Sub Minimum Diameter L-2050 Build Thread

Rocketcamper123

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I dont want to take this thread off course however I disagree, T2T can be required for any size build. I don't think you can make the decision based off of the motor casing diameter as there are multiple factors that go into accounting for fin flutter, with motor characteristics and fin profile being the 2 major contributing factors. You could be flying a moon-burner and have a MD rocket with low acceleration but designed for high altitude flights in which case T2T is likely not needed however you could also have a very aggressively burning motor which will have drastic effects on the rockets acceleration. In such instance T2T may be required to prevent fin flutter no matter the material choice and adhesive used. I've had a 38mm flying case using the Loki K1127 shred on me using an aerodynamic fin profile with a span of about 1.4" which used loctite E120-HP for the properly sized fillet. This rocket accelerated to over 90G in less than 2sec and finally shredded right at max Q 11k up. While yes T2T is not always needed its important not to just rely what you think, rather do the analysis to ensure that the construction is adequate. I know that some obviously may not go as in depth into analyzing stresses on basic "daily flier" however in this case where it's a high performance MD rocket it should be part of the design process.

i think it is entirely possible to build a 98mm min diameter with the n5800, o3400, ect.. using all composite materials without any metal and without tip to tip. it just takes the right design. same goes with a 54mm with the loki 54mm M motor. tip to tip is added insurance but not required. i have built both 75mm and 98mm minimum birds that have exceeded mach 2 without tip to tip and were short as possible birds and recovered
 

rocketlabdelta

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Hi @Michael Wilson! Welcome to TRF!

First, you are totally right about the Loki 54/4000. It seems purpose-built to smash records and I've spent a lot of time thinking about a project like this.

Let me tell you why I am not building a rocket like this one, at least not yet.

The forces that the launch vehicle encounters in a flight that reaches the kind of altitude you are talking about that quickly blur the lines between hobby rocketry and aerospace engineering. But, it can be done. It can also be successfully accomplished by young, enthusiastic engineers (or engineers in training). Check out the technical documentation for the Princeton SpaceShot, in particular, their final report. The sustainer of that rocket is basically what you're trying to build. It's a challenging project. EDIT: You want the details of the Rev1 sustainer, not the Rev2 from the final report (but the final report has a lot of good stuff too).

When I assess my skills critically (helped in part by listening to Matt Steele talk about the engineering process in a recent episode of The Rocketry Show) they're just not up to it. I'll need to do a some smaller projects first that prove out the materials and techniques that are required. Reading things like the still-unfolding Eyelash build thread by @kbRocket shows just how much there is to explore, even if the rockets are a bit on the small side. Now, I've got my eye on the Loki 38/1200 and spent several hours this morning reading up on different approaches to making a curing oven for high temperature epoxy parts.

The most important thing is to stay safe, learn as much as you can, and have fun. Godspeed.
 
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GrouchoDuke

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I saw an L2050 do 39,000 feet, but not per Tripoli record rules.
Uhhhh, might not be good to share a Loki launching in California...right? (Is education exempted from the rules?)

Still, I'm curious what wasn't by Tripoli's record rules. 39k is right is definitely in the ballpark of what I'd expect.

Someone's going to break the L & M records with Loki motors...it's just a matter of time. Fun discussions.
I should have added earlier...the J & probably the K record can be broken with Loki motors too.
 

Michael Wilson

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Oh wow! A lot of posts jeez! ok here we go.

The fin can is going to be aluminum, it’s a Max Q fin can, except with 4 38mm fins instead of just the three 54mm fins, as I wanted to reduce coning (pitch roll resonance)
I’m sure you guys are completely correct about using composites and all that, but I’m trying to have the highest level of success and a COTS fin can seems to me to have a better chance of working
Hi @Michael Wilson! Welcome to TRF!

First, you are totally right about the Loki 54/4000. It seems purpose-built to smash records and I've spent a lot of time thinking about a project like this.

Let me tell you why I am not building a rocket like this one, at least not yet.

The forces that the launch vehicle encounters in a flight that reaches the kind of altitude you are talking about that quickly blur the lines between hobby rocketry and aerospace engineering. But, it can be done. It can also be successfully accomplished by young, enthusiastic engineers (or engineers in training). Check out the technical documentation for the Princeton SpaceShot, in particular, their final report. The sustainer of that rocket is basically what you're trying to build. It's a challenging project. EDIT: You want the details of the Rev1 sustainer, not the Rev2 from the final report (but the final report has a lot of good stuff too).

When I assess my skills critically (helped in part by listening to Matt Steele talk about the engineering process in a recent episode of The Rocketry Show) they're just not up to it. I'll need to do a some smaller projects first that prove out the materials and techniques that are required. Reading things like the still-unfolding Eyelash build thread by @kbRocket shows just how much there is to explore, even if the rockets are a bit on the small side. Now, I've got my eye on the Loki 38/1200 and spent several hours this morning reading up on different approaches to making a curing oven for high temperature epoxy parts.

The most important thing is to stay safe, learn as much as you can, and have fun. Godspeed.
Thank you! I looked at all you linked, all of it really interesting. I understand that this is a difficult project, but that’s the reason I picked it. I wanted a difficult project that I could still have success in and learn a lot along the way.
 

manixFan

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This may be a very unpopular opinion, but using a commercial fin can unit should disqualify a rocket from an altitude record. The fins are without a doubt the most difficult thing to deal with when you approach Mach 3. I agree that even with a COTS fin can it is still a challenge, but it eliminates the biggest test of the flyers skill in fabricating a high performance rocket.


Tony
 

watheyak

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This may be a very unpopular opinion, but using a commercial fin can unit should disqualify a rocket from an altitude record. The fins are without a doubt the most difficult thing to deal with when you approach Mach 3. I agree that even with a COTS fin can it is still a challenge, but it eliminates the biggest test of the flyers skill in fabricating a high performance rocket.


Tony

I'm disappointed to hear this as well, Michael! But I completely understand your reasoning and motivations.

While those fun cans are super slick, the record should have an asterisk. It's like climbing Mount Everest but Mike Fisher is the bada$$ Sherpa carrying all your gear.
 
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eggplant

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Uhhhh, might not be good to share a Loki launching in California...right?
It looks like this flight took place at FAR (Friends of Amateur Rocketry). All of their events are attended by a certified pyrotechnic operator, which is how they do things typically not allowed by the CSFM. The rocket team I was on legally flew experimental O and P motors there, and we would usually see someone firing or flying liquids while there.
 

ether

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They should just do away with the altitude record keeping it does not help in promoting safety

improved building methods should not be discourage by such rules
 

watheyak

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They should just do away with the altitude record keeping it does not help in promoting safety

improved building methods should not be discourage by such rules

Please do explain.

That's the most ridiculous and un-fun thing I've heard in a long, long time.

In your opinion, Ether, is any innovation ever safe? Probably not.

I feel this kind of competition and the discussions happening in this thread are exactly what leads to better building methods and therefore better safety.

Not much is learned by just bolting on a fin can or even just building a kit.

It's also very boring and not why we do this.
 

ether

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on the same page for for innovation

the statement that fin-can should be dis-allowed actively discourages innovation

hardest part of rocketry is not going up, is the coming down part, to discourage innovative uses of new techniques is problematic (agree with you 1000%). a fin-can in this instance is a great method for keeping the fins attached. don't see that as a reason there should be an asterix for someone pursuing a record. Aluminum is a great material to overcome fin flutter, especial with the difficulty in predicting failure velocities, better to over-build it and simpler to use aluminum materials
 

Michael Wilson

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I've taken consideration in what all of you guys have said. I think it'd be in my best interest to make a minimum diameter rocket and make my own fincan out of composites. It'll open my options up for where to launch and I think make the project more feasible while keeping the original spirit and similar altitude. Thoughts?
 
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ether

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don't disagree that using ready made components naturally lends itself to less active learning - agree on that
 

GrouchoDuke

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It looks like this flight took place at FAR (Friends of Amateur Rocketry). All of their events are attended by a certified pyrotechnic operator, which is how they do things typically not allowed by the CSFM. The rocket team I was on legally flew experimental O and P motors there, and we would usually see someone firing or flying liquids while there.
Oh cool, I didn't know that about FAR. Awesome!
 

MClark

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I just looked at the TRA rules for altitude records and saw no mention of commercial fincans being prohibited.
Could someone please give a reference to this rule.

M
 

watheyak

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on the same page for for innovation

the statement that fin-can should be dis-allowed actively discourages innovation

hardest part of rocketry is not going up, is the coming down part, to discourage innovative uses of new techniques is problematic (agree with you 1000%). a fin-can in this instance is a great method for keeping the fins attached. don't see that as a reason there should be an asterix for someone pursuing a record. Aluminum is a great material to overcome fin flutter, especial with the difficulty in predicting failure velocities, better to over-build it and simpler to use aluminum materials

That makes a lot more sense, we're on the same page. I've been trying to put the largest possible motor in the smallest possible rocket since was about six years old, so forgive me if I bristle a bit a the thought of stifling that portion of the hobby.

I've taken consideration in what all of you guys have said. I think it'd be in my best interest to make a minimum diameter rocket and make my own fincan out of composites. It'll open my options up for where to launch and I think make the project more feasible while keeping the original spirit and similar altitude. Thoughts?

One thing you might want to consider is using one of the Max Q fin cans at first. Set a record with that, then set to work on your composite fin can and set an even higher record with that.

You've obviously put some thought I to the Max Q and switching out the fins for the 38mm size.

My disappointment in your choice of aluminum is surely colored by the fact that I'm into composite fins...

So yeah, hike your own hike.


I just looked at the TRA rules for altitude records and saw no mention of commercial fincans being prohibited.
Could someone please give a reference to this rule.

M

No rule official rule. Just the court of public opinion weighing in.
 

MClark

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With so few members attempting altitude records creating “false rules" and presenting as real does no good. Those who will never attempt a record should not be applying their morals/agendas to rules that will never apply to them.

Performance is the real test, typically a commercial fin can will not be as good as one made to match the rocket, but if a commercial unit will beat the current record it should not be prohibited.

Mark.
 

Neutron95

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Personally, I feel that the challenges in getting everything above the motor to both be optimized for performance while being safe and reliable is a large challenge in and of itself. Besides, you can always come back and build a composite fin can if you design the metal one to be removable and you feel the need for even more performance.
 

MClark

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Personally, I feel that the challenges in getting everything above the motor to both be optimized for performance while being safe and reliable is a large challenge in and of itself. Besides, you can always come back and build a composite fin can if you design the metal one to be removable and you feel the need for even more performance.

Why does the fin can need to be removiable?

M
 

manixFan

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With so few members attempting altitude records creating “false rules" and presenting as real does no good. Those who will never attempt a record should not be applying their morals/agendas to rules that will never apply to them.

Performance is the real test, typically a commercial fin can will not be as good as one made to match the rocket, but if a commercial unit will beat the current record it should not be prohibited.

Mark.
Mark,

I did not state it or present it as a rule, my post clearly says it is my opinion. Please reread it. In fact I am building a 38mm MD rocket around the Loki K627. While I won't break any records with that motor, it will be a good test of my technique. I'm trying something similar on the opposite end of the scale with the CTI L265, which of course is 54mm. I've built a fair number of all CF rockets working my way up to this point, and I've flown past Mach 2 at BALLS on numerous occasions without failure. So if your comment about "Those who will never attempt a record should not be applying their morals/agendas to rules that will never apply to them" was meant to apply to me, it does not.

Moreover, there are no morals or agendas involved in my opinion, it's just that, an opinion. Using a commercial fin can bypasses, in my mind, the biggest obstacle in building a high performance rocket. That's a perfectly valid opinion for me to have. You obviously disagree.


Tony

PS: to add for the OP (Michael) - I was just expressing my opinion and I should not have done so in your thread, I apologize for that. I would never want to dampen any enthusiasm in our hobby, especially by someone young and who obviously has a lot of interest and excitement for what it is. Please don't make any decisions based off a bunch of strangers on the internet, follow your own goals and don't let me or anyone dissuade you from them unless it's for reasons of safety.
 
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Rob702Martinez

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on the same page for for innovation

the statement that fin-can should be dis-allowed actively discourages innovation

hardest part of rocketry is not going up, is the coming down part, to discourage innovative uses of new techniques is problematic (agree with you 1000%). a fin-can in this instance is a great method for keeping the fins attached. don't see that as a reason there should be an asterix for someone pursuing a record. Aluminum is a great material to overcome fin flutter, especial with the difficulty in predicting failure velocities, better to over-build it and simpler to use aluminum materials

Can't get a record if the rocket comes down in pieces or not as planned..sooo...
 

ether

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exactly!!! so why discourage use of fin-can? there are many failure points for rockets with such motors that a builder needs to address
 

Rob702Martinez

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I thought the discussion mentioned that off the shelf fin cans were not allowed in regards to records. Not sure if that is what track we're on at the moment. Not sure if that is even a rule.
 
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