2019 Launch Reports
LDRS 38, August 29 - September 2, 2019, Argonia KS
Real Life has gotten in the way of my rocket launching activities for a while, as you can see. However, I did finally get back in the field for LDRS 38, hosted by Kloudbusters on the weekend normally reserved for Airfest.
Jiminy Cricket, I242
With its hollowed-out nose cone, Jiminy has enough room to pretty comfortably fit a four-grain motor. I didn't want to fly it on a bigger motor until I had worked out a way to put a tracker in it, although as it turned out the tracker wasn't needed. Jiminy carried a Jolly Logic AltimeterTwo, a Jolly Logic ChuteRelease, and a BigRedBee RDF beacon.
|Launch time:||Friday, August 30, 2019, 12:45 pm|
|Weather conditions:||mostly cloudy, wind NE @ 5 mph, 77 F, 64% RH|
|Motor:||Cesaroni Pro38 548I242-15A White|
|Max altitude:||3623 feet AGL (AltimeterTwo, barometric)|
|Max velocity:||958 ft/sec (653 mph, Mach 0.85) (AltimeterTwo, accelerometer)|
|Max acceleration:||15.3 G (AltimeterTwo, accelerometer)|
* That V seems really sketchy - altitude matches the sim almost exactly, but the sim predicted 544 mph - over 100 mph lower.
Jiminy landed upright in mowed hay field on the north side of 80th, right across from the away RSO. Very easy recovery, but the body tube was zippered.
First flight of my first minimum-diameter rocket, which I had intended to fly at the previous year's Airfest. Weather on Saturday was too cloudy to fly, so I only got one of my two planned flights in (the other motor was a K660). Kestrel carried an Altus Metrum TeleMega. I used a launch tower constructed by Dan Welling.
|Launch time:||Sunday, September 1, 2019, 9:45 am|
|Weather conditions:||fair, wind SSE @ 6 mph, 72 F, 81% RH|
|Motor:||Cesaroni Pro54 2285K260-P Classic Longburn|
|Max altitude:||20846 feet AGL (TeleMega, GPS), 19761 feet AGL (TeleMega, barometric)|
|Max velocity:||1766 ft/sec (1204 mph, Mach 1.6) (TeleMega, accelerometer)|
|Max acceleration:||24 G (TeleMega, accelerometer)|
Kestrel landed in a plowed field about 1/4 mile NE of the intersection of Dixon Rd. and Highway 44, about a mile southeast of the launch pad. Easy recovery and there was no damage to the rocket. All recovery deployed, but the primary main charge did not fire. The TeleMega stopped acquiring data 270 seconds after launch, which was also about the time the main parachute should have deployed. I later discovered that one of the electrical connections to the magnetic power switch, held by a #4 machine screw, was loose. Earlier in the trip, the computer had mysteriously switched on while the av-bay was stored in a bin, and I think this loose connection was the reason for both. Lessons: tighten the crap out of all screws which serve as electrical connections, and don't ignore things that mysteriously turn themselves on or off.
Raw flight data (CSV)
Kestrel leaving the launch tower. Photo by Richard Lipham.
Ground track of Kestrel's flight.
Kestrel landed after flight.
Kestrel landed after flight.
Statistics for Kestrel's flight.
Graph of Kestrel's flight profile.
2021 Update: In a presentation I heard at NARCON 2021, mention was made of high-performance rockets using three fins being more susceptible to coning than those with four fins. The Wildman Mach Two kit from which Kestrel was built came with four fins. I simulated it in OpenRocket and found that it would have plenty of stability margin with only three fins, so I emailed Tim and asked him if there was any reason not to build it with three. He said he didn't know, only that it was designed with four. So, I went ahead and built Kestrel with three fins, reasoning that less drag was good.
After hearing about the coning issue, I realized that I had no idea whether Kestrel had coned on this flight or not. So I loaded up the flight data, and...
Marvin the Martian's Space Oddity, Research O
Sunday, September 1, 2019 Weather conditions at launch time: partly cloudy, wind SSW @ 8mph, 85 F, 59% RH
The St. Louis Rocketry Association club project, led by Dan Welling, took to the skies late on Sunday. Marvin the Martian took off briskly before turning to the south, flying about half a mile horizontally, and pulling the ripcord on his parachutes to abort the mission to Mars. The rocket landed right on the road, making for a convenient recovery. The official investigation revealed that there was a bee in the cockpit with Marvin, causing him to lose control and inadvertently deploy the parachutes.
Initial CAD design. Photo by Mike Walsh.
Cutting rings on the waterjet. Photo by Dan Welling.
Rings cut from foam insulation. Photo by Dan Welling.
Cutting parts for "launch lugs".
Fiberglass layup for "launch lugs".
Stacking rings. Photo by Jay Draper.
Stacking rings. Photo by Jay Draper.
Beveling wooden rings. Photo by Don Hanson.
Stacked airframe. Photo by Don Hanson.
Airframe being expertly forklifted by Dan Welling.
Working on launch structure.
Arriving at Airfest.
On display in the St. Louis camp.
Liftoff. Photo by Tim Cubbedge.
In flight. Photo by Tim Cubbedge.
Under parachute. Photo by Tim Cubbedge.
SLRA Club Launch, October 20, 2019, Elsberry MO
Flooding earlier in the year prevented crops from being planted in the Elsberry fields, so we found ourselves with a long fall flying season there. The first of three scheduled launches was on October 20.
Berthimus Prime, CTI I212
I flew Berthimus Prime for the first time on an I212 smoky motor. It had a good boost, but unfortunately a very late ejection (10.2 seconds vs. the 7 seconds I set when building the motor).
|Launch time:||Sunday, October 20, 2019, approx. 10:30am|
|Weather conditions:||cloudy, wind calm, 58 F, 72% RH|
|Motor:||Cesaroni Pro38 364I212-14A Smoky Sam|
|Max altitude:||987 feet AGL (AltimeterTwo, accelerometer)|
|Max velocity:||238 ft/sec (162 mph) (AltimeterTwo, accelerometer)|
|Max acceleration:||8.2 G (AltimeterTwo, accelerometer)|
Result: lower airframe mangled due to late ejection; needs major repair.
SLRA Club Launch, November 9, 2019, Elsberry MO
Berthimus Prime, CTI J400
Undeterred, I repaired Berthimus Prime's airframe by cutting off the mangled section of cardboard tube and replacing it with a Wildman fiberglass tube. Zipper that.
|Launch time:||Saturday, November 9, 2019|
|Weather conditions:||partly cloudy, wind WSW @ 12mph, 57 F, 37% RH|
|Motor:||Cesaroni Pro38 700J400-16A Smoky Sam|
|Max altitude:||(not recorded)|
|Max velocity:||(not recorded)|
|Max acceleration:||(not recorded)|