Vulcan Fin Tip Reinforcements Part 2



 Slide the angle cut toothpick down into the outside crease of the air scoop.

Keep sliding down until the angle cut of the toothpick is even with the angled top of the air scoop fin tip.

While the card stock fin is wet with glue, you can press and reshape some of the creases. Roll a dowel over the card stock against the dowel inside the air scoop.





When the glue is dry, you can trim off any excess toothpick with a very sharp knife.







Here's the finished reinforcement toothpick glued and trimmed inside the crease of the air scoop.

Vulcan Fin Tip Reinforcements Part 1

After a few flights, the air scoop fin tips on the Vulcan are getting a little bent up.

These will need some sort of reinforcement if the rocket is to last.

Toothpicks were cut in half at a sharp angle to fit the angle of the scoop.

Just cut an angle for now, you'll be able to trim them to size later.

A line of glue is transferred onto the inside high fold of the air scoop fin. 

Rebuilding the Vulcan Part 2

I had hope to re-use the fins and air scoop on the rebuild. But, cutting them off the cone body made a big mess.

I could use the rear bulkhead. It was cut, removed and the edges sanded to clean it up for gluing again.

The picture on the left shows the angle of the rod if the launch lug were glued under a fin and along the angled cone body.
I was always concerned about the off center thrust going up the launch rod. This might be the cause of some tail wagging Vulcan flights I've read about.

The picture to the right shows how I ended up gluing the lug, under the airscoop.

Looking from the rear shows the final position of the lug. (The picture makes it look like the lug is crooked, but it is straight.)

The back of the lug was glued to the end of the tail cone. The top of the lug was glued to the inside of the air scoop. This is a better angle than just gluing it down the sides of the angled body.

It's not perfectly aligned with the internal motor mount tube, but it's at a better angle than the instructions would have you place it.

FOLLOWUP:
The rebuilt Vulcan was flown at the schoolyard on April 18 with a B6-2 engine.
There was no tail wagging during boost. As the model reached apogee there was a little wiggle, but not what I had read about in other reviews. Maybe the straighter lug glued closer to the body helped!

Rebuilding the Vulcan Part 1 Canopy

After that "Fireball B6-2" engine reamed out the inside of the Vulcan, I decided to make another and get it right this time.
The canopy should have been made correctly.
The instructions tell you to crease it around the front curve of the windows.
The front crease is a half circle with straight edges down the sides.

A dowel was sharpened and the tip slightly rounded with sandpaper.
The straight lines were impressed with a straightedge.

A freehand line was "embossed" around the curved window line.












A 1/2" diameter dowel was held under the curved window edge and thumb pressure sharpened the bent edge.
The side lines were creased over the end of a straightedge ruler.
On the finished canopy you can see the straight sides and rounded crease over the black window. The top orange area is flat.

Centuri Vulcan Build Finished

Once all the parts were collected and printing done, this was actually a fast build.

The picture on the right shows the final rod slot under the nose.

If I were to make another, I'd follow the Centuri instructions. they obviously did it for a reason, the same reason the X-24 Bug and Quest HL-20 have their lugs glued to the outside of the conical body.
Live and learn!

Centuri Vulcan Build Part 14 Nose Cone Weight

You'll need a hollow plastic nose cone for this build. Almost 1/2 oz. of clay nose weight will need to be added. That's a lot of washers to be screwed on if you were to use a balsa cone.

Looking at the Centuri instructions, their plastic nose cone is almost filled to the end of the shoulder with clay.

Glue in the shoulder and cut off the base with a razor saw.
Sand the shoulder smooth.

The instructions show a different way to attach the shock cord to the nose cone.

Knots or a loop is tied in the end of the elastic.
This is pushed forward in the top of the hollow cone.
The clay is pressed in over the shock cord locking the elastic into place.

One inch down from the base of the nose cone a loop was tied.
A new Mylar balloon parachute with a sanp swivel was joined to the shock cord loop.

Centuri Vulcan Build Part 13 The Rod Slot!

After I thought the model was finished, I went back and checked the lug and rod slot.

THERE WAS TOO MUCH LUG BINDING THROUGH THE FRONT SLOT!
The slot had to be extended to 3" long!

In the original kit, this is why the lug was glued to the outside of the cone body under a fin.
Too many reviews talk about the Vulcan "tail wagging" on the way up. Most assume (like I did) it was from the launch angle caused by the lug glued on at an angle.
I was trying to correct this by moving the lug to the center.



Some glue was snuck under the slot edges and a dowel rolled over to set the edges down.
Don't go too far back, you don't want to change the profile of the cone.






The tips of the fins were pointed, weak and prone to bending.
Just the tips were cut back and the underside strengthened with white glue applied with a Q-tip.

Centuri Vulcan Build Part 12 Fin Gluing

The fins and air scoop were harder to glue in place than I would have thought.

The "Double-Glue" technique might help here.
The first side of the fins glues on without too much problem. Here I'm using a sharpened dowel to set the tab down.

Let the first tab dry thoroughly before trying to glue down the other side.

Before applying glue the other fin tab, be sure the tab bend is straight from one end to the other.

When gluing the fins, handle the cone with a "light" hand. It's easy to put bends in the card stock when pressing the fin tabs down.

As mentioned earlier, these fin tabs won't want to sit in their location rectangles printed on the cone. You are doing some paper "forming" here, changing the way the fins want to fold and sit on the cone.



While the first air scoop tab was drying, I went ahead and tied the elastic shock cord to the Kevlar with a simple overhand knot. These tied lines were fed back through to the front of the model.

Centuri Vulcan Build Part 11 Rear Bulkhead Gluing

Slowly advance the bulkhead over the motor mount tube and launch lug.
Try to keep it level as you get nearer to the cone sides.
If you press it in crooked, you might not be able to pull it back and re-position it.



When you get into the cone walls, you'll understand why I sanded a slight angle to the bulkhead sides. That angled side lets you get the bulkhead in without pressing a bulge in the smooth cone sides.

Press and check the outside, press and check again.


The few times I've seen a Vulcan (a X-24 Bug or HL-20) at a launch, there is always a bulkhead ridge seen from the outside.
Some of the ridge is caused by too much glue being used for an internal fillet.

Apply the fillet using a Q-tip and remove the excess immediately with another Q-tip.
Too much glue will shrink the cone wall and surface dips can show on the outside.

Centuri Vulcan Build Part 10 Rod Slot Cutting

NOTE: Doing an internal lug requires a long slot to be cut in the conical body. After the model was finished, I wished I had just glued the lug under a fin like the Centuri instructions showed.




With the motor mount tube pressed flush with the top of the cone body, the launch rod is pushed forward until it makes contact with the angled shroud.

I marked the intersection point with a pencil.




Using the rotary punch, a hole was made slight above the pencil mark.

With sharp scissors, the side lines of the slot were cut.

As mentioned before, I made a guess as to how long this slot would have to be to allow a launch rod to fit without binding. I was way off!



With the forward slot cut, glue the internal motor mount tube into the small end of the cone.

Look from the back and center the tube.
Be sure the launch lug is in line with the cone seam and the forward slot you just cut.

Centuri Vulcan Build Part 9 Internal Tube Plan

Test fit the internal tube before gluing to the top of the cone.
My tube fit was too tight! I didn't want it to swell up the joint and break the glue joint.







I decided to cut away about 3/32" from the top of the cone.
This makes the opening wider and made for a good fit of the tube.




On this model, the 2" long launch lug will be glued to the back end of the motor mount tube. At the front end of the model, the launch rod will go through a slot cut in the cone end beneath the nose cone.

For a test fit, the launch lug was taped to the motor mount tube. A launch rod was slid through the lug.

NOTE: Doing an internal lug requires a long slot to be cut in the conical body. After the model was finished, I wished I had just glued the lug under a fin like the Centuri instructions showed.

Centuri Vulcan Build Part 8 Engine Mount Gluing

Because we're using on continuous 9" length of ST-7 tubing, you con't be joining two separate pieces with a coupler shown in the instructions.

With a file, the thrust ring (engine block, or whatever you want to call it) gets a notch for the Kevlar. I wouldn't use a Tri-Fold Mount in a tube this small, it could block a parachute from ejecting.


When installing an engine block, have everythng ready before grabbing the glue.

The Kevlar is already threaded through the open engine casing. (the nozzle has been removed)
My dowel is marked to apply glue at the correct distance in the motor mount tube.

Centuri Vulcan Build Part 7 Cone Gluing

When the edges are lined up from top to bottom, burnish down the tape on the inside.

Here I'm using an engine casing stuck in a dowel to roll over the tape edge.




White glue was set on one side on a single edge razor blade (the side facing up) and applied under the lifted edge.
TIP: Never use a lot of glue when adhereing paper to paper. These bonds don't take a lot of glue, just a light coat.




Inside the cone and directly under the seam is a 1/2" diameter dowel. Another clean dowel is rolled over the seam from the outside. The inside dowel gives you something hard to roll over.

Note: I always say use a CLEAN dowel. Any dirt, oil or old paint will transfer from the dowel onto the shroud surface and be locked onto the surface by any glue that is pushed out.

Centuri Vulcan Build Part 6 Cone Shaping

Wash and thoroughly dry your hands before making the printed cone shroud.
Any oil or dirt on your hands will transfer onto the printed surface.

Step 13 of the Centuri instructions have you pull the large body shroud under a ruler or over a table edge. I've never gotten good results doing it either way.

In the picture, note the front end of the dowel is tapered. when forming a shroud this large in your hand, you'll have to curve the back end, turn it over and form the smaller front end.
The tapered front of the dowel prevents a crease from forming in the middle of the cone. A square end on the end of the dowel could make a line around the center.


Clear tape is placed down the edge with the sticky side facing out.
You'll be able to line up the edges with just the tape (no glue yet) to get it right.
It did take a few tries to get the orange edges to line up.




Here's what the open edge looks like from the outside.

The edge is glued down in the next step.

Centuri Vulcan Build Part 5 Bulkhead Ridge

Sand the edge at an slight angle to match the inside wall of the body shroud cone.
The angle in the picture is a little exxagerated for clarity. Try to match the angle of the finished cone.

This might help get rid of a ridge that can be seen when the bulkhead is pressed into the cone. The bulkhead presses against the cone forming the end area into a rounded triangle shape.


I wanted a internal launch lug, instead of gluing the lug down the angled cone body.

NOTE: This internal lug idea didn't turn out quite as I hoped. The cone body turned out longer and thinner than I though it would be.
The rounded slot that had to be cut into the front end of the cone body (for launch rod clearance) ended up being 3" long! I thought it might be under 1" long.
There were good reasons why Centuri wanted you to glue the lug under a fin and against the angled body.

The lug will go under the body in the same location where the engine hook would normally sit.

Set your rotary punch to the largest barrel and punch a 3/16" diameter hole.
TIP: A 3/16" hole fits a 1/8" launch lug perfectly.

Centuri Vulcan Build Part 4 Rear Bulkhead

The bulkhead print was glued to a piece of framing mat material.
TIP: You can pick up mat material scraps from a frame shop for next to nothing, sometimes free! It's strong and great for home made LPR centering rings.



After drying, Cut out the center with a sharp #11 blade.

I wrapped 220 grit sandpaper around an engine casing to get a better, clean edge.
When sanding, constantly check the fit of the ST-7 tube.



You can keep the rolled over "lip" on the back side of the bulkhead. It gives you a wider gluing surface.

On the printed side, roll the lip into the center hole and sand off. You'll want a clean edge when seen from the outside.

Centuri Vulcan Build Part 3 Fins and Canopies

Here's all three fins, lower air scoop and squared canopy.








You are given two different canopies to pick from.
The rounded canopy took a little extra effort to get right.

As done before with shrouds, it was given a rounded contour by rolling a dowel in the heel of my hand.




The gluing tab is tiny!

Use tweezers to make the bend.
Use the tweezers again to hold it shut when gluing.