Failure Analysis of Hyperion

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Did you have a time delay for the backup apogee charge? If you're absolutely positive it wasn't your wiring, maybe both charges fired at the same time for a harder than wanted yank? Have only heard of that being a possibility...
 
FWIW I had issues with blowing the main at Apogee with my RW Stinger (with a slight nose cone extension). I had to go to 3 6-32 nylon screws for shear pins because 4-40 were not enough. Maybe the 3g charge I use is too much for the shear pins (as opposed to too much weight).
 
Did you have a time delay for the backup apogee charge? If you're absolutely positive it wasn't your wiring, maybe both charges fired at the same time for a harder than wanted yank? Have only heard of that being a possibility...

I have seen this happen several times, and had it happen to me even when I had a time delay
 
You should have NEVER made that flight without a RF tracker. You would have rocket back if one was in there.That's the hard cold fact. I would not have allowed you to make that flight with out one, especially when uppers were raging like that.

GPS's lose lock & fail...I have seen it way too many times. In 10yrs of using RF trackers, I have never lost one, nor any of my mates using them. Yes I use GPS & that will get me to a rocket real quick, but there is ALWAYS a RF in there for back up. I can't believe Gus or Jim didn't offer or insist, you one to use. They are the last defense for anything going wrong in a flight other than destruction.

I cyphered your flight, by the way...[I've been all over that field in 9yrs] Checking the layered winds from 6,000 [39mp] 5,000 35mph 3000 [24mph] 2000 22mph surface 7-17 gusts[] that day....using a very forgiving 30/sec rate I figured rocket is 3.7-4.5 miles from launch......we'll see how close I come..LOL

RF tracker or lack there of, is your failure. Everything else was "matters not'' , you would know where it is/have it back . :wink:

And they should have had a tracker board. I pulled rockets twice because there was another flyer using the same frequency.
 
Did you have a time delay for the backup apogee charge? If you're absolutely positive it wasn't your wiring, maybe both charges fired at the same time for a harder than wanted yank? Have only heard of that being a possibility...
I had apogee and apogee +1 sec.
 
That's good. Still doesn't rule out both going off at the same time though...

This was one of my theories, except that I was flying the same brand of altimeter (RRC3 and RRC2+), which means that the algorithms for determining air pressure should be either the same or really close to the same. If I was flying 2 different brands of altimeters, this theory would be more pressing.
 
Is it possible that one of the altimeters was set for single deploy mode rather than dual deploy?
The altimeters beeped out that they had continuity on 2 channels. I don't actually know if there's a way to set it for single deploy only...
 
Along the lines of an earlier post..

How big was your drogue?

Perform the drag calculation to determine what the tension on the cord would be at various deployment speeds:
50 ft/s
100 ft/s
200 ft/s

You were probably booking when the apogee charge failed.
 
Were you also using 4-40 shear pins for the sustainer or were you using smaller pins there?
 
Along the lines of an earlier post..

How big was your drogue?

Perform the drag calculation to determine what the tension on the cord would be at various deployment speeds:
50 ft/s
100 ft/s
200 ft/s

You were probably booking when the apogee charge failed.

I was actually flying drogueless.

Were you also using 4-40 shear pins for the sustainer or were you using smaller pins there?

4-40 for the sustainer.
 
Could the apogee charge pressure leak into the av-bay pressurizing the compartment?
Reasonable theory. My bulkplates weren't a totally tight seal to the ends of the avionics bay.

Has anyone ever added o-rings or similar material to the av-bay lids?
 
Reasonable theory. My bulkplates weren't a totally tight seal to the ends of the avionics bay.

Has anyone ever added o-rings or similar material to the av-bay lids?

Typically do not have to do that, you would need a big leak to pressurize the av-bay to less than 1000' from 7000'. But if there was an av-bay lid structural failure when the apogee charge blew....... Things like that.
 
Matt,

When I was looking at your rocket I was thinking that your av-bay looked symmetric, was it possible that you flipped it end for end and the apogee charge was now the main?

Dennis
 
4-40 for the sustainer.

I bring it up because I noticed that rockdoc likes to use larger pins for the cargo bay and smaller pins for the sustainer and sizes his charges accordingly, and this seems like a good idea for helping to avoid spitting out the main at apogee.
 
Matt

You have way more experience than I do with Rockets, but having used LiPo batteries in RC for a long time everyone is giving you sound advice on the voltages. Here is what I use to test and check my LiPo's. It will balance them as well, if you leave it on for a long time. I tend to balance on my charger because it is a better, safer and more accurate to be done during the charging process. The picture below is from a 2S, 7.2v LiPo. As you can see C1=4.18v and C2=4.19v for a total of 8.37v which is higher than the nominal voltage of 7.2v. It is also telling me the battery is @99% charge. I have my Low Voltage Detection set to 3.2/C or 6.4v for the battery. I personally don't like 1S and will avoid them if I can use a 2S because of the extra capacity. Not sure if your battery died or not, but this a cheap way to double check all your batteries super quick. I hope you find that rocket.

IMG_2246 (1).jpg
 

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A fully charged one cell Lipo is 4.2V. Most, if not all lipo chargers will automatically stop charging once the battery is fully charged. In the RC world, most have a LVC (low voltage cutoff) and that's usually at 3.2V. Your battery was pretty low and I wouldn't be surprised if a low battery is the reason you lost tracking capability.

Ummm, I've been running all my EggFinders with a 2S lipo and yes, one can get away with it using a 1S but I want a steady voltage supplied to the EF. There's a 3.3V regulator on the board and tracker reliability should be strived for.
If the voltage drops too low, power output tanks and range therefore stinks. With a 100mah, 900Mhz tracker this is vitally important. Jim's contention of an RDF backup tracker on a cert attempt that's going up "a ways" is valid.
So much so that I'm going to do it from now on for large projects that can handle the extra tracker and certainly on an L3 attempt.

Remember, not every position with an EggFinder is decoded while the rocket is in flight. I believe it is due to 1. The 100mW power output and 2. The random antenna orientation that occurs with the rocket under drogue affects the polarization of the
signal the can be overcome with increased power output but is limited to 100mW with the EF. Once the rocket settles down under the main chute, I find the decode rate goes up. Only takes one position to find a rocket.
That's where GPS can help because in the event of a ballistic flight one just needs a single position, preferably before it hits, and the hole will be found. I found that out and only had 2 maybe 3 positions come through with an EF flight and I was probably
a little over 100 yards from the impact point. RDF one is out of luck as a bearing likely won't be had nor held without a visual.

I agree, an RDF tracker in Hyperion's case would likely have saved the day. With the luxury of the visual lock, could have "honed-in" on the bearing and if a mapping GPS was used that could lock a bearing, one would have a GPS reference to follow a line
to the last known bearing. (Hold the mapping GPS parallel to the Yagi beam to lock the bearing if the rocket can't be seen.) Folks said they lost sight of the rocket when it was 3000 feet up. The LOS (loss of signal) of the tracker could have occurred much later and the final bearing (plus a mapping GPS to lock the bearing) would have saved the recovery. There would have been a tremendously good chance one could have proceeded to at least the ground footprint of the tracker and home in to make the pickup. Hopefully the rocket will be found and flown again with two trackers and a 2S lipo on the GPS tracker. Matt read up on lipos and chargers to get a handle on this battery chemistry. Kurt
 
Quote Originally Posted by VernK View Post
Is it possible that one of the altimeters was set for single deploy mode rather than dual deploy?





The altimeters beeped out that they had continuity on 2 channels. I don't actually know if there's a way to set it for single deploy only...



That's not too good of an answer, the RRC3 has deployment modes one of which will deploy both the drogue and main at apogee. Should have known which mode it was set at. You also said you do not have a wiring diagram for the av. bay, isn't one required for an L3 attempt?
 
Matt,

Nice to meet you and cool boost, man! Sorry the big bird is missing; I'm confident it will turn up over time. I'll begin wading through photos today to see if I got a shot of the liftoff. If it's the flight I'm thinking it was, I remember watching for an apogee event, seeing a puff of powder smoke, noting it was apart, then the main blossoming a few seconds later....it appeared that the main "shook loose" following the apogee event. IE: the main charge did not deploy the main at apogee.

Based upon weather conditions, etc., I'd bet a nickel that the three #4-40 let go at apogee. Most rockets were headed upwind at a pretty good clip due to the winds...I too suspect that upper winds were 50+mph. For reference, my 7.5" Patriot that flew earlier in the day (calmer) with a very reefed drogue drifted 1.13 miles downwind after arcing heavily upwind and deploying as intended from 8175' up. It was definitely notably windy up there! Forces involved with a speedy horizontal deployment are significantly greater than those of a calm day where the bird really slows down before arcing over.

Note, I have #6-32 and even some mega #8-32 pins for certain big honkin' cones. (But I did use *only* four #4-40 nylon screws on the 7.5" Pat on Saturday and it worked well).

-Eric-
 
As a point of reference, I used three #8-32 pins in my nose, and two in my booster. Everyone laughed at me, but I kept saying that under certain conditions and with certain motors, I was concerned about popping the nose too early.

I deployed my drogue with 4.5g and my nose with 6.0g. Broke those #8s like toothpicks.
 
Matt,

When I was looking at your rocket I was thinking that your av-bay looked symmetric, was it possible that you flipped it end for end and the apogee charge was now the main?

Dennis
It is physically impossible for the bay to be assembled backwards.
 
As a TAP for this project, I was not going to "demand" anything. It's the job of the RSO to make those decisions. Would I have flown under those conditions? Hell no. Matt is a big boy, making big boy decisions. I told him before he took it out, "I wouldn't fly, but it's your decision". I don't use trackers at all, never have so I don't have a dog in that hunt. We can disect this forever. **** happens, Matt is second guessing everything he did. He doesn't need to do that. It's a learning process. Yes, we even learn from cert flights. Just because you attempted a cert doesn't mean you know everything, just that you believe you are comfortable in your attempt. I respect everything CJ says, he knows alot more than I do, even though I have been here longer. He pushes the envelope regularly, I remain in the low comfort zone. I have good feelings about Matt eventually getting his rocket back and telling us what happened. OK, rant done!
 
This was one of my theories, except that I was flying the same brand of altimeter (RRC3 and RRC2+), which means that the algorithms for determining air pressure should be either the same or really close to the same. If I was flying 2 different brands of altimeters, this theory would be more pressing.

I am beginning to question this premise.

I have two rockets configured this way, and I keep having issues with the main (RRC3) and the back up (RRC2) firing at about the same time (with the RRC2 set with the delay). I have confirmed that it's NOT because the charges are interacting with each other and ripple firing. This is in 2 different rockets with 2 different sets of computers. I've had it happen twice on each rocket.

The first time it happened at about 3500 feet on each. After re-checking my math and again doing ground tests, I flew them again on motors to go about 1800 feet to make it easier to see. Sure enough, same darn thing, both ripple fired.

Don't rule it out just because it didn't happen on the ground (you did ground test your main charges with the back ups in place to rule out a ripple fire potential?) that it won't happen in flight. Mine NEVER failed on the ground in every ground test that I did, but BOTH rockets failed in flight BOTH times.

Since moving to only one altimeter in each rocket, they've flown 100%.

I'm thoroughly convinced that the sense of the RRC2 and RRC3 are so close that the delay set up for back up just hasn't worked for me. If I were to NEED to guarantee the back up, I would use 2 of the very same computer.
 
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Ummm, I've been running all my EggFinders with a 2S lipo and yes, one can get away with it using a 1S
According to the docs, the Eggfinder uses an NCP1117 regulator which has a typical dropout voltage of about a volt or a little more. Since the output is 3.3V the input has to be at least 4.3V, and since the maximum output voltage of a 1S lipo is 4.2V, on paper an Eggfinder simply won't work on 1S. If people are getting away with using 1S, that is sheer luck based on the datasheet.

There are many regulators that can produce 3.3V from 1S lipo voltages but the NCP1117 is not one of them.
 
I am beginning to question this premise.

I have two rockets configured this way, and I keep having issues with the main (RRC3) and the back up (RRC2) firing at about the same time. I have confirmed that it's NOT because the charges are interacting with each other and ripple firing. This is in 2 different rockets with 2 different sets of computers. I've had it happen twice on each rocket.

The first time it happened at about 3500 feet on each. After re-checking my math and again doing ground tests, I flew them again on motors to go about 1800 feet to make it easier to see. Sure enough, same darn thing, both ripple fired.

Don't rule it out just because it didn't happen on the ground (you did test your main charges with the back ups in place?) that it won't happen in flight. Mine NEVER failed on the ground, but BOTH rockets failed in flight BOTH times.

Since moving to only one altimeter in each rocket, they've flown 100%.

Interesting, as I'm planning on running the same combo as you and Matt. Perhaps it would be a good idea to run the RRC2+ as primary for the drogue, and program the -3 for a longer delay after apogee than the 2+'s one-second option.
 
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