Avoiding the Bends?

[Kruegon]

I was talking to a rocketry friend about a design I'm working on. It's a very skinny, very long, high power rocket. It's 1.6" diam by 6'6" long to be exact.

He told me that he recalled an old article in sport rocketry about these designs. He thinks it was called "Avoiding the Bends". Is anyone familiar with this article?

 

[ratchet01]

I'd be interested in that also. When I built and launched the Mean Machine back in '79, it......folded in half on its second launch.��

 

[rharshberger]

Quick search found this...

My search criteria was "Super Roc Avoiding the bends", and voila very first hit on google was the PDF.


View attachment Avoiding_the_Bends.pdf

 

[ratchet01]

THANKS!!!!

 

[Kruegon]

That is awesome. I was searching for "sport rocketry magazine avoiding the bends" and didn't get any legit hits.

Thanks for the help.

 

[rharshberger]

The source of the PDF was the NAR website contest section iirc the link correctly.

 

[ksaves2]

I built a fair number of longnecked rockets in the past and if the rocket "warps" in time, not necessarily a need to retire it. The only thing I've noticed is the rocket corkscrews on ascent and leaves a spiral smoke tail.
Sure, don't use a stupid powerful motor once this behavior is seen. A lower powered long burner leads to an entertaining flight. Kurt

 

[Kruegon]

The curiosity of the article for me is in regards to an upcoming build. I love the Mean Machine. Had one that was awesome until someone in my house crushed the body. No one will own up to it.

I'm about to begin a build on a custom, scratch, clone of one. The Mean iMachine. Designed to run on up to an I200. No one makes a 38mm cone that matches the Estes cone. And the Estes 1.6" BT-60 is slightly bigger than 38mm tubing. So in order to use the proper cone, I need to use the Estes sized tubing.

So the article says in basic, drag/ pressure vs stiffness is the issue. Easiest fix on the front end? Make the tubes stiffer. Thank you BMS for 34" couplers. The design is about 3/4 complete right now. I still need to design the a/v bay and finish calculating the coupler lengths. Other than that, I'm ready to start the build.

The a/v bay will be designed by utilizing aspects of the bay found on the arctic wolf rocket. It's a rather ingenious design. And the bay alone will most likely take a few weeks to build. I'm going to start building the motor tube and cutting the fin slots next weekend. I may post a build thread on this one. I've been having issues keeping up with my own build threads in the past. I hate leaving people hanging like that.

 

[neil_w]

I've been amusing myself thinking about a Mean Machine goonie as of late.

Not so much worry about strengthening with that one...

 

[Bat-mite]

I'm going to launch my new Richter Recker on 3 E9s tomorrow. Will it cato, or will it bend? You make the call!

 

[Kruegon]

I've been amusing myself thinking about a Mean Machine goonie as of late.

Not so much worry about strengthening with that one...

Now the mean machine is already BT-60. You need to make a BT-80 goonie of it. BMS carries the BNC-80BB. That'd be a nice goonie at 36" BT length. Half the length, almost twice the girth. And it would still run on 24mm motors. But that's just my laughing thoughts.

 

[Kruegon]

I'm going to launch my new Richter Recker on 3 E9s tomorrow. Will it cato, or will it bend? You make the call!

Pfft… just 3 E-9's? It's going to fly just like it's supposed to. The real question you need to be asking is: "Will all 3 motors light?"

 

[ksaves2]

I'm going to launch my new Richter Recker on 3 E9s tomorrow. Will it cato, or will it bend? You make the call!

I have flown one a lot in the past and it works fine. Still have it and it's capable of flying except I do more HPR stuff with the group I fly.
The E9's as long as they all burn and don't cato is an entertaining flight. Three ejection charges ensures the chute will get out. Kurt

 

[Bat-mite]

I have flown one a lot in the past and it works fine. Still have it and it's capable of flying except I do more HPR stuff with the group I fly.
The E9's as long as they all burn and don't cato is an entertaining flight. Three ejection charges ensures the chute will get out. Kurt

Yes, that is exactly how it's supposed to go. If all three motors light, and none of them cato, and if it doesn't bend, and if the chute comes out, and if the chute opens, then it will land in a lake. That's just how my luck rolls.

 

[Kruegon]

Yes, that is exactly how it's supposed to go. If all three motors light, and none of them cato, and if it doesn't bend, and if the chute comes out, and if the chute opens, then it will land in a lake. That's just how my luck rolls.

And why do you fly next to a lake?

 

[Bat-mite]

I've never actually landed in a lake. I guess I was exaggerating. :grin: Pond, yes. Creek, yes. Ditch, yes. Trees, yes. Lake, no.