Wolverine Rocketry Phoenix AIM-54A Build Part 15 Fin Primer Sand

The fins are large so they'll be sprayed with primer/filler on side at a time.

Here I've stuck them down to masking tape, the sticky side of the tape is up.

TIP: Before setting the tape on the spray board, set the tape on your pant leg and remove. This picks up some denim fibers and diminishes the stickiness of the tape a little. If the tape is less sticky, it won't pull the filler out of the balsa grain when you pull up the fins.

After both sides of the fins were sprayed, here's how they looked.
I tend to spray one (heavier than most would) coat of primer/filler, and sand almost to surface.

It's hard to see the sanded taper line running vertically in the picture.
It's there, but very subtle.

Even the primer/filler will help define the high points of the tapers.
In the picture you can see how the primer is darker at the tops of the tapers.
Try to sand and leave a bit of the primer to keep the lines sharp.

On this fin, my sanded taper wasn't straight.
I sanded down opposite sides trying to get the taper line to run vertically.

Wolverine Rocketry Phoenix AIM-54A Build Part 14 Nose Cone Fill

This is the largest balsa nose cone I've seen in a kit for quite a while.

After painting with thinned CWF the upper surfaces were sanded with 220 grit sandpaper. This removed the bulk of the filler.
Use the 220 grit until the dried brush strokes are removed.

Here you can use sandpaper over your fingers. Be careful not to get any creases in sandpaper, it could scar the nose cone.



Near the base shoulder I switched over to 220 grit on a block.
Sanding with a block helps keep the shoulder thickness consistent around the cone at the body tube joint.

400 grit was used for final smoothing before primer was shot.

As careful as I was, there were still some shoulder edge that needed attention.

Some CWF was set along the shoulder edge, a little higher that the sides of the nose cone.

Using the back side of a razor blade, excess filler was removed from the shoulder base. This was done while the filler was still wet.

Try to build up a "bead" over the lip of the shoulder to be sanded to surface after it's dry.

The base of the shoulder had some shallow pits.
These were filled with CWF and sanded smooth.

I know this might be seen as a little extreme. Some would say: "You'll never see it anyway!"

Where feasible, I like the internal construction to be as clean as the outside surfaces.
Your models will be lighter and stronger in the end.

Wolverine Rocketry Phoenix AIM-54A Build Part 13 Lower Fin Fill

Sand the top taper of the lower fin first.
Again, use a block.

Using a block prevents any "dipping" of the flat surface you are trying to achieve.
Using sandpaper over your fingertips could make a concave dipped area.

Here's another way to preserve the sanded taper edge.
After sanding the top, measure down 1" from the top and draw a pencil line.

Sand up to ( and a little over the line is okay) but try not to sand off the pencil line. This guarantees you'll end up with a sharp edge at the 1" mark.

The lower fin has been sanded.

Look close and you can still see a little of the pencil line from the second picture still there after sanding.

Wolverine Rocketry Phoenix AIM-54A Build Part 12 Upper Fin Fill Sand

You'll need a sanding block to sand the filler down and keep the taper edges sharp.
Here I'm using 220 to knock down the bulk of the filler. I'll switch to 400 grit for final smoothing.

Don't just sand back and forth and hope for the best -
Set your block down on the outside taper. Before moving the block, be sure the flat sandpaper side is laying flat on the taper you sanded earlier.

Sand a few inches at a time, always being sure the flat side of the block is laying on the same plane.

After the long outside edge is sanded, switch to the upper taper.
Sand only one tapered side at a time - don't jump around between surfaces.

This picture shows how I'm setting the block on the same angled plane as the upper taper before sanding.

After sanding the upper taper, sand the large flat area of the fin.

If you maintained the block angle on the outside (long) and (short) top tapers, sanding the large flat area of the fin should "reinforce" and keep the edges sharp.

18mm Retainer Article In Apogee Peak Of Flight #317

The Apogee Peak Of Flight Newsletter features an article I co-wrote with Geoffrey Dean Jackson or GDJ. (His signature on the Rocketry Forum)

http://www.apogeerockets.com/education/downloads/Newsletter317.pdf

All the inspiration behind the 18mm water bottle retainer came from a posting by Geoff on the Rocketry Forum.

Geoff didn't get the credit due to him. The posted article focused on my 18mm retainer and not so much on Geoff's 29mm submitted copy and pictures.

Pretty simple,

Drop in an engine, screw on the cap -

DONE!

It's very secure, that engine isn't going anywhere.

When properly made, these caps don't melt.

I've flown the (pictured) Centurion with the 18mm water bottle retainer a dozen times with no problems! 

Everyone that has seen it likes the idea.

Sure, it takes a little more effort a than just taping on an engine hook, but it's a great change from the ordinary.

Wolverine Rocketry Phoenix AIM-54A Build Part 11 Fin Tapers Part 2

With the fin edge marked (or left dark brown from the laser burning) you can clearly see how thick the edges are as you sand.

Sand a few strokes, and check the edge.
Turn over the fin, sand a few strokes and check the edge on the other side.

Some builders will sand an equal amount of strokes on each side. I tend to sand a little, turn it over and sand a little. I'm constantly checking the darkened edge to be sure it is straight and an even thickness down it's length.

This is the top of the forward fin after sanding the short leading edge and forward edge tapers.

The side of a pencil lead was rubbed over the inside edge on the right side.
This inside edge will take care of itself as you sand the leading and forward edge tapers.

If sanded correctly, it should be pretty straight.





This is the root edge of the lower fins.

Be careful sanding here. You can see where the taper starts to "scoop" in a bit at the base or start of the 1" taper.
The CWF filler should help fill that slight concave in the taper.

This is all eight fins ready for filling.

Without a doubt, this was the longest part of the build.

Wolverine Rocketry Phoenix AIM-54A Build Part 10 Fin Tapers Part 1

Cut out the fin taper template and trace it onto the face of the fins with a sharp, soft pencil. A softer pencil will make a darker line.





TIP: If the laser cutting process left a dark brown edge, don't sand it off!
You'll be able to use that dark edge to better see the thickness of the taper as you sand.







If the edges are light you can darken them up with the flat side of a pencil.
Make this coloring as dark as you can using a soft pencil.





This method is not recommended for this model.
The fins on the Phoenix will be painted white - a Sharpie marked edge might bleed through the white finish coat.

If you use a Sharpie, mark quickly not allowing the ink to soak into the balsa.
A black edged fin will be the easiest to see when sanding the taper.