trying to understand how the rules work:)

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@Lt72884 Given the quote below, could you post up your OR sim that says that the optimum delay for the LOC IV is 14 seconds? A picture of the fins would also be nice since shaping on the fins has a big impact on the altitude/optimum delay.
As to the OR Sims. The LOC IV with an H550 gives optional delay as 10.1 sec. The Default delay for this motor is 14second so possible this is where the student got this delay time from. With a 14sec delay OR says the rocket will be descending at 70f/s when the Main chute deploys. I am not surprised it zippered but the other flights got very lucky.
 
this is our first l1 flight and 4 of the 5 passed with the exact same settings. so its a mystery to us haha
We are in the process of fixing it. not to hard to fix this.
Roger that! Make the repairs, analyze your data, do your course corrections.

Setting an optimal delay takes more than just looking at the sim data - knowing the variations in delay timing for the motor you’re using takes experience, both with the rocket/motor combo and your flying field. Good luck on your next attempt.
 
Over complicating things. Others, correct me if I'm wrong, but the general idea is you need to be able to throw another motor in & fly it again.

The zipper you pictured is without any doubt catastrophic from any flyers viewpoint. Sure anything can be fixed. So can this...
thank you for this piece of information. I now understand that its catastrophic because if i were to put in another motor, it would not fly. Thank you for stating this. I know others probably have chimed in since my last reply and i will read those as well.
 
Rather than trying to justify that “it’s not that bad”, own the failure - we all have them. Do a root cause analysis, and learn from it. Rather than convincing yourself “they were all the same”, think about the variables.
correct, we have owned it and thats why i said im not slamming the committee but we need to understand the rules and why its deemed catastrophic so that we can learn and fix this rocket for the next flight. I have now learned some things from some searches and others who are RSO's. its catastrophic because if we were to put a new H550 in it, it would be destroyed on flight. This makes sense to me now. I was under the impression from some others that to get lvl 1 it goes up, and must come down safely and be recovered. We were not told that in order to pass, it had to be able to fly again immediately.
in one of my earlier posts on this thread, i mentioned that the rocket that failed was not painted or smooth. it was rough, therefore causing drag, and so you are correct, this rocket was not the same:)
 
His rocket was hte only one flown naked and not painted, which i think was the problem

You had burnout at what, a few hundred feet and coasted for a thousand more? Do you think there was enough time for the finish to make a significant difference?



Thats odd. so there is no standard or standard definition? its up to someone's interpretation?

There's no need for a definition.

Here's what the TRA website says:

"Non-certification – Any of the following will result in non-certification for a certification flight:


  • Motor Cato
  • Excessive Damage
  • No recovery system deployment or tangled recovery system deployment
  • Rocket drifting outside the specified launch range
  • Components coming down not attached to the recovery system.
  • Any other violation of TRA safety code associated with this particular flight.
  • Any other legitimate reason the certifying member deems merits non-certification"

The airframe is not longer able to support a flight, excessive damage without a doubt. No prefect would have passed it.

If you had dinged up a rail button and it would be a good idea to replace it, that could be interpreted differently. If you had a small zipper that's fully supported within the nosecone shoulder or the coupler, then that could be interpreted differently.

Here's the procedure for all 3 cert levels (Tripoli, right?)
https://www.tripoli.org/content.aspx?page_id=22&club_id=795696&module_id=468541
 
The rocket could have been repaired in the amount of time spent on this thread.
or repaired in field and flow again for cert the same day.
i know i agree. thats why i stated at the very begining that this is a simple fix. in fact it has already been fixed. took less than a couple of hours to do so.
 
You had burnout at what, a few hundred feet and coasted for a thousand more? Do you think there was enough time for the finish to make a significant difference?





There's no need for a definition.

Here's what the TRA website says:

"Non-certification – Any of the following will result in non-certification for a certification flight:


  • Motor Cato
  • Excessive Damage
  • No recovery system deployment or tangled recovery system deployment
  • Rocket drifting outside the specified launch range
  • Components coming down not attached to the recovery system.
  • Any other violation of TRA safety code associated with this particular flight.
  • Any other legitimate reason the certifying member deems merits non-certification"

The airframe is not longer able to support a flight, excessive damage without a doubt. No prefect would have passed it.

If you had dinged up a rail button and it would be a good idea to replace it, that could be interpreted differently. If you had a small zipper that's fully supported within the nosecone shoulder or the coupler, then that could be interpreted differently.

Here's the procedure for all 3 cert levels (Tripoli, right?)
https://www.tripoli.org/content.aspx?page_id=22&club_id=795696&module_id=468541
possibly. looking at some rough numbers in OR with polished vs unfinished, it does drop delay time down by 1.6 seconds. so maybe it was enough time after freefall, that when it opened up, it was to much force? just ideas. But its fixed now and we will relaunch it. Simple fix and only took a couple of hours.
based on others responses and some searching, we now know what it means by excessive damage.

tahnks much:)
 
i know i agree. thats why i stated at the very begining that this is a simple fix. in fact it has already been fixed. took less than a couple of hours to do so.

Just as a clarification- if that had been fixed onsite, it could have been flown again same day as a 2nd L1 cert attempt. Keep that in mind for L2.
 
There isn't a standard definition--it's up to the individual certification team. The standard is something like "can be flown again with minimal repairs" (someone can correct that with exact wording if needed). I wouldn't exactly call that catastrophic damage because it could be repaired in an afternoon with a coupler and a piece of body tube, but it's definitely failing a cert damage.

[edit] I forgot that the NAR guidelines say catastrophic damage. I remembered them being more like the Tripoli guidelines. Same final answer, though.

If I had to guess, I'd say that the 4 that passed packed their chutes differently from the 5th. If they wrapped the shroud lines around the chute, that might have given just enough time for the rocket to slow down before the chute opened.
ok, this makes sense. Now that i see this information along with the others, we can better prepare for the l2. The rocket has been fixed and it did not take long at all. couple hours ish. i think they cut the section out and used a coupler as you mentioned. that was the fastes way
 
Just as a clarification- if that had been fixed onsite, it could have been flown again same day as a 2nd L1 cert attempt. Keep that in mind for L2.
for sure. we actually document everything on this forum for our notes and designs haha. the information here is priceless
 
Because the rocket is not safe to fly unless a MAJOR repair is made to it.
Having to shorten the airframe by several inches is a major repair.
man, im sorry guys. I keep thinking of major repair as something like a car transmission or engine work. BUT if i think about it from the perspective and scale of the rocket itself, i can see this as major repair, even if its just a cardboard tube.
 
I think it is always good to pay a lot of attention to flights happening throughout the day, even if it isn't your flight or a flight within your group.

Wind conditions change, sometimes other rockets are non-nominal flights and it is best for you to have eyes on that flight to make sure you are aware of the situation around you.

I can't imagine a scenario where this rocket didn't eject very early or very late and got that level of damage, but I guess there is some possible scenario. Having said that, the damage shown is 99 times out of 100 due to very early or very late ejection. The key word for me is *very*.

To be clear, while saying that a naked rocket vs a painted rocket do absolutely have different drag, the issue here is not drag, IMO. Consider that a possible cause, but give it a 5% chance in the root cause analysis, not 99% chance.

The fact that you had 4/5 successful flights on the same rocket with the same motor and same delay means that there is a big change for that one flight. I agree that posting the OR file will help people discuss things in the file that may or may not be optimized, but the reality is that you pretty much have to check the actual rocket, not what somebody simmed, especially if they don't know the software. Weight is important, but also the CG of each component is, the CG of the assembly as ready to fly, wind conditions, paint finishes etc. You can't just go half way and expect to get a perfect estimate. When I was flying more aggressively, I would take the data from my datalogger and tweak sim results for the hard to guess variables in an effort to dial the sim in. Not sure it ever mattered, but I tried it at least.

Moving forward, I would think the best advice you can give the team is to question why and at the next launch, actively observe and make notes of each flight, not just each members flight. It is a team, so leverage the eyes, ears, random observations and make notes to share. That is real engineering, IMO.

Just my thoughts.

Sandy.
 
Two more pieces of unsolicited advice and a bit of an opinion - a mentor (whether it’s a formal or informal relationship doesn’t matter) is a nearly indispensable resource. I’m lucky enough to have several club members who have been involved in HPR from nearly the beginning and their insight and advice was key to my successful L1 flight. Second, fly, fly, fly your rockets - hobby rocketry is nearly as much an art as it is a science so experience can be just as important as data. The more, and different, rockets you build and fly, the more tools you have in your mental tool box to solve problems.

Now the opinion part - the zipper you experienced is, of course, repairable - shoot, anything is repairable given enough time and resources (heck, why not raise the Titanic - its just a fixer upper 😉), but that’s not the point - the zipper is indicative of the bad delay choice - it’s the evidence that the rocketeer doesn’t meet the standard for an L1 cert and needs to do more work in order to safely fly high-powered rockets. The certification is for the person - not the rocket.

Again, good luck on the next attempt.
 
My interpretation is that a rocket should be capable of flying again after undergoing only a standard recovery system packing and motor replacement sequence without the need for further repairs. Exceptions exist for dragging damage, having to cut the shock cord to remove it from a tree, etc., but the common factor is that these do not have a significant implication for the rocketeer's designing, building, and flight prep skills.

One rule that we operate under is that the word of the RSO (Range Safety Officer) is as the rule of God. Nobody on the range is allowed to make a more permissive ruling than the RSO. For the special case of certification flights, I like to think of the witness as taking on some RSO-like responsibilities, assessing your ability to make safe flights. For this reason, I don't consider the decision of a certification witness subject to overrule.

You can, however, make another flight with a different certification witness. Some are more forgiving than others.

For your specific case though, I'd say three things:

1.) Any RSO worth his salt would judge that rocket unsafe for flight in that condition.

2.) Any competent certification witness would mark it as a failure, whether independently or concurrently with the RSO's ruling.

3.) An RSO or witness who does not do these things would be acting negligently.
 
My interpretation is that a rocket should be capable of flying again after undergoing only a standard recovery system packing and motor replacement sequence without the need for further repairs. Exceptions exist for dragging damage, having to cut the shock cord to remove it from a tree, etc., but the common factor is that these do not have a significant implication for the rocketeer's designing, building, and flight prep skills.

One rule that we operate under is that the word of the RSO (Range Safety Officer) is as the rule of God. Nobody on the range is allowed to make a more permissive ruling than the RSO. For the special case of certification flights, I like to think of the witness as taking on some RSO-like responsibilities, assessing your ability to make safe flights. For this reason, I don't consider the decision of a certification witness subject to overrule.

You can, however, make another flight with a different certification witness. Some are more forgiving than others.

For your specific case though, I'd say three things:

1.) Any RSO worth his salt would judge that rocket unsafe for flight in that condition.

2.) Any competent certification witness would mark it as a failure, whether independently or concurrently with the RSO's ruling.

3.) An RSO or witness who does not do these things would be acting negligently.
perfect. thank you for this. the first paragraph is what i have found out over the last hour. I thought the lvl 1 was for the ROCKET, not the PERSON. IE, it launches, and has a safe recovery. I did not know it had to be in a place to be able to be re-launched as a passing criteria. I mean, i understnad that if a rocket explodes in half, even though its fixable, its in pieces. I thought a zipper like this was still good. 95% of the rocket is intact. But i now know different. this helps a TON. thank you
 
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perfect. thank you for this. the first paragraph is what i have found out over the last hour. I thought the lvl 1 was for the PERSON, not the ROCKET. IE, it launches, and has a safe recovery. I did not know it had to be in a place to be able to be re-launched as a passing criteria. I mean, i understnad that if a rocket explodes in half, even though its fixable, its in pieces. I thought a zipper like this was still good. 95% of the rocket is intact. But i now know different. this helps a TON. thank you
My pleasure!

I have never seen that particular point of confusion before (certification being for the rocket instead of the flier). But it makes sense.

You can think of it this way: Rockets are generally designed to fly on a specific set of two or three impulse ranges. A rocket that can be flown on a L1 motor (H or I) wouldn't really be appropriate for L2 (J, K, L) or L3 (M, N, O) certification flights. Trying to put an I motor in a rocket optimized for M motors generally won't get it off the pad in a safe manner. Conversely, Putting an M motor in a rocket designed for I motors will usually make it disappear if you are lucky enough to avoid catastrophic structural failure. The same is generally true for smaller model rockets as well. A rocket that can fly on 1/2A motors usually will disappear if you shove a D motor in it (which you can verify for very little cost if you wish). Having the certification be valid for particular rockets would be highly impractical. It would also open up a lot of "Ship of Theseus" questions. Would a rocket with 50% of its empty mass replaced be the same rocket? 51%? 75%? 99%?

Certifying flyers based on skill and knowledge opens up more flexibility in rocket design and flight without creating an excessive hazard for range-goers and the public. It's also a lot less burden for clubs, range personnel, and flyers.
 
On the rocket with the zipper, at the moment of ignition, the zippered tube would have opened up allowing the NC to press into the void it created. Now you have a live rocket with no NC in place, but instead dragging it along behind a rocket skywriting. Do you think that is a safe flight?
 
As an aside, yes putting a good paint job on a rocket will reduce drag and increase the optimal delay. It won't add 40% to the coast time. It sounds to me like the rest of the group got lucky, with the parachute deploying 4 seconds after apogee.
 
oh yeah for sure. hence why i asked. wanting to find out all possibilities of what happened. This way we can learn for next launch. Yeah we are cutting out that section or replacing with a spare we have. Not to tricky but yet it is. Its simple in the idea of cutting or replacing:) not simple like "yeah, we taped it and are trying again hahaha" though i wonder if duct tape would work hahahahaha im kidding of course.. i think
You keep saying “we.”
Certification is a measure of individual skill in building and flying a rocket. Each rocket must be built by the person who is attempting the certification. When a rocket must be repaired to fly another attempt, only the original candidate for certification should do the repairs. Certification is absolutely not a team activity.

As others have already stated, that is too severe of damage to pass a certification flight. Only minor damage that doesn’t prevent a person from immediately re-flying the rocket is allowed.

Simulations are valuable, but you will quickly learn that’s it’s very easy to make mistakes during simulation so the simulated rocket flight is nothing like the actual flight. When the flight result is different from the simulation, the simulation was wrong. There’s just no substitute for experience and the best way to achieve that is to build and fly lots of rockets.
One of the very best ways to learn is to video every flight and look at the timing of events during the video. I use a handy little app called “Video Stopwatch” that allows you to import a video and set markers at specific points in the video. Then it tells you the elapsed time between those points.

Finally, every rocket has its own flight characteristics. Five people building the same kits will have five different flights, even though all five share the same simulation. Weights will be slightly different. Fit and finish will be different. Alignment of rail buttons will vary, resulting in different speeds off the rail. Preparation of the motors will be different. Delays will differ as well, especially if the surface of the delay becomes contaminated during assembly. Wind conditions may change from one flight to another.
Frankly I’d be surprised if the delay times for the other rockets were all perfect.
 
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If you have video of the flight you can check time to apogee and compare it to the sim.

Cosmetic damage is allowed, and the rocket must be able to be reloaded with a new motor and flown again for it to be a valid cert flight. Zipper is way past what is allowed. Sometimes these things happen. As others have said, make the harness a bit longer, maybe z-fold it, and you might be able to strengthen the cardboard by soaking a little cyanoacylate glue (superglue) into it (but don't glue the nosecone on). Search the forum for z-fold.

Analyse. Figure out what you need to improve and fly again. That's what we all do from time to time.
 
The question raised in this thread should have been answered by the certifier and understood by the cert candidate before leaving the field. Having participated in a few certifications over the years I’m going to assume that the answer was given but the understanding part did not happen.
It doesn't appear that you’ve been able to line up local mentors for this project. That’s unfortunate because WITH them your goals are extremely ambitious. WITHOUT them your May 2023 goal is beyond your reach. IMO.
 
2 things.
1) Please post your OR file "as it was" when you saw 14seconds as optimal.
(Others, and I, have LOC-IV OR files which show way less than 14sec. as optimal. I would like to see the differences.)

2) As engineers looking to move up thru the process so quickly you should be documenting each and every flight for review [post flight analysis].

If you have/had at least 1 video of each of the 5 flights posted to a common youtube channel. There are 100s (well lots) of people here who would watch them frame by frame. We (and mainly your team) would be able to talk of specifics, not just speculation.

Saying and SEEING things like the following (COMPLETELY MADE UP FICTIONAL REVIEW ) would be great analysis:
* flights v, w, & x were ejection at apogee, chute opened in .5 seconds, and flights appeared to be nominal.
* flight y "chuffed" on the pad, and the motor looked came up to pressure slow, and had ejection early by 2seconds.
* flight z was near apogee but the chute / harness "were fouled" for 3 seconds during which time the the descent rate rapidly increased. The chute then managed to "pop" open pulling out the rest of the harness, and likely zippered the tube.

Having a recording flight recorder flying along on EVRRY flight would correlate what you see in the video, and flight data. (Simple data is all that's needed.) Making a single spreadsheet with these flight recordings layered on top of each other would show the flights of v, w, & x while looking nominal, would probably have significant differences.

NASA , SpaceX, .... all use lots of cameras to track every launch/flight/landing. Every launch then has a post flight review of the video and flight data to look for any anomalies. Hopefully they are quick reviews and confirm that everything worked well. But even seemingly optimal flights often have minor events, which can be learned from.
 
You keep saying “we.”
Certification is a measure of individual skill in building and flying a rocket. Each rocket must be built by the person who is attempting the certification. When a rocket must be repaired to fly another attempt, only the original candidate for certification should do the repairs. Certification is absolutely not a team activity.

As others have already stated, that is too severe of damage to pass a certification flight. Only minor damage that doesn’t prevent a person from immediately re-flying the rocket is allowed.

Simulations are valuable, but you will quickly learn that’s it’s very easy to make mistakes during simulation so the simulated rocket flight is nothing like the actual flight. When the flight result is different from the simulation, the simulation was wrong. There’s just no substitute for experience and the best way to achieve that is to build and fly lots of rockets.
One of the very best ways to learn is to video every flight and look at the timing of events during the video. I use a handy little app called “Video Stopwatch” that allows you to import a video and set markers at specific points in the video. Then it tells you the elapsed time between those points.

Finally, every rocket has its own flight characteristics. Five people building the same kits will have five different flights, even though all five share the same simulation. Weights will be slightly different. Fit and finish will be different. Alignment of rail buttons will vary, resulting in different speeds off the rail. Preparation of the motors will be different. Delays will differ as well, especially if the surface of the delay becomes contaminated during assembly. Wind conditions may change from one flight to another.
Frankly I’d be surprised if the delay times for the other rockets were all perfect.
correct, i am saying we because there are 5 of us on our team for our aerospace engineering capstone project. He fixed it himself, but we gave ideas so, yes, we fixed it as a team but he made the final choice of how to fix it.
 
correct, i am saying we because there are 5 of us on our team for our aerospace engineering capstone project. He fixed it himself, but we gave ideas so, yes, we fixed it as a team but he made the final choice of how to fix it.
Could be a Feng Shui thing going on here, try adding another member to your team or drop the guy with zipper and get to an even number
 
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