• Home Page
• What's a Kinetic Sculpture ?

• 2005	2006
  2007	2008
  2009

• Sponsors
• Contact Info

The Kinetic Pelican was built in 2004-05 by twelve senior project students at OIT. It was a very large project and they did an amazing job to get it built and on the race course.

As seen above, it is a large vehicle piloted by four riders. The front riders face forward and the rear two face backwards. The tubular space frame is center articulated for steering, and to keep all four wheels on the ground when operating on uneven terrain. Four six foot wheels are similar to bicycle wheels but much larger. Each has 100 spokes in a 5 cross pattern. Water propulsion is accomplished with six paddles added to each wheel.

The goal of the senior project was to complete the Pelican for the World Championship Kinetic Sculpture Race in Northern California. It was touch and go whether it would be done or not. The steering mechanism gave us trouble up to the end. The night before the race a 1/2 inch bolt was taken off the trailer to fix the steering, truely last minute. The vehicle ran very well in this race. It was able to complete the course which is exceptional for a first year vehicle. The steering depends on having no slack in these chain drives. This was not the case at the start so steering was iffy. On the second day a link was taken out the the final drive to tighten up the steering. This worked but put so much drag in the drive that speeds were abismal. We made the cut off times, sometimes by minutes, each day though. The wheels were held on to the main axles by split collars. These turned out to be inadequate and slipped on steep hills. But for this snaffu the Pelican would have "Aced".

Modifications were made before the local Klamath Race. Idlers were built for the final drive chains allowing them to be correctly tensioned. Also the wheel split collars were lock-tighted (red) to the axles. These minor modifications worked very well and the Pelican "Aced" the Klamath race.

On the way to the Corvallis Race the Pelican flew off the trailer at highway speed. This was a disaster, and very scary. The wheels survived the 3 foot drop off the trailer but not the subsequent jacknife.

All in all this was a great first year of Kinetic Racing at OIT. An amazing vehicle was constructed and performed very well.

Engineering

Since OIT is an engineering school, we should explain some engineering details of the vehicle.

The OIT Kinetic Pelican built in 2004-05 accommodates four riders. Two riders face forward and two backwards. It has four giant 6 foot wheels, one on each corner. The frame is a center articulated design which allows all four wheels to stay on the ground no matter what the terrain is like. Turning is also accomplished through the center articulation hinge.

The innertubes are for added floatation. Twice a wheel was laced without the innertube. The only solution is to un-lace it, insert innertube, then re-lace. Bummer.

Large diameter wheels were chosen to accommodate mud and sand. Large, relatively narrow wheels give low rolling resistance under these conditions. They also roll easier on hard surfaces but the main reason was for mud and sand. Six foot irrigation line wheels were used for the rims. Hubs to accept the many spokes were made on a Kira CNC machine in the OIT machine shop. The spokes, similar to bicycle spokes, were also made in our shop. The spoking pattern is 100 spokes in a 5 cross pattern. A strip of rubber, re-tread material, is glued and riveted to the rim as a tire on hard surfaces.

Having two riders face forward and two backwards was initially to simplify the design. It was thought the front and rear frame sections could use the same design. In the final configuration the two "pods" are similar but not identical. Having two riders facing backwards complicated the drive train but simplified pedal clearances.

The frame sections are a space frame design constructed of 4130 thin wall aircraft tubing. A computer FEA analysis was done to verify its strength. CAD design was used to verify clearances and turning radius. Construction involved many, many miter cuts and un-tolled hours of MIG welding. The articulation hinge is also built from tubing. It, as well as the frame, is a thing of beauty at least to an engineer. It allows rotation about a vertical axis for steering, and about an axis along the length of the vehicle to keep all four wheels on the ground.

Kinetic Sculptures need gearing to travel along the roads at 10-15 mph but also to crawl through the sand and mud as very low speeds. This vast difference is gearing is a challenge. The OIT Sculpture, as most such vehicles, have two variable stages of gearing. This is analogous to a 4 wheel drive vehicle with a normal transmission plus a high/low range box. The OIT vehicle uses a standard mountain bike drive train for each rider. The front and rear "pod" drives are separate. In each "pod" the bicycle drives are brought together to one shaft. A high/low chain drive connects this shaft to a differential. The speed reduction, and inherent increase in torque, forces this chain to be a heavier industrial chain, a #40. This high/low chain is shifted, while stopped, by hand. The shafts from the differential are connected to the drive axles using another chain reduction, a #50. This gearing gives a top speed of about 15 mph and a low gear producing 12 inch travel for each pedal stroke.

To allow the riders in the rear "pod" to pedal normally the direction of their pedaling motion needs to be reversed. This is accomplished with a reversing chain. The figure below shows how this system of sprockets and idlers is arranged.

Steering is accomplished with the very tricky application of a differential. The system was pioneered by another Kinetic Sculpture designer Bob Durst. If the center of a differential is held and one differential axle [1] turned, the opposite differential axle [2] will turn at the same rate but in the opposite direction. The first differential axle drives one drive axle [A] directly through a chain. This drive axle [A] will turn the same direction as the first differential axle [1]. The second differential axle [2] drives another drive axle [B] through a reversing chain similar to the reversing mechanism described above. This reversing forces the drive axle [B] to turn opposite the second differential axle [2]. Thus the two drive shafts will turn the same direction at the same rate. Now, if the center of the differential is turned it will force a difference in rotation between the first [1] and second [2] differential axles. This in turn forces the drive axles [A&B] to turn at different rates. This causes a turn. The differential center is turned through a bicycle chain and hand crank. Voiala, steering. One problem of this scheme is that the steering differential gears are in motion whenever the vehicle is moving. This causes friction which is unwanted in a human powered vehicle. However, it is more reliable than other steering options in this center articulated vehicle. Amazingly the design, even with the 6 foot wheels, provides a very tight turning radius. It is capable of pulling a U-turn on a two lane road, very maneuverable.

Flotation is provided by four pontoons, one under each rider. These have enough buoyancy to keep the craft afloat and nearly enough for stability. There are inner tubes inside each wheel to provide slightly more flotation and necessary stability. The four pontoons are less desirable than two longer pontoons, a catamaran. However, a two pontoon design is very difficult to accomplish with the center articulated frame. Propulsion is provided by paddles on the outside of each wheel, six per wheel.

STUDENTS

Chris Salyer	Fabricator Extrodinair
Bryce Johnson	Fabricator Extrodinair and Layout Man
Jon Wulff	Design & Construction
Zack Grant	Wheel/Spoke Man
Mallory Swan	Wheel Analysis
Ryan Hite	Drive Train Design
David Belau	Drive Train
Jeff Gunter	Drive Train
Keri Johnson	Floatation Design
Travis Power	Floatation
Jay Hinostroza	Brakes