Will it shred?

The Rocketry Forum

Help Support The Rocketry Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.
Joined
Feb 22, 2017
Messages
191
Reaction score
18
I'm starting to contemplate my L2 cert. I have an extremely well built LOC Vulcanite that I would like to be a contender for this flight, but only if I can be reasonably assured it will hold together. My simulations indicate that even with the smallest J I can put in it, it's going to break mach. (1264 ft/s on a J285 for example, and others are in that same zone). I've flown it beautifully on I motors.

There seems to be the implication in the world of high-power rocketry that if you go as much as 1 fps over mach with a non FG, unglassed, non tip to tip rocket it's going to explode in a fiery death show. But is that always the case? This is thick LOC cardboard tubing, ttw fins, titebond II'd for the apocalypse and nice beefy fillets. What are the factors that would lead to failure in a cardboard and plywood rocket?

In other words, will it shred?

I have a lovely FG Madcow Adventurer I plan on building soon, so I could make this one the flyer, but the Vulcanite is a beast and it's ready to go.

I haven't had much luck getting Rasaero to work on my Mac as I understand it to be better at simulating mach+ flights.

This will be motor-eject with a JL chute release. Either AT DMS or I also have a CTI 5 grain case on hand. (please note I do plan making good old-fashioned pyro dual deploy my next skill to learn, but for my L2 flight I want to keep it as simple as possible.)
 
I think you’re going to be just fine with this rocket. The modes of shredding I’ve experienced have been fin flutter causing fins to fail just above the edge of the fillets (thicker G10 would have prevented that), Epoxy failure (not surface prep, actual failure of BSI epoxy) when through the wall tab was short 54 mm BT, 38 mm MMT, and coupler failure during transition from supersonic to subsonic.
It sounds like you did your homework; let it fly!
 
I think you’re going to be just fine with this rocket. The modes of shredding I’ve experienced have been fin flutter causing fins to fail just above the edge of the fillets (thicker G10 would have prevented that), Epoxy failure (not surface prep, actual failure of BSI epoxy) when through the wall tab was short 54 mm BT, 38 mm MMT, and coupler failure during transition from supersonic to subsonic.
It sounds like you did your homework; let it fly!

Thanks Steve for confirming what I already suspected. See you at LDRS!
 
I did my L2 with a Nuke ProMaxx and it held up just fine. It's one of my most rugged and reliable rockets. Easily my favorite flier. I'll end up building it's brother the Vulcanite one day.

Make sure you track it. Mine went over 7000'.
 
Speaking from the been there and done that you should be fine.

I did eventually glass mine, but it was more about handling/transport.


Sent from my iPhone using Rocketry Forum
 
Opened this thread REally hoping it was the Rocketry equivalent of "Will it Blend?"

Am disappointed.


In seriousness, that sounds like a solid rocket. Some sort of tracker recommended though.
Also, in the vein of ECayemberg's posts, (provided your fins won't flap away) doubling the wall with couplers is a lightweight method of strengthening paper rockets without going to fiberglass.
 
Opened this thread REally hoping it was the Rocketry equivalent of "Will it Blend?"

Am disappointed.


In seriousness, that sounds like a solid rocket. Some sort of tracker recommended though.
Also, in the vein of ECayemberg's posts, (provided your fins won't flap away) doubling the wall with couplers is a lightweight method of strengthening paper rockets without going to fiberglass.

Setting aside who knows how many safety code violations, I would definitely watch that!

I have a TeleGPS for it and also an Eggfinder waiting to be built. Doubling couplers is a great idea - I'll definitely work that in to the design of my next paper rocket that could possibly go trans-sonic. Do they need to be glued in or can they simply slide?

That brings up an interesting question for me. I'm sure it has been covered elsewhere on the forum but I'll ask it here because we're talking about it: Where would the point of failure on an airframe typically be? At the coupler? Or is it that the aerodynamic forces "crush" the tube equally?
 
Setting aside who knows how many safety code violations, I would definitely watch that!

I have a TeleGPS for it and also an Eggfinder waiting to be built. Doubling couplers is a great idea - I'll definitely work that in to the design of my next paper rocket that could possibly go trans-sonic. Do they need to be glued in or can they simply slide?

That brings up an interesting question for me. I'm sure it has been covered elsewhere on the forum but I'll ask it here because we're talking about it: Where would the point of failure on an airframe typically be? At the coupler? Or is it that the aerodynamic forces "crush" the tube equally?

Coupler fail is more likely than pure tube-crush. The coupler acts as a joint between two solid pieces, so it's no as fixed at all points, and if it ends up located at the point of max bending-moment in an airframe (usually near the middle), that's even worse. LOC has Stiffy Couplers that slide into E-bays for that very reason.
 
Setting aside who knows how many safety code violations, I would definitely watch that!

I have a TeleGPS for it and also an Eggfinder waiting to be built. Doubling couplers is a great idea - I'll definitely work that in to the design of my next paper rocket that could possibly go trans-sonic. Do they need to be glued in or can they simply slide?

That brings up an interesting question for me. I'm sure it has been covered elsewhere on the forum but I'll ask it here because we're talking about it: Where would the point of failure on an airframe typically be? At the coupler? Or is it that the aerodynamic forces "crush" the tube equally?

From what I've seen (not too many, and none of mine fortunately), this is the rough order of likelihood of airframe failures:
Zipper from recovery issues (not what you asked, but really common)
Fins (broke or broke off, leading to shred)
Coupler stability (rocket folds over at coupler, carnage ensues)
Overall airframe stability (coning leads to going sideways, carnage ensues)
Airframe tube failure

Maybe other people can weigh in?
 
That rocket will probably work to get your cert, but then what? Are you going to keep flying it on Baby J motors?

My suggestion is, unless you plan to fly those baby Js, is to build the 3" Adventurer with the 54mm MMT. Do your cert on that, even if it is on a small J. Then you can start with L2 motors like a large J and K motors.

I know people use MPR rockets to get their L1 on baby H and L1 rockets to get their L2 with on baby J, but I've never seen the point. They don't have a rocket sized to their cert to actually fly all the motors in their cert range until they get around to building one later. Why not build one right away for the cert? You can always wimp out and cert on the baby J but at least you have something you can kick with a big K after to find out if you really learned how to build rockets for that level.

Just my unpopular opinion. Good Luck.
 
That rocket will probably work to get your cert, but then what? Are you going to keep flying it on Baby J motors?

My suggestion is, unless you plan to fly those baby Js, is to build the 3" Adventurer with the 54mm MMT. Do your cert on that, even if it is on a small J. Then you can start with L2 motors like a large J and K motors.

I know people use MPR rockets to get their L1 on baby H and L1 rockets to get their L2 with on baby J, but I've never seen the point. They don't have a rocket sized to their cert to actually fly all the motors in their cert range until they get around to building one later. Why not build one right away for the cert? You can always wimp out and cert on the baby J but at least you have something you can kick with a big K after to find out if you really learned how to build rockets for that level.

Just my unpopular opinion. Good Luck.

So more is always better? I think not. Flying a Vulcanite on a baby J is not a wimpy flight by any means. Fly what makes you happy, and what you are comfortable with.


Sent from my iPhone using Rocketry Forum
 
That rocket will probably work to get your cert, but then what? Are you going to keep flying it on Baby J motors?

My suggestion is, unless you plan to fly those baby Js, is to build the 3" Adventurer with the 54mm MMT. Do your cert on that, even if it is on a small J. Then you can start with L2 motors like a large J and K motors.

I know people use MPR rockets to get their L1 on baby H and L1 rockets to get their L2 with on baby J, but I've never seen the point. They don't have a rocket sized to their cert to actually fly all the motors in their cert range until they get around to building one later. Why not build one right away for the cert? You can always wimp out and cert on the baby J but at least you have something you can kick with a big K after to find out if you really learned how to build rockets for that level.

Just my unpopular opinion. Good Luck.

I don't think its unpopular at all - in fact I pretty much agree with it. I'm not in a hurry. I still have a lot to learn and I'm really looking forward to taking the time to learn it... because that means building and flying more rockets. There is no downside to that at all! My thinking is simply this: I have a well constructed rocket that just needs a motor, so that and a test is all I need to cert. From that point on, it's all stress-free flying on both old rockets and new. So yeah, I'm pretty much getting my cert for rockets yet to come. I like having the options.

I'll admit that there is some sentimentality to this as well. I spend a LOT of time building my rockets and I'm particularly proud of this one. So if it can take the heat, I want to be it the one that gets the shot. My level one rocket holds a similar place of honor in my small but growing fleet. So I'm sort of like Deke Slayton picking astronauts.
 
my totally stock vulconite has flown on the j600. Never saw the apogee, but the tracker lead me right to it.
 
From what I've seen (not too many, and none of mine fortunately), this is the rough order of likelihood of airframe failures:
Zipper from recovery issues (not what you asked, but really common)
Fins (broke or broke off, leading to shred)
Coupler stability (rocket folds over at coupler, carnage ensues)
Overall airframe stability (coning leads to going sideways, carnage ensues)
Airframe tube failure

Maybe other people can weigh in?


On this question, specifically, what are the limits on a typical thin wall 4" FWFG airframe? At what point is the thin wall tubing no longer enough? At what point is it best to move to hand laid tubes?

Would a 12" long unsupported length of 4" thin wall FWFG tubing be able to withstand Mach 2 with a regular thickness 4" nosecone and the standard to light associated hardware?


Are there any rough guidelines?
 
On this question, specifically, what are the limits on a typical thin wall 4" FWFG airframe? At what point is the thin wall tubing no longer enough? At what point is it best to move to hand laid tubes?

Would a 12" long unsupported length of 4" thin wall FWFG tubing be able to withstand Mach 2 with a regular thickness 4" nosecone and the standard to light associated hardware?


Are there any rough guidelines?

What are you building with this?
Short stubby rocket?

What size motor?
You have to be more specific to get a good answer.
You will have a fit issue with a standard wall NC mating to thin wall tube, Why do that?

So far I have had good luck up to hammer M motors. Mach -2 should not be an issue....M-3 is.
 
I’m in the same boat with a Nuke Pro Max that I used for my L1. Flying it in March for my L2.

I just finished a Dark Star 2.6” which will be my back up in case the Nuke doesn’t survive. Just think it would be cool to cert on the same rocket. Loc makes a solid kit. It’s survived my learning curve and keeps coming back for more. Good luck!


Sent from my iPhone using Rocketry Forum
 
just stick a tracker in it. I helped Grouch find his Nuke Pro Maxx for his L2. Without the tracker it would have been lost.

I’m in the same boat with a Nuke Pro Max that I used for my L1. Flying it in March for my L2.

I just finished a Dark Star 2.6” which will be my back up in case the Nuke doesn’t survive. Just think it would be cool to cert on the same rocket. Loc makes a solid kit. It’s survived my learning curve and keeps coming back for more. Good luck!


Sent from my iPhone using Rocketry Forum
 
just stick a tracker in it. I helped Grouch find his Nuke Pro Maxx for his L2. Without the tracker it would have been lost.

Absolutely. Used my club’s Walston for my L1 and have been using my own Telemega for subsequent flights.


Sent from my iPhone using Rocketry Forum
 
Follow up for posterity: It did not shred. Successful L2 flight on a CTI J285. 7123ft and 841 mph. TeleGPS on board took me right to it - almost a mile away. Thankfully overshot the wheat field that ate so many rockets that weekend.
 
I'm glad I stumbled across this thread-- my L1 was built from the same LOC components, and I've been waffling back and forth about sticking a J425 in to hit about mach 1.3 and ~6500 ft. The fact that yours survived gives me a lot more confidence. Thanks for posting the update!
 
I think we tend to forget that in "the good old days" rockets were made from cardboard and wood glue, nothing else. There were a bunch of really impressive flights, you just have to think about what you're doing and how. Along came FG/epoxy and that became the standard. For 95% of the rockets out there it's way overbuild. I will confess to having mostly FG rockets because I love the fact they are much more durable in transport. IMHO that's the biggest difference. Throw a FG rocket or 2 in the back of my truck, literally, and forget them for a couple of weeks until you want to fly, pull them out (perhaps from what ever else is back there) and fly them...can't do that with cardboard....
 
Anything will shred will enough power and the right harmonics. Congrats on the cert.
 
Back
Top