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Progeny Mk5 Initial Launch Series Completes with Fully Automated Flight
Well, this week was rather insane, with three launches and an almost backed-up schedule. Everyone on the team managed to pull through like champs however and we got it all done! After a three-day weekend (just the rocketry teams) kerbs will be back to begin analyzing and comparing all the data from the Mk5 launches against each other and against the Mk4 flights. We expect to have a report from them in early October.
You can review the flight analysis for the third launch and also check out the statement we released on the actions of the KerVoyant merchant ship that caused the launch to be delayed almost an entire day.
The flight analysis for the fourth launch explains what happened to cause the rocket to break up in flight. We took measures starting on the fifth launch to begin collecting more data on wind shear via a high-altitude KerBalloon released prior to launch.
We won’t have any immediate analysis of the fifth launch from today, but there has been some initial review of telemetry data. We changed up our 3rd stage ascent profile a bit by having the rocket hold a TWR of 3 upon ignition and then go to full throttle once dynamic pressure eased off. This failed to work properly during the 4th launch but this time the code worked and the rocket did as it was supposed to. There was a small spike in dynamic pressure after throttle up as shown in the graph below, so if done again in the future we may want the rocket to wait until dynamic pressure falls about 1-2kPa before throttling up to full thrust.
Dynamic pressure in kPa over the duration of the 3rd stage boost (in seconds)
Going to full throttle rather than maintaining a set TWR throughout the burn did not seem to provide any benefit, as our apokee only ended up being 87km whereas we had hoped this ascent would allow the rocket to surpass the 135km record of the Mk4. However there are several other factors that need to be considered such as how well the rocket pitched over during ascent, precession during coasts triggering early boosts, altitude comparisons, etc. This will all be covered in the full review. Still, even if it did not set a new altitude record this fifth flight of the Mk5 has earned its place in history as being the first successful fully-automated rocket flight – to space and back no less!
The full review of the Mk5 will allow us to decide how to proceed with the program, but based on this initial launch series we feel confident in allowing agencies to begin applying for sub-orbital science flights with their choice of payload instruments for any data they wish to collect. These contracts will take 2 weeks to construct and launch from the day they are signed so the launch cadence will be much slower moving forward but fear not, we are still developing new rocket designs – engineers have not forgotten about this.
Deuce Preliminary Crash Report
After a successful ground trial the Deuce was slated to fly earlier this week but the return to flight mission was pushed back numerous times thanks to Progeny launch delays and weather. Captain Jebediah, recovering from a sickness that also delayed operations, finally was able to take the aircraft up on Thursday although the initial attempt was foiled by not having enough pitch authority to bring up the nose during the takeoff run. Engineers dampened the pitch controls during the rebuild but with the changes that were also made to better balance the aircraft the lowered pitch settings were not really needed. After a quick adjustment in the Horizontal Assembly Building to return the control settings back to where they were during the earlier flight trials, the Deuce was able to lift off on its second attempt.
Unfortunately while the pitch instability seemed to be fixed, the Deuce still exhibited a strong left-roll tendency that seems a bit too much for engineers to attribute to a yaw problem. Applying opposite rudder worked but it took about 50% of travel and caused a 5° sideslip that noticeably increased the drag on the aircraft. Even more unfortunately, Jeb had trouble again on his final approach, coming in too slow and nearly stalling the aircraft in a similar manner to his last accident. He did manage to recover well, but as he was fast approaching the runway he did not give the aircraft enough time to gain some more speed before dropping the landing gear, which increased the drag and immediately threw the plane over into a leftward spiral down into the ocean.
Thankfully proper restraints and the nose cone being designed to crumple led to Jeb being knocked unconscious but only with a minor concussion. Although rescuers had to blow the emergency cockpit hatch to extricate Jeb, the Deuce did not take on enough water to sink before we could get back to it and tow it ashore. Also by design the engine pods broke off the wings on impact, and we will be calling in a salvage vessel next week to haul them up off the ocean floor. Flight recorders in the tail section survived without damage and will be studied thoroughly. We expect a full report sometime in late October or early November.
ATN Database Update
The weekly update for the Asteroid Tracking Network database is available here, containing 978 asteroids, 22 updates and 0 alerts issued.
Celestial Snapshot of the Week
While Val captured a telescope view of Mun and Minmus hanging out together, Bob wins this week with this zoom lens shot from his camera as Mun rises
From the Desk of Drew Kerman
Out of Character Behind the Scenes stuffWritten on 9/19/17
Damn this is almost like a real-time transmission to you all in the future. Yea I’m cutting things pretty tight, closing out a Friday on a Tuesday. Still, when I started this 5-launch series I only had 1 week of lead time and now I have 4 days, so that’s not too bad of a loss considering all the stuff I had to do (31 images this past week). There was a day of sickness and some IRL stress making my focus go away completely at some points and robbing me of a lot of sleep, but I still managed to hop onto GTA:O for some sessions, watch some movies and keep up with news, forums and twitter timelines. So yea, it was a bit much but it wasn’t too much. Still, as I said before this kind of thing will not be the norm so I hope you all enjoyed it. Lots to talk about from this past week so let’s get to it.
“hurricane” hits KSC
I actually wrote the storm a little after Harvey before it was clear that Irma would impact Florida, but yea the idea was to have a nasty storm sweep through the area. It’s happened before and it will happen again to varying extents, as storms off the ocean near the equator just make sense. Besides that though they do grant me a bit of free time since I have to suspend operations for them, although in this case it was over a weekend and I wanted to show what it looked like so it probably took up more time than it saved. Still, I had it setup so that I could use it to delay launches this past week if I felt I needed to in order to not run out of lead time. Thankfully I didn’t have to make it that serious of an event.
Mk5 mass incorrect somehow
I learned while working up the data for the third launch that I had somehow mis-reported the mass of the Mk5 rocket on the blueprint and for the first two launches. WTF. I really hate stupid mistakes like this because they take time to fix. Since the mass was off, the delta-V calculations were also off. Then I checked and found the price was off! Shit shit shit. How?? I have no clue. I don’t recall modifying anything between then and now that should have changed these values, so it must have just been a mistake. Unfortunately I make them.
comm signal code not really used
Although the AFCS includes code for handling comm loss, this is mainly just for roleplay purpose and the fact that the code should have a means of dealing with comm loss. In reality Kerbalism doesn’t have ground stations so as long as the probe can see Kerbin it has a connection. There’s no reason for me to actually toggle the comms on & off in the game because when comms are lost the log data is written internally, and then after recovery it would be combined with the ground-based log data before being displayed publicly so there’s no point in me doing the extra work to actually combine it. If the rocket didn’t get recovered, I could also manually just remove any data that would have only been on the rocket from the full telemetry log.
I should also comment that the code for the science instruments is pretty lame, just toggling an action group that holds the instruments. Just a time issue, not having enough of it. Hopefully it can get more “realistically” complex moving forward.
Deuce flight was unscripted
Yeap, I was actually giving myself a pat on the back after saving the Deuce from a stall on final that got me on the first flight, then dropped the gear and went “awwww shit”. I really did want to do some more Deuce flights but in retrospect I suppose this is for the best as I really do want a lighter workload moving forward for a bit so I can build my lead time back up, and moreso than rocket flights aircraft flights are very time consuming. I honestly have no idea why the hell the plane wants to roll to the left so much, but I’m suspecting it is some inherent build problem from how I put it all together in the editor. While the ” crash investigation” continues I’ll be busy trying to figure this all out.
Mk5 launch #3
This was fun, because it let me start to introduce some repercussions for the Monolith Incident and all the talk I’ve been dropping about protests over the government decision to block religious access to the Monolith. So it wasn’t put in there just to delay the launch and buy me time. Reactions to the event were pretty much what I expected them to be, and I am glad so many people were around to provide some interaction. I originally wanted the ship to have a huge banner with kerbs on the deck, but I realized that was rather impractical because I would spend a lot of time working up things to be able to get a screenshot of it in the game. Doing the launch itself I got stupid and tried to launch at the wrong time, which of course triggered the launch script as soon as I loaded it into the rocket’s probe core. A special consideration for this launch I almost forgot about as well was taking into account the extra drain on the batteries due to progressing through almost an entire terminal count before scrubbing the launch & resetting.
Mk5 launch #4
So, this launch was planned in advance to go kablooie, I have been wanting to introduce wind shear for a while now. Prior to this it’s good enough to say the rockets weren’t really large enough to be affected by shear, weren’t traveling fast enough or just were lucky not to have any shear when they launched. The third stage throttling up immediately was a code bug I discovered in testing but decided to leave it in as a bug to be discovered in flight for once, and also it lent itself well to the accident by increasing the rocket’s speed to make it more susceptible to breaking up when slammed with vertical shear. I was also planning on using this event as another buffer for an excuse to delay the 5th launch if I felt I was not going to be able to get things done ahead of time. Again as with the storm, thankfully I did not have to. Also, when launching manually & resetting to get around a FAR bug, the upper launch rail tends to get destroyed. I don’t know why pressing spacebar leads to a different result when calling stage from kOS code but it does. I used this as inspiration for the launch rail needing to be replaced due to wear.
Something also I realized about this launch is that this was supposed to be the first fully automated launch but I did a very poor job making this fact known as much as I did for the 5th launch. I think this is because I knew ahead of time I planned to let this launch fail. I realized this on the day of the launch as I was reviewing tweets, after I had written tweets for the 5th launch. This is why I prefer having so much lead time, as I would have likely come to this realization with much more time to make changes for the better.
Mk5 launch #5
I actually didn’t realize when I first scheduled this launch that it would be on the same day as the first time KSA launched a rocket, but hey that worked out great and is the reason I didn’t really want to delay the launch unless it was Thursday and I couldn’t get everything setup in time for Friday. If you don’t count the fact that I initially setup the game for a launch at 15:00 hours instead of 13:00 again like the 3rd launch (FFS) and also had to debug a script error that was due to me accidentally using my mouse buttons to paste random text into the script file – when I actually launched the rocket it flew its mission and I got it all done on the first try at last! Hurray for automation! A new era!
moving on now
Alright so the craziness is behind me. Time to refocus a bit on Extremis, plotting out orbital rocketry development, working more on the Ops Tracker, figuring out what the hell is wrong with the Deuce and of course digging through all the Mk5 data & comparing it to the Mk4 and coming up with some conclusions as to how to make it even better. I really enjoyed putting together the analysis for the Mk5 flights.
