EVENT BALLS 28

[manixFan]

....<snipped>...This is also why I believe that Class 3 project participants should be encouraged to write post-flight reports.....<snipped>...

I do agree that there should be a summary of class three flights failure modes. Some seem to be obvious - like a motor CATO. But even with that kind of a failure, post flight analysis could help others with future motor designs. I see folks make the same mistakes others have already made and it's frustrating as those failures could have been avoided. Having write-ups others could review may help decrease the failure rate by exposing failure modes that are easy to avoid.


Tony

 

[JCRL]

Is the BALLS event at the same location every year, or does it change locations. Also, does BALLS stand for something?

 

[mikec]

Do suppliers of altimeters using accelerometers with tilt protection test their products to assure they will work correctly?

I'm sure they try, but as you say, there is no way to do complete testing on the ground, and IMHO experience suggests that all of the current ones are deficient in some way except maybe Kate 2, which as I understand it doesn't use orientation sensing.

There was a request from the BALLS organizers for post-flight reports for all >50K projects and I have seen many responses. I don't know if there is any plan to make that public, and I can see pluses and minuses in doing so.

I'll summarize my report: My M-to-L two-stage broke in half at the interstage coupler about 3 seconds into the flight. Lesson learned, make stronger interstage coupler.

I am a professional aerospace engineer and I am not in the hobby to justify every one of my design decisions to uninvolved parties, I get more than enough of that at work.

 

[Bat-mite]

Is the BALLS event at the same location every year, or does it change locations. Also, does BALLS stand for something?

1) Yes. 2) Not originally. It was simply the idea that it takes BALLS to launch huge rockets to incredible heights. But later, someone came up with the acronym "Big Ass Load Lifting Suckers." Take your pick.

 

[JCRL]

Thank you @Bat-mite , also I love your avatar pic with the fully assembled rocket; wow!

 

[jderimig]

GPS cannot detect a tumbling rocket. You need a gyro.

 

[Bat-mite]

Thank you @Bat-mite , also I love your avatar pic with the fully assembled rocket; wow!

Thanks. I would love to launch that sucker at BALLS, but I don't think it's in the cards. My wife would never go, and I'd have to leave her home for two weeks with the kids, and that's not happening.

 

[Binder Design]

I am a professional aerospace engineer and I am not in the hobby to justify every one of my design decisions to uninvolved parties, I get more than enough of that at work.

Agree. And nobody that had a "non nominal" flight at BALLS owes anybody an explanation.

 

[JimJarvis50]

.... except maybe Kate 2, which as I understand it doesn't use orientation sensing.

Kate does use orientation sensing as a backup to gps tilt. The data output includes both the gps trajectory and the IMU tilt. Rotation rate is not in the data output, but is available.

Jim

 

[MClark]

1) Yes. 2) Not originally. It was simply the idea that it takes BALLS to launch huge rockets to incredible heights. But later, someone came up with the acronym "Big Ass Load Lifting Suckers." Take your pick.

The Big Ass... was coined by Aeropac for the few times they hosted. They don’t host anymore. Look at the background of the logo for what it means. https://www.ballslaunch.com/

The launch site has moved a few miles over the years. We used to be farther from the dunes. It has always been at Black Rock.

It’s unlikely to see a report on this forum as most attending BALLS do not post to any forum.
M

 

[Richard Dierking]

Nothing exotic. The sustainer video is from something called a "Muvi Veho Pro".

https://www.amazon.com/Veho-VCC-005..._1_3?keywords=veho+muvi&qid=1569937296&sr=8-3

The battery will last for 2-3 hours depending on how you use it, and the form factor has some features that allow it to be easily mounted.

The fin-cam is just an 808 #16. It has a flat bottom, so I just use a little CA to glue it to the fin.

Jim

Here's a couple photos of what I use for the camera Jim mentions. I've tried the pro and the HD version (similar shape, but HD is a little thicker), and can't see much difference. The bay is 3D printed and conforms to the inside of the compartment with the main. Good, because you can turn on the camera at the pad and place in the camera compartment. Also, I put a very small drop of epoxy where you insert the micro SD card.

 

[manixFan]

Agree. And nobody that had a "non nominal" flight at BALLS owes anybody an explanation.

Interesting position. Class 3 flights need to be reviewed before the event, so you are opposed to a post flight review and analysis? Do you not think lessons can be learned from other's failures?

Things that I thought were common knowledge and have avoided doing have turned out not to be and others have suffered ill consequences as a result. For example, early on in my 'career', I saw a rocket separate under drogue and the fin can was destroyed when it hit with no chute. Inspection showed that the eyebolt that was screwed into the forward closure backed out due to heavy spinning of the fin can. To me it now seems like an obvious issue that everyone can and should avoid. Yet I still see that same failure almost 20 years later, and many folks I've talked to said it never even occurred to them it could happen. As we move up the ladder of more and more complex flights, there are many more opportunities for such 'obvious' failures to occur. But of course they are only obvious in retrospect. It seems to me post-flight analysis would be a valuable contribution to the hobby by helping to reduce the failure rate of big (and often very expensive) projects. Not to mention improving overall safety.


Tony

 

[Binder Design]

Interesting position. Class 3 flights need to be reviewed before the event, so you are opposed to a post flight review and analysis? Do you not think lessons can be learned from other's failures?

Under the current regulations, the rocketeer is not required to determine the cause of failure, and document/report it to anyone. In many cases, it's not even possible to determine the cause post mortem. If the rocketeer wants to share, that's up to them but they don't owe it.

 

[Steve Shannon]

As part of the class 3 and over 50k review we ask all of the flyers to provide an after action report with several specific data points. We want to understand failures in our procedures as well as flights in an effort to improve both. I believe the results will be shared in some way.

 

[Richard Dierking]

That's good Steve. Thank you. I could think of many reasons why individuals/teams would not want to present specifics on RF. But, if the info was reviewed by experienced folks and summarized that would be excellent. Then, we could have fun with it here. (Sorry, just kidding.) Anyway, even general info from the C3 committee is useful.
For example, a couple years ago, I saw the Class 3 summary and noticed the high percentage of fails with recovery. I wouldn't have known this otherwise. Because of this, I started to work on side deployment bays and now mechanical side hatches in place of drogue chutes.
Also, I just took a good look at all the ISC I have including the one I'm currently building. And, developing a way to test tilt safety for my multistage rockets. I bet other people are thinking about this stuff too. So, seeing and learning about the experience of others potentially helps many people.

 

[FredA]

Second thing I heard in this thread is "what happens at BALLS stays at BALLS." This is funny of course, but probably really true and a little disappointing. I believe that a lot of knowledge is being concentrated with a few people and teams because of a lack of sharing. I would be interested in hearing why? Maybe there wouldn't be so many failures if information flowed a bit more freely. This is also why I believe that Class 3 project participants should be encouraged to write post-flight reports.

Try one and then ask again....they are a sh*tload of work.
To pull off these flights, a person needs to spend time EXECUTING instead of documenting for the public - and especially for the nit-picky, "having fun" crowd that often gathers here.

 

[Richard Dierking]

I will.

 

[manixFan]

Try one and then ask again....they are a sh*tload of work.
To pull off these flights, a person needs to spend time EXECUTING instead of documenting for the public - and especially for the nit-picky, "having fun" crowd that often gathers here.

I didn't mean to imply that failure reporting would be for forums like this or even the general rocketry crowd, but more for the review committee that approves the Class 3 flights. My rocketry partner is on that committee (class 3 review) and I have heard about a lot of things that I now know to take into consideration when I go down that route. If the review committee saw design issues they knew had caused problems before, it seems like all involved would benefit from avoiding past mistakes. I certainly would welcome any input that increases my chances of a successful class 3 project. I would hate to think that I am in the minority in that respect.


Tony

 

[daveyfire]

I am a professional aerospace engineer and I am not in the hobby to justify every one of my design decisions to uninvolved parties, I get more than enough of that at work.

Ain't that the feeling!

Had a great time at Balls. Flew an L, an M, and an N, didn't make any groundbreaking discoveries, had fun, but more importantly:

• Guided Tim through easy (and hard!) Black Rock recoveries (with a major assist by Tony!)
• Caught up with so many people I haven't seen in years
• Very much enjoyed hanging out with Bob 2.0, Charlie, Chris, Cory, and AMY!

Can't decide whether to do Balls or XPRS next year, but I'll be back at Black Rock. I missed it too much.

 

[tfish]

Ain't that the feeling!

Had a great time at Balls. Flew an L, an M, and an N, didn't make any groundbreaking discoveries, had fun, but more importantly:

• Guided Tim through easy (and hard!) Black Rock recoveries (with a major assist by Tony!

I think this one was Tim's

Not up the side of a mountain..but..
a tad off the Playa : )

Tony

 

[mikec]

GPS cannot detect a tumbling rocket. You need a gyro.

If you have reliable high-rate GPS during boost (and it's my understanding that Kate 2 does, though I'm not sure how) then you can determine if you are ascending stably from that.

I'm still skeptical that any of the presently available tilt sensors are reliable at all accelerations and orientations. The chips they use are intended for 1-g applications, after all. I tried to build my own tilt sensor for BALLS, but in the end used a simple altitude lockout (and then my rocket broke in half anyway, bummer.) I am not an advocate of an absolute hard requirement for tilt sensing at this time for that reason.

 

[plugger]

When it comes to publicly publishing post flight reports regarding Class 3, ludicrous speed (as in approaching M3) or aggressive staging attempts I can easily see both sides of the coin. Personally I can understand why some people wouldn't want to have to sit down and document their failure, especially when it's fresh in the memory and especially painful. On the other hand the failure mode analysis could possibly be invaluable to someone else who is considering going down the path you already have and aren't across the "unknown unknowns" that you now possess.
Plus in reality the failure mode analysis can change over time, even with data. The best recent example I can bring up is my own. In April I flew a CF MD rocket on a M2245 that went suboptimal at the the end of the motor burn. Over time and countless hours of obsessing about what happened I've changed my mind twice regarding what occurred. And that's with Raven3 data to guide me. For the record I recovered the nose cone and avionics bay, everything else is still somewhere in outback Queensland.
Initially I wanted to (and did) blame the 75mm FARG I used for the attempt. Then it was kindly pointed out to me that my rocket was off axis by a few degrees in the FARG relative to the rail it was hanging off of. FARG failure lesson 1 learned; always ensure your rocket is linear on the rail when flying with a FARG. Simple in hindsight but I didn't even consider checking this when I racked up. This is what caused my rocket to not fly straight but instead cant to the right immediately off the pad. That caused the rocket to corkscrew and it probably took 1 to 1.5 seconds for it to start flying true as a result.
But as mentioned the anomaly occurred near motor burnout (and at roughly Mach 3) so the FARG issue didn't fit the failure. After that I wanted to blame my fin attachment bonds as the rocket folded and the upper (non motor casing) section sheared off the base of the rocket. My expectation was that a) I lost a fin, b) the flight AOA went pear shaped and c) the airframe folded and the NC/AV Bay section sheared off the vehicle. I held onto that for a month or two as my prime candidate for the failure.
But in the back of my mind that didn't feel right either and I finally realised why. Charlie Savoie was the RSO/chief button presser on the Saturday when I flew and was on the mic when my flight went squirrelly dan. After everything rekitted in the air the lower section (airframe+fins with motor casing inside) just kept going. Charlie made the offhand comment of "well drew, looks like the bottom half might still get 30k". And he was right in so far that the aft section of the rocket stayed together, stable, and momentum kept it honking long past visibility. For the record I've never seen a rocket shred a fin required for stability and still stay stable and fly straight after the shread.
This led to the somewhat obvious conclusion that my fins stayed on and my failure was due to something else. And the only logical explanation remaining was that my airframe buckled between the forward section of the motor casing and the aft section of my AV Bay/threaded rod motor retention point. I had a roughly 2 inch section of airframe that wasn't reinforced where the forward closure and threaded rod coupled for positive motor retention. I rolled the airframe myself and iirc it was 4 wraps of 199gsm 2x2 twill. And thinking back it was something that I had considered and then discounted because I didn't think it was an issue. So moving forward any rocket I build that utilises this design will have internal stiffening on the airframe at any point where there isn't motor casing or AV Bay/coupling tube reinforcement. And if I'm being honest I suspect I'm not the first to suffer this failure mode and yet it bit me.
So as the above example not so succinctly illustrates failure analysis can be complex and uncertain even with video and flight data. But it's still worth sharing these failures with one another. We have a good community filled with (mostly) good people who are exceptionally generous with both knowledge and time. Ideally we would leverage that for mutual benefit. A rising tide yada yada yada.
And if others feel the same way the next hurdle would be the fact that this knowledge is hidden in various pockets of the internet, various threads here on TRF and other rocket forums, personal web sites etc. To make this work and worthwhile it might make sense to have a centralised location where we as a community place this data for others to access. I'm kinda ok with the ITs and know a thing or two about the cybers and would consider building a wordpress site to host all of this content for the community. But I'm not 100% as I'm sure I'll inevitably be abused by people for doing or not doing something that they disagree with. Still, I reckon the knowledge is worth the headache.

 

[Charles_McG]

To make this work and worthwhile it might make sense to have a centralised location where we as a community place this data for others to access. I'm kinda ok with the ITs and know a thing or two about the cybers and would consider building a wordpress site to host all of this content for the community. But I'm not 100% as I'm sure I'll inevitably be abused by people for doing or not doing something that they disagree with. Still, I reckon the knowledge is worth the headache.

Putting that kind of info in a place like TRF invites a lot of speculation and second guessing. And third guessing. From ‘It was Broken As Designed’ to ‘you built it wrong’ to ‘you did your analysis wrong’. With guesses and hearsay to boot. Useful info sometimes survives, but few people like watching sausage being made.

Having a resource would be good. Having it somewhat central and known would be good.

How about something like motorcato.org, but for the whole rocket. Especially V2, where reports are visible. Simple database. No discussion in-situ. Perhaps editable by the original poster or the admin. Voluntary but recommended.

Maybe even approach John Coker about it.

 

[FredA]

Remember -- as a general statement, the Balls community does not NEED TRF for anything.
We have plenty of "community" to provide commentary on a flight or rocket, pre or post flight.

Posting here is for fun.
Posting here and being second-guessed by people who really don't have the experience and knowledge is NOT usually fun.
Frankly, I think this place is lucky they get the postings they do.......

If you want to learn about Balls-level rockets, goto Balls.

 

[Chad]

Putting that kind of info in a place like TRF invites a lot of speculation and second guessing. And third guessing. From ‘It was Broken As Designed’ to ‘you built it wrong’ to ‘you did your analysis wrong’. With guesses and hearsay to boot. Useful info sometimes survives, but few people like watching sausage being made.

Having a resource would be good. Having it somewhat central and known would be good.

How about something like motorcato.org, but for the whole rocket. Especially V2, where reports are visible. Simple database. No discussion in-situ. Perhaps editable by the original poster or the admin. Voluntary but recommended.

Maybe even approach John Coker about it.

a document repository of PDFs with no comment support would work too. Seems like it should be managed as a joint effort between NAR and Tripoli but that's just my two, likely naive, cents. Personally, if it caught on, I think it would be a great research resource.

 

[Steve Shannon]

Putting that kind of info in a place like TRF invites a lot of speculation and second guessing. And third guessing. From ‘It was Broken As Designed’ to ‘you built it wrong’ to ‘you did your analysis wrong’. With guesses and hearsay to boot. Useful info sometimes survives, but few people like watching sausage being made.

Having a resource would be good. Having it somewhat central and known would be good.

How about something like motorcato.org, but for the whole rocket. Especially V2, where reports are visible. Simple database. No discussion in-situ. Perhaps editable by the original poster or the admin. Voluntary but recommended.

Maybe even approach John Coker about it.

Summaries prepared by Tripoli belong to Tripoli. If (hopefully when) Tripoli publishes such information it would strictly be on the Tripoli forum.

 

[Charles_McG]

Summaries prepared by Tripoli belong to Tripoli. If (hopefully when) Tripoli publishes such information it would strictly be on the Tripoli forum.

Absolutely.

I was thinking of self-reported data. Like MESS reports. But for more than motors.

And don’t Class 3 flights fall outside TRA and NAR jurisdictions? Yes, I know they aid in the submission process.

At least you don’t have to do NTSB reviews

 

[Steve Shannon]

Absolutely.

I was thinking of self-reported data. Like MESS reports. But for more than motors.

And don’t Class 3 flights fall outside TRA and NAR jurisdictions? Yes, I know they aid in the submission process.

At least you don’t have to do NTSB reviews

You’re right; people self reporting could do so wherever they wish and the forum Richard Dierking suggested might be a great avenue.

Class 3 is an FAA classification but all Class 3 flights or flights expected to fly above 50k (both of those at Tripoli launches only of course) go through the C3RC process which includes a request for an after flight summarization. That’s what we hopefully would share somehow on the Tripoli Forum.

 

[Nytrunner]

You’re right; people self reporting could do so wherever they wish

And a couple folks like Kip and Jim-J choose to do so here, for which we are very grateful.

Others don't care to share in a forum populated by opinionated fliers of lesser skill, and that is their prerogative. As freda said, If you want to learn, come find us on our ground.

 

[jderimig]

Some information is personally valuable. This is also a commercial forum and some may find section 6.2 of this forum Terms of Service annoying to them.

https://www.rocketryforum.com/tos/

 

[kevindcornwell]

I'm actually surprised to hear you say this Steve. Rockets are predictable. Only questioning and understanding will increase our knowledge of why things like this happen.
I would suggest looking at the pad. Was there a blast deflector, and how is the pad configured? I question sim exit velocity vs actual for many flights I've seen including my own. There needs to be more data on this.
Maybe it would be better if pad rails were longer, there was passive retention at launch, or blast deflectors were not attached to the structure of the pad?
The wind velocity at increasing altitude is interesting at Black Rock. Because it's smooth, there should only be gradual increases in wind velocity immediately above the deck, well, until you are over a thousand feet and the mountains are less of an obstacle. I know this all too well from a two stage flight last year at XPRS.
Second thing I heard in this thread is "what happens at BALLS stays at BALLS." This is funny of course, but probably really true and a little disappointing. I believe that a lot of knowledge is being concentrated with a few people and teams because of a lack of sharing. I would be interested in hearing why? Maybe there wouldn't be so many failures if information flowed a bit more freely. This is also why I believe that Class 3 project participants should be encouraged to write post-flight reports.

Do suppliers of altimeters using accelerometers with tilt protection test their products to assure they will work correctly? I can test my barometric altimeters in a vacuum chamber, but how to test an accelerometer for it's safety features? Again, is this something we are going to accept and repeat?

I suspect that what Steve was implying was that there are some variables that are exceedingly difficult if not impossible to accurately predict and therefore to preemptively mitigate. Thank you to all those who responded regarding the Ariel's flight path. I left my questioning as open-ended as I could in order to not bias any responses and I truly appreciate the knowledge presented here on TRF. My suspicion is that it was weather cocking off the pad. There were blast deflectors in place and the rail was vertical. I didn't measure the rail length from my two rail buttons to the top of the 1010 rail. Eight feet seems like a reasonable guesstimate. The wind however offered a surprisingly unexpected variable. I had noticed that the smoke trails of previous flights did not shift in a smooth or predictable way. There appeared to be significant and very abrupt wind shifts within a hundred feet of the surface. My strong suspicion is that one of these wind patterns created the weather cocking observed. I also suspect that my Ariel rocket's (my daughter's middle name - an aside: my wife chose our children's first names and I got to choose their middle names my son's middle name is Talon and yes, I have built a rocket dubbed Talon) parameters affecting weather-cocking were likely effecting a greater force than those builds which took greater care towards minimizing those same attributes. In the end I was extremely pleased with the flight and the solid performance of the removeable fins and locking body-tube joint. The rocket was designed as a semi-modular to facilitate ease of shipping (to/from Hawaii). Photo as shipped and as launched.

Here's the build picture-book. I know it's a great read as it puts my wife to sleep in no time flat. https://www.dropbox.com/s/glx8yoc9uahpjr2/Ariel_ Prometheus Class.pdf?dl=0

Thanks for all the valuable input