Luther CD Mini-Saucer
Based upon a design by Art Applewhite.
Luther, Right

I saw my first saucer launch about two years ago.  I was not impressed.  It was at a NEFAR launch, where rockets routinely zoom to thousands of feet real quick, pop a chute or two, and drift far away.  This rocket burned a J motor and went perhaps 300 feet.  Fell back to Earth with a clunk.  
I was thoroughly underwhelmed. The owner didn't even have to walk.  It seemed like a waste of a perfectly good motor, and a failure to get good exercise.  It's just not right.

Funny how things turn around.  Don Edvalson called me in late June asking if I could make loads for a 29mm motor.  He was doing a rocketry presentation for the Fourth of July at his church.  His church?  In town?  

Well sure.  He has a saucer.  The saucer only goes a little ways up, and with no parachute to impede its descent, it lands pretty near where it took off, even when there is some wind.  So I made some loads for my 29mm Loki motor, took them to the celebration, and had a blast.  The church had a large parking lot which had been cleared of vehicles for the occasion, so it was safe enough.  There were launches of several model rockets, most of which escaped the grounds but all came back OK.  The saucers were a big hit, flying with enthusiasm to low altitude and tumbling down again.  

So I ordered a couple of Applewhite kits for myself.  One for 29mm motors and one for 38s, which I use a lot.  I have flown these saucers many times, particularly the 38mm saucer.  They have served me well, being useful in demo launches where there just isn't enough room to send up a streamlined airframe.  

Art is such a nice guy.  Besides offering a range of nice kits at very reasonable prices, he has a number of free designs on his website, mostly for making little saucers for 13mm motors, but a couple for 18mm and even 29mm motors.

I upscaled his basic 13mm design to 18mm, and cut a disk of thin plywood to serve as its backbone.  The only hard part was making that plywood disk.  Not really that hard, just time-consuming.  I had to hole-saw the middle hole 1 inch diameter, then cut around the 5 inch outline with whatever saw was handy, then sand down to the line to get it nearly circular....  This would be a really elegant design if it weren't for that troublesome disk.

Then it occurs to me that I have a whole big bunch of disks this size, just laying around waiting or something to happen.  Some were sent to me by AOL.  Some are out-of-date leftovers from my photography classes.  Others just didn't get burned right.  Some are badly scratched....CDs!  DVDs!

Trouble is, the hole in a CD is too small.  It needs to be about an inch in diameter.  I tried to cut one with a hole saw and "POW!"  The teeth grabbed it, tore it from my hands, and sent it spinning across the workshop.  Good thing I was wearing gloves.  I tried again.  Broke it.  Big wide crack.  Tried again...   You know, those things are a real pain to drill.  I went through a sizeable stack without getting one that was usable.  Hey AOL!  Send more disks!

Tried the router.  It cut big chunks from the disk, leaving an ugly rough edge and cracks in the disk.  Tried my sanding drum in my drill press.  It might have worked, but was too big to go into the little hole in the CD.  

In frustration, I threw a broken one in the wood stove and watched it melt.  MELT!  What kind of pyro fool am I?  Never do any work when you can use fire!  
So I looked through my scrap pile and found a section of EMT tubing about 1 inch OD.  Stuck one end in the ground, heated up the other end, and it melted a hole in a disk easily.  With a little practice, I was able to get them centered and fairly smooth.  

Now the ducks fall into line.  We can make an 18mm saucer from next to nothing.  

Here is what I mean by "next to nothing"

1 sheet posterboard
Printer paper, plus a printer to print on it, and a computer to run the printer.  
(Hopefully you will already have that.  Otherwise, this is going to be an expensive project.)  
3M Super 77 (or similar) spray glue
Elmer's Glue, or Titebond, or some other good PVA glue
Epoxy.   5-minute will do, slow epoxy is fine if you have the patience

3/4th inch hardwood dowel, about a foot long.  (Or one could use a short piece of "1/2 inch" EMT tubing, actually just under 3/4ths inch OD)
Plastic wrap like Handi-Wrap, Saran Wrap (or better, aluminum foil duct tape - Nashua 324A)
"Disposable" foam Paint brush
Rubber bands
Propane torch or other strong heat source
3/16ths inch diameter rod, made of brass, steel, or some other substantial metal.  A large nail or long bolt might do.  
Wooden spring-type clothespins, or similar small clamps
Primer and Paint (optional)

So here we go with the photo show

glue-and-posterboard 3 Sisters

On a bright February morning, I get ready to party with three of my favorite glues and some posterboard.  

I've already printed two of the cone-templates, as you can see.

Click Here to download these templates (Word format)
top-and-bottom-landscape.gif Cone Templates

The Word file prints out two circles, each with lines marking 1/8th of the circumference.  
Each circle makes one cone.  

Two top-cones (large) and two bottom-cones (small) are needed for each saucer, so print two of these.  

BTW:  Since this is in Word, you could insert logos, names, photos... anything that can be printed!  You could use good-quality photo paper for excellent results.  The challenge?  Keeping it clean and pretty through all the glue and roughness to follow.  And remembering that you will cut away 1/8th of the picture and there will be a big hole in the middle.  

0120-spray-posterboard-with-3M77.jpg Glue #1

I sprayed the posterboard lightly with 3M Super 77 spray glue.  

0130-press-templates-to-posterboard.jpg ...and patted down the templates onto the board.  

0140-cut-out-disks-from-posterboard.jpg After a few minutes' drying time, each "Pac-Man" pre-cone is cut out.

0150-glue-connecting-strip.jpg Glue 2

A strip of posterboard 1/2 inch wide and 2 inches long is cut out and covered with Titebond.  Elmer's glue should work just as well, I just happen to have Titebond out.  

0160-form-first-cone-with-connecting-strip.jpg Large Cone 1 is formed by bending the edges together and pressing the connecting strip over the junction.  

Small Cone 1 is done the same way.

0170-clamp-cone1-with-clothespins.jpg Two clothespins are used to clamp the joint while the glue sets.  
This will only take a few minutes.  
0180-section-EMT-tubing.jpg And now for something completely different...

Holing the CD

While the glue dries, I get ready for today's pyro drama.  

Here is a section of EMT tubing about a foot long.  

It's outside diameter is 0.925 inch.  

0190-heat-EMT-tubing-small-torch.jpg Heat the tube

One end of the tubing is clamped in a vise so I can heat the other end with a torch.  

No vise?  Just stick one end into the ground.  

This little torch would do it eventually...

0200-heat-EMT-tubing-big-torch.jpg ...but not quickly.  We need a stronger heat source.  

That's more like it!  

This scary torch could  have the end glowing red pretty quickly, but we don't want it that hot.  

0210-heat-EMT-tubing-big-torch-closeup.jpg Just heat until the metal barely begins to glow.  

That should be about 900 degrees which is plenty hot.

Looks like there is no flame here.  Rest assured that there is, a clear, bluish flame encompasses the end of the EMT.

0220-centering-disk-over-hot-EMT.jpg Melt the hole

The disk is centered over the hot pipe and gently lowered down.  

The gloves are a good idea - touching that pipe would not be a pleasant thing.  

And sometimes this action throws little bits of molten plastic.  Fi

0230-melted-hole-on-EMT.jpg Hold your breath!  Don't want to breathe plastic fumes!  

The disk slips easily onto the pipe.  

Best thing to do might be to drop it down to the cool part and take it off that end.  

But NOOOO, I'm not nearly that smart.  I took it off the hot end.  

0240-rough-melted-hole.jpg So it picks up some greebles.  Not to worry.  We can fix it.  

0250-clean-up-hole-with-sandpaper.jpg Clean the hole

After the disk has cooled, I wrap some sandpaper around a dowel and use it to smooth out the hole.  If you have a Dremel or similar tool with a tiny sanding drum, this might be a good time to use it.  I did.  Didn't show you that.  

0260-cleaned-up-hole.jpg So now we have a nearly-centered, nearly-round, and nearly-smooth hole in the disk, with some really nice reflections.  

0270-spray-cone1-with-3M77.jpg Double-layer the cones

Back to the cones.  They have dried enough.  I'm spraying the inside of the first cone with a little Super 77.  

0280-curl-cone2-overlap-edges.jpg The second cone-blank is curled up a little tighter than the first cone, so that it will fit inside easily.  It is lowered into the first cone, the holes centered, then expanded until it presses evenly against the first cone and sticks there via the Super 77.

Note that I've rotated the second cone so that the bias of the posterboard is crossed.  I think this will make for a rounder, stronger double cone.

0290-press-cone2-into-cone1-overlap-strip.jpg Another strip of posterboard 1/2 inch wide x 2 inches long is glued over the seam with Titebond.  Since it is not under stress, I can just press it with my fingers for a minute, then let it set.  

0300-find-posterboard-bias.jpg Making the motor mount tube

Now we need to think about making the tubes.  Actually we should have thought about making them yesterday, as they need to dry for a day or two before use.  

Here I'm checking to posterboard to determine its bias.  Most posterboard likes rolling in one direction more than the other, and we want to be nice to it.

So try gentle bending, and notice how much resistance you feel.  The direction with less resistance is the bias.   The tubes will roll much more smoothly in that direction.  

0310-pre-curl-end-of-posterboard-strip.jpg Be sure to pre-roll both ends of the posterboard strip before moving on.  

Here I'm rolling and pinching the posterboard around a 1/4th inch dowel.  

This is a bit manual, and will tire your hands out if you are doing several.  

But don't omit this step, or it will make the final roll really hard.

0320-dry-roll-posterboard-strip.jpg I want to have this tube to be a snug fit into the hole in the CD.  It must go in the hole, but it should not be very loose.  We can fill a small gap with epoxy later, but not a large gap.  

So I roll the posterboard tightly around the 3/4 inch dowel, allowing it to skew slightly.

0330-mark-where-disk-fits.jpg The skew makes a ziggurat on one end.   The CD is forced down onto this end until it will go no further, and the posterboard marked at that point.  

The mark tells us how long to cut the posterboard.  

Since posterboard varies in thickness, any single length I give you is likely to be wrong for your posterboard.   This method allows you to find the right length for your board, your hole, your personality, etc.

I forgot to measure this one.  But look, you count 6 turns, right?  The dowel is 3/4ths inch diameter, and the hole it's in is about 1 inch diameter.  Average diameter is thus 7/8ths inch.  So 6 times 0.875 times pi is 16.5 inches.  Now I'll have to try that and see if it is right.

0334-squirt-titebond.jpg This tube is going to need better glue than 3M 77.  Titebond is good, but Elmer's works fine.  Dilute Titebond with about half water, dilute Elmer's a little less to get a good spreading consistency.

0340-paint-posterboard-with-glue.jpg The glue is diluted, stirred well, and painted on the posterboard.

It just occurred to me to add food coloring to the glue.  That way you can see it.  
So can I.  Since this little demo, I've been adding coloring to my glue every time, to ensure that I get good coverage.  

Note that the 3/4ths inch hardwood dowel has been wrapped with plastic wrap, also red.

The wrap keeps this wood glue from sticking to the wood.  It does that really well.  
Aluminum-foil duct tape works even better (Nashua 324A from Tyco Adhesives).

0350-roll-posterboard-with-glue.jpg The tube is rolled tightly around the 3/4ths inch dowel.  

0360-secure-tube-with-rubber-bands.jpg Bondage

A buncha rubber bands are applied to keep the tube from unrolling.  They will only need to be there a few minutes.  

Slip the tube off the dowel, and place it in a warm spot to dry.  

The glue will be set within an hour, but the tube will still be wet.  You can dry these in a very low oven (150 degrees F) to speed the process, at risk of shrinking and delaminating the tube.  Patience.  

0370-cut-tubing-2-sizes.jpg After a day in that warm spot, the tubes are pretty dry.  I cut a 3-1/2 inch section of the larger tube to serve as a motor mount, and a 1/2 inch-long section of the smaller one to serve as a thrust ring.  

Oh, guess I forgot to do a demo on the smaller tube.  It is just like the larger tube, but rolled from an 18-inch long strip of posterboard around a 1/2 inch diameter dowel.  Just like making motor tubes, but with a little longer posterboard strip, to ensure a tight fit.

It will be glued in the head end of the motor mount tube to prevent the motor from exiting in that direction.  

You could just use a section of motor tube.  It will be loose, so glue it in with epoxy to fill the gap.  

0380-epoxy-tube-to-disk.jpg Glue #3

The tube is inserted into the CD so that 1.5 inches sticks out from one side.  
Epoxy is applied to keep it in that position.

Note the use of a pickle jar to support the disk 

0390-epoxy-tube-to-disk-holding.jpg Since I can't get the epoxy spread evenly in that position, I'll pick it up and go around and around...

0390-epoxy-tube-to-disk-holding.jpg Now it gets to sit until the epoxy is hard.  Check to be sure the tube is straight... perpendicular to the disk.

Little cuts in hole Scoring the cone

If the hole in the cones is too small to fit over the motor mount tube, try cutting 8 slots, evenly spaced, 1/8th inch deep, around the perimeter of the hole.  This should allow the central tube to squeeze in, and may even provide a better glue joint.

0396-tube-in-cuts-in-hole.jpg Yeah.  Here it is, working.  The cone is now a tight fit on the motor tube, and the angled "fingers" provide more surface for the glue to stick.  Now Elmer's might be the best glue, not that smelly epoxy.  

0410-epoxy-inside-of-large-cone.jpg Smelly or not, it's time to mix up some more epoxy.  This is applied to the inside of the larger cone, right near the edge.  

0420-insert-tube-and-disk-into-cone.jpg The cone is placed in the jar, epoxy-side up.  The CD and tube are lowered into it to contact the fresh new epoxy.

0430-jar-presses-disk-into-cone.jpg And a weight is placed on the CD to press it down into the cone.   This is to ensure good contact with the epoxy.  

You know... this might work better turning it upside down.  That way the epoxy would drip down from the cone and fill the gap around the edges.  I'll try that next time.  

OK.   I did try it.  And you know, it works fine both ways.  Take your pick.

0440-small-cone-epoxy-ready-to-place.jpg Let that epoxy set, and it's time to do the little cone.  Bead of epoxy run around the inside  cone...

0450-small-cone-pressed-into-place.jpg And is pressed onto the  CD.  

0460-jar-weighs-small-cone-too.jpg Again, the jar holds it down while the glue sets

0470-insert-thrust-ring.jpg Inserting the thrust ring

Remember that smaller tube?  And the short section we cut from it?  That is your thrust ring.  It is glued into the end of the motor tube to keep the motor from coming out in that direction.  

0480-press-down-thrust-ring.jpg If the tube is a snug fit, coat it with a little Elmer's or Titebond glue and press it in.

If it is a loose fit, use epoxy instead.  Epoxy fills gaps much better than Elmer's.

0490-seal-seams-with-epoxy.jpg Run a nice, neat bead of epoxy around the junction of the lower cone and the motor tube.

OK, so my bead isn't neat.  But it is strong!

Do the same thing to the top.  Let the epoxy cure until all is hard.  

0500-trim-edge-of-cone-to-disk.jpg Round it out

Remember that rough edge on the larger cone?  Now is a good time to trim it off.  Scissors work well at this point.  And since you have the CD as a guide, getting it round is easy.  

0510-sand-edge-of-cone-to-disk.jpg There may still be some irregularities on the edge, probably more aesthetic than aerodynamic.  

Rubbing the edge on sandpaper can remove these irregularities quickly.  

0520-heat-brass-rod.jpg Basic (minimal) launch lug

Now you might think I'd forgotten about launching this thing.  For instance, where is the launch lug?  

Don't need one!  Remember the pyro rule?  

A 3/16ths inch diameter brass rod is heated pretty hot.  

Oh, go easy with the torch.  Even a little torch like this gets hot enough to melt brass or aluminum.  

0530-burn-launch-rod-hole.jpg The hot rod is used to create a hole right next to the motor tube. You may have to reheat the brass rod a time or two.  

Try to avoid breathing the smoke.  Stand upwind.  Hold your breath.  Whatever it takes. Epoxy smoke smells really bad, like it might be harmful.

0540-launch-rod-hole-goes-through.jpg This kind of "launch lug" seems to work OK.  But occasionally a saucer gets thrown at a funny angle, makiing me wonder if it is binding on the launch rod.

I think it might be good to roll a paper tube on a 3/16th inch rod to make a launch lug, make the hole large enough to accommodate it, and glue a section of it in this hole.  But I haven't tried it yet.

0544-launch-lug-in-saucer.jpg Alternate (better) launch lug

OK, so now I've tried it.  I made a launch lug tube by spreading Elmer's glue on 1/2 of a 3x5 index card and rolling it around that 3/16ths inch brass rod (which had been allowed to cool, by the way.)

The hole throught the saucer is made by heating a long 1/4th inch bolt red hot and easing it through all three layers.  The launch lug tube fits fairly tightly in its hole in the CD 

0546-cut-off-extra-launch-lug.jpg Using a fine hacksaw blade, the excess launch lug is cut off flush with the saucer cone.  This should make for a more streamlined appearance.  Note the use of the word "appearance."  This is intentionally NOT a streamlined airframe.  Quite the contrary.  

0548-glue-end-of-launch-lug.jpg The ends are glued with Elmer's. Epoxy might be safer, but it's gluing paper to paper so I think Elmer's will be OK here.  

This is clearly the better method.  The saucer slips on and off the rod very smoothly with this internal launch lug.  

The burned-holes saucers work, but they do not slide as easily, and have that occasional odd jump, as I mentioned.  I believe the simpler burned-hole version binds on the launch rod sometimes.  
0550-sand-saucer-lightly.jpg Make it smooth

It may seem hopeless, but I'm going over this saucer with very fine sandpaper.  Somehow, it got gluey fingerprints all over its little body.  And I want it smooth for the paint job!

0560-spray-primer.jpg Make it pretty

It won't stay pretty, but it's going to start out nice!  Here I'm spraying it with white primer, preparing it for the color coat.  I like primer.  Primer is good.  Use primer.  It's good.

Spray Saucer Dayglo Pink Make it ugly

This color might be hard to look at, but it sure is easy to see!

These fluorescent paints are very dependent upon their base coat.  
They are not very opaque, and whatever is underneath the paint shows through.  

That's why I used the white primer first, and lots of it.  

After that, a coat or two of clear lacquer is a good idea, to seal in the pink paint, which soils easily.  With lacquer to protect it, you can wipe off most dirt and exhaust residue with a damp cloth.  Without lacquer, you can rub in most dirt and exhaust residue, but you can't wipe it off.  

0580-insert-taped-motor.jpg Load 'er up!

Another thing that lacquer does is bring out the depth of color, in this case making it more red than pink.  

Here, I'm inserting an 18mm sugar motor, getting ready to launch.  Note that the forward end of the motor is wrapped with purple masking tape to build it up so that it is a snug fit in the motor mount.  

The motor doesn't need to be very tight, as there is no ejection to deal with.  Just tight enough that it doesn't fall out before ignition.  

0580-insert-taped-motor.jpg Insert Igniter

The foil seal inside the nozzle is pierced, and the igniter inserted.  This is just a fuse paper igniter with a tiny pinch of BP inside for insurance.

0600-saucer-on-launch-rod.jpg On the rod

Now that it's loaded, I gotta launch it, right?  Right!  

Good news is that these little saucers don't need much room, so I can launch it in my backyard with little worry.  

0610-saucer-on-launch-rod.jpg 3.... 2.... 1....

Yes, it is pointed up.  That last shot was for drama.  

Click for video

Click the button for video of this flight
(3 meg .wmv file, 17 seconds playtime)

Talking Hands Productions
Jimmy Yawn