Monday, April 30, 2012

Back Home Again!

Sorry there wasn't a post yesterday - I was in transit from Costa Rica back to Orlando.
My show on board ship went very well, hopefully this could lead to more work again on the ships.

TIP: Don't ever (ever, never, ever) fly on Copa Airlines!
Two hours waiting in line to trying check in with incompetant employees!
Two flights were cancelled. The employees wouldn't make an announcement to the 75 customers stuck waiting.
I was told Copa Airlines might be going out of business. I'm not surprised.

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!

Saturday, April 28, 2012

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.

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.

Friday, April 27, 2012

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.

Thursday, April 26, 2012

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.

Wednesday, April 25, 2012

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.

Tuesday, April 24, 2012

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.

Monday, April 23, 2012

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.

Sunday, April 22, 2012

Screw Eyes in Kits

I received an email asking about screw eye sizes.
Sometimes I'll go a bit larger than the use the screw eye supplied in the kit.

The smaller 1" long screw eye was in the Estes Phoenix Bird kit, a BT-55 sized model.
The threads are low and probably wouldn't grip well in a soft balsa nose cone shoulder.

The larger screw eye might be considered a "medium" size at 1.375" long measured from end to end. I'll be using that screw eye in the Phoenix Bird build.
There's not that much difference in length or eye diameter and I'll feel better about the grip of the higher screw threads.

A BMS clone kit of the FSI Viking 1 includes a big, heavy screw eye. It's heavy enough to improve stability (moving the C/G forward) without adding nose weight washers.

Centuri Vulcan Part 2 Scoring Cardstock

Because I used a single 9" long piece of ST-7 tubing and dropped the engine hook, you can skip Steps 1 - 5 in the Centuri instructions.
You don't have to join two separate pieces of body tube.

All the cardstock prints were done from the JimZ website on 110 lb. cardstock.
To stiffen the fins and air scoop, a sheet of 24 lb. copy paper was laminated to the printed cardstock.
The back of the cardstock was hit with spray adhesive and the 24 lb. paper applied.
This made the fins just strong enough to help prevent damage at recovery without adding too much weight.
The body shroud didn't get laminated, it was just a single printed piece of 110 lb. stock.

Score all the fold lines before cutting out the pieces on their outside lines.

The back end of a single edge razor blade makes a good scoring edge.
Notice all the masking tape over the sharp side facing up.

It should go without saying - Score all the fold lines using a straight edge.

Once again using a valuable tool, the back end of a Sharpie pen.
It's just a good, cheap burnisher.

My fins were printed on 110 lb. cardstock.
The white cardstock showed through on the sharp, bent edge.

A quick pass of the Sharpie blackened out the white.

Saturday, April 21, 2012

Centuri Vulcan Build Part 1 Parts

This is another I wanted to build since first seeing it in the 1971 Centuri catalog.
Definitely different, a combination of conical stability and card stock wedge fins.

PDF Prints and Centuri instructions available from JimZs at:

For a great design variation, check out the "Black Vulcan" HERE
Thanks go out to Chris Gonnerman

Body Tube - 9" ST-7 Semroc
Nose Cone - Original was Centuri PNC-70 1 1/2" long Tip to Shoulder
You could use:
1.75" Apogee PNC-18B
fits ST-7 tube very well, hollow for clay nose weight
1.5" BC-715 Semroc
Balsa Equivalent to Centuri PNC-70, needs washer weights added.

I went with the Starlight nose cone from the spare parts box. Those nose cones are available now from Apogee. This nose cone is a little longer than the 1 1/2" long original. Made for the BT-20, it fits the ST-7 tube very well.
The picture shows an engine hook, I didn't use it, opting for a wrap of masking tape around the end of the engine for retention.

The original had a smaller launch lug glued underneath a wedge fin. This would put the lug at an angle, down the conical body side.

I tried for a central lug, down the 9" long motor mount tube.

Spray the printed cardstock sheets with clear acrylic to keep them clean when building and flying.

The rear plate is already glued to a piece of thick mat board.

Ranger Clone Build Finished

The two 12" parachutes have been assembled and have snap swivels added.
One parachute was tied to the shock cord on the lower half.
The other joined to the screw eye on the nose block.

With the single plate baffle, you will need flameproof wadding to protect the parachutes.
The nose cone might need screws or a wrap of tape (on the outside) to keep it together at ejection.

Ranger Clone Finished

The two 12" parachutes have been assembled and have snap swivels added.
One parachute was tied to the shock cord on the lower half.
The other joined to the screw eye on the nose block.

With the single plate baffle, you will need flameproof wadding to protect the parachutes.
The nose cone might need screws or a wrap of tape (on the outside) to keep it together at ejection.

Friday, April 20, 2012

Cruising April 20 - 29, Panama Canal

I'm doing my show on the Holland America Zuiderdam from April 20 - 29.

TIP: If you've never been on a cruise ship, don't bother with the on board Internet connections. A guest is charged $.75 per minute and the speeds feel like a bad dial-up connection. You'll spend a few dollars just waiting for your home page to open!

I write my blog entries a week ahead so everything is in draft form. Most of my posting is done in port at restaurants like a Starbucks.

So, if I miss a day, understand it wasn't my choice! Some days on a ship are "at sea". On April 29th I'll be traveling home so you probably won't see a post that day.