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Four intrepid students tackled a new vehicle this year. This is a very large project for four students but the project was a success.

We weren't able to finish in time for the Arcata World Championship race, just too much to do. We did enter the Klamath Kinetic Challenge and did well. Everyone left for the summer break so we didn't compete at the Davinci Kinetic Challenge in Corvallis.

The Klamath race was the first outing for the new vehicle. The first float test was Friday night and the race was the first time the vehicle had been ridden more than a 1/4 mile. The biggest problem was in hub bolts coming loose. Replacing and tightening these slowed our progress but didn't stop up completely. We were able to Pel, which is completing the course without pushing or pulling the vehicle, a major accomplishment for a first outing. We also were awarded the Pelican Brief Award, first vehicle to break down after the start. This one were weren't trying to win.

A few weeks after the Klamath Race we were in the Fourth of July Parade with several other OIT vehicles. All in all a successful project. Still there are areas of improvement to work on.

ENGINEERING

As mentioned, a new vehicle was constructed in 2009. It turned out to be a three wheeled tandem trike, two driven wheels in from and a steered rear wheel. We went from four riders to two. It is slightly narrower. Sadly it is not half the weight of the four rider vehicle.

Swing arms were used on the front wheels. These are activated through worm gears to raise and lower the frame. The idea was to simplify raising the pontoons for mud, and raising the wheels for better performance in the water. This worked very well but lead to a heavier frame than would otherwise be necessary.

Steering was done with a horizontal fork on the rear wheel. The actuation was through a #40 chain drive. Two gears were used so the steering wheel turned the correct direction. The rear pilot controls steering and braking. Once on the road we found the steering could be improved. The forward offset of the steering axis made it sensitive to any side loads on the vehicle. The steering needed quite a force to keep the vehicle going straight. Any side hill created such a load. It may be best to implement a goose neck to get away from this tendency. More gear reduction on the steering would also help.

Braking was accomplished through industrial conveyor hydraulic disk brakes. There ran on a “ sproter ”, a combination brake disk and chain sprocket. A hydraulic cylinder was used to actuate the brakes. Braking was marginal and is one area which could use improvement.

The dive system was fairly standard. A bicycle drive was used by each pilot giving independent gearing. These both fed into a differential. The differential let outboard to sand gears on each side, these give essentially a high/low range. The braking sproters were one of the sand gears on each side. The sand sprockets end up on the axis of the swing arms. A #50 chain gives the final drive to the front wheels, again with one sprocket on the swing arm axis to allow these to move without changing the chain length.

Some parts were donated from the prior vehicle. The wheels used the same rims and spokes but new hubs were build. The new hubs use needle bearings. These seems to run very smoothly. Also many of the drive components were from last years sculpture.

There was a squealing vibration in the rear dive when coasting. We first thought this was in the brakes. But after the races we tracked it down to the rear freewheel. A split collar was rubbing on the rotating portion of the freewheel causing this vibration. A nylon washer was cut to fix this and it wasn't noted during the Fourth of July Parade. This vibration into the drive is thought to be one reason hub bolts were coming loose.

The vehicle is tail heavy in the water as seen in the water picture. May go to a four foot wheel in the back which would move the CG forward and also help the steering. It may be useful to move the pilots forward for water balance.

Oh, and we need some paint.

STUDENTS