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.

Attached Thumbnails

       

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.

That's a great looking clone, Tweener. Let us know how she flies when you get the chance to try it out.

__________________
Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies!
Ye Olde Rocket Forum
WOOSH NAR Section #558

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.

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!

__________________
John Lance Ladd
Yoyodyne Propulsion Systems
Grovers Mill, NJ
Established 1938
lladd.netau.net

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?

__________________
John Lance Ladd
Yoyodyne Propulsion Systems
Grovers Mill, NJ
Established 1938
lladd.netau.net

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

__________________
Low Prices, Fast Delivery. The Webs #1 Rocket Shop

YORF the rocketry forum where vendors can actually post in the vendors section.

TRF Banned and proud

Uncle Mikes Rocket Shack

Any Questions/Comments Click To Email Us

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.

__________________
John Lance Ladd
Yoyodyne Propulsion Systems
Grovers Mill, NJ
Established 1938
lladd.netau.net

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.

__________________
Scott D. Hansen
Ye Olde Rocket Shoppe - Your One Stop BAR Shoppe!
Ye Olde Rocket Plans - OOP Rocket Plans From 38 Companies!
Ye Olde Rocket Forum
WOOSH NAR Section #558