Monday, April 30, 2018

Sunday morning launch...

The Longshots begin unpacking their equipment for practice (Click to enlarge).
The weather was practically perfect this past weekend - not only did I get rockets built (Centuri Stellar Starlifter), primed (Sniple), and painted (Mach 10, Estes KL-3 Marauder), but I also got to fly a couple during the Longshots' TARC practice on Sunday. Duane and I showed up at Pegasus Field around 10 AM, whereupon I started to set up the low power pad and Duane began grilling his finals-bound team. It is good to have the "benevolent dictator" back in the States; things were kinda quiet at Pegasus without him. Having been gone for 5 weeks, Duane had a lot to catch up on, and the Longshots were eager to show what they had done in his absence. I was happy to see a green and white backup rocket next to the red and white "Phantom Flier" on the prep table - always a good idea to have a backup at the TARC finals. The Longshots made two flights, striving to hit an altitude of 775 feet. The first, involving the green and white rocket, clawed its way to 717 feet, but the trusty Phantom Flier missed the mark by only 4 feet, reaching 771 feet. Pretty good, but they need to work on their durations a bit in the wind - their time on the second flight was way long (56 seconds).

Patrick inspects "Sign Here Please" (Click to enlarge).
 We were joined on the field by Patrick, a new member of HARA. Patrick brought with him a scratch orange and white rocket, "Sign Here Please". "Sign Here Please" featured 3D printed fins, nose cone and motor mount; it would make two flights on Sunday, both on Estes F15 motors. The first flight went well, with the rocket slowly ascending into the blue sky and deploying a colorful chute a bit past apogee. The second flight, not so much, as the model arced over right after leaving the rail and followed a flat trajectory to the northwest. Breaths were held as the rocket nosed towards the ground, but the ejection charge deployed the parachute at the last minute, saving the model from a ballistic impact. I figure the F15 did not provide enough thrust to weight to get the rocket moving fast enough off the rail - the first flight was lucky to have occurred during a lull in the wind. An F32 or something like it would be better for "Sign Here Please"; 3D printed parts are heavy beasties.

"Sign Here Please" leaves the rail (Click to enlarge).Coming in for a nice soft landing (Click to enlarge).
I packed two rockets for this launch - an Estes Meteorite White crayon and my recently repaired Probe-18, its payload section loaded with two altimeters. The Meteorite White was the first rocket to fly on Sunday, reaching maybe two hundred feet on a B6-4. Recovery was nominal, with the orange ripstop nylon parachute softly landing the model in the field. The Probe-18 was also powered by a B6-4; the purpose behind Sunday's flight being to compare the data recorded by my Altus Metrum Micropeak and Adrel Alt-BMP altimeters. The Adrel is a new addition to my electronics collection - measuring less than 1x2 centimeters, it is the smallest recording altimeter I have, and was designed for use in rocket competitions. The flight was picture perfect, with a good landing under chute.

Meteorite White leaves the pad (Click to enlarge).Probe-18 starts another flight (Click to enlarge).
I am always amazed by modern tech - As we waited for the Longshots to make their final flight, Patrick and I were able to use our phones to watch the live stream of the Blue Origin New Shepard launch to the edge of space. Mannequin Skywalker got a fantastic trip to 350,000 feet, and I shook my head in awe at the spectacle of the booster landing. Truly great things are happening!

The New Shepard booster touches down on the pad (Click to enlarge).
Back at the apartment, I plotted the data from the Adrel and Micropeak altimeters on the same graph. I did not expect an exact match, but was surprised by the 4 meter difference in peak altitude, and the 7 meter discrepancy during the descent. Gonna have to think about this a bit, as both units shared the same payload section.

Comparison of Adrel data to that of the Micropeak (Click to enlarge).
To close this post, here are a couple of screenshots from altimeter software - the Micropeak works on multiple platforms, while the Adrel application is Windows-only. An unfortunate thing that altimeter manufacturers have in common is that they don't update their software as the operating systems go though major updates, which can cause issues. The Adrel software was a pain in the rear to install under Windows 10, though I see a new version was released back in January (I installed an older version in December) - maybe it makes things easier. The Micropeak app also had issues under High Sierra on my Mac - I had to disable a security feature to get it to run. Sigh...
Micropeak summary screen (Click to enlarge).

Adrel summary screen (Click to enlarge).

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