A-N-D-R-E-W
Well-Known Member
Truly awesome project! Looking forward to the after action report. Congrats!
One pellet. Plus some mag. Thanks Jim!!Outstanding! Looks like they all lit on the money.
I would be interested in what altitudes the upper stage motors lit, when you publish your data.
Did you use the pellets?
Yes, I do too. The boost part was really nice. So far, I don't have a complete video of the flight, but I'm sure one will appear.
It was also nice that Steve Shannon was able to see the flight, after working so hard to try to fly the rocket twice last year. And it was great that Kip helped out this year.
Jim
Well, we pulled out what we could. Seems like it was mainly the lower air frame with the motor (about a third of the motor was peeled back). However, I'm not certain that the upper air frame was there. Further, the 4x3 transition that was the "nose cone" for this stage came off and was recovered not far away from the lower section. I think the main just popped and the transition section came loose. However, I'm going to take a quick look around that area just on the chance that the upper air frame came free. Stranger things have happened.
Jim
I looked briefly for the upper air frame. No joy.Interesting, that would seem to indicate no drouge came out but maybe the main got out. Main would shred and upper airframe would go into a rapid spin, which could fling the transition off. I’ve seen a lower airframe recover stability after such a deployment so it’s quite possible that the lower airframe simply went on it’s way after a small diversion. I would assume the upper airframe would follow the wind to some extent. If perhaps the drouge survived it would descend fairly slowly so could have drifted some distance.
The ITAR limits were revised in 2016 and the 15,000m limit was removed. The GPS data sheet does list an operational limit of 50,000m.The attached pics illustrate the above data. The gps track shows the "missing" portion of the flight due to the COCOM limit.
Great work once again Jim! As to the COCOM limit, that makes sense. According to the documentation uBlox locks out above 50,000 meters / 164,000 feet ASL. So anything above that you wouldn't have had GPS lock from a uBlox chipset GPS tracker.Second, it turns out I ran into the COCOM limit. At around 160K feet, the gps quit recording and transmitting data. Recording and transmission resumed when the rocket went below 160K. I compared the simulation for the flight against the gps data before and after the COCOM gap. Prior to the time the rocket started to tumble (at 75 seconds), the altitude was almost exactly on the simulation. Roughly speaking, it looks like the rocket actually reached about 175K, and that the tumbling cost about 10K in altitude. I'll take 175K.
One thing that happened is that the rocket started to tumble at around 140K feet. Kip said that the same thing happened on his flight at about the same altitude. Interesting ...
Thanks for the clarification. It quit working just below 50K meters.The ITAR limits were revised in 2016 and the 15,000m limit was removed. The GPS data sheet does list an operational limit of 50,000m.
Great work once again Jim! As to the COCOM limit, that makes sense. According to the documentation uBlox locks out above 50,000 meters / 164,000 feet ASL. So anything above that you wouldn't have had GPS lock from a uBlox chipset GPS tracker.
Can you give more detail on that? When you say tumble how exactly did it tumble is what I'm curious about.
It quit working just below 50K meters.
Well, even with one of CJ's magic pellets (0.9 grams BKNO3) and about 4 grams of magnalite, it still took 4.5 seconds for the 3rd stage to light. It would have actually come up to pressure right at 45K feet. I chose the magnalite quantity to be about twice what one might use with a burst disk (since I wasn't using a burst disk). Good thing I ran into CJ at Airfest.One pellet. Plus some mag. Thanks Jim!!
Third stage should have been around 45K, but it will take some time to know for sure.
Jim
As others' have mentioned above, you pegged the GPS .
ecarson just pointed me recently at the relevant pages of the data sheet from ublox for their GPS receiver. See here for the discussion and to get the expurgated pdf:
https://www.rocketryforum.com/threads/enabling-galileo-gps-on-u-blox-m8n.148088/
Even if airborne mode is selected the lockout on position data is on altitude, so yep, 50km is the limit for position reporting.
That is a very useful table if considering high flights. I have it printed out for reference .
And here's that table without the watermarking posted on the ARF 5 weeks ago.
Vern, I assume you are still getting position as well? What attitude? Were you over 50km and 100m/s?
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