weekend to fly with another E75!? This time it did not get lost.

Jim Livingston flew his AAMRAM on a 76mm L motor made from the latest refinement of a propellant called Jim Scarpine Tribute Blue #4.? This version used a 50:50 mix of AP200 and AP400 which produced a burn rate that was a lot less hairy than the all-AP200 version.? We plan to stick with the 50:50 mix in the future.

As always, I am very grateful to everybody who stayed to help with packing up the trailer.

Alan Whitmore, Prefect, Tripoli East NC