Bare Minimum: M2245 to 50,000 feet

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
So Bare Minimum had the same flight profile as it's namesake.

Judging from how the fins are bent, it obviously hit a major angle of attack at about Mach 3.5. The tricky part is figuring out what's a cause and what's an effect. Did it go sideways because the nosecone came off, or did the nose come off because it went sideways?

Right now there are two possible causes. First is some kind of dynamic instability that lead to a massive angle of attack and thus the shred. Or there was a structural failure of the nosecone coupler leading to the rest of the failures.

Overall, this project was a massive learning experience, and it really forced me to better my design and construction skills. I'll be back at Black Rock with an even better rocket in the future. I have lots of ideas on how to improve this design even more.
 
So Bare Minimum had the same flight profile as it's namesake.

Judging from how the fins are bent, it obviously hit a major angle of attack at about Mach 3.5. The tricky part is figuring out what's a cause and what's an effect. Did it go sideways because the nosecone came off, or did the nose come off because it went sideways?

Right now there are two possible causes. First is some kind of dynamic instability that lead to a massive angle of attack and thus the shred. Or there was a structural failure of the nosecone coupler leading to the rest of the failures.

Overall, this project was a massive learning experience, and it really forced me to better my design and construction skills. I'll be back at Black Rock with an even better rocket in the future. I have lots of ideas on how to improve this design even more.
Really glad you found it. Nothing more frustrating than trying to do forensics on missing parts.

Good luck with the analysis and with the next build!
 
Glad you found it and thank you for keeping all of us up to date. This is a fun project to follow!

Is there a possibility that the altitude that things went wrong is where winds change?
 
So Bare Minimum had the same flight profile as it's namesake.

Judging from how the fins are bent, it obviously hit a major angle of attack at about Mach 3.5. The tricky part is figuring out what's a cause and what's an effect. Did it go sideways because the nosecone came off, or did the nose come off because it went sideways?

Right now there are two possible causes. First is some kind of dynamic instability that lead to a massive angle of attack and thus the shred. Or there was a structural failure of the nosecone coupler leading to the rest of the failures.

Overall, this project was a massive learning experience, and it really forced me to better my design and construction skills. I'll be back at Black Rock with an even better rocket in the future. I have lots of ideas on how to improve this design even more.

Thanks for the update @Neutronium95 !
.
I can't thank you enough for sharing the details of your project.

It is fantastic that you found your booster.

Please let us know as you learn more and I'll be watching for your next one !

-- kjh
 
Becoming a find-able lake-stake was fortunate.
The impact rules out the fins were bent on landing.
Best guess would be flutter with some heat added.
Good job finding it.
Keep us posted on what you learn upon further inspection.
 
So Bare Minimum had the same flight profile as it's namesake.

Judging from how the fins are bent, it obviously hit a major angle of attack at about Mach 3.5. The tricky part is figuring out what's a cause and what's an effect. Did it go sideways because the nosecone came off, or did the nose come off because it went sideways?

Right now there are two possible causes. First is some kind of dynamic instability that lead to a massive angle of attack and thus the shred. Or there was a structural failure of the nosecone coupler leading to the rest of the failures.

Overall, this project was a massive learning experience, and it really forced me to better my design and construction skills. I'll be back at Black Rock with an even better rocket in the future. I have lots of ideas on how to improve this design even more.
This is a familiar chicken and egg puzzle. Looking forward to hearing more of your thoughts here or in person!
 
This is a familiar chicken and egg puzzle. Looking forward to hearing more of your thoughts here or in person!
Front is FG, rear is min dia aluminium fin can. M3.5 heats FG nosecone. Nosecone cannot play anymore resulting in nosecone misalignment at M3.5. Other things bend.....
The chicken came first. :)
 
Front is FG, rear is min dia aluminium fin can. M3.5 heats FG nosecone. Nosecone cannot play anymore resulting in nosecone misalignment at M3.5. Other things bend.....
The chicken came first. :)
The only structural damage to the nosecone was a small zipper from the shock cord. I doubt the nosecone deformed enough to cause the failure.

A structural failure of the nosecone coupler attachment is one of the possibilities I'm considering.
 
The only structural damage to the nosecone was a small zipper from the shock cord. I doubt the nosecone deformed enough to cause the failure.

A structural failure of the nosecone coupler attachment is one of the possibilities I'm considering.

A small zipper indicates the cone came off under thrust. The nose cone tilted , and then pulled the rocket sideways. it pulled off due to aero friction and the rest is history.
 
A small zipper indicates the cone came off under thrust. The nose cone tilted , and then pulled the rocket sideways. it pulled off due to aero friction and the rest is history.

Or the rocket could have gone unstable, and the force of the air from going sideways ripped the nose off. There's no way that I can tell to determine the actual failure mode with any certainty.

I'm planning on coming up with a list of all of the likely causes and addressing all of them in future high performance builds. Also flying a few more 54mm extreme performance flights before trying 75mm again.
 
Or the rocket could have gone unstable, and the force of the air from going sideways ripped the nose off. There's no way that I can tell to determine the actual failure mode with any certainty.

I'm planning on coming up with a list of all of the likely causes and addressing all of them in future high performance builds. Also flying a few more 54mm extreme performance flights before trying 75mm again.
Any data off of altimeters?
 
Sorry about the project man. That is a lot of hardware to lose to the lakebed.

My guess would be heating caused the aluminum to soften, making it not strong enough to withstand flight forces. Just a guess though.
Very impressive rocket and attempt though. Mach 3+ is very hard to get right.
 
Last edited:
Sorry about the project man. That is a lot of hardware to lose to the lakebed.

My guess would be heating caused the aluminum to soften, making it not strong enough to withstand flight forces. Just a guess though.
Very impressive rocket and attempt though. Mach 3+ is very hard to get right.
I really doubt the heating caused the metal to soften. In my experience, rockets only experience significant heat loads above Mach 2.5. The time between the rocket hitting Mach 2.5, and the failure was on the order of 1.5 seconds. That's enough time for the surface of the nosecone to get a bit damaged, but not enough total heat transfer to significantly increase the bulk temperature of the fin can.
 
I really doubt the heating caused the metal to soften. In my experience, rockets only experience significant heat loads above Mach 2.5. The time between the rocket hitting Mach 2.5, and the failure was on the order of 1.5 seconds. That's enough time for the surface of the nosecone to get a bit damaged, but not enough total heat transfer to significantly increase the bulk temperature of the fin can.
But what about the additional heat flow through the casing? Since the fincan is directly on the motor case, it will transfer the heat much faster than if there was a composite tube in the way.
 
But what about the additional heat flow through the casing? Since the fincan is directly on the motor case, it will transfer the heat much faster than if there was a composite tube in the way.
There's a large time delay between motor ignition and the motor casing heating up. Heat was not a factor in any of the structural failures. The only heat damage was a roughed up surface on some parts of the nosecone. That would have certainly added drag and reduced the apogee, but did not contribute to the rocket going sideways and coming apart.
 
I finally got around to taking a look inside the nosecone. And there's a lot of soot inside the nose, near the joint between the two parts. I did do a ground test, so this might have come from that, but I didn't have the test charge put that high up in the nose, unlike the flight configuration. Someone else on discord noticed what looked like a small puff of smoke after motor burnout. So right now my leading candidate for the failure is an early deployment.

PXL_20240622_212036004.MP.jpg

I'm not sure which flight computer is the more likely culprit. I've flown EasyMinis over Mach 2 before, and Blue Ravens to around Mach 3 before.
 
I'm not sure which flight computer is the more likely culprit. I've flown EasyMinis over Mach 2 before, and Blue Ravens to around Mach 3 before.

I wonder if there was a programming error? I think both flight computers offer the option of popping a separation charge, prior to staging event, or even igniting a second stage motor. Both of those options would pop the charge at burnout, or just after burnout.

It's too bad the flight computers were destroyed, no way to tell what really happened.
 
I finally got around to taking a look inside the nosecone. And there's a lot of soot inside the nose, near the joint between the two parts. I did do a ground test, so this might have come from that, but I didn't have the test charge put that high up in the nose, unlike the flight configuration. Someone else on discord noticed what looked like a small puff of smoke after motor burnout. So right now my leading candidate for the failure is an early deployment.

View attachment 652198

I'm not sure which flight computer is the more likely culprit. I've flown EasyMinis over Mach 2 before, and Blue Ravens to around Mach 3 before.

The puff of smoke you can see in the “enhanced” video was well after the rocket made a hard right turn. It might have been at apogee after the breakup. But soot on the inside of the cone seems like a good clue if there was another charge that might have fired earlier. The Blue Raven votes 2 of three sensors for apogee detection, between accel, gyro, and baro, and it would be hard to spoof more than the baro sensor. The Blue Raven’s main charge and the backup charges need all need this fault-tolerant apogee to have happened too. Were you using the default settings?
 
The puff of smoke you can see in the “enhanced” video was well after the rocket made a hard right turn. It might have been at apogee after the breakup. But soot on the inside of the cone seems like a good clue if there was another charge that might have fired earlier. The Blue Raven votes 2 of three sensors for apogee detection, between accel, gyro, and baro, and it would be hard to spoof more than the baro sensor. The Blue Raven’s main charge and the backup charges need all need this fault-tolerant apogee to have happened too. Were you using the default settings?
I used the default deployment settings, just with an apogee delay and a higher main deployment altitude. I do think that tumbling at a high mach number might be enough to spoof a Blue Raven, but that's kind of a moot point since the flight's already ruined if it starts tumbling.
 
If it took a hard turn at burnout, that becomes apogee and therefore charges should have been fired.

Once the NC is off at high speed all manner of things can happen.
 
Back
Top