Semroc (Centuri) Taurus Build, Part 3, Engine Mount

TIP: The coupler ends are always cut at a slight angle. To get a flatter, slightly wider edge gluing joint, sand the ends flat.

TIP: Along with glue on the flat edge, roll some glue on the inside so you will get an interior fillet.

Press the disks into the glue and turn the disk to even out the inside fillet.

Before the glue sets up, roll the glued disk and coupler on a flat surface to even up the edges. I'm not sanding here, I'm just rolling the the coupler and disk on the flat side of the sanding block to even out the edges.

I was surprised there wasn't a laser cut notch for the engine hook.
TIP: Notice the line down the black coupler. Notches are cut on both disks, the pencil line helps keep both notches in line.





Here's the finished engine mount.

With 1" space at the bottom, the upper ring goes right over the upper bend of the engine hook. The Kevlar tied line loop went under that upper bend.
TIP: When Kevlar is tied under the hook, try to glue the centering over the upper bend of the hook - much stronger.

Launch! Schoolyard Soccer Field, September 7, 2019

Usually the first Saturday of the month is Launch Day for the Orlando ROCK. Rain from hurricane Dorian has the field too wet to allow cars on the field.

I wasn't going to the club launch today - Lowe's was supposed to install my new patio door but the delivery guys screwed up! No door install, no club launch? Off to the schoolyard for a maximum B6-4 launches.

Still a favorite for first off the pad - 
The Estes CURVILINEAR with an A8-3.
Altitude was an estimated 200' with 12" chute recovery.
Okay, launcher batteries are good, launch rod angle good, the camera works - moving on.

My old Hot Rod Rockets BELL BOTTOM was perfect with a 13mm A3-4t engine. This 22nd launch probably got to 300' with a loud pop from a strong ejection charge. The ribbed plastic streamer brought it back close.

The grass is very wet and so are my shoes - no mud but lots of morning dew. I always pack paper towels to dry off rockets when they touch down.




My Odd'l Rockets STEALTH was another A8-3 flight.
Everything looked great until a second after ejection when I realized the shock cord snapped - unusual for the elastic I use.
No damage and the nose cone with chute landed close.





I had prepped my Estes Saros clone for flight but couldn't pull the friction fit engine to see what it was. If it was a B6-4, it would fly too high for this small field. I didn't take the chance on losing it. When I got home I found out it was a B6-4.

Final flight of the morning, the Semroc CENTURION.
This is the one with interchangeable engine mounts, today it flew with a Estes B6-4 to 275'.
The Centuri style baffle worked like a charm - no wadding and no melts on the 12" parachute.







Keep the camera running - 
I caught this right before the nose cone and chute touched the ground. Gee, that's a beautiful parachute.

Only four launches this morning, but four recoveries with only a broken shock cord.

Semroc (Centuri) Taurus Build, Part 2, Planning Ahead

Remember when the instructions would say: "Read through all the instructions before assembling the model."
That's a great idea for this build. The masking could be difficult if you don't plan ahead. I like a challenge so I'll be painting the rocket in the "Admiralty Colors". Most all of the color separations are done by spraying the sections and nose cones separately before gluing it together.

TRIVIA: This is definitely an old school engine mount. At one time, kits had a black fish paper coupler glued between the heavy card stock engine mount centering rings.

This style of mount can freeze in the wrong place when gluing it into the body tube. There is just too much surface contact with the coupler against the body tube interior.

Test fit and sand, test fit and sand some more. Get a easy, smooth sliding fit inside the main body tube. Check the low inside edge of the main airframe tube to be sure there is no "burr" turned inside the interior.

Free Tri-Fold Mounts PDF

Most build as directed by the instructions - including the tri-fold shock cord mounts.
I've never been a big fan of the tri-fold mounts. The mount is usually printed on the instruction sheets, on thin 20 lb. paper. If I have to use these mounts, thicker stock would be a better choice.

I drew these up to be printed on 65 lb. card stock.
There are three different sizes, mounts for BT-20, BT-50,  BT-55 and BT-60 sized models.
TIP: I can't recommend using a tri-fold mount on a BT-5 sized model. The folded mount is usually too thick and can block a streamer or small parachute ejection.


Make your Tri-Fold mounts as thin as possible as shown here: CLICK HERE
This link shows the shock cord glued on all three sections, the way it used to be done. Now most instructions show it glued just on sections 2 and 3.

If you are a Patreon supporter, email me at:
oddlrockets@bellsouth.net
and request the Tri-Fold Mount PDF.

Semroc (Centuri) Taurus Build, Part 1, Parts

Lots of balsa to fill - Four nose cones and two adapters!
Six sections of body tubes, seams to fill.
The parts of interest:
The water slide decal sheet in printed in black only.
Below the decals is a metallic trim sheet for the rear of the small pod tubes.

I had opened the kit and the balsa fins and trim pieces were off the sheet.
Three fins, three standoffs and three "tunnels" to fill! I may have to mix up some more Carpenter's Wood Filler.

Semroc (Centuri) Taurus Background

Here's the New Centuri Taurus from the 1972 catalog. In small type at the lower left it says: "Available February 1, 1972.

I built and launched many Centuri kits but never owned this one. The build to follow is the Semroc reissue kit I bought six or seven years ago.
To see the old Centuri instructions: CLICK HERE

This is going to be an involved paint scheme, lots of preplanning before gluing it all together.

The catalog description says: "You can fly this interstellar craft from the planet of Taurus at your next launch. If you are unfamiliar with the extra-terrestrial civilization of the Taurians, you'll learn about them in the kit's illustrated Science Fiction story sheet."

Many Centuri Sci-Fi kits, like the Vulcan and Vector-5, had background story sheets included with the instructions.
Here's the Taurus story sheets, courtesy of Jim Z's. Enlarge to read -

Parachute Shroud Line Material?

From the Facebook Model Rocketry Fanatics page, a question:
Any suggestions on what thread or string to use on DIY parachutes for low power?

Then the answers come in - 

• "Use Kevlar thread" - Yes, it works, probably overkill and expensive.
• "Use Button and Rug Thread" -  This used to be what Estes and Centuri sold, but it's not what it once was. It is still very strong, but now more of a poly or nylon blend, subject to melting.
• "Use paper reinforcement disks" -  Not recommended. Paper rings tear, but plastic "permanent" Avery disks are stronger thin plastic.
• "Use nylon thread" - Can melt if the ejection charge hits it.
• "Use Dental Floss" - Strong, but can melt. Keep it in the medicine cabinet.

After years and messing with every possible (available at the time) string, I now use this -

Aunt Lydia's Classic (Size) 10 Crochet thread.
100% Cotton and strong. Just try to break it with a strong pull!

This cotton thread is what comes in all Odd'l rocket kits that have a parachute. I does stretch a bit when pulled hard.
You can find it at Hobby Lobby or Michael's with your 40% off coupon.

If you are a gambling man, give a good tug on pre-made parachute shroud lines supplied in kits. The lines can easily break! Now you know why your rocket recovered with a broken shroud line. I've replaced weak shroud lines on many kit parachutes.


Add some Avery Permanent PLASTIC (not paper) reinforcement disks, #5720. These are poly vinyl and won't tear when a shroud line is pulled. Some kits include paper disks. 

I'm not looking to get into debates, these are simply my recommendations for LPR plastic sheet parachutes.