LOC - Clyclotron

[JAL3]

By a miracle, I actually did get to go to Hearne with several people from my club and enjoy the hospitality of Tripoli Houston. The night before the launch, I spent several hours going over the NAR L2 questions and was feeling confident. I got out the TRA questions and hit 2 roadblocks. The first was that for me my eyes, at least, the printout I had made was almost too small to read. The second was that it was late and I was tired.

It was at that point that I made dumb decision number one. I assumed that the TRA questions would be much like the NAR ones and went to bed.

Yes, I know I can just certify with one organization and get cross certified by the other but, opportunity presenting itself, I wanted to certify under both sets of rules.

My NAR exam proctor was not at the launch site as early as my TRA proctor so I took the TRA test first. The "science questions" were easy and very similar to the NAR ones and I aced that part of the test. It was on the "safety" questions that I got into trouble. There were plenty of areas not covered under the NAR questions. I missed one too many.

I was bummed but still feeling pretty confident about the NAR exam. My proctor had arrived and I aced it. Now it was time to prep the Cyclotron and bad decision 2 came into play.

I had been told that with this rocket, "if it fits, it flies". David Bachelder of Quickburst (not the one who told me that) was serving as the LCO/RSO at the time. He had earlier told me that I was the only one to whom he had sold one of the Loki 24" cases or the reloads. I decided to use the J650, a sparky that fit that case. The motor went together fine was was presented to Art Applewhite for the NAR inspection.

[JAL3]

I took the Cyclotron to the RSO/LCO and David Bachelder passed me and sent me out to a pad where I hooked it up.

[JAL3]

The wait as David announced the "certification attempt" and did cruel things such as count in the wrong direction, stop to make comments and snide remarks, "forget" where the count was stopped and start from the beginning, activated the wrong pad so we had to start again, etc. was interminable and diabolical as well as cruel. I was learning from a master.

[JAL3]

Finally, he pushed the button and things started to look pretty good.

[JAL3]

Yep. I was feeling pretty happy.

[bandman444]

Can you please write more than one line per post?

One paragraph takes ten posts!

Its like an unboxing thread but with words

[JAL3]

It was too good to last.

The rocket began to disolve before my eyes. It was ugly in a spectacular sort of way.

I didn't take pictures at this point because I was in shock.

On the plus side, the chute I had re-sewed had held up to an extremely ugly deployment and my shock mount seemed to have worked.

[JAL3]

With a red faced not caused by the cruel sun, I went out to pick up the carcass and retrieve my casing.

[JAL3]

In looking things over, I could say that the tubes delaminated, the motor had too much thrust and plenty of other things but the real reason for the disaster is that David Bachelder pushed the button too hard.


All things considered, I had a great time. It was my "vacation" and the first full day off I had had since April. I have no complaints.

[gpoehlein]

So John; would you recommend the Cyclotron as a good model to Cert Level 1 with? I've narrowed my choice down to three models and this is one of them.

[JAL3]

So John; would you recommend the Cyclotron as a good model to Cert Level 1 with? I've narrowed my choice down to three models and this is one of them.

I don't have a lot of HPR experience but I don't see why the Cyclotron would not be a good L1 choice. If I were to do it over again (the Cyclotron I mean) I would go with the Kevlar and tubular nylon right from the begining instead of the stock LOC style mount and I would put in a provision for motor retension right from the begining instead of trying to retro fit it.


I liked mine and am sorry it is gone but was glad it was handy to at least make the L2 attempt. Good luck on yours.

[BobCox]

The Cyclotron is an excellent choice for L1 certification. It is big and draggy enough that it can fly on an H motor without requiring a huge field for recovery.

I agree with John that motor retention should be planned for during assembly, not as an add-on. I would NOT recommend going with Kevlar shock cord, at least not by itself. I had four cert attempt failures, and all could be attributed to the Kevlar shock cord being too inelastic. Even with a 25-foot cord, the sudden jerk when it reached the end puts a lot of stress on everything. A combination of Kevlar plus nylon or Kevlar in parallel with elastic works fine.

[JAL3]

I finally got around to locating the tape that my "flight" was caught on.

It's not too good because the videographer was no better than the rocket builder. It's here: http://www.flickr.com/photos/23694991@N03/5016463802/

The actual flight is over pretty quickly. In a vain attempt to get a better view, I made another copy, made it run at 25% speed and then tried to zoom into the area of interest. The result tell me nothing I did not know before: it failed.

Anyway, the second vid is here: http://www.flickr.com/photos/23694991@N03/5016684904/

[Donaldsrockets]

Most definitely WAY too much motor for that rocket.

Very cool flight though. I definitely gotta give you an A for effort.

[JAL3]

I definitely gotta give you an A for effort.

That kind of reminds me of a prof in engineering school. Somebody asked him about partial credit on a particularly nasty exam problem.

He promised to give partial credit as soon as a lawyer could be found who would conduct only a partial lawsuit if only part of the bridge fell down.

We all sucked it up and took our grades. I think the high one was in the mid 30s.

[Fore Check]

I built one of these back in '96 for my TRA L1 project. Used wood glue and an Aeropack retainer. A real workhorse of a rocket.

[JAL3]

I built one of these back in '96 for my TRA L1 project. Used wood glue and an Aeropack retainer. A real workhorse of a rocket.

I agree its a good rocket and I will miss mine. It was the only non-oddroc I had sitting around that was suitable for H&I flights. I get so little opportunity for those kinds of flights that I don't do much in the way of HPR builds.

[5x7]

I agree its a good rocket and I will miss mine. It was the only non-oddroc I had sitting around that was suitable for H&I flights. I get so little opportunity for those kinds of flights that I don't do much in the way of HPR builds.

Here is a version with body tube for tube fins:

http://cgi.ebay.com/LOC-Precision-Cy...-/280565081446

[tsai]

In looking things over, I could say that the tubes delaminated, the motor had too much thrust and plenty of other things but the real reason for the disaster is that David Bachelder pushed the button too hard.


All things considered, I had a great time. It was my "vacation" and the first full day off I had had since April. I have no complaints.

Search for Larry Brand. He's done a LOT of research on tube fin behavior.
What you've experienced is classic fin flutter as applied to tubes. More specifically, check this: http://www.rocketreviews.com/reviews..._da_bomb.shtml

Larry glasses the outside diameter of lower portion of the tube fins, but I think it's the "inside" lower outer quadrant of the tube fin that gets incredibly stressed when speeds approach mach. The simplest solution is to use a stiffer tube (Blue Tube, Magnaframe, FG, or carbon), or to laminate the INSIDE of the tube fins with a layer of glass for reinforcement.

I've also had tube fin rockets spontaneously deconstruct themselves in flight for the same reason.

Because of the incredible drag of tube fin rockets, mach speeds are usually just not part of the equations, but with a big enough motor, even a plate could reach mach.

Layne (Pem Tech) says the scalloped fins on the King Kraken don't have the same issue, and he's even offered a replacement kit if one fails on a commercial motor. I've got a CTI 38-6xl motor waiting to put it to the test once I get around to buying/building one.

Cheers,
- Ken

[qquake2k]

Great build thread! Very detailed, informative, and entertaining. I loved all the photos, especially the launch photos of the sparkies. Great job!

[JAL3]

Search for Larry Brand. He's done a LOT of research on tube fin behavior.
What you've experienced is classic fin flutter as applied to tubes. More specifically, check this: http://www.rocketreviews.com/reviews..._da_bomb.shtml

Larry glasses the outside diameter of lower portion of the tube fins, but I think it's the "inside" lower outer quadrant of the tube fin that gets incredibly stressed when speeds approach mach. The simplest solution is to use a stiffer tube (Blue Tube, Magnaframe, FG, or carbon), or to laminate the INSIDE of the tube fins with a layer of glass for reinforcement.

I've also had tube fin rockets spontaneously deconstruct themselves in flight for the same reason.

Because of the incredible drag of tube fin rockets, mach speeds are usually just not part of the equations, but with a big enough motor, even a plate could reach mach.

Layne (Pem Tech) says the scalloped fins on the King Kraken don't have the same issue, and he's even offered a replacement kit if one fails on a commercial motor. I've got a CTI 38-6xl motor waiting to put it to the test once I get around to buying/building one.

Cheers,
- Ken

I came to my conclusions because I actually found most of the tube fins after the flight. I the paper that the tubes were rolled from just separated layer from layer. I even found what I thought at first was some of the paper but turned out to be the outer skin of the bronzeish paint. On another fin, there was separation at the epoxy joint pure and simple. The joint failed.

I made some bad decisions. I did have some gentler Js but went with the 650 because I wanted the sparky and because nobody had ever actually seen the 1200 Loki case being used.

I had a King Kraken. It was a great rocket but I never got to fly it with anything more than a G because of my local field. Then one day, it landed next to Hiway 87. As I walked to pick it up, some kids in a pickup stopped, threw it in the back of their truck and took off.

Boy was I POed.

[JAL3]

Great build thread! Very detailed, informative, and entertaining. I loved all the photos, especially the launch photos of the sparkies. Great job!

Thanks. I do appreciate it.

[tsai]

I came to my conclusions because I actually found most of the tube fins after the flight. I the paper that the tubes were rolled from just separated layer from layer. I even found what I thought at first was some of the paper but turned out to be the outer skin of the bronzeish paint. On another fin, there was separation at the epoxy joint pure and simple. The joint failed.

I had a nearly identical shread. Based on the evidence I have, the delamination of the paper happens first as a result of fin flutter. Once the paper delaminates, it acts as a vector force for airflow just like flaps or rudder on a plane. The resulting vector force is stronger than the stabilizing force of the fins, and the rocket destabilizes.

The tube fins with their huge cross-section get ripped off pretty much immediately once it destabilizes. On mine, it was the tube that failed, and not the epoxy joint. I found a tube fin that still had a couple layers of the body tube attached to it. The force of the tube fin being pulled off actually delaminated the body tube. It was nice to know that my glue joint was solid.

Cheers,
- Ken

[JAL3]

I had a nearly identical shread. Based on the evidence I have, the delamination of the paper happens first as a result of fin flutter. Once the paper delaminates, it acts as a vector force for airflow just like flaps or rudder on a plane. The resulting vector force is stronger than the stabilizing force of the fins, and the rocket destabilizes.

The tube fins with their huge cross-section get ripped off pretty much immediately once it destabilizes. On mine, it was the tube that failed, and not the epoxy joint. I found a tube fin that still had a couple layers of the body tube attached to it. The force of the tube fin being pulled off actually delaminated the body tube. It was nice to know that my glue joint was solid.

Cheers,
- Ken

That makes sense and its pretty much like what I observed. I hope never to observe it again...at least in one of mine. In one of Todd's or Andrew's or Ken's or Art's it would be hilarious.