Vulcan clone

[Tweener]

Just cloned the Centuri Vulcan last week. I tried to kit it as close to the original as possible.

Parts:

1 Semroc 3" ST-7 tube
1 Semroc 6" ST-7 tube
1 Semroc 2-3/4" engine hook
1 Semroc CR-78 centering ring
1 Semroc ST-7 inside tube coupler
1 Semroc 12" parachute
1 Semroc 24" shock cord
1 Semroc 1/8" launch lug
1 PNC-70 nose cone from Moldin' Oldies
1 piece 1/16" balsa ply stock for rear bulkhead fabrication
2 sheets 8-1/2" x 11" medium card stock
modeling clay

I printed out the patterns from JimZ's site after converting the jpegs to pdf files to get a smoother print out. (Printing the jpeg files directly results in ugly jagged lines on the diagonals.) A small slit was made for the engine hook 3/8" from one end of the 3" ST-7. The original Centuri instruction sheet was then followed to the letter, substituting the CR-78 centering ring for the mylar engine hook ring and an Estes style fold and glue shock cord mount instead of the self adhesive type. After cutting out the rear bulkhead overlay, I used it as a pattern to trace the bulkhead on the balsa ply stock. I believe that the modeling clay in the nose cone is essential to the stability of this rocket. I have read reviews where the clones have wobbled badly on launch, and don't remember having that problem with my two originals years ago.

[A Fish Named Wallyum]

I did one of these last year. Mine flies, but it really shakes it's tail as it climbs out. It results in a corkscrew smoke trail. Not terrible, but I think it could greatly benefit from some extra nose weight and some thin CA applied to the fins. Those are the planned mods for this flying season.
Did you find this build a difficult process? I printed it out long before I ever got the nads up to start the project. What got me going was the fact that it was made out of paper and easily reprinted if I screwed it up.

[Ltvscout]

Just cloned the Centuri Vulcan last week. I tried to kit it as close to the original as possible.
That's a great looking clone, Tweener. Let us know how she flies when you get the chance to try it out.

[Tweener]

I built two of the original kits within a few years of each other years ago. There wasn't anything really any more difficult about the clone except fabricating the rear bulkhead. I highly recommend using the pdf files though. This made the cone shroud and bulkhead hole fit the ST-7 tube EXACTLY; just choose "none" in the scaling section of the Adobe Reader print dialog. I measured the length down the center of it after printing and found it was just a bit over 9". This is how I determined using a 3" and 6" tube with a thrust coupler as per the original design. If anyone wants the pdf format, just PM me and I'll email them. I tried posting, but they're way beyond the kilobyte limit for the forum. I'll post launch results when the weather improves enough to give it a go.

[Tweener]

March 16, 2005, approximately 17:30 GMT. Powered by Estes C6-3, winds at 0-3 MPH. Tracked very straight during the thrust phase, but began to show the spiraling roll on the coast phase until apogee. 'Chute deployment was seemingly perfect, very slow descent (a little too slow). After recovery the reason for the super-slow descent became obvious - no engine casing. The forward part of the engine hook was ripped backward along the engine tube for about 1-1/2 to 2 inches from the force of the ejection charge. :(

Will have to disassemble and make an assessment of the failure. At this point I believe a card stock reinforcement heavily glued over the front part of the engine hook forward of the retaining ring would help, as well as ensuring that the nose cone, 'chute and wadding are not packed too tightly before launch.

Back to the workbench for Vulcan Clone II! ;)

[Tweener]

Oops! I just revisited the instructions for assembly of the Vulcan. Step 3 clearly states: "Apply a drop of glue where the engine lock sticks into the tube." I know I overlooked that step. Who'd a thunk it'd be so important? :o

[UMRS]

Tweener its still a sweet looking clone, even if it doesnt fly straight :)

[Tweener]

Tore it apart last night. Turns out the lock didn't rip through the engine tube, but pulled right out of the tube slot and slid along the tube until the retaining ring forced it to dig in. Seems that overlooked "drop of glue" would have been all that was needed to avoid the mishap. However, I still think number 2 will have at least a ring of masking tape over the slot as well.

I'll post assembly pics of this one.

Ah, well. Live and learn.

[A Fish Named Wallyum]

I think I actually glued a centering ring over the forward end of the engine hook. This is the same problem that I had with my Centuri Taurus clone, and that one had to be retired. I wish Estes would cut down on the power that the ejection charges pack these days.

[Ltvscout]

I think I actually glued a centering ring over the forward end of the engine hook. This is the same problem that I had with my Centuri Taurus clone, and that one had to be retired. I wish Estes would cut down on the power that the ejection charges pack these days.
This is where those mylar rings that Centuri used to sell come in real handy. I could've sworn I saw these around again recently, like maybe Semroc or Flis Kits was making them or something.

[A Fish Named Wallyum]

I think Doug Holverson has some. I've been meaning to buy some, but it must be in my blind spot. (Kind of like launch lugs.)

[A Fish Named Wallyum]

For your viewing pleasure:

[Tweener]

I'd like to get hold of some too. As well as some of the fibre board that engine mount rings are cut from. My whole attitude about a clone is to make it as close to the original as possible, inside and out. I substituted a CR-78 centering ring lock retainer and ply wood for the bulkhead out of necessity. To me the greatest thing would be if I were able to reproduce the semi-gloss card stock of the original printed parts as well.

I am also currently working on a Thunder Roc clone which is a kit-bash of a Mean Machine with laser-cut Semroc fins. I actually cut the "lever" off the Estes engine lock to better reproduce the original kit.

Of course, the best thing of all would be to resurrect the entire Centuri line in kit form. Then I could buy two of each. One to build and one to save - like I should have done years ago. :(

[A Fish Named Wallyum]

Be sure to use the big launch rod. This one wants to whip around like crazy in the slightest breeze. Nice thing about it is that it's easier to transport than the Machine. Strangely enough, I missed the launch shot despite the slow takeoff.
http://www.rocketreviews.com/reviews/oop/cen_thunder_roc.html

[Tweener]

Be sure to use the big launch rod. This one wants to whip around like crazy in the slightest breeze.

Yeah, I remember. ;) So far the only clones I'm building are of (Centuri) kits that I once owned as originals. The Vulcan and the Roc were my two favorites. Though I've done an X-24 "Bug", too. (My avatar. I'm having trouble with the glide on that one.) :confused:

BTW, the Roc will have dual 18" parachutes also. Just wish I could find 'em reproduced with the Centuri logo. I wouldn't build ANYTHING if it were a bonifide original now.

[A Fish Named Wallyum]

Check Ebay. There have been quite a few Centuri chutes for sale of late. I bought six of them.

[Tweener]

Still haven't gotten around to pulling the construction photos off the camera, but I did launch the second Vulcan clone today.

Winds 11-15 MPH, powered by Estes B4-2. No noticable spiral roll at all, but very pronounced weather cock. Ejection was a problem once again. Engine lock held fine, but shock cord ripped apart at the mount. Luckily, the CG fought the CP for a nice light tumble type recovery on the main body. Nose cone floated gently down on the 'chute. I loosened the packing on the wadding, 'chute and cone fit this time, but the mass of the weighted cone was probably too much for the cord. I'll try either a heavier cord, or a longer one on the repair. I'm trying to stay away from the Kevlar leader, since that's not historically accurate, but then neither are the engines I'm flying it with. It may come to that.

On the bright side, the X-24 "Bug" glide problem was solved. Used Estes C6-3 on previous flights which resulted in ejection of the casing after apogee. This caused a nose first spin to the ground, even though glide tests were still successful after the launches. Today I used a C6-0 which ejected on the way up, causing the rocket to achieve glide CG prior to apogee. This resulted in a very nice glide from max altitude with a gentle circling left turn.

[Tweener]

Construction photos of the "kit", body tube construction, and everything ready for final assembly.

[Solomoriah]

This is where those mylar rings that Centuri used to sell come in real handy. I could've sworn I saw these around again recently, like maybe Semroc or Flis Kits was making them or something.
Sorry if rebooting an old thread is considered rude, but I'm considering a "clone" of the Vulcan myself. I may change the color scheme; in fact, I may do it in black and white (I'm a monochrome sort of fellow, just look at my website...)

BUT... the mylar rings used to hold the engine hooks. Some of the Estes kits have these now. I realize the original posts looking for the mylar bands were made in 2005, but I thought I'd point it out for anyone still looking.

I'm thinking strongly of starting with an Estes kit to get the parts. This would mean that I'll be pushing a thrust ring up the tube rather than using a thrust coupler. I'd probably go with the kevlar leader attached to the thrust ring; historical accuracy isn't a big thing for me. But I will need the shorter nose cone...

[Solomoriah]

Hmph. Moldin' Oldies is offline for several months, or so the home page says. Where else can I get a stubby plastic nose cone? The Estes Pioneer has a small pointy one, not the parabolic cone such as came with the original Vulcan, but it's as close as I can find in plastic.

I'm doing a Black Vulcan. The Estes Sizzler kit contains a 9" BT-20, thrust ring, engine hook, mylar band, parachute and shock cord which I can use; I'm planning to buy a couple of the Wal-Mart two-packs with the Sizzler and Hi-Flyer to bash for parts for other rockets anyway. But the nose cones just won't look right on a Vulcanoid.

[Solomoriah]

Just put a page on my website detailing my progress so far on my Black Vulcan:

http://rocketry.newcenturycomputers.net/blackvulcan.html

[A Fish Named Wallyum]

Just put a page on my website detailing my progress so far on my Black Vulcan:

http://rocketry.newcenturycomputers.net/blackvulcan.html

An idea that I've toyed with is coating the paper "fins" with thin CA. I plan to try again with thicker paper and a coating of CA on the back side of the shroud where the fins will be mounted. Mine wobbles a good deal in flight and I think it's because the shroud is collapsing under boost.

[Solomoriah]

You said you used "medium cardstock" for your build. What weight is that? I'm using 110# paper for mine; it seems to be as heavy as, if not heavier than, the original material my old beat-up Vulcan was made of.