Problem with LOC Cyclotron Kit?

soopirV

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Hi all- I'm building the LOC Cyclotron, and have run into an issue that surprises me. Per the instructions, the launch lug is supposed to be mounted to the airframe, and the tube fins surround it. I reinforced my tubes with a layer of FG inside, and plan to install rail buttons, but wanted to include the 1/2" launch lug because having the ability to launch from a rail or rod sometimes means reduced wait time. However, when I was mocking the build up, I discovered there's no way the lug can fit, at least not without disrupting the continuity of the fin ring. Has anyone else built this stock, with success? At this point I can only see that I leave the lower lug out, and use the gap in the fins to ride the rod; that isn't the worst thing possible, but it seems like a major miss on LOC's part- I'm not trying to throw shade, but surely I'm not the first to encounter this?

**Can't seem to post images at this point, will try again in a bit after a restart**
 
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I ditched the 1/2" lugs and subbed 1/4" ones. It's considered midpower, so shouldn't be a problem. If rod whip is a concern, you can use the rail buttons. I agree, a fail on LOC's part.

OR, you could glue the lower 1/2" lug in one of the tubes, instead of between them. Maybe a short strip of tubing to act as a standoff for the upper lug.
 

ECayemberg

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Hi all- I'm building the LOC Cyclotron, and have run into an issue that surprises me. Per the instructions, the launch lug is supposed to be mounted to the airframe, and the tube fins surround it. I reinforced my tubes with a layer of FG inside, and plan to install rail buttons, but wanted to include the 1/2" launch lug because having the ability to launch from a rail or rod sometimes means reduced wait time. However, when I was mocking the build up, I discovered there's no way the lug can fit, at least not without disrupting the continuity of the fin ring. Has anyone else built this stock, with success? At this point I can only see that I leave the lower lug out, and use the gap in the fins to ride the rod; that isn't the worst thing possible, but it seems like a major miss on LOC's part- I'm not trying to throw shade, but surely I'm not the first to encounter this?

**Can't seem to post images at this point, will try again in a bit after a restart**

I'm guessing your tube fins are made of 3" airframe, correct? If so...

The Cyclotron used to be supplied with tube couplers as fins. The smaller diameter left a gap between two of the tube fins large enough to fit a launch lug in the void. The newer Cyclotrons are supplied with the slightly larger diameter and glassine covered airframe tube, which is a vast improvement in my opinion. But, you are correct, you will no longer be able to fit a launch lug in the voids between the tube fins.

That said, as you say, glue a 1/2" inside the tube on one side of the rocket, put your rail buttons inside a tube fin on the other side of the rocket, and you have both options.

The unique feature I found with the Cyclotron is that the thing flew straight...as in it did not weathercock. Didn't arc into the wind as much as other "traditional" fin rockets.

Have fun!
 

soopirV

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I'm guessing your tube fins are made of 3" airframe, correct? If so...

The Cyclotron used to be supplied with tube couplers as fins. The smaller diameter left a gap between two of the tube fins large enough to fit a launch lug in the void. The newer Cyclotrons are supplied with the slightly larger diameter and glassine covered airframe tube, which is a vast improvement in my opinion. But, you are correct, you will no longer be able to fit a launch lug in the voids between the tube fins.

That said, as you say, glue a 1/2" inside the tube on one side of the rocket, put your rail buttons inside a tube fin on the other side of the rocket, and you have both options.

The unique feature I found with the Cyclotron is that the thing flew straight...as in it did not weathercock. Didn't arc into the wind as much as other "traditional" fin rockets.

Have fun!

I had read that, about earlier models shipping with coupler fins, but I just figured they'd update all parts of the kit when they went with the AF tubing (which I do have, and am glad- the coupler tubes left gaps (and clearance for a lug!). I'm going to put a strip of glass on the air frame and potentially on the two approximating tube fins just to give the area that rides the rod a little extra protection. Probably not worth it, but hey, why not. It's hard to get any accurate sims on this since TubeFins aren't easily set up in OpenRocket, but I am surprised there's no added nose weight- nice to hear that it's a good flier. Now if only I can settle on a color scheme!
 

dhbarr

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I had read that, about earlier models shipping with coupler fins, but I just figured they'd update all parts of the kit when they went with the AF tubing (which I do have, and am glad- the coupler tubes left gaps (and clearance for a lug!). I'm going to put a strip of glass on the air frame and potentially on the two approximating tube fins just to give the area that rides the rod a little extra protection. Probably not worth it, but hey, why not. It's hard to get any accurate sims on this since TubeFins aren't easily set up in OpenRocket, but I am surprised there's no added nose weight- nice to hear that it's a good flier. Now if only I can settle on a color scheme!
OpenRocket has a TubeFin button... ?
 
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1. Per Rocsim, CP is 50.46", CG is 35.5" unloaded. No wonder it flies stable.
2. At one time LOC offered its' customers the option to download a pdf from its' website and home print the decals on decal paper. Now they only offer the Cyclotron decals in vinyl at $40 a crack. Don't know if you like home printed decals, but Wayback has the archived pdf page here:
https://web.archive.org/web/200610212...ron-decals.pdf


Thanks to Thorfire, see thread below.
 

soopirV

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1. Per Rocsim, CP is 50.46", CG is 35.5" unloaded. No wonder it flies stable.
2. At one time LOC offered its' customers the option to download a pdf from its' website and home print the decals on decal paper. Now they only offer the Cyclotron decals in vinyl at $40 a crack. Don't know if you like home printed decals, but Wayback has the archived pdf page here:
https://web.archive.org/web/200610212...ron-decals.pdf


Thanks to Thorfire, see thread below.

hey hey! Thank you! I never think to check the wayback machine...
 

blackwing94

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I installed a lug inside a tube fin. Never used though, since the motor size is 38. To big for our clubs rods. I also installed rail buttons, the lower one inside a (different) tube fin. You have to launch from a skinny launch rail. Our club also has larger launch rails with supports running behind the rail that the tube fin will not fit around when loading the rocket on the tower... if that makes sense.

Mine flies straight every time. When it comes down, it tends to drift/sail upwind with the motor/tube fin end lining up into the wind. Kinda cool.
 

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Blackwing94:
Tail sliding into the wind seems to be a characteristic of tube fin rockets. I have a ASP tube fin that flys the same way. Look forward to flying the LOC Cyclotron this summer.

Tom
 

LOC

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Interesting! Where did you find this kit? We haven't made any since we purchased LOC back in 2016. It got shelved until we could completely understand what's going on with this thing! It looks like you found an issue so we'll take notes if we ever bring it back. Off the top of my head, a suggestion would be to have us send you "stand-offs" for the lugs. We could cut them so they'd line up straight and you can then mount a lug in the fin tube and one further up keeping the distance from the main airframe the same. As long as the stand offs are cut properly, it "shouldnt'" be a problem. Drop us an e-mail and we'll get some out to you. We'll need to math it out, but can easily get it out next week.
 

soopirV

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OpenRocket has a TubeFin button... ?

The RKT file I downloaded had tube fins already installed, but also a fin set, so I didn't even notice the tubes. The CP moves forward 100cm when I delete that set, and I go from 4.68cal stab to -8. Tells me that the Tube fin modeling is cosmetic only? However, I can't find any references from LOC on where the CP actually is, so I'm a little skeptical of the sim. Anyone know? Otherwise I'll do the cardboard model...although I don't know if that's relevant for tubers...
While on the subject of tube fins in OpenRocket- is there a trick to model a different color inside the tube? I suppose I could export the image and do it in PhotoShop, but that's not my forte!
 

soopirV

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Interesting! Where did you find this kit? We haven't made any since we purchased LOC back in 2016. It got shelved until we could completely understand what's going on with this thing! It looks like you found an issue so we'll take notes if we ever bring it back. Off the top of my head, a suggestion would be to have us send you "stand-offs" for the lugs. We could cut them so they'd line up straight and you can then mount a lug in the fin tube and one further up keeping the distance from the main airframe the same. As long as the stand offs are cut properly, it "shouldnt'" be a problem. Drop us an e-mail and we'll get some out to you. We'll need to math it out, but can easily get it out next week.

Hi! Nice to hear from the new owner! I ordered mine from HobbyLinc.com, they had it on sale, and I snatched it up when I heard here they were OOP (confirmed now!). I'm not worried about it not fitting, I've got lots of other solutions on the table, but thank you for the offer! I hadn't noticed this post when I just replied to DHBarr, but any chance you have the CP location documented anywhere? I want to check the accuracy of my sim. Awesome kit!
 

soopirV

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Interesting! Where did you find this kit? We haven't made any since we purchased LOC back in 2016. It got shelved until we could completely understand what's going on with this thing! It looks like you found an issue so we'll take notes if we ever bring it back. Off the top of my head, a suggestion would be to have us send you "stand-offs" for the lugs. We could cut them so they'd line up straight and you can then mount a lug in the fin tube and one further up keeping the distance from the main airframe the same. As long as the stand offs are cut properly, it "shouldnt'" be a problem. Drop us an e-mail and we'll get some out to you. We'll need to math it out, but can easily get it out next week.

Hi! Nice to hear from the new owner! I ordered mine from HobbyLinc.com, they had it on sale, and I snatched it up when I heard here they were OOP (confirmed now!). I'm not worried about it not fitting, I've got lots of other solutions on the table, but thank you for the offer! I hadn't noticed this post when I just replied to DHBarr, but any chance you have the CP location documented anywhere? I want to check the accuracy of my sim. Awesome kit!
 

o1d_dude

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Tube fin rockets have a huge amount of fin area compared to your typical 3FNC bird. The center of pressure is often down inside the fin can area. An average or long length HPR motor will have significan mass forward of the center of pressure.

Explains a lot about stabilty in the wind and tail sliding behavior.

Larry Brand, the Tube Fin Daddy, often extended his motors out the back of his rockets...
 

dhbarr

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The RKT file I downloaded had tube fins already installed, but also a fin set, so I didn't even notice the tubes. The CP moves forward 100cm when I delete that set, and I go from 4.68cal stab to -8. Tells me that the Tube fin modeling is cosmetic only? However, I can't find any references from LOC on where the CP actually is, so I'm a little skeptical of the sim. Anyone know? Otherwise I'll do the cardboard model...although I don't know if that's relevant for tubers...
While on the subject of tube fins in OpenRocket- is there a trick to model a different color inside the tube? I suppose I could export the image and do it in PhotoShop, but that's not my forte!
I think this is a .rkt vs .ork type deal.

If I pop OR, add a NC & BT, make it an MD MMT, and hit the tuber button I get a pretty rational result straight out of the box. It only gets weird if you make too many tiny tubes or shorten them a bunch.

K'tesh I bet you can't phantom fin the inside-only of a tuber, I double-dog-dare you! :p
 

tbonerocketeer

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Interesting! Where did you find this kit? We haven't made any since we purchased LOC back in 2016. It got shelved until we could completely understand what's going on with this thing! It looks like you found an issue so we'll take notes if we ever bring it back. Off the top of my head, a suggestion would be to have us send you "stand-offs" for the lugs. We could cut them so they'd line up straight and you can then mount a lug in the fin tube and one further up keeping the distance from the main airframe the same. As long as the stand offs are cut properly, it "shouldnt'" be a problem. Drop us an e-mail and we'll get some out to you. We'll need to math it out, but can easily get it out next week.
I have one in stock 😁

Sent from my Pixel XL using Rocketry Forum mobile app
 

soopirV

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That's the last one I know of then other than the one we have on the shelf for R&D. It will be quite a ways down the road before we can tear into it with the new mini line coming out...

I saw one on the AMW table at the SARA launch yesterday, too- the more "recent" version with AF tube for fins instead of coupler.
 

soopirV

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Ok- so back to the question I had posed earlier about tube-fin support on OR. I started from scratch, and got favorable stability from the get-go, unlike the .rkt file I downloaded from Rocket Reviews (which included planar fins in addition to tube fins- when the planar are deleted, CP flies way forward). However, I still haven't seen anyone with a measured CP, and the OR view states: "Warning: Tube fin support is experimental"
I'm expecting this bird to be over-stable, but want to be accurate...any one have any ideas?
 

blackwing94

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I made my own rocksim file for my Cyclotron. I have the CP at 46.51 from the nose. Mine is set up for 38mm and use I use AT reloads. I show stability always being good. The CP is so far back, the front of bigger motors (ex. J575FJ) pass the CP and start moving the CG froward again. I can't get stability to go below about 1.8 on any motor combination. Love this rocket. I have 2. And heir and a spare. I want to build a fiberglass version in the future... sometime...
 

mcderek

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I have a coupler version Cyclotron. It has 30+ flights on it. Great rocket. G80 through I motors. Fun, fun fun!
 

soopirV

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I made my own rocksim file for my Cyclotron. I have the CP at 46.51 from the nose. Mine is set up for 38mm and use I use AT reloads. I show stability always being good. The CP is so far back, the front of bigger motors (ex. J575FJ) pass the CP and start moving the CG froward again. I can't get stability to go below about 1.8 on any motor combination. Love this rocket. I have 2. And heir and a spare. I want to build a fiberglass version in the future... sometime...

I'm at 50.51 from the nose...about 1 caliber further back (or about 10%, which ever is most important). Is yours built on 15.03? Or did you use an earlier version? At this point I'm quite content that the simulation model is close enough for gov'mnt work...just waiting on some kevlar to arrive so I can finish the motor mount.
 
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