The 8480 Space Shuttle orbiter from 1996 is the model that got me hooked on Technic and the model I would keep if forced to get rid of all the others. Some of this attachment is no doubt nostalgic, but the model is spectacular in its own right. Besides being the first (and only) space themed model from the Technic line, this model just has everything. It was only the second motorized model other than a Universal Set, and as a single model it was able to focus more fully on optimizing the motorized experience. While 8880 introduced the first synchronized transmission, the space shuttle used the same parts to create a function switching transmission which allows the single 9V motor to drive 4 separate functions. If that weren't enough, there's also an independent micro motor on another circuit. Finally, there are also a pair of fully mechanical functions, landing gear and ailerons. The engine function is simulated with the new fiber optic system. The 8 fiber optic cables are routed through the main engines and light sequentially when the function is powered.
Most of the motorized functions are centered around the payload bay which can open the bay doors, deploy and rotate the Remote Manipulator Arm, and then open the solar arrays on a super secret satellite. Although these functions are certainly not driven by a 9V motor on the real orbiter, the motion and concept behind each is quite accurate and represents a typical shuttle mission. This is the only Technic set to have minifigure seats and although it does not come with any minifigs, adding some Classic Space figs is a must. The model is too small to be truly minifig scale, but they look pretty good in there anyway.
There are many stylistic details including a compound curved nose (the most elegant part of the model), 3 canted main engines, and pair of boosters. The ribs of the delta wings are represented with Technic beams. The generally open Technic appearance mimics what you might see during a major overhaul with the skin removed. The vertical tail is strong enough to provide support when the shuttle is placed in a vertical launch position as can be seen in the extra photos. I've always thought it would be excellent to build the external fuel tank and the Solid Rocket Boosters for a fully realized launch display, but then I'd have no choice but to build the mobile launch platform as well.
Because this model uses the ungeared 9V motor which rotates at a very high speed (~4100 rpm), most of the functions are geared down 1000:1 or more which, in combination with the gearbox, makes for a fantastically complex model. All this complexity comes at a price. At 1350+ parts it was one of the biggest sets made so far and all the gears and wiring made for a challenging build. The instruction book was tiny by modern standards. The wire routing was particularly tricky since it had to be routed along the bottom of the fuselage and kept away from the all the moving parts with very little clearance. The landing gear assembly was also not simple and in fact I am forced to admit that I screwed it up the first time and it didn't work. I blame my inexperience at the time (it was my first Technic model).
This model uses all of the new parts for 1996, and some of the white parts (such as the axles) never existed in this color in another set.
One last thing which I'd be remiss not the mention is the wonderful alternate submarine mode which deserves a page of its own to explain. I like it so much that I own a second copy of this set to keep the sub on display alongside the shuttle.
If there was any lingering doubt about what it is that makes 8480 so great, these images should clear up the confusion nicely (make sure to look at the full size versions). You can see that the insides of the model are positively packed with mechanical and electrical functions. In fact, the gearing is so dense that it is difficult to see what is happening without dissecting the functions individually. This is precisely what will follow below.
8480 features by far the most complex electrical system up to that time with two motors, two switches, and a fiber optic system. A 9V (6xAA) battery box is tucked away in the aft fuselage where it blends in nicely and yet remains easily accessible. The battery output goes to a 2x4 electrical plate which spans a pair of pole reversers. These are used as both on-off switches and as a means to reverse the polarity of the motors. An axle protruding from each switch is accessible from outside the model and centered by a rubber band overhead as seen in the computer image. Simply turn the round knob and a motor runs as long as the knob is held. Release the knob and the motor shuts down. Turn the knob the other direction and the motor reverses. The knob on one side controls the main 9V motor which runs the gearbox. The knob on the other side controls the micro motor which is connected to the satellite. The fiber optic box is wired to the same switch as the main motor, so it is illuminated (but not turning) any time the main motor is running, regardless of direction.
The motors in the computer image are shown in a false location for ease of display. They are actually located at the opposite end of the model from the battery box and connected by very long wires which must be painstakingly routed through the lower fuselage. The main motor is nestled between the astronauts' seats.
The heart of the model is a 4 position gearbox. It uses the same basic principles as the pioneering gearbox in 8880, but instead of being used to change gear ratios it is used to connect a single input motor to one of four different output functions.
The first photograph shows the shift lever and gate with the 4 positions. Each function is marked with a sticker. As the lever is moved through the H-shaped gate, one or the other of the two driving rings is forced into position. Note that only one driving ring can be engaged at a time. Passing through the center of the H returns the opposite ring to center. Whereas 8880 had a custom shift lever and mounting plate, the shuttle uses a new pair of shift gates and lever which would become the standard for the immediate future.
The driving ring is the key to everything. It slides over the ridged axle joiner. Small tabs on the driving ring allow it to lock along these ridges, but still slide with some extra force. The driving ring grips the longitudinal grooves on the axle joiner causing them to rotate together. A circumferential groove in the middle of the ring allows it to be pushed along the axle joiner in either direction. A set of 4 driving dogs on either end then mate with a 16 tooth idler gear allowing the idler's rotation to be either synched with the axle or allowed to spin freely.
The animation shows how the driving rings work to engage and disengage the clutch/idler gears. The driving ring is shown in red. The lower axles are joined with the gray axle joiner. The driving ring rotates with the axles. At first, the driving ring is disengaged so both the dark gray and green gears are not driven and slip on the axle. The driving ring then engages the green gear and thus drives the blue gear. Because the driving ring does not use gear teeth but rather uses four tapered driving dogs, there is considerable backlash between the driving ring and the gear. The allows the driving ring to be engaged even while it and the mating idler gear are turning at different speeds.
The lower computer images are color coded to show the different gear paths for each of the 4 functions. Red is the input from the motor which uses two stages of belts. This both reduces the motor's speed 9:1 and allows slippage if any of the functions stalls. The pair of red axles in the upper part of the image are driven continuously by the motor. The white lever is used to switch gears. Yellow is the door mechanism, blue turns the crane, orange lifts the crane, and green runs the fiber optic engine. Any of these functions individually is pretty complex, but making them all fit together in such a small space with no interference is the real achievement.
The cargo bay doors open when driven by the main motor. The doors are synchronized to move together, although sometimes one or the other can skip a gear tooth if too much resistance (like a finger) is present.
The computer image shows how the mechanism works. After the initial belt reduction of the motor, there is still a lot more reduction to come. The gearbox driving ring passes torque downward through several levels of the gearbox via 16 tooth idler gears, then uses a belt to provide another 3:1 reduction. Next a worm gear is used to mate with a 24 tooth gear mounted laterally. This drives a pair of crown gears which drive the 16 tooth gears mounted to each door. The worm gear allows the door to maintain any position without backdriving. Final reduction from the motor is 3:1 x 3:1 x 16:8 x 3:1 x 24:1 x 16:24 = 864:1 which drives the doors at a very reasonable speed.
Because this function has such a huge gear reduction, the use of the additional belt further downstream from the motor provides an effective torque limiting function.
The Remote Manipulator Arm can raise and lower using the same motor. Since the arm can both lift and pivot, the lifting function must pass concentrically through the turntable to the arm. The whole arm only lifts about 45 degrees at full extension.
The computer image shows the torque path. After the initial belt reduction of the motor, the gearbox driving ring passes torque downward through several levels of the gearbox via 16 tooth idler gears. A set of bevel gears then turns the corner and passes through the turntable. A further 3:1 reduction happens with spur gears prior to the worm gear. The vertical worm gear drives a 24 tooth gear whose axle lifts the arm. It is a little tricky to picture how the arm mechanism works, so I've color coded the axles which are grounded to structure in red. The links pivot at these axes resulting in a 4-bar linkage.
Final reduction from the motor is 3:1 x 3:1 x 16:8 x 24:8 x 24:1 = 1296:1
The Remote Manipulator Arm can also rotate on on a turntable driven by the same main motor. It is capable of pivoting about 70 degrees from center in either direction before the wire which runs up the arm to the satellite becomes taut. There are also a pair of plates which mechanically limit the rotation at ~90 degrees.
The computer image shows the torque path, the simplest in the model. After the initial belt reduction of the motor, the gearbox driving ring passes torque downward through a level of the gearbox via a 16 tooth idler gear. A set of bevel gears then turns the corner and drives the turntable with a worm. Final reduction from the motor is 3:1 x 3:1 x 16:8 x 56:1 = 1008:1
The satellite hangs at the end of the arm and is driven by a micro motor. The output pulley of the micro motor drives another pulley through a 3:1 reduction (keep in mind the micro motor turns very slowly to begin with). A worm gear then drives a pair of 8 tooth pinions directly connected to the solar arrays of the satellite. Final reduction is 3:1 x 8:1 = 24:1.
This is the slowest function of the model. Full deployment of the solar arrays takes about 10 seconds.
Because this function uses a separate motor not driven through the gearbox and powered by a separate switch, it can be run simultaneously with other functions. For example, it makes sense to have the solar arrays opening as the arm rotates.
The engines use the new fiber optic system. While power is available to the lights inside the unit any time the main motor is in use, the unit only sequences the lights when the function is engaged at the gearbox. After the initial belt reduction of the motor, the driving ring passes torque downward through several levels of the gearbox via 16 tooth idler gears before making the long journey to the rear of the vehicle. A final 1:1 system of belts rotates the fiber optic unit. Final reduction from the motor is 3:1 x 3:1 x 16:8 = 18:1 which drives the engines very quickly.
The fiber optics are not very bright and are certainly best appreciated in the dark, though they are certainly also visible in the daylight.
From this angle you can see the 3 unique engine parts used for the shuttle's main engines tilted slightly upwards. You can also see the boosters on either side of the vertical tail.
Although it is not motor driven, the landing gear is probably the most mechanically complex feature of the model. The input is a yellow lever on the port wing, but the spring which holds the whole system either up or down is way up in the nose wheel well. The images at the bottom show the gear in both the up and down positions. Note that on this model even when the gear is up it still protrudes slightly from the bottom of the vehicle and therefore still provides support. When extended, the gear holds the vehicle up higher and with a slight nose down angle, just like the real shuttle.
The computer image color codes all the axles which are supported by structure in red as an aid to understanding the mechanism. The spring in the nose gear passes over center and therefore holds the gear against the stops in either the up or down position. The up stop is a pair of 3L dark grey axle above the main gear, and the down stop is within the nose gear linkage.
The yellow lever rotates a lateral axle which then drives a longitudinal axle running the length of the vehicle through a set of bevel gears. At the aft end, a lateral axle drives the links which lower the main gear. At the forward end, a more complicated 4-bar linkage pivots the nose gear down. Both gear lock in such a way when deployed that the weight of the model is transmitted directly into structure and not through the gear train. It is a mechanism which must really be seen in motion to be fully appreciated.
Last but least are the functional elevons. The elevons in the real shuttle act in two different but interconnected ways. As ailerons, they move in opposite directions on each wing for roll control. As elevators, they move in the same direction on each wing for pitch control. The elevons on the model function only as ailerons.
A yellow lever on the starboard wing drives the ailerons via a 1:1 linkage as shown in the computer image. Care must be taken while building to get the gears synchronized so all the control surfaces are level at the same time.