The fun and enjoyment of theme park shows and attractions tends to overshadow the innovative engineering that goes into them. Beneath the glamorous exteriors, these attractions usually challenge the very essence of the engineers who must transform concepts and ideas into nuts-and-bolts hardware.

As you would expect, safety and reliability are prime objectives. But these goals are meaningless unless the engineer comes up with something that actually works. This is where creativity and experience, lubricated with plenty of engineering know-how, become the basic tools for success.

monster
 

When major new attractions are planned, Disney Imagineers become part of a team that develops ideas and sketches into spectacular attractions. After drawings, models, and prototypes have been developed and revised, the attraction comes into being. But when officials at the Walt Disney World Co. decide to develop a live show or special event, they often call on their Ride & Show Engineering Div. Disney’s Ride & Show Engineering Div. encompasses roughly 90 people, including engineers, managers, designers, technicians, and individuals representing a variety of subdivisions. One of these individuals is Matt Lenz, senior engineer.

Defining the project
Disney’s Creative Entertainment Div. had undertaken a project, and Lenz became involved midway through its development and helped orchestrate some pretty impressive results. The project, Splashtacular, was set to open in November 1993, to coincide with President Clinton’s proclamation of National Kid’s Day. The show made extensive use of music, dancing, and a spectacular fountain, provided by Walt Disney Imagineering, consisting of nearly 320 nozzles, some of which would shoot water 180 ft into the air. Lenz pointed out that this is as high as Spaceship Earth, the familiar silvery sphere that has become synonymous with EPCOT Center. He also revealed that pneumatics makes this incredible height possible by boosting pressure of the water behind the nozzles, “but that’s a different story altogether,” said Lenz.

Ride & Show Engineering’s task was to design and construct the climax of the live show special effects: an alien space creature that would rise up out of the earth in a cloud of smoke and extend to a height of 65 ft. The project originally commissioned by Disney’s Creative Entertainment Div. had a 12-week schedule. However, six weeks into the project, the west-coast contractor supplying the monster informed Creative Entertainment that only the head of the monster could be delivered on schedule. This was when the Ride & Show Engineering Div. was called in to produce the design and Walt Disney World’s Central Shops was tapped to manufacture all of the monster except the head. Lenz said, “At that point we had about six weeks to come up with a complete design, build it, install it, test it, and integrate it with the show’s programming, dance routines, and other cues so it would fit into the system.”

Some parameters were defined when Lenz entered the project. A hydraulically actuated scissors-type lift in the bottom of a concrete pit would extend from a collapsed height of 3 ft to 18 ft to raise the monster into the view of spectators. Lenz explained that, “When the lift was raised to its full height, locking pins engaged sockets, so we didn’t depend on the hydraulic system for support. The lift platform then became a rigid structural floor, upon which this huge monster operated.” As the lift extended, the monster simultaneously unfolded upward to a maximum height of 65 ft with lift and monster fully extended.

Working within restrictions
Weight was a big issue with this design, because making the monster too heavy would have required a more powerful lift. The lift was designed for a maximum load of 20,000 lb, so the total weight of the monster — including the head — could not exceed this value. Hydraulic power units (HPUs) had already been specified and were under construction, so the design would have to operate within the pressure and flow capabilities of the HPUs originally prescribed.


John Deere 940D

Lenz elaborated: “At one point, we had estimated that the monster would end up weighing somewhere around 23,000 lb instead of 20,000. We absolutely couldn’t reduce weight once we had all the hardware built, so we found ways of cutting 100 lb here or 40 lb there. But 3000 lb was an awful lot to get rid of. We ended up weighing every piece of structure that went on the system. The only thing we didn’t weigh was the fluid in the hoses, tubing, and cylinders. After calculating and adding in the weight of the fluid, we arrived at a final weight of 19, 995 lb!

“During all this, the lift manufacturer played it safe and smart and said they could not increase hydraulic pressure or resize anything to make the lift handle any more than 20,000 lb. They did tell us, however, that we’d need the greatest lifting force when the lift first started from a fully retracted position. As with all structures like this, at low angles, the effective force from the cylinders to drive the lift up vertically is at a minimum. But because the monster was so huge, we had to retract the lift all the way to get it out of sight. We developed a contingency plan to integrate some auxiliary cylinders that would help lift the monster when the scissors lift was fully retracted. Once the lift extended, its cylinders acted on a more effective angle.”