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Doc's Rocket Jets Amusement Park Ride

Doc's Rocket Jets Amusement Park RideHi folks, Doc here, with a model that I designed and built to display at the 2001 ACGHS Convention in Carlisle, PA. I am pleased to tell you that it won First Prize in the Model Building competition, and our entire display won Second Prize in the Display competition. To accompany the Rocket Jets, I also built a Classic Period White Truck Tour Bus - check the Model Gallery for a pictorial. I was very gratified with the response to the Rocket Jets model, and many people expressed a desire to build it for themselves. So, for all of them, and for you, here it is, in a little greater detail than usual. In addition, I have added model construction and lighting pictorials to the How-To workshop page, and a parts list is available on the Downloads page. On a related note, in 2005 the Museum of American Heritage (MOAH) in Palo Alto, CA, opened a new exhibit called Construction Toys in Motion. The exhibit featured, among other items, a very close re-creation of the model shown on this page. I was flattered that they chose to acknowledge my unique design by including it in their exhibition. You can visit the exhibit page here, and you can see their version of my model here.

When I was trying to decide what to build for the Convention, I knew that I wanted a fairly elaborate display, so I searched for a concept to base the display on. I decided that Girders & Gears could also be the name of an Erector-themed Amusement Park. With my concept in place, I decided to design a brand new model, and my wife suggested that I go with something "futuristic." I wanted a model that had great action, but one that would requir a simple mechanism that was easy on the motor and would also have limited opportunity for problems to occur, as I intended for the model to operate non-stop during the six hours of the Convention.

After much consideration, I decided on a carnival ride concept with a rotating action like the various Erector airplane ride models. With "futuristic" as a consideration, I remembered the rocket jets ride I had ridden at Disneyland so many times, and so the basic idea for my model was born.

The final model was constructed primarily from a 1953 10½ Amusement Park set, plus a variety of additional parts and a large number of extra screws and nuts. The design evolved slowly. For the tower itself, I wanted something different, so I decided to build a round tower, if possible. After some experimentation, I found that I could create the foundation for a "round" tower design by bolting six MC base plates to a NS 41-hole formed strip to form a kind of spoked ring. I bolted C 10" girders to the center hole on the inner end of each MC plate, and bolted EX 12" big channel girders to the outer end of each MC (see detail photo). To create the main tower section, I stacked two of these assemblies, bolted them together, then bolted the whole thing to a square base.

The base is a two-level construction: the bottom section is constructed from 7 MN 12" base plates that form a square platform open in the center. A second smaller platform is build around the opening in the lower platform; MD base plates form the sides, MC base plates form the front, and MF base plates form the top, which is also open in the center (both plaftforms are open at the rear). I built a hexagonal "ring" using MF and ME base plates and bolted it to the lower platform, around the upper one, where it serves as an anchoring point for the tower. The outer tower supports (EX girders) are bolted to this ring, while the C girders that make up the tower's central "tube" are flared out and bolted to the top of the upper platform (see photo below).


I attached the base assembly to a 23" x 15½" piece of 5/8" particle board which I spray painted bright red. The model is powered by an A49 motor in the No. 11 slow-speed vertical drive configuration which is screwed to the wooden base so that its vertical drive axle is centered beneath the openings in the base platforms above it. A shaft made from several long axles joined with P-15 couplings connects to the motor's vertical drive axle and runs up through the tower's central "tube" to power the rocket jet assembly.


I wanted as much appropriate detail as was reasonable to create, so I added a number of items to the base of the ride. My idea was that people riding would enter a doorway at the center of the base, walk inside, then take an elevator in the tower's central tube up to a loading platform, where they would board the rocket jets. I went as far as creating the main entrance to the ride, complete with a lighted sign over the entry (see photo). An MX Erector house is my ticket booth, and I used FA 1¾ screws and string to cordon off the line which my riders will stand in as they make their way to the entrance, up a short flight of steps made with MC base plates, then into the tower under the entry arch and sign.

The rotating top section of the tower, from which the rocket jets are suspended, began with a ring constructed from 8 CS wheel segments. I added spokes and a hub to the ring using I 21-hole strips, CH angles, and a CR turret plate (with hub). I formed a "nose cone" on top of the ring by bolting an E 5" curved girder midway along each spoke with a CH angles, then I attached the upper end of each E girder to a second CR turret plate with more CH angles. Finally, I topped off the assembly with a boiler, boiler top and Erector flag. The long drive shaft from the motor below passes through both CR turret plates and is secured to them to make the top assembly rotate.

To support the weight of the entire top assembly (with the rocket jets attached), and to facilitate its rotation, I sandwiched 6 TB bearings and a TC bearing plate between two BN turret plates. If you look carefully at the large photo at the top if this page, you'll see why I called the top part of the ring a "nose cone": in keeping with the rocket theme, I wanted the tower itself to look like a rocket ship (that's why the "fins" at each side of the lower part of the tower). Actually, in silhouette, the final design is shaped more like the space shuttle than a traditional rocket, but that's okay. With the top assembly installed, the final model is 44" tall.


The rocket jets are suspended from arms attached to the outside of the ring; I made each arm using 2 EX 6" big channel curved girders bolted together at one end with M small double angles. The arms are bolted to the ring with more M double angles. At the outer end of each arm, an F 5-hole strip is bolted between the M double angles, then a large N double angle in bolted to the center hole of the 5-hole strip. The rocket jets hang from the N large double angles on supports made from 21-hole and 11-hole strips.


The body of each rocket jet is a T boiler; a U boiler top forms the nose cone, a W boiler stack is the exhaust nozzle at the rear of the rocket, and 4 P79 car trucks act as fins. A couple of O pawls serve as hanging brackets, and a couple more support the boiler stack.

To add extra action and realism to the ride, I wanted to have a light in the nose of each rocket jet, and a second light in the tail to act as an exhaust flame. In order to get the effect I was after, as well as simplify the process, I needed a lightweight battery-powered solution. The answer was to use LEDs. I designed a makeshift circuit board from the same foam core art board that I used to make all of the signs on the ride and shaped it to fit snugly inside of a boiler. A bright, wide-angle red LED protrudes through the bolt hole in the boiler top, while a large diffuse red LED sits inside of the boiler stack. A coin cell provides the current. See the Tips & Tricks page for more details.


In addition, I used a combination of static yellow and blinking red LEDs in the entry sign and in the rocket plaque on the front of the tower. Wires run down the backside of one of the tower "legs" and under the base platform. Although these LEDs could also have been powered by coin cells, I opted to use a low voltage transformer instead.


Finally, to further incorporate the model into the overall Amusement Park display concept and to complete the illusion, I designed and rendered an "Girders & Gears" amusement park scene on a tri-fold foam core presentation display board to serve as a backdrop for the ride. To hold the 48" wide by 33" tall backdrop, I built a framework of DP and MB angle girders which protrudes 9" from the rear of the base. I lighted the backdrop in selected locations with a string of white mini-lamps which protrude through from the rear.