Rocket Kids Playhouse

I'll admit it, I'm a sci-fi junkie. I've been storing a stockpile of foam blocks for a special project, and I finally decided that what I needed most was a big shiny rocket ship.

My initial plan was to make a simple art installation, but the longer I thought about it the more the plans changed. The result is this kids playhouse. The body of the rocket is made from about fifty, two-foot square by one foot tall styrofoam blocks, and the fins are made from four discarded hot-tub covers. Getting into the rocket is a tight squeeze, so it's really just for kids.

The foam body of the rocket is mounted to a central core made up of two pairs of plywood rings with sliding leaves sandwiched in between to make aperture closures. A tunnel entry, made from a water barrel, leads to the lower aperture hatch, which opens and closes with a lever. The center pole provides stability in high planetary winds and also allows astronauts to exit the rocket by sliding down the pole. A game table and control panel, with light-up toys, slide up and down the pole. At the top, the center pole includes guy wire mounts, an antenna for deep space communications and a light-up acrylic ball, just for fun.

Astronauts enter the rocket by climbing up the entry tube, or by using the stairs hidden inside one of the fins to access an escape hatch. To exit the rocket, astronauts move the control panel and table up out of the way and slide down the center pole.

Inside, a circular grab bar mounted to an overhead shelf helps keep the astronauts steady during rough landings. The overhead shelf also hides a strip of multi-colored LEDs that provide indirect lighting for the astronauts when they are in deep space.

A second aperture closure slides out from beneath the bench seat, converting the seat into a bunk. Wall-to-wall sleeping pads, padded back rests, and blackout window covers allow the astronauts to enter cryo-sleep (naps) for long flights.

Finally, the entire exterior of the rocket is covered with aluminum duct-sealing tape to protect the foam and make it shine.

50 Styrofoam blocks (2-foot square, by one-foot thick).

Four discarded hot tub covers (for the fins, free from hot tub dealer)

Plywood (6 sheets 3/4-inch, 2 sheets 1/4-inch)

Great Stuff aerosol foam (about 6 cans)

Foil Tape, 3-inch wide (about a dozen rolls)

Light weight Spackling Compound (about 5 gallons)

Ultra-high molecular weight tape, 3-inch wide (3 rolls)

Four Turnbuckles (1/2-inch)

Four All-thread rods (1/2-inch diameter)

About 30 pulleys and strings

Eight "U" bolts for mounting the fins.

Silver spray paint (four cans)

Plastic water barrel

Auto door trim (for steps in the barrel)

Four six-foot steel pipe-posts

Four sixty-inch rebar rods (3/4-inch, one end pounded flat)

Six 60-pound sacks of pre-mixed concrete

1-inch PVC pipe (10-foot, and coupler/glue for the grab bar)

Steel shower curtain rod mounts (10, used as stand-offs for mounting the grab bar)

Sand (for bending the PVC to make the circular grab bar.)

Escape hatch

Center Pole (1 1/2-inch galvanized pipe, ten feet long, plus an additional four-foot section and coupler for the top) (I ended up adding a one-foot piece of pipe at the bottom so that the control panel and table could be slid up further to get them out of the way.)

Various pipe fittings (for the antenna)

1/8th-inch stainless steel cables (for the guy wires)

3 10mm turnbuckles (for the guy wires)

Eye bolts/screws for anchoring the guy wires to trees and the house

Stainless fittings for the antenna

90mm Acrylic ball for the end of the antenna (illuminated!)

Solar yard light

Foam Pad, sixty-six inches in diameter (cut down to 63 inches)

Additional foam rubber padding for the wall panels

Fabric for seats, wall panels (about nine yards of stretch vinyl)

Blackout fabric for window-coverings

Window shade for pickup truck (to cover the escape hatch)

Fiberglass rod and 1/4-inch copper tubing for making the window-covering rings.

Toys for the control panel (plasma globe, theremin, memory game, recordable dog training buttons)

LED Light strip for internal lighting

Soldering setup and wire (for extending the LED from the yard light to the antenna)

Rubber stopper for mounting the LED

Jump starter USB power supply

Wood glue for making fin mounts and attaching fabric to the fins and the underside of the engines.

U-Bolts for the fin mounts

For the hot-wire foam cutter:

NIchrome wire 22 gauge

Lamp cord (five feet)

Ceramic electrical connectors

Old computer power supply

Light switch

Plywood scraps for the table, arch, slide, and other parts.

Two-by-four ripped in half for the legs

Scrap hinges for mounting the legs.

Lots of screws

Bolts and wingnut for the hot-wire angle adjustment

Spring and fender washer for the lower hot-wire mount

Box-fan fitted to window for exhaust from hot-wire foam cutting

Tools:

Router

Biscuit joiner

Jigsaw

Tablesaw

Sander

Drill

Drill press

Vibratory multi-tool

Utility knife

Sewing machine

Shop Vac

Various hand tools for working the foam

I'm sure there are more, but this list is already too long.

The rocket core is basically two sets of plywood rings, an entry tube, and all the hardware to hold it together. Each set of plywood rings has four "leaves" sandwiched between the rings. These leaves slide in and out to open and close the hatches. The lower hatch has a closure mechanism that operates with a lever (attached to dozens of pulleys) to move the leaves. The upper closure leaves slide out manually from beneath the seat, converting the seat into a circular bunk.

The lever-operated, hatch took a lot of head scratching to figure out, but after a few re-designs I got it to work. The lever is an inverted "Y," and the two legs of the Y are attached to two sets of strings, four for opening and four for closing.

The plywood rings for the bench seat needed to be larger than four feet in diameter. The pictures show the method for cutting two half-circles from a sheet of plywood to make a 68-inch diameter ring.

Each of the closure leaves is cut with three intersecting arcs, each with the same radius. The convex edge opposite the narrow stem of each leaf rests inside the concave inner edge of the next leaf. I tried cutting the arcs with a jigsaw on a trammel arm, but the router worked much better. It was kind of tricky cutting the parts in a way that made the most from a sheet of plywood, as the pivot points for the trammel arm sometimes fall outside the sheet you are cutting.

There's a trick to getting the four leaves to close together tightly. If there is a gap between the leaves, you adjust the center point of the leaves by offsetting them slightly to make a small square hole in the middle. Keep adjusting this gap until the edges of the leaves fit together tightly. The center pole goes through the middle, so the gap doesn't matter. To saw the hole for the center pole, screw the four leaves to a block underneath, and use a hole saw to cut a circle around the square hole.

The entrance tube is a blue plastic water barrel with the ends cut out, and holes cut for footholds. This tube is mounted to the lower ring of the aperture hatch, just below where the leaves slide out. The barrel was a bit floppy, so I cut a narrow plywood ring to keep it's round shape.

Four half-inch all-thread rods hold the core together. At the top, carriage bolts are attached to the rods with coupling nuts. The rounded carriage bolts are nice to have at the top of the seat. Diagonal bracing keeps the two assemblies stable against gravitational forces. At the bottom, the all-thread rods fit into turnbuckles that connect the ship to the docking posts.

I've always been nervous about hot-wire foam cutting, but I gave in after my last project. For the rocket I needed to cut foam blocks into arc-shaped pieces that would fit together to make rings. The outer surface of these arcs also need to be angled to approximate the curved shape of the rocket. Lastly, the sides of each block needed to be cut to match the radius of the circle, so they would fit together neatly. I built this hot-wire foam cutting table to meet those needs. Shaping the rings with the hot-wire cutter also minimized the amount of chaff from working down the foam parts.

The foam cutting setup is composed of a plywood arch (with an arc-shaped slot to adjust the cutting angle) mounted to the shop bench with plywood scraps, a table with a long arm extension, and a sliding setup to move the blocks to the appropriate position for making the cuts.

At the upper end, the hot-wire is mounted in a little ceramic connector that slides in the slot. The lower end of the hot-wire is held in another ceramic block beneath the cutting table. Changing the cutting angle can cause slack in the wire, and the wire also gets slack when it heats up. Both problems are solved by mounting the lower ceramic block on a spring (with a bolt and wingnut assembly), and letting the ceramic block slide between two plywood pieces to limit the amount of deflection of the wire. An old computer power supply powers the hot wire.

On one end, the cutting table is mounted to the shop bench, the other end has three fold-down legs (one for the long arm extending outward from the cutting table. A sliding plate moves back and forth along this arm to change the radius of the cut. This sliding plate has a long "swing-plate" mounted on top. This swing plate moves back and forth to make arc-shaped cuts. You move the slide along the arm to whatever radius circle you want to cut, and anchor it in position with a screw that extends through the swing plate and the slide into the arm. Brads extending upward from the underside of the swing plate keep the foam block in position while you're making the cut. Once you make the arc cut, you loosen the anchor screw from the table arm, and lock the swing plate to the slide with a screw on each side. Moving the slide forward makes a radius cut so the arcs will fit together to form a circle. Cutting the arc for the inner wall of the rocket was a bit more complicated, but uses the same setup.

You don't want to breathe the smoke from a hot-wire foam cutter. To minimize the smoke, I installed an old light switch on the plywood arch, so I could cut the power as soon as I finished making a cut. You also need a strong flow of air to draw the smoke away, so I mounted a box-fan in the window and built a makeshift cardboard hood to vent the smoke.

For straight cuts, I made a removable fence, mounted to the cutting table with pocket hole screws. The setup isn't pretty, but it works.

Note: Consult a licensed professional before using any power supply to build a hot wire foam cutter. There is a risk of serious electrical shock and burns from modifying any electronic components. You have been warned.

I drew circles of the required diameters on a sheet of plastic, taped to the garage floor, and positioned the blocks around the circle. Once I had the blocks cut to form a complete circle, I squirted aerosol foam between the blocks and added skewers to hold them in place. Subsequent rings were made by stacking the blocks to match the upper diameter of the previous ring. This process went fairly quickly, but I did let each ring sit overnight to allow the foam to set.

The nose piece is made without using the slide or the swing arm of the hot-wire cutter. Instead, I set a nail into the cutting table and centered the foam block on the nail before turning on the hot-wire and moving it to the correct angle for the cone.

The completed rings are stacked and glued together with aerosol foam. On some of the rings I used cardboard spacers between the rings to make room to insert the foam nozzle. Skewers help keep the rings in position. As soon as the foam is injected all the way around, the spacers re are removed, being careful to keep the ring in position as it settles.

I added plywood disks between the top three rings that make up the nose of the rocket. These rings add strength where the center pole goes through the top. Steel flanges mounted through the holes in the plywood rings are probably overkill. I included them because I was initially planning to mount the rocket on springs, but I decided that would be too much to expect from a styrofoam rocket.

Hold on tight! Rocket landings can be rough, so I added an overhead grab bar. The bar is made from 1-inch PVC pipe. To bend it in a circle, I filled the pipe with hot sand and laid the big noodle inside one of the rings that makes up the bench seat. The pipe ring is mounted to the overhead shelf with metal stand-off rings that were intended for use with a shower curtain rod.

The plywood shelf for the grab-bar mount is sandwiched between two of the foam rings that form the upper part of the cockpit.

To shape the outside of the rocket, I used a wood-working rasp and a big bow-sander made from a block of foam and a sanding belt.

Once I had the basic rounded shape with the rasp, I went over the surface with the sander, sanding first in one direction and then the other to achieve a smooth surface, switching to a finer grained sanding belt for the final few rounds of sanding. With the sanding done, I applied an even coat of spackling compound to fill in plucking holes and irregularities in the surface. You need to avoid sanding areas that are partially covered with spackle and partly bare styrofoam. The bare styrofoam is softer, so the surface becomes more uneven, and it only gets worse if you continue sanding. It looks better if you just apply more spackle.

I tried a number of spreading tools for the spackle, but I found that a plastic insert from a three-ring binder worked best. This light-weight spackle is easy to apply. A plant mister works well to improve bonding in thin areas. Repeated applications of the spackling compound, with sanding in between, were necessary to achieve a smooth surface.

I had three pieces of porthole glass, 12-inches in diameter, that I've been saving for the right project. The fourth window is an escape hatch, originally intended for use on a boat. Cutting the holes for the windows requires the right tool. The walls of the rocket are about 11-inches thick and my first attempt with a hacksaw blade was a disaster. The bendy blade strayed far off course, requiring a lot of repair to the foam. For my next attempt, I bought a 12-inch blade for a reciprocating saw, which is more rigid and worked much better. I cut a circle just large enough to get a foam shaping tool inside and worked the window openings to about ten-inches in diameter. The openings are flared a bit on the inside to improve the viewing angles. A sanding belt curled into a tube worked well to make the hole smooth and even.

For each of the porthole windows, I cut a circle about a quarter-inch deep around a window template, and then removed a slice of foam, to make a step for the glass. The windows are set in place with silicone seal, and the foil tape skin overlaps the windows to cover the foam and provide additional leak protection.

I added the escape hatch because I was concerned that the lower aperture hatch could jam, trapping kids inside. The escape hatch is heavy, so it's mounted in a piece of half-inch plywood that is secured to the bench seat. The styrofoam threshold in front of the hatch needed protection, so I formed a piece of plastic to fit on top of the foam. Stick-on vinyl stair tread material is mounted to the plastic to make it easier on the knees.

Safety is always a concern for our astronauts, so hand-ropes are attached to eye bolts extending through the plywood, above the escape hatch. The eye bolts protrude several inches inside the rocket, so I mounted a leftover piece of closet hanger rod on the inside to use as an additional grab bar. I also mounted a leftover diagonal brace to connect the grab bar to the overhead shelf for added support. The lower ends of the hand-ropes are secured to another set of eye bolts at the bottom of the stairs.

Shaping the interior took a lot less effort than the exterior. Most of the concave work was done with the little yellow curved rasp. I only did a couple of rounds of spackling and sanding on the inside. Areas where I cut the blocks too sort were filled with aerosol foam to make the wall look smooth. A couple of coats of gesso also helped fill in any irregularities.

The lower part of the inner wall is covered with padded backrest panels, and hollowed out areas behind several of the backrests are handy for storing things like window shades, flashlights, and emergency rations (snacks). We have some pretty large ants around here, so a pair of blasters are hidden behind one of the backrests in case the astronauts need to fight them off. A vibrating multi-tool worked well for removing foam and smoothing the bottoms of the hollowed out spaces.

The padded backrest panels are nice for when the astronauts are in cryo-sleep. Each wall-panel is composed of a plywood backing piece, topped with an inch of foam rubber, and a stretchy vinyl cover. The cover material is mounted to the plywood with hot glue, and Velcro strips hold the panels in place. The Velcro strips kept coming off of the backrests, so they are held in place with tiny screws. For the Velcro strips on the wall, I wound up poking holes at the corners with an awl and pushed pins dipped in glue into the foam at each corner to keep them from coming lose.

For lighting, a car jump-start pack (mounted to the overhead shelf) powers a long strip of LED lights that's mounted on top of the shelf to provide indirect lighting of whatever color the astronauts choose. A wave-effect light cube is also mounted to the underside of the shelf to provide calming ripples of light during long flights. Lighting controls for both lights are mounted on the control panel.

Deep space communications require an antenna. This rocket's antenna is an extension of the center pole. It doubles as a mount for the guy wires and a flag pole for our astronaut's flag. I couldn't resist adding a glowing light at the top, made from a solar yard light with the wires extended. The LED is mounted in a cork, stuck in the top of the pipe. An acrylic ball, drilled and tapped to screw onto the half-inch pipe covers the LED. Sanding the outside of the acrylic ball helps diffuse the light. To keep birds from perching on the ball, I added a couple of little wire "bird-spikes" to the top of the ball and epoxied them in place. Spade fittings complete the LED connection to the solar panel, which is simply taped on near the top of the rocket.

Every interplanetary explorer needs to represent their home planet, and this flag is the finishing touch. I made a simple pattern of the old earth-day flag symbol, and cut out a piece for each side out of ripstop nylon. A sleeve at the edge of the flag slides over the antenna before screwing the ball on top.

Adding the foil duct sealing tape really makes the foam shine like a rocket. Applying the tape seems pretty straight forward, but there's a trick for avoiding wrinkles in the tape that I wish I had figured out sooner.

Start with a strip of tape no longer than you can hold by both ends. Peel down an inch or two of the backing from the top of the tape, leaving the backing at an angle so a dog-ear sticks out to the side. Hold the lower end of the tape where you want it, and move the upper end so the whole strip overlaps the previous strip of tape. Stick the top of the tape to the foam, and check to make sure the tape is perfectly flat. then you tug down on the dog-eared piece of backing, sliding the backing off of the tape while holding the lower end in place. Smooth the tape with the palm of your hand as you slide the backing off the tape and you will get a wrinkle-free strip of tape with no gaps. Flattening the tape first with the soft roller and then with the hard roller makes for a good seal.

You have to be careful not to leave roller tracks by pressing too hard. Knuckles and elbows will also leave dents, so you have to be careful when applying the foil tape. Pulling too hard on the tape can cause wrinkles, so you have to watch the tension when you're removing the backing.

Launch day was a big milestone in our rocket program. I hired a neighbor with a skid-steer to lift the two main pieces into place. The sequence of mounting required careful planning: first, the rocket core needed to be fitted to the turnbuckle mounts; then, the upper part of the center pole needed to be slid down though the nose cone and locked in place. The main part of the center pole had to be set down through the core, with the bottom set in a 30-inch deep hole to make room for the nose cone to be slid into position. With the removal of the temporary frame under the nose cone, and the mating of the parts of the center pole, the mounting was essentially complete.

The docking station mounts are four steel posts set in concrete, with a five-foot piece of 3/4-inch rebar is set inside each post. I heated the ends of the rebar in a fire and pounded them flat to fit the turnbuckles before drilling the mounting holes. There is a lot of play in the turnbuckles, so it was easy to get the pins lined up to hold the rocket core in place.

The center pole prevents lateral movement, but it is not actually mounted to the rocket. The nose of the rocket can slide up and down the pole when the rocket sways. The center pole is mounted at the bottom to a short cedar log set in concrete. A floor flange fitting keeps the center pole secure.

A ring of thin foam blocks fills in the space between the nose cone and the lower half of the rocket. The filler-ring sections are held in place with skewers and glued with aerosol foam.

Note: The rocket sways a bit in response to movement inside. This could be fun, or a disaster. Time will tell.

The fins and the lower half of the rocket were made upside down, using the same circle drawn on plastic taped to the garage floor. The fins are made from discarded hot tub covers with thin plywood cores glued into grooves ripped in plywood blocks for mounts. Before gluing, the mounts, are notched, and holes are drilled in the core pieces to fit the U-bolts.

The stairs from the escape hatch are simply two plywood side pieces with treads mounted between them using pocket-hole screws. Since this fin needs to handle extra weight, the stairs get a double plywood core and beefier mounts.

The fins are vulnerable to attacks from alien feathered dinosaurs (chickens), who crave styrofoam. Covering the lower foot of each fin with adhesive-backed canvas before applying the foil tape has been effective... so far. Anything can happen in space.

The quarter-panels are three blocks high, but I needed them to extend a bit lower to hide most of the water barrel. I used pieces of the hot-tub covers, leftover from making the fins, to add another six inches of foam at the bottom of each quarter panel. I gave the quarter panels a final shaping on the outside and a couple of coats of spackle before mounting them to the rocket. The inside part of the quarter-panels needed to be fitted around the core components. You just have to keep checking the fit and removing material until the parts fit.

With the pieces all in place, I trimmed the top parts of the fins to fit the curve of the rocket and used the wood rasp to shape the contact between the nose cone, and quarter panels. Removing the foil tape from the lower part of the nose cone made it easier to blend the parts together. I settled for two rounds of spackling and sanding the transition because rain was coming.

Applying the tape to the lower half was easier than the nose cone. When all the foam was covered, I applied short strips of foil tape, horizontally, along the seams were the fins meet the body of the rocket. A hard plastic bowl scraper worked well for getting the tape into the corners.

During construction, I had a problem with the hatch assembly jamming, and I had to dismantle the entire thing to find the problem. A small frog had climbed into the hatch assembly and jammed the mechanism. To avoid this problem with the finished rocket, I made cone-shaped "engines" that are mounted to the support posts. Each "engine" has a recessed pocket carved into the underside. A layer of petroleum jelly smeared into the pocket area will hopefully keep alien frogs from playing havoc with the hatch mechanism.

After mounting the engines, it became apparent that alien frogs aren't the only risk to the rocket. Our hens figured out that they could jump up and peck holes through the foil tape to get at that irresistible styrofoam. I rebuilt the engines and covered the bottoms with fabric and glue. The finished engines got a coat of black spray paint underneath. A strip of gold foil hides the seam between the foil tape and the cloth.

Note: I have doubts about whether these engines will actually keep the frogs out, but it was worth trying.

The control panel is a shallow cone that fits around the center pole and can be locked in position. Since the hot-wire cutter only tilts to a 45-degree angle, I made a tilted table to fit underneath the foam block to make the cone.

The control panel has cutouts to hold various toys. It also has a few cup holders for our thirsty astronauts. The cup holders are made by cutting the top rim off of a metal can and using the sharp edge to cut holes in the foam. Plastic yogurt containers give the cup holders a more finished look. Small components, like lighting controllers and dog training buttons, are mounted with Velcro. The dog training buttons can record a 30-second message. The buttons play recordings from various old movies, including a pre-flight checklist, and a countdown to launch. Most of the gadgets on the control panel are battery powered, but some can also be powered by a USB cable from the overhead battery pack.

Since the control panel will get a lot of wear, I covered the foam with cloth and glue before applying the foil-tape.

Below the control panel, a larger plywood table can also be locked in position for eating or playing games. The pole clamps are originally meant for holding weight-lifting weights to a bar. The panel and table are slid up out of the way for sliding down the pole. Lastly, a 12-inch plywood ring with a split piece of hose mounted around the edge can be used as a foot rest or additional support under the bunk leaves.

For long flights, astronauts may need to enter cryo-sleep (nap time). The seat cushion converts into a round bunk by sliding out the leaves and setting the half-circle pads around the pole. The cushions are made from a pre-cut three-inch thick, foam circle, split in half and trimmed to fit inside the rocket. I used the same hot-wire foam cutting setup to trim the foam rubber pad and to cut the opening for the bench seat.

The slide-out leaves are lower than the seat so I added an inch-thick piece of foam rubber on top of the center pads before making the covers.

To make the pad covers, I laid the foam pieces out on top of the material (wrong-side up) and drew the outlines with a fine-point marker. Then I used a compass with a marker taped to one leg to add 5/8ths of an inch for seam allowances. Strips for the sides of the pads are pieced together from scraps of the same material. Wrestling the foam parts into the covers was difficult, but the cover material is stretchy, so that helped.

The last thing this rocket needs is a way to simulate the darkness of deep space. Window coverings are also necessary for when the astronauts enter cryo-sleep, or if they just want to play with light-up toys. I made black out window shades from some curtain fabric I had left over from another project, and I used sections of fiberglass rod and copper tubing to make circular frames for the window coverings.

The shades overlap the window openings by about an inch and are stuck on with Velcro strips in the same fashion as the Velcro for the backrests. For the big escape hatch, I bought a truck-sized window shade (which comes in two pieces), and stitched the two pieces together to increase the light-blocking power. The window coverings all fit into a cavity behind one of the backrests.

With that final touch, the rocket is ready for takeoff to anywhere the imagination allows!

I would like to express my gratitude to all the people who provided free styrofoam, helpful advice, and heavy lifting to get the rocket off the ground.