This rocket was my first dual deployment rocket. This made Icarus a fitting name. For those not familiar with the myth, Icarus (and his father Daedalus) needed to escape from the island of Crete but couldn't do so by water. They build wings from wax and feathers to fly away from the Island. The plan worked, until Icarus decided to go higher and higher, ignoring his father's warnings to not get too close to the sun. The wax in the wings started to melt and Icarus came falling from the sky. The Icarus rocket will also go higher and higher, only to drop from the skies (after drogue deployment). To move away from the myth, we hope to have a happy ending where when the main deploys. Rocksim File : icarus.rkt

Parts list

There's quite a shopping list of items involved in building this rocket. The good news is that they are, for the most part, inexpensive.

- 3" nose cone (PML)
- 3" diameter airframe tube (37" long)
- 3" diameter airframe tube (25" long)
- 3" diameter airframe tube (1" long)
- coupler for 3" airframe (PML)
- 2 coupler bulkheads, 2 forged eye-nuts, 1/4" all-thread
- 1/4" birch aircraft plywood (12" x 24")
- motor mount tube (54mm, 17" long)
- 3 centering rings (3" to 54mm)
- 2 brass inserts, 2 machine screws, 2 nylon standoffs, 2 railbuttons
- 4 brass inserts, 4 x 6/32" truss machine screws
- 3" diameter tube with thick wall (4" long)
- 2 1/4" quicklinks
- 54mm motor retainer (Aeropack)
- 1/16" styrene rod
- 5' tubular Kevlar
- 15' tubular Kevlar (full length shock cord)

The thicker wall tubing used for the rings on the high power rocket has a 0.12" wall thickness. If you can't find that tubing, use the mailing tube you can pick up at Staples.

Motor Mount Assembly

Cut a notch out of one of the centering rings, on the inside of the ring as shown in the picture. The ring on the left had a section removed using a Dremel tool with a drum sander accessory.

Next, we need a length of tubular Kevlar, 5 foot long. Usually, Kevlar is very hard to cut. To get around his, some cyanoacrylate (CA or super-glue) was put on the area to be cut. The material could then be cut very easily with a Dremel tool with a diamond tipped cutting disc. A regular cutting disc should work fine here too.

Epoxy the top centering ring at 3/4" from the forward end of the motor tube. Epoxy one end of the shock cord to the tube at the same time, as shown in the picture. Make a loop at the free end of the piece of Kevlar. You will attach your shock cord to this loop using a quicklink. Epoxy the second centering ring at 6 1/2" from the aft end of the motor tube.

Do not yet attach the last centering ring, this will be attached only after the fin can is built and inserted into the rocket's airframe.

Quick note on the 5' length of shock cord... You could also attach a full-length shock cord to the motor mount. The method used here is cheaper as you can use your full-lenght shock cord between multiple rockets.

Time to overbuild with fiberglass

Yes, I know, there is probably no real need to fiberglass the parts for this rocket. Our favorite club flies on a failed addition where road landings are frequent. The fiberglass is mostly to ensure the rocket can easily survive a road landing without major damage.

The fins were cut from the birch plywood with a jig saw and match sanded. Next, they were fiberglassed and vacuum bagged. The photo on the right shows (left to right) a fin ready for use, one with the fiberglass trimmed and one fresh out of the vacuum bag.

The 37" and 25" airframe tubes were both fiberglassed. Usually, couplers fit into the mailing tubes without a problem. In this case, they didn't and couldn't be vacuum bagged as a result. The tubes were glassed without vacuum bagging them. The 1" and 4" strips of mailer tube were also fiberglassed. The 1" strip will go around the coupler/ebay and you want it to have the same thickness as the rest of the rocket's airframe. The 4" strip will be used to create the rings that go around the model rocket.

Attaching the fins

Before the fins can be attached, fin slots must be cut. This is done after fiber glassing.

Slide the motor mount into the airframe tube and tack the fins in place with 15 or 30 minute epoxy. To not glue the motor mount into the airframe yet.

Remove the motor mount with fins and apply epoxy fillets where the fins are joined to the rocket's motor mount tube. Next, put a ring of epoxy on the inside of the rocket's airframe, 16" from the aft end. Slide the motor mount with fins into the airframe and set it upright. Let it stand until the epoxy cures.

Two holes are drilled for the inserts. These will be used to screw the railbuttons into place. Drill one hole 18" from the aft end and the other 1" from the aft end. Screw the brass inserts into the holes and poor a little epoxy on the inside of the airframe, around (but not on top of) the inserts. Apply epoxy fillets on the inside of the airframe, where the fins meet the mailing tube.

Now the aft centering ring is glued into place. Finally, external epoxy fin fillets are applied (where the fins meet the airframe).

At this time, the motor retainer (a 54mm Aeropack retainer in this case) was secured into place with some JB Weld. Obviously, you could use a different motor retention system.

Building An Electronics Bay

This next section deals with setting up the coupler to become an ebay. Note that it doesn't complete the setup. It takes it far enough to be able to use it without an altimeter, for motor ejection. If you've built an ebay before, it will take you no time to complete the ebay setup.

To prepare the coupler, it will be re-enforced. I used a piece of thick-walled mailing tube and cut a coupler out of it to fit inside the existing coupler. The inside coupler is shorter than the outside one. The coupler bulkheads used were 3/16" thick. The inside coupler was made 6/16" (2 x 3/16") shorter than the outside one and epoxied into the middle.

When done correctly, you'll have 3/16" on each side out the coupler where there is no inside coupler. The bulkheads will sit there and rest on the inside coupler.

Draw four lines on the 25" body tube (all the way across), at equal distances. This divides the tube in four. Draw a circle around the body tube, 1 1/4" from the aft end. Next, insert the coupler 2 1/2" into the marked body tube and keep it in place with some masking tape. Drill 4 holes (3/16" drill bit) when on the marked areas, where the lines meet the ring around the body tube.

Drill through both the outside and inside coupler. One the holes are drilled, a brass insert (for 6/32 screw) is glued into each hole.

When prepping the rocket for flight, you'll use the 4 trusshead screws to ensure the 25" body tube stays connected to the coupler. If you complete the electronics setup, this will keep the main bay attached to the ebay for dual deployment flights.

Epoxy a 1" strip of body tube around the middle of the coupler. If you plan to complete the electronics bay setup, this strip is where you'd drill the port holes and attach the on/off switch. Next, get (or cut to size) some 1/4" all-thread that is about 1/2" longer than the coupler. Put the bulkheads into the coupler and insert the all-thread. Secure one end with a nut and the other (aft end) with a forged eye-nut. The shock cord which attaches to the fin can connects to this eye-nut using a quicklink.

Draw a line around the 25" body tube, 1 1/4" from the forward end. Insert the nose cone and keep it in place with some masking tape. Drill two 1/16" holes (on opposite sides of the tube) where the lines across and around the airframe meet. Drill through the airframe and into the nose cone.

Before flight, you will insert some styrene rod into the holes, all the way into the nose cone. This will prevent the nose cone from falling out after parachute deployments. If you complete the dual deployment setup, this will the keep the nose cone in place after drogue deployment, until main deployment.

Adding some character

This rocket was designed to have something different, in this case, three rings above the fins.

The rings were made from the 4" strip of thick-walled mailing tube. You can use regular mailing tube also, the rings simply won't be as pronounced. Each ring is 1" long. This tube was 3" diameter, so obviously it wouldn't fit around the 3" diameter airframe. Cut a slit on each of the rings, so that they can be opened up and fit around the rocket's airframe.

The bottom ring is placed at 10" from the aft end of the airframe. Next is a 1" space, then the next ring, a 1" space and the third ring. The rings were epoxied down and held in place with some rubber bands. As you can see in the picture, there's open space, the rings don't go all the way around the airframe. To fill the open gaps, cut a fourth 1" long ring from the thick-walled tubing. Cut strips out of it to fit snugly into the gaps. Fill any small gaps left over with your filler of choice. White putty or spot putty work fine.

Do not forget to drill a vent hole in each of the sections of airframe tubing. A 1/8" for each should work fine. Drill it to about 1" below where the nose cone (or coupler) shoulder will be inside the airframe.

Finishing

After sanding or filling imperfections smooth, the rocket was given several coats of gray automotive primer. It was sanded smooth, while fixing any small blemishes, between each coat. Once smooth, a layer of white primer was applied which would serve and an undercoat. It too was sanded smooth (with 400 grit sandpaper) once the primer was dry.

Flight Data

The first three flights show the rocket in primer, without paint, for some test flights. These were all motor ejection flights. The first flight landed on a road, it would have done a number on the paint job.

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