Failed Level 2 attempt: but many things learned

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PT3

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Today I unsuccessfully tried for my level 2. Like many of you I was heavily into model rocketry as a kid flying estes kits to their limits and then frankensteining parts from crashed or otherwise worn out rockets to build new and unusual birds. When my oldest child's science teacher did a unit on rocket flight, it was time to come back. Now with greater funding, and a very understanding wife, I started on the road to high power.

My plan was to start with a Loc Precision Nuke Pro Max cardboard rocket that would allow me to ease into high power starting with high powered G's and moving up to baby H motors. Even so, I overbuilt my rocket using strong epoxies, doped balsa fins, and chopped carbon fiber. Because why not. For a paper rocket, the Nuke turned out to be a tank. So, I scrapped my plan and went for a my level one with a medium H. My first attempt failed with a great flight but a parachute that didn't fully deploy. Despite the less than soft landing, the Nuke survived without a scratch.

My second flight was picture perfect and I scored my level 1 in September. By November I'd added a Telemega flight computer to be able to track my rocket and flew the Nuke on a largish H. It was a perfect flight. Still had a few kinks to work out on using the telemetry downlink and tracker, but felt great about moving on to try for my level 2.

Although I'd nearly finished a fiberglass dd with a 54mm motor mount, I thought it would be cool to use the Nuke for my level 2 flight. So, I loaded up my rocket, flight computer and a J270WL and headed for the field. The LCO and my cert witness looked over my rocket before I went to the pad, and I think they were a little surprised that I was flying paper. But, it checked out and the countdown began. After replacing a bad igniter, it had continuity but the pyrogen was too weak to get ignition, the motor lit and the rocket screamed off the pad. Having worked the bugs out of my flight procedures with the telemega, I got to enjoy the crowd that gathered around me as the computer voice announced the telemetry mid flight. So cool.

I hit a reported 7600 feet (not too far off from the sim) and mach 1.2. Because this wasn't set up as a dd, I was using motor ejection with a backup charge set at 500'. We could hear the event at apogee even though we couldn't see it, But, the numbers coming back from the telemetry showed an alarmingly fast descent. Sure enough, while my rocket came down, the parachute was (and may still be) taking its own flight path

Looking at the data, I think I lost the parachute at the motor ejection charge. Keep in mind, the J270 is so long that it took up about 2/3rds of the lower body tube. So, despite the Nomex blanket I suspect that the force of the charge blew the parachute out so quickly that it snapped the shroud lines right off of the bulkhead.

So, my take away is this: First, while I had fun with the nuke, and it may yet fly again, I think it's safe to say that level one motors are clearly the limit to what it can handle. Second, though I'm still struggling with getting my TeleBt to work wirelessly, the telemega was a great purchase and really added to the flight. Third, even a failed flight is still a heck of a lot of fun.

Many thanks to Paul Reed and his crew from Tulsa Rocketry for a great day flying.
 
We have all had not so perfect flights. Maybe a silly question but did you hook up the chute to the shock cord? Were all quick links tight? It is kind of rare for the chute to separate all together from the rocket. What was the shock cord material? If you got the nose cone back something went wrong with the chute attachment?
 
We have all had not so perfect flights. Maybe a silly question but did you hook up the chute to the shock cord? Were all quick links tight? It is kind of rare for the chute to separate all together from the rocket. What was the shock cord material? If you got the nose cone back something went wrong with the chute attachment?

The shock cord was the kit supplied heavy duty elastic. Really just a tad better than the rubber ones used in the small Estes kits. The good thing about it was that it was super long. The kit supplied an eyebolt that attached directly into the bulkhead. Because the airframe is so small, I had to loop the shroud lines directly through the eyebolt. Even a small quick link was too large.

The rocket remained connected, just sans chute.

My fg dd uses a Kevlar harness with ss quick releases. I learn quickly, but this really was a first step.
 
So did the shock cord break. Most of us call the elastic shock cord under wear strap. Do you know if the ejection was very early or very late. That could strip the chute. Was it a LOC chute?
 
Easiest L2: LOC Precision Warlock. Short and fat. Complete kit, cardboard, plywood, and plastic, straightforward single-deploy hardware, simple as cake. Low and slow on a variety of J motors.

If you want to do DD on your L2 more power to you, just recognize you're adding more complexity to a problem than the problem requires.

It's only now AFTER L2 that I've started working on DD rockets out of necessity because I want to send stuff beyond 4000 feet. And even now I'm struggling to find a reason to go with traditional DD when I have a JLCR...
 
So did the shock cord break. Most of us call the elastic shock cord under wear strap. Do you know if the ejection was very early or very late. That could strip the chute. Was it a LOC chute?

No the shock cord stayed in tact. An early eject does seem plausible.
 
I had two suboptimal flights in Tulsa today. The chute on my "Let's get Kraken" didn't unfurl from the rubber band stranglehold of the JLCR. The rocket landed flat and crushed 2 of the tube fins, along with crimping the BT.
 
My "Intimidator 3" also landed flat after the Adept 22 failed to go into launch mode and begin it's job of deploying ejection charges. This was the first time I have seen a FG rocket flat spin from apogee completely intact. Most such failures result in a lawn dart.
 
My "Intimidator 3" also landed flat after the Adept 22 failed to go into launch mode and begin it's job of deploying ejection charges. This was the first time I have seen a FG rocket flat spin from apogee completely intact. Most such failures result in a lawn dart.

I saw that. Was a good flight up to that point.
 
Easiest L2: LOC Precision Warlock. Short and fat. Complete kit, cardboard, plywood, and plastic, straightforward single-deploy hardware, simple as cake. Low and slow on a variety of J motors.

If you want to do DD on your L2 more power to you, just recognize you're adding more complexity to a problem than the problem requires.

It's only now AFTER L2 that I've started working on DD rockets out of necessity because I want to send stuff beyond 4000 feet. And even now I'm struggling to find a reason to go with traditional DD when I have a JLCR...

Your approach makes a lot of sense. But, it’s the challenge of learning the skills that makes the hobby fun for me. I don’t want to do just bigger versions of the stuff I did as a kid. I want to build and fly things I never thought I’d get the opportunity to do.

I’ve found a really great group of people to learn from and every time I try something new I feel like I’ve accomplished something. It cracks me up to watch the old footage of the Redstone tests. Just look at how many times NASA had to blow something up before they got it right.

Yeah, today’s flight could have gone better. But a hundred other things could have failed but didn’t. It’s still a win. The card will come when it comes imho. But, to each their own.
 
by any chance did you use any sort of glue to secure your knot(you did knot the shroud lines)? agree with crossfire it is odd to completely lose a chute, normal high speed deployment usually leaves something behind.
Rex
 
I have not seen a lot of chutes break all the shroud lines. Do you have a picture of the remaining shroud lines?
 
I have not seen a lot of chutes break all the shroud lines. Do you have a picture of the remaining shroud lines?
Remarkably there are no remaining shroud lines. It appears they all snapped together. That was my first clue.

After looking at the data from the flight computer here's what I think happened: At 15:16 seconds into the flight the speed drops from 64 fps down to 30 fps within about 3 tenths of a second. The motor had a 15 sec built in delay charge which I didn't alter. The shroudlines on the chute were single strand Kevlar which were great for resistance to the heat of the ejection charge, but clearly were not able to withstand an early ejection at roughly 44 mph.

Why did I rely on motor ejection? It's what I was comfortable with. Although I'm getting pretty good with setting up my flight computer and charges, motor ejection has never failed me before. The sim put optimal ejection at just under 16 seconds. But, in previous flights that's never caused me any problems. Those flights however, didn't go anywhere near as fast as this flight (mach 1.2). Had ejection happened two or three tenths of a second later, I think this would have been a normal recovery.

The parachute was a 24inch ripstop crossform. I was using that one specifically because it had the thinner shroudlines. The body tube is such that my beefier chutes wouldn't fit with the J270 taking up most of the lower tube.

Conclusion: the setup was insufficient to handle the flight stresses of a motor as powerful as the one I flew. While the airframe had no problem with the speed or the g forces (29g) the early ejection coupled with a chute that was too weak for the forces encountered. Remarkably, while I need to redo the epoxy on one external filet, most of the damage was paint.

While I really like the security of using motor eject, for the flights I'm doing it's time to take the leap and go to a fully electronic deployment. So for now, I'll be ground testing my new rocket till I'm comfortable with the electronics and charge set up.
 
Care to upload your Telemega data? 44 MPH (65 fps) is not that extreme for main deployment . Most drogues come down anywhere from 50-100 fps and have never seen the main shroud lines tear apart. I once experienced drag separation and there was nothing left of the main and that was probably about 30 G's.
 
The shock cord was the kit supplied heavy duty elastic. Really just a tad better than the rubber ones used in the small Estes kits. The good thing about it was that it was super long. The kit supplied an eyebolt that attached directly into the bulkhead. Because the airframe is so small, I had to loop the shroud lines directly through the eyebolt. Even a small quick link was too large.

The rocket remained connected, just sans chute.

My fg dd uses a Kevlar harness with ss quick releases. I learn quickly, but this really was a first step.

When you say you tied the chute directly to the bulkhead, which bulkhead are you referring to? Please show us a picture that shows the pieces of your rocket as it would be after the ejection charge fired.
 
No the shock cord stayed in tact. An early eject does seem plausible.
You should be able to tell from the log files when ejection occurs and how fast you were going at the time.
 
Motor ejection is okay for smaller, easy to manage flights. But there's a reason why bigger motors don't have ejection charges: they just aren't very accurate. Too early, too late ... the heavier and faster the rockets get, the less likely you are going to get a good motor deployment.

I encourage you to continue to seek your L2, and to do it with DD. Lots of L1 rockets you can learn and practice DD on.
 
There are only two possibilities so if you rule one out the other is your answer.

1. Forgot to attach the parachute to the recovery system or the quick link (if used) was not completely closes - common and you would not be the first or last.
2. Snapped the shroud lines: Usually something is left behind when this happened and the log file from the telemetry my give clues.
 
...

While I really like the security of using motor eject, for the flights I'm doing it's time to take the leap and go to a fully electronic deployment. So for now, I'll be ground testing my new rocket till I'm comfortable with the electronics and charge set up.

With respect to the power source of your electronics, I would encourage you to use LiPo's. I started out using 9V batteries, but they lack the power density needed for many flight controllers. LiPo's are small, light, relatively inexpensive, and pack a punch. Electronics that use WiFi or radio telemetry are difficult to power with alkaline batteries. Properly sized, you can get many flights on a fully charged LiPo, or get extra run time to mitigate long pad or recovery times.
 
With respect to the power source of your electronics, I would encourage you to use LiPo's. I started out using 9V batteries, but they lack the power density needed for many flight controllers. LiPo's are small, light, relatively inexpensive, and pack a punch. Electronics that use WiFi or radio telemetry are difficult to power with alkaline batteries. Properly sized, you can get many flights on a fully charged LiPo, or get extra run time to mitigate long pad or recovery times.

This depends on the altimeter. Read the instructions for recommended batteries.
 
so from your statements I gather that the chute was Not your normal chute for this rocket. 44fps is not excessive speed for deployment, folks routinely deploy chutes at speeds up to 80fps (or higher). no evidence of the chute was left behind. using Occam's razor, this suggests to me one two possibilities 1) your chute was not properly attached or 2) not attached at all. I suspect that the lines were pulled through the eyebolt and not tied.
Rex
 
Care to upload your Telemega data? 44 MPH (65 fps) is not that extreme for main deployment . Most drogues come down anywhere from 50-100 fps and have never seen the main shroud lines tear apart. I once experienced drag separation and there was nothing left of the main and that was probably about 30 G's.

I wasn't able to upload the excel file directly, but here's a dropbox link: https://www.dropbox.com/s/v5njoz3u9jsviwu/2018-07-08-serial-3463-flight.csv?dl=0

It is certainly possible that the chute wasn't attached, but I can't remember having detached it between flights, or why I would have done so. But, I've made plenty of other dumb mistakes, so it isn't impossible.

No glue on the shroud lines. I looped the four sets of lines together, threaded them through the eyebolt and then pulled the chute through the shroud lines. For my heavier duty chutes I use a quicklink and Kevlar harness. But, this rocket is both small and simple, so I attached directly to the eyebolt.

I use lipo with my telemega. Currently I'm using a single battery to power the computer and the pyro charge. The mega is equipped to use a dedicated lipo for the pyro channels, so I intend to get a second lipo for my next rocket.
 
I don't see the main slowing it down at all. I will turn this over to a more learner compadre with these files but I don't see a change in decent with the main but then again I am on my phone. I would expect a change of at least a little if the chute filled and ripped the lines.

I guess that is why I am not a physics major or engineer.
 
Did the chute shroud lines happen to get a BP blast on the other flight. If the nylon shroud lines were melted some what from the first flight they would become very brittle and would have broke on the next flight. Most of the time on a not so perfect deployment the lines will rip off the nylon fabric not break. We don't really know the whole story here.
 
Use caution if using 9V batteries. Some are just stacks of individual cells held together by the external case. Large accelerations can actually cause the stack to go open circuity temporarily. If using a 9V battery I usually get a few and do an autopsy on one to check out the internal construction as it varies between models even for the same brand. Another hazard happens if you solder to the terminals as the plastic insulator on the top can melt and create an intermittent connection with the internals, because the terminal studs are crimped in place.

I use LiPos exclusively now. Would use a 9V in a pinch if I had to. YMMV.
 
Use caution if using 9V batteries. Some are just stacks of individual cells held together by the external case. Large accelerations can actually cause the stack to go open circuity temporarily. If using a 9V battery I usually get a few and do an autopsy on one to check out the internal construction as it varies between models even for the same brand. Another hazard happens if you solder to the terminals as the plastic insulator on the top can melt and create an intermittent connection with the internals, because the terminal studs are crimped in place.

I use LiPos exclusively now. Would use a 9V in a pinch if I had to. YMMV.
Duracell Coppertops have the cells soldered to the terminals.
 
Duracell Coppertops have the cells soldered to the terminals.

Some yes, some no. Depends on the model even, within a brand. Remember too that if a tag is soldered to the cell and the terminal then crimped to the tag (with the plastic end cap between), all bets are off if you solder to the terminals. Consider using the snap clips instead.
 
I don't see the main slowing it down at all. I will turn this over to a more learner compadre with these files but I don't see a change in decent with the main but then again I am on my phone. I would expect a change of at least a little if the chute filled and ripped the lines.

I guess that is why I am not a physics major or engineer.

Maybe I failed to connect the chute. I don’t see that as likely, but the data seems to suggest it. Unless the charge burned through the shroud lines on this flight. I did inspect the chute and the shroud lines in between flights. But for the life of me don’t recall taking the chute off of the eyebolt.
 
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