Wednesday, February 09, 2011

High Power Rocketry magazine, October 1999

Last night, I had a few minutes to kill so I randomly grabbed an old issue of HPR.  I'll briefly review the contents and point out that the last item is really what prompted me to post.

The cover article is about the construction and flight of a beautiful 12" diameter IRIS.  Sonotube, custom nose cone, modular mount, professional paint, M1938.  Although recovery was unsuccessful, the causes were clear so you can still learn from it.

There were two articles on clustering.  One was a typical but thorough review of the subject and included sample cluster geometries, a review of core geometries and propellant types, their relative ease of ignition (i.e. Blue Thunder is the easiest and Black Jack is the hardest), how to dip your e-matches, and much more.  The second was about the less commonly discussed subject of launch lug placement.  The author was the TRA prez Bruce Kelly.  He surrounds his tips with the description of a 3x 'J' motor rocket in which the motors were in-line.  When only one of the outer J700's ignited, it has enough lateral force to whip a 3/4" rod.  He premise is simple.  If you have in-line motors, don't also place the lug(s) in-line. Instead, place it orthogonal to the 'motor line' and centered between a pair of fins.  On all other geometries (three in a triangle, four in a square, a central mount surrounded by 'n' motors), nestle the lug in a fin root.  A more current tip would now be to fly large clusters on rails instead of even large diameter rods!

There's also a short article on Why Altimeters Fail, the 4th installment of Ed Miller's long running series on Rocket Art, and a single launch report on Nebraska Heat III.

Finally, in the Section Soundings section, I noticed a report from Don Brown on a NARHAMS launch.  Say what?  A NAR report in a TRA magazine?
August 14th dawned a beautiful, slightly breezy, HOT, HOT, HOT day....
In attendance were Don, Carly Truszynski, Bob Utley and Kathy Gilliand (now of MDRA fame), Tom Anderson, David Mann, Richard Pennington, the Bittle family and, at the last minute, Alan Holmes.  I'll point out that nothing over an E15 was flown.  Bob and Cathy flew C6's including a cluster with four 1/2 A's.  They also pulled out the mighty D12's.   Don, you flew an Estes Bull Pup on a C5 and a Silver Comet on a D12.  The latter landed in the field over the tree line.  This gave you a dose of something poisonous and itchy.