Friday, August 18, 2017

F-104 Intake Pattern Development, Part 1

The upcoming F-104 Starfighter kit from Odd'l Rockets had some interesting kit design challenges. One is the intakes on each side of the body.
The old Centuri kit folded card stock rectangles. They didn't look like the round intakes on the real jet.

I wish I could say the intake shape was developed using some complex geometry. I took the easy way out - I guessed.

Some BT-20 tube was cut into half wedge shapes. This picture shows how many tries it took to get the best fit.

Final shaping is done by sanding the rough cut edges with 220 grit wrapped around the BT-50H body tube.

Okay, here's a good fit!
To make a paper cutting pattern I could just wrap a paper around this intake and trace, but I wanted something more accurate.
More in next post - 

Estes Starship Nova #1371 Build, Part 16, Fin Gluing and TIP

Glue on the rudder directly opposite the engine hook.

The "Q" piece works well to align the rudder on the body tube.

The instructions have you bevel the outside edge of the wing pieces after they are glued onto the boy tube.

TIP: You'll find it much easier to sand in the flat bevel into the wing edge before gluing it onto the body tube.

On the left is the 3/32" wide bevel.

On the right shows the approximate bevel angle of the fin against the sanding block.

Here's how the mode looks up to this point with the wings glued on.

The wing tips still have to be added.

Thursday, August 17, 2017

Estes Starship Nova #1371 Build, Part 15, Wing, Rudder Dowels and TIP

TIP: Recently I've been cutting off the corner tips on the parachutes. This allows the shroud line knot to be a little closer to the tape disk hole.

Three dowel lengths are cut - Two at 3" long and one at 4 1/2" long.

One end of each dowel is rounded.

TIP: You could simply glue the dowels on the outside edges of the rudder and wing extension piece. Sometimes I'll sanded a slight curve into the outside edges with some 220 grit wrapped around the dowel.

On the right is the is the sanded inside curve. It makes a better fit and a stronger glue joint.

Estes Starship Nova #1371 Build, Part 14, Engine Housing Caps

The inside of the end caps were "painted" with orange fluorescent acrylic paint. It took a few coats to get full coverage.

The outside was blackened using a permanent marker. The inside edges were also blackened.

The end caps are glued on, flush with the ends of the body tube halves.

Wednesday, August 16, 2017

Estes Starship Nova #1371 Build, Part 13, Engine Housings Paint

This is the engine halves after sanding down the interior seam fills. (Yep, I can hear you now - "Why fill the interior seams? Nobody will see them!)
The interiors were spray painted gloss white, then sanded.
TIP: To properly "glow" fluorescent paints require an opaque white undercoat.

I didn't use a spray paint this time. I found some fluorescent orange acrylic at Michael's crafts. It was a good match for the orange decals.

The first coat was brushed on. It seemed a little rough and showed the brush strokes. I lightly sanded with 400 grit.

The next two coats were applied using a fingertip.

That seemed to smooth it out. On the left is the finished interior orange.

On the right I scraped off the edge to glue on the end caps.

Tuesday, August 15, 2017

Estes Starship Nova #1371 Build, Part 12, Rear Engine Housings & TIP

A tube wrap is used to mark the BT-60 in half.

An aluminum angle was used to mark the tube and then used as a knife guide to cut the tube in half.

After the first side was cut I slipped my sanding block between the halves and sanded the cut edge straight.

The insides will be painted fluorescent orange. The tube seam was filled with CWF and sanded smooth.
The end caps were laser cut and a bit rough.
The centers were removed first.

TIP: Leave the caps on the card stock to lightly file the edges smooth. I used a fine diamond file. It's easier to file the edges smooth with the support of the outside card stock still in place.

I only filed in one direction. That left the side that will be facing out flat and square. There might be a little lip (right side) on the inside of the plate but it won't be seen.

Monday, August 14, 2017

Estes Starship Nova #1371 Build, Part 11, Intake End Form Gluing

The gluing area on the intake was scraped for better adhesion.
Notice to the left a scraped line for the ends of the intake form.

Slightly wider intake ends were traced and cut from 110 lb. stock.

A glue stick was used for most of the gluing onto the intake end. The bottom edges were glued down using wood glue.

To harden up the card stock, medium CA was wiped over the outside of the intake form.

After drying it was polished smooth with 400 grit sandpaper.

Here's the finished look with full closure of the ends against the body tube.

Sunday, August 13, 2017

Estes Starship Nova #1371 Build, Part 10, Intake End Forms

The intake forms were cut from the card stock sheet.
I cut curves with scissors and the straight lines with a knife and straight edge.

To smooth out the curve sand with some 400 grit.

I pre-curved the pieces with the back end of a Sharpie in the heel of my hand.

There was a crease in the card stock, you can see it right above the pen barrel.

GOTCHA! The pieces weren't long enough! When set at the center lines the edges don't reach the body tube. Both were cut right on the black border edges.

I'll have to trace two wider pieces on some 110 lb. card stock.

I found this interesting - The instruction sheet shows the same "U" piece in the same direction on the front and rear of the intake. The side view has it correct.
Not a big deal but it could confuse a builder.

Friday, August 11, 2017

Estes Starship Nova #1371 Build, Part 9, Low Intake Tube Fitting TIP

TIP: There is one great thing about having instructions sheets in different languages. Cut out your tube marking guides off the sheet you won't be using! This saves your English instruction sheets intact.

TIP: Glue the lower intake tube in place AFTER the engine mount is glued in. You won't be fighting the glue (that is quickly setting up) trying to get the engine hook centered with the lower intake position.
Glue the engine mount in first, wrap and mark with the fin guide in line with the hook, then glue on the intake.

GOTCHA: Well, another fin marking guide that didn't quite match up! Maybe this is why Carl at Semroc didn't include them in his kits.

I rotated the grey overlap area directly above the engine hook for a line to place the intake.

Here's a better view to show what I meant.
The center notch on the ring is directly above the engine hook line.

Estes Starship Nova #1371 Build, Part 8, Low Intake Tube Fitting

Here's what I meant about blacking out the interior. Do it after cutting out the long segment.

Nobody will probably notice this but you won't be able to get spray paint inside when it is glued to the underside of the body tube.

I didn't get a picture of it, but there are thin balsa strips that glue inside the edges of the long cut out section of the intake tube. I glued them so a very small bit extended below the cut tube. That extended lip was taken down when the intake was sanded to fit the main body tube

400 grit was wrapped around the BT-50 tube and the edges contour sanded for the best fit.

TIP: Look at the top of the ring and you can see a small white area.
Be careful when sanding the edges to the body tube curve. The ring can flex and crease at the top.

Estes Starship Nova #1371 Build, Part 7, Low Intake Tube Rings

Draw the cut and alignment lines down the length of the tube, don't cut until after the reinforcement rings are in place.

The rings are glued on the ends of the tubes, lining up with the pencil lines.
On the right I'm adding a small inside glue fillet with a Q-tip.

After the glue dries the burnt edges were cleaned up with some 400 grit wrapped around a pen barrel.

You can see the inside edge is lighter with the burnt edge sanded off off.

I did try to paint the inside of the tube black before gluing on the ring ends. I found out it's easier to blacken the inside after the long piece is cut out as shown in the next post.

Estes Starship Nova #1371 Build, Part 6, Wing and Rudder Glue and Shape

The two piece fins show the balsa grain direction.
Here I'm lining up the root edges to check the fit. Notice the curve between the pieces at the leading edge. It's not a smooth flowing line.

Everything was glued up and set under my clear cutting board to dry.
This cutting board give the right amount of weight against the flat counter top. The top of the board has a pebbled surface but the underside is smooth.

After all was dry I tried to get a better curve on the leading edges of the wings and rudder.
I don't know if this was a mistake or direct copy of the the original kit lines. It just didn't look right to me.

Some 220 grit was wrapped around the BT-60 tube from the kit to round it out.

Here's the reshaped wing on top of the other, yet to be shaped second leading edge. You can see how much was taken off to get a better, flowing curve line.

Thursday, August 10, 2017

Estes Starship Nova #1371 Build, Part 5, Nose Cone and Balsa

The nose cone tie down loop is pretty thin, about the same as the Bullpup nose cones. There was even an air bubble in the corner making it even weaker.

I'll have to cut this off and drill a hole in a thicker area of the plastic shoulder.

The seams were slight and required little sanding.

I did have to go over the recessed detail lines with a sharply folded piece of 400 grit sandpaper.

The wiggling laser cut lines were pretty evident when they were squared up with a sanding block.

The intake support pieces are very thin after they are cleaned up.

Ebay - What the Hay?

Talk about your "fixer-upper"!

A little Joe II is up for bids on Ebay: CLICK HERE

You get a tube with glue on it and some white things.
There's a capped coupler and a drawing.

Thanks, but I'll pass.

Wednesday, August 9, 2017

Estes Starship Nova #1371 Build, Part 4, Engine Mount TIPS

The rear ring is split, they are a little difficult to glue on.
TIP: I set the rear end in the BT-50 air frame tube to hold the ends down while the glue dried.
The instructions show the upper ring flush with the top of the engine mount tube.
TIP: The right side of the picture shows a dry fit, no glue. For a stronger mount, notch the inside of the ring and slip it down, halfway over the top bend of the engine hook.

Notice the notch near my thumb on the left side picture. That's the Kevlar line slot.

A 150 lb. Kevlar line was attached behind the upper ring.
Mentioned earlier, there is very little room for a knot in the Kevlar. It could show up as a bump through the body tube on the finished model.

TIP: Instead of a knot, the Kevlar was wrapped around itself three or four times before pressing it into the wet glue fillet.