LAUNCH! Small Stuff 10/17/10

I wanted to get in a small launch before leaving for the cruise job tomorrow morning.

I can't make any guarantees about regular posting for the next 12 days or so. While the ship claims fast internet connections, they are painfully slow!

I'll bring a few small things to work on and post when I can.

The new carded downscale WOLVERINE made it's first flight this morning. I used one of the 35 year old MPC 1/2A3-5m engines.

There was a tight corkscrew at the boost, I'll add a little noseweight and it should be better next time around. Altitude was lower than I would have expected, a better engine choice would be the A3-4t.

My "freebie" Art Applewhite SCIMITAR flew on a A10-3T. Lots of smoke and a fast spin. Ejection came after apogee with the nose down.

The downscale carded SKYWRITER had it's 11th flight! This is a favorite now, finally a Micro Maxx that gets good altitude before the 1 second delay pops the streamer.

The downscale Gooney MISSILE TOE flew on it's MMX engine.

And finally, a Bob Harrington's downscale RED MAXX flew again on a Micro Maxx.

The WHISTLER! - that didn't! Part 1

Recently there has been forum posts about whistling rockets.

Rockets with split fins like the BSD THOR do whistle. I've heard the THOR whistle at N.E.F.A.R. launches. Bullpups have also been known to whistle.

Estes had their SCREAMIN' MIMI design.

It didn't whistle loud enough to be heard over the engine. There wasn't enough directed airstream to activate the whistle.

The Mimi rocket had tubular plastic "Whoopee" whistles attached to the outside edges of small fins.

You can hear a "Whoopee Whistle" HERE

Two years ago I experimented with split fins trying to get a good whistle. The WHISTLER fins had opposite and angled trailing and leading edges. My hope was to direct and split the airstream over the angled leading edge of the lower fins.

Look closely at the leading edge of the lower yellow fin. You can see the angle cut.

On the BSD THOR, the upper trailing edge and lower leading fin edges are square.

It was launched a twice with a B6-4 and C6-5. No whistle was heard.

Someone would have to build a prototype where the distance between the split fins could be adjusted.

For example, one flight with 1/4" space between the fins. On the next flight, the upper fin moved up to 5/16" between the fins. Adjustments could be made until a possible whistle is loud enough and consistent.

Pigasus Build Part 9 Ears

I wanted the pig's ears to have a blown back look.

To get the correct angle of the ear on the nose cone "head":
1. 220 grit sandpaper was wrapped around the main body tube.
2. The ears were held at what I thought was the correct angle against the sandpaper.
3. The inside edge of the ear was sanded down by going in a straight line, back and forth, over the sandpaper.

Here's the inside angle (or the gluing surface) of the ears, ready to be glued to the nose cone.

After checking the ears on the nose cone, I ended up sanding more off the edge so the ears would lay back farther. This picture was taken before the second sanding adjustment.

Pigasus Build Part 8 Nose Cone Weight

The 1/2 oz of clay weight is formed into a snake and pressed into the pre-drilled hole in the nose cone base.

The dowel was used to press the clay forward and level out the top.

The screw eye is turned into the plywood plug, just far enough until where the screw threads aren't visible.

Don't screw too far in or there won't be any threads to hold the eye in the disk!

The disk edges took a little bit of sanding to fit into the pre-drilled nose cone hole.

After the disk was pushed in as far as it could go, a fillet was applied around the edges using a dowel as an applicator.

Pigasus! Build Part 7 Fin Filling

If you look at the fin pattern sheet post #2, you know these fins have a complicated shape.

With all the inside surface edges of the wings and razor back pieces, it'd be much easier to fill the balsa before gluing onto the main body tube.

I wasn't looking forward to filling the inside angles but it turned out being much easier than I thought.

Thinned Carpenter's Wood Filler was brushed on all surfaces. The inside edges were sanded first.

I simply folded a piece of 400 grit sandpaper, stuck the fold in the angle cut and sanded back and forth - DONE!

The picture shows the razorback balsa piece with the sandpaper tucked in a recess. The fold of the sandpaper would knock down the filler, two edges at once.

Pigasus! Build Part 6 Engine Mount

The engine mount was glued into the ST-18 (1.840" diameter) body tube.
The rear ring is recessed 3/4" up from the rear.

TIP: On a mount this wide, I don't lay a glue ring in the main tube and slide the mount into the glue. The mount is slid in place, up to the 3/4" line, then add fillets on the bottom and the top.

With centering rings this big, you've got plenty of room to lay a fillet and smooth it out with a finger.

Keeping Filler in the Body Tube Seams

It's frustrating when Carpenter's Wood Filler pops out of the body tube seams. Depending on the width and depth of the seam, results are unpredictable.

This is an adaption from ideas suggested on TRF posts from BradyCross.

In the picture, the dried filler has been sanded down, just above the body tube surface. I didn't sand the filler all the way down to the surface - yet. The filler is still a slight raised area over the seams. Most of it was removed with 400 grit sandpaper.

The idea is to remove as much as possible, but not get close to where it could pop out of the seam.

A drop of CA was applied to the filler line and spread out down the seam. The CA would "lock" the filler down and glue it in the seam.

Now I can sand off the remaining filler bump to the surface of the body tube without much worry of the filler flaking out of the shallow seam.

I'll post again with the results after priming and sanding.