Friday, September 30, 2011

Adding Ping Pong Balls Part 1

Artist and rocket designer Shrox has been given credit for being the first to use ping pong balls in rocket designs.
Take a look at the FlisKits Alien8 kit to see how they can add to a great design. Click HERE

Cutting holes in a ping pong ball can be problematic. Take your time and you can get a clean, tight fit around the body tube.

It's hard to see in the picture, but the ping pong ball seam is parallel to the end of the body tube. You don't want to be cutting into the ball and hitting the seam.
Before marking with a very sharp pencil, rotate the ball so the inside seam is centered between the two holes you want to make.

Holding the tube against the ball, draw around the tube edge making a sharp pencil line on the ball.

Hold the blade still and turn the ball underneath the blade tip. Turn the ball until about 1/4" is scored with the knife. Reposition the ball and score another 1/4" length.
I tend to cut just inside the pencil line with a new knife blade.
Don't try to cut all the way through in one pass. It'll take three complete cuts around the circle before the top starts to free up. Be ready, it tends to "pop off" when you don't expect it.

Don't flex and crack the dome cap off like you might do with vacu-form plastic. Continue to score around the pencil line until if comes completely off.

Custom Nomad Build Part 8 Nose Cone Disk

Smooth and round up the edges using a sanding block.

In the picture, the edge on the right side has been smoothed over, the left side has not.

One of the centering rings is used for a shoulder and support.

I did sand the edge of the ring a bit to get it to fit under the vacuform disk edge.

For a reference point when gluing, pencil tick marks were made where I found the best fit of the ring and the overhanging lip of the disk.

The instructions suggest using CA quite a bit. I've had experience with CA becoming brittle with time and pieces have separated at launch! CA (Super glue) has it's place but not on a rocket you want to keep longer than a few years. I'll use it to fill mold marks on a nose cone, but not on fins, launch lugs or nose cone connections.

I've really got to buy a new bottle of contact cement! This one is over 10 years old and has browned up quite a bit.
Brush contact cement on both surfaces and allow to dry thoroughly.

Contact cement give an instant bond when two pieces are joined!
Be ready, it grabs fast and won't let go.
Be sure your placement is right before pressing the two glued pieces together.

Thursday, September 29, 2011

Custom Nomad Build Part 7 Nose Cone Disk

The nose cone disk is next.
The instructions say to cut it out with scissors but I think you'll have better control with a sharp hobby knife.
Trace around the outside of the disk with a pencil. It's easier to cut on a dark pencil line instead of the white plastic.

Lightly score around the outside edge of the disk keeping your knife on the outside of the pencil line.
Your knife should "trace" along the edge without too much trouble.

There is no need to cut all the way through the thin plastic. Cut about halfway through.

At the halfway point, I continued the cut line to the outside of the plastic to make the cracking easier.
Flex the plastic back and forth over the cut scored line and it should break in two.

Letter from NAR President, Trip Barber

Several weeks ago the U.S. Department of Transportation (DOT) decided that, based on a 2010 change in some obscure shipping safety test procedures, it should terminate a special shipping exemption that it has granted since 1978 to companies and vendors who ship model rocket motors and igniters. This special exemption, DOT-SP 7887, lets these products which are technically classified as "Explosive 1.4S" get shipped in containers labelled with a black and white "Flammable Solid" hazardous material label rather than a bright orange "Explosives" label.

This DOT action will not increase your cost or change your access to the products; the same HAZMAT shipping fee applies in either case and consumers can buy them the same way regardless of how they are labelled in shipping. The issue is one of public perception: we all know that model rocket motors are not going to "blow up" and are not really "explosives" in the way that the public interprets that term. Having them start to show up in schools, hobby stores, and private residences with an alarming orange "Explosives" label on them will simply feed public fears and misperceptions about our safe hobby and these safe products. It will not improve public safety, because shipping them has never posed a risk to that safety.

The largest model rocket motor manufacturers, Estes, Quest, and Aerotech, have filed petitions to get this exemption continued rather than canceled. This will be tough to achieve. To help their case they have asked their vendors to send e-mails of support for continuing the exemption to the Department of Transportation Associate Administrator responsible for making this decision. I think that it is in our hobby's interest for us as NAR members to join the manufacturers in this effort. If you would like to be part of this, please cut and paste the text below the dotted line into an e-mail from you to as soon as possible, preferably by the end of this coming weekend.

Be safe, have fun, and pay forward.

Trip Barber
President, National Association of Rocketry

- - - - - - - - - - - - - - - - - - - - - - - - -

Subject: DOT-SP 7887 Show Cause Response

Dear Associate Administrator,

The purpose of this e-mail is to request that DOT-SP 7887 exemption to ship model rocket motors and igniters in containers marked as "Flammable Solid" rather than as "Explosive 1.4" be kept in force asit has been since 1978. This Special Permit, previously DOT-E 7887, is important to those ofus who enjoy the hobby of model rocketry.

To my knowledge, there has never been a fire or safety incident involving the shipping of model rocket motors and igniters, whether by public carrier or USPS. Further I believe that shipping these safe and non-explosive consumer products labelled as "Explosives" will create unnecessary fear and difficulty for those handling, transporting, receiving, storing, selling and using them. Model rockets have a superb safety record and wide public acceptance as a safe product based on 54 years of experience. Having them now start to arrive in consumer hands labelled as explosives could put at risk the reputation that our hobby has earned.

After 33 years of use, the termination of the Special Permit is unwarranted and will not contribute to public safety because shipping model rocketsas Flammable Solids has not created any risk to safety.
Please keep the Special Permit in place as written.

- Your Name and Address (city & state)

Take a minute and email your letter.

Custom Nomad Build Part 6 Internal Ring Fillets

Apply a fillet by transferring a drop of white glue from the end of a rounded dowel.

Smooth out the fillet with the rounded end of the dowel.
You should be able to do 1 1/2" of the fillet at a time.

You can pick up excess glue with a cotton swab.

When the white glue fillets have dried, apply some CA to the outside half of the centering ring.
Keep the CA away from the center hole and gluing surface.
Applying CA to the outside perimeter of the ring seals it and makes a for a smoother surface after sanding.

Wednesday, September 28, 2011

Custom Nomad Build Part 5 Gluing the Centering Rings

These 50/60 centering rings fit inside the edge of the BT-60 tubes.
Apply a line of glue inside the tube edge.
Be sure the rounded lip is facing inside the tube end. With the square cut side of the centering ring to the outside, you'll get a stronger edge with almost no gap to fill.
Press the ring into the tube on a flat surface.

Roll a dowel over the edge to get the ring flat and even with the end of the BT-60 tube.

Check the ring tube joint under a strong light. If any part of the ring is below the edge, you can push it back up from the inside while the glue is still wet. Here I'm using a dowel to get the flat surface of the ring even with the end of the tube.

After the ring is pushed up, roll the dowel over the top again to level it.

Custom Nomad Build Part 4 Ring & Tube Prep

In Step 4, the large "disks" (5060 Adapter Rings) are glued to the main BT-50 body tube. The outer BT-60 tubes are to be glued on later. Past experience tells me to glue the rings to the outer tubes then glue the two larger tube assemblies over the main tube. I was concerned that any measuring mistake (in gluing the rings to the inside BT-50 first) would make an accurate fit of the larger outside tubes impossible.
You could build this model as in the instructions, but I wanted to get a guaranteed best fit of the parts.

The ring on the right is facing up, the edges are slightly rounded. The ring on the left is facing down, the edges are square. This is from the way the blades hit the card stock when they were die cut.

For the best fit, when gluing the rings on the BT-60 tubes, the square edges should be to the outside.

Before gluing, sand the edges of the BT-60 tubes square.
Here again, most tube ends have a beveled edge from when they were cut. Square them flat for a better gluing surface and fit of the centering rings.

Tuesday, September 27, 2011

Custom Nomad Build Part 3 Engine Mount Parts Prep

The first step of the instructions don't mention notching the centering rings for the engine hook.

You should cut a recess notch. Otherwise, the hook could press and deform the tube out of round. You don't want the tube to press against an inserted engine.

TIP: When cutting the notch, keep the cuts away from the inside centering ring seam. If cut too close, the ring might de-laminate or unroll. Sometimes there isn't enough glue holding the rolled paper together.

In the picture I've marked the notch and the seam. Just keep your cut notch away from the seam.

The rest of the engine mount is a normal assembly. I did add a length of 135 lb. Kevlar looped under the top bend of the engine hook.

Here I'm dry-fitting the mount into the body tube.

TIP: Always dry fit the mount before using any glue. More often than not, you'll have to sand down the centering rings for a slip fit.

Custom Nomad Build Part 2 Parts Prep

On this build I'll concentrate on how to prep the parts, before gluing.
Your internal construction will be stronger and all parts should fit better.
Your finished model will have better structural integrity and last much longer.

BT tubing (Estes style tubing) are thin in the smaller BT-20 and BT-50 sizes. Strengthen any exposed edges with medium CA (Super Glue).

Place a drop on a scrap of paper. I use the back of old, used 400 grit sandpaper. Being 400 grit is used wet or dry, it is watertight and the CA glue won't soak in very much.

Use a Q-tip (or cheaper generic cotton swab) to apply the CA. Dip the swab into the CA drop and run it around the inside of the tube end.

Using a cotton swab gives better control of the amount of CA glue used.
After it dries, lightly sand the inside edge smooth with 400 grit.

Centering ring sides can be sanded flat.
Rings are cut using sharp blades. Depending on how sharp the blades were, the edges could be cut at a slight angle (a wedge cut) or rough.

Run them over a flat sanding block with 220 grit sandpaper.

Monday, September 26, 2011

Custom Nomad Build Part 1 Parts

Hard to believe, but I haven't built a Custom Rocket before.
They've always seemed to have some of the lowest prices in the industry. Pretty amazng, considering they are made and assembled in the U.S.!

In the past FEW YEARS, many of the Custom designs looked to be standard fare, but the new P.O.N.G., S.L.V. and Nomad designs caught my attention.
To be honest, when I first saw the Nomad, I thought it looked like two toilet paper rolls, side by side. This one turned out to be a great build!

Here's all the parts, right out of the bag.

Some interesting pieces going clockwise from the upper left:

An addendum to the parachute instructions now has the shroud lines tie through the tape disk center hole.
The vacuform nose cone is a flat, dome shaped circle.
Large, pressure sensitive stickers
Five, black launch lugs
Large tape disks for shroud line attachment.
A balsa coupler for the nose cone shoulder assembly.
In the center: A short 5055 centering ring and short BT-55 outer ring.

Raisin' Maize FINISHED!

This was a fun break from the norm.
After the pictures were taken, it was prepped with a A10-3t engine, the only
engine I would use in it.

The Raisin' Maise has been flown twice.
First as a test and more recently at the last TTRA Tampa launch.
It was a spectator favorite.

Sunday, September 25, 2011

Raisin' Maize Build Part 10 Fin & Lug Gluing

I did my best marking the body for three fins.

A corn cob doesn't fit any available fin alignment guide.

Slots were cut for the fins using my aluminum angle as a guide.

The fins were cut from 3/32" thick balsa. I had to go back and widen the slots.
Not a big deal - the fit was very tight and secure.
The fins were glued in place with white glue.

A launch lug was glued beside a fin root edge. I slid a segment of launch rod into the lug to make sure it would clear easily.

Raisin' Maize Buils Part 9 Adding Color

This was the only small Styrofoam corn cob left in the Hobby Lobby store. It was red with black highlights, pretty boring and not how I remember "Indian Corn" when I was a kid.
With a Q-Tip dipped in orange paint, I painted random kernels.

After that dried, some yellow was sprayed on a paper towel.
The yellow was lightly rubbed over the outside of the cob.

Then some permanant marker was added to some of the kernels.

The added colors really made a difference in the finished model and made it a little more realistic. Well, realistic for a rocket powered, Styrofoam corn cob anyway.

Saturday, September 24, 2011

Raisin' Maize Build Part 8 Nose Weight

The plywood ring was pulled from one of my Odd'l Rockets Sputnik kits. The diameter was sanded down to fit tight in the coupler. A small hole was drilled for the screw eye attachment.

The plywood disk was glued in place against the clay weight.

I picked out a large screw eye.
When in doubt with an odd-roc, add more nose weight.
I only screwed the eye in until the threads were just inside the plywood.
Going past the screw threads there wouldn't be anything to hold the eye in place. You only have the 1/8" thickness of the ply disk to hold the screw eye.

Raisin' Maize Build Part 7 Tissue Glue Putty

This model does not have an engine hook.
The engine will stick out the rear by 1/4". To keep the engine in place at ejection, a single wrap of masking tape will go around the BT-5 tube (extending out the back) and around the exposed nozzle end of the engine.

TIP: To make sure the masking tape wrap doesn't lift and tear the thin BT-5 tube, a layer of white glue was smoothed over the back of the tube. This'll strengthen the tube end for a longer life of the model.

Here's a real "Old School" technique to fill a gap. I remember this on the old Estes Cobra instructions from way back. It's called Tissue Glue Putty.

Cut up some facial tissue or toilet paper into the smallest pieces you can.
I cut the paper into 1/8" wide strips. Stack them and cut small pieces off the end.

Shut off the fan and don't sneeze! These little pieces of paper go everywhere!

Add some white glue to the mix. As you stir the glue in, try to break up the pieces even smaller if you can.

Here I've pressed some of the Tissue Glue Putty into the gaps at the top of the body. It's hard to see against the white Styrofoam.
Smooth out the filler putty and remove excess with the end of a rounded dowel.

Years back on my Estes Cobra, I used pink tissue paper to make the glue putty. A mistake and not very manly!

Friday, September 23, 2011

LAUNCH! Soccer Field September 22, 2011

I'm getting a little more ambitious with engine power at the soccer field.If I get out early enough, drift is minimal and I can fly B engines without losing the model.

First up was my carded downscale ASTRO 1.
With the old MPC 1/2A3-5m engine it probably got to 500' before ejecting the streamer.
It still drifted all the way to the school parking lot next door.

Here's a new one for me - the Custom NOMAD.
Custom recommends a B4-4 engine for the first flight, I used an Estes B6-4.
Boost was good to about 425', but at ejection just the nose cone blew. There was no parachute. It landed without damage.

You can see the melted parachute in the inset picture. I haven't fried a parachute in years! Oh well, I've got more.

I was sliding the MPC MARTIAN PATROL down the launch rod and noticed the upper lug (connected to the fin can) was cracked at the base. I carry Super Glue with me and it was an easy fix applying it with a toothpick.
The kit was already 35 years old when I put it together, plastic gets brittle over the years.

The rocket was launched (without saucers) with a B6-4. Without the Styrofoam saucers the drag was much less. I'd estimate the altitude to be 600'. Full parachute recovery with no damage.

Also flown:
The Semroc ASTRON with a A10-3t engine to an estimated 400'. This model is designed for 18mm engines, I simply shoved the 13mm into an empty 18mm casing.
Good flight, I caught this one before it hit the asphalt in the basketball courts.

Raisin' Maize Build Part 6 Cutting The Internal Tube

While the epoxy dries, the nose cone was taped down to be sure it stayed closed.

After all was dried, the nose cap was removed with the coupler glued in place.

The internal BT-5 was slid through and above the main body probably 1/2" higher than where it will be glued.
The nose cap and coupler were set in the BT-5

Now push the nose cap down and seat it against the main cob body. This pushed the BT-5 into the correct position inside the cob.

At the rear end, mark the BT-5, 1/4" from the rear of the cob body.
Cut the tube off at this mark. The internal BT-5 is now the correct length.

Thursday, September 22, 2011

Raisin' Maize Build Part 5 Nose Block Gluing

Gluing the adapter into place will be tricky.
Use epoxy to glue the adapter into the hollow in the nose cap.

The internal BT-5 has not been glued in the cob yet. Right now, it is a little longer than it needs to be.
Slide the BT-5 into the cob body. Slide the adapter into the top of the BT-5 tube. Mix a small amount of 15 minute epoxy.

Epoxy is applied in the nose cap hollow recess and inside the upper lip of the black adapter.

Line up the kernels on the nose cap with the cut kernels on the cob body.
Press the nose cap onto the black adapter.

Don't let the epoxy glue the adapter to the BT-5 tube!
You only want an epoxy bead on the top edge of the black adapter and the nose cap hollow area.

Before the epoxy cures, you should remove the nose cap (and glued in adapter) to be sure the adapter and nose cap aren't glued to the cob body and internal tube.

It would be a good idea to let this adapter dry with the nose and body pointed down. This way the epoxy won't drip down into the internal BT-5 tube.

Raisin' Maize Build Part 4 Cleaning Up The Bore

Here's what the tube will look like coming up from the bottom through the top. You can see the cut Styrofoam inside the sharpened brass tube end.

Wrap some 220 grit sandpaper around a BT-5 and remove some of the excess Styrofoam from the inside edge of the upper cut hole.

To give yourself a better gluing area for the nose cap adapter, cut a round hollow into the nose cap. Make the hollow about the diameter of the 5 sized black fish paper adapter.