May 04 2018

Progeny Mk6 Block I Flight 3 Analysis

In our continued quest to explore the region of high radiation found above our planet the third launch of the Progeny Mk6 Block I was carried out earlier this week.

The Flight

The initial launch time of 18:18 UTC was missed due to wind shear in the upper atmosphere that would have hit the rocket during its unpowered coast stage after dropping the first booster. A second weather balloon was sent up and returned nominal wind readings for a launch at 19:35 UTC. The rocket flew off the pad heading 135° ESE with an initial force of 67.2kN for 4Gs of acceleration to prevent drag at the nose from flipping the rocket over during this early flight phase. After only three seconds the lower 0.625m booster had reached its maximum thrust output of 68.9kN before beginning to fall off and prevent the rocket from exceeding 80kPa of dynamic pressure. At L+17.9 seconds the rocket reached a MaxQ of 76.318kPa at an altitude of 4.958km ASL as the lower booster continued to tail off thrust until flame-out at L+33.7 seconds. Now at 14.070km the Automated Flight Control System staged the booster after one second, cleanly pushing it away so when its fins were exploded a second later the debris did not damage the rocket, which continued to coast upwards for another 6.9 seconds before the nose fell 1.5° and the second stage booster was ignited at 18.601km.

The second stage boost concluded without issue after 13.2 seconds after which staging occurred in the same manner as the first stage, leaving the third stage liquid fuel engine to ignite two seconds afterwards to continue the push for space, starting from an altitude of 29.090km. After 30.7 more seconds of powered flight the final booster cutoff occurred just half a second before passing 70km ASL and entering space at precisely L+1m28s. Both detached booster stages fell back to the waters of the Kerblantic, with the first stage impacting 19km downrange at L+3m4s and the second stage impacting 46km at L+4m33s.

At L+9m58s the rocket passed through an apokee of just 483.314km. All systems continued to operate normally and data telemetry continued to stream in through radio comms.

Just prior to re-entering the atmosphere signal was lost due to the rocket falling below the horizon, leaving everyone at KSC waiting to hear of its fate until the recovery craft sailed back in range of over-horizon comms to report a successful splashdown. Data shows the rocket entered the atmosphere at L+18m29s traveling at 2.068km/s so the air brakes and parachute had no trouble decelerating the rocket for a relatively soft 7.656m/s landing 326.642km downrange. This is yet another record for longest recovery distance.

Full flight telemetry data.

Flight Analysis

The performance of the rocket continues to meet with expectations. On this flight shorter coast times and a lower apokee were predicted due to the heavier payload mass and the greater inclination of the trajectory, which doesn’t allow us to use the spin of Kerbin to help speed up the rocket during ascent. No anomalies occurred during the flight.

Radiation data gathered while in space shows that not only did the rocket pass through peak levels before apokee, they did not reach the highest levels seen on earlier flights. This is tantalizing because it means than while we are still reaching the region of higher radiation levels things seem to be “fuzzing out” and the next launch could potentially record no increase or an even smaller one still. Or it could have a totally opposite finding and discover another strong area of radiation instead. Thankfully we won’t have to wait long to find out!

Future Plans

No major changes are being made to the final flight set to lift off next week – a little bit earlier than planned now that we can speed up the build of the rocket by reusing the entire payload section that was recovered as the same instruments will be carried. One small change that will be made is the fairings will no longer be jettisoned now that the airbrakes are there to help slow the rocket down. We are seeing some damage being done to the payload trusses and nose cone chute casing as a result of the fairing pieces impacting them after detaching. Additionally the water-proofing needed for the payload instruments was not standing up as well as hoped and just adds time to the integration process.