vehicle engineering design competition

[aubman247]

Hi I've posted here before, I was hoping you guys could give me some help again

Ok well my physics teacher is making all the juniors in my class enter a engineering competition. My partner and I already made our main car but it really sucks. We decided to go with size and power but then I just saw the past years designs (the majority of which are small cars with a slanted front - which means our car will just run over it and come crashing down)

We now need to make our backup car and well we're kinda of stumped out... I was hoping any of you would have any weird crazy ideas that me and my partner could do??
OK so the rules are as follows:




Label B S P A

CL
Name Bottom Start Line Pass Line Apex

Centerline
Distance from B - 1 ft. 4 ft. 8 ft. 8.5 ft.

THE CHALLENGE:

To design and construct a vehicle that will climb a hill under its own power, knock over its flag (located to the right of the vehicle as it approaches the “top of the hill”), stop at the “top of the hill,” hold its position against an opposing vehicle and be closest to the centerline at the end of the 15 second run.

THE TRACK:

The illustration above shows the approximate dimensions of the hill. The 12" width of the track may vary by ±0.5" as the vehicle travels from the bottom to the apex. The side rails are made from 1-by-3-inch #2 pine. The carpet is a standard, commercial grade. A vehicle is considered to be on "top of the hill" if it is completely between the two pass lines, including any extensions, strings, dropped and/or jettisoned objects. Two flags, each consisting of a 1/2” dowel extending 5 inches above the track bed (see illustration), will be mounted on either side of the track at the centerline of the “top of the hill.” The flag to the right of a vehicle as it approaches the “top of the hill” will pivot only in the direction of the forward motion of that vehicle.

VEHICLE SPECIFICATIONS:

• The complete vehicle must be designed to fit inside a 12-inch cube at the beginning of each run. (A “run” is defined as a single attempt up the hill against another vehicle; a “round” is defined as one or more runs against the same vehicle.) The complete vehicle is defined by all its parts. Appendages, such as a ram, may extend beyond this limit once activated, but cannot be activated before the start of the run.

• The vehicle must include at least three wheels and must roll on its wheels while traversing the track. Sample vehicle

• The vehicle must have an original chassis constructed by the students. Component parts (motors, wheels, gear boxes, etc.) may be "cannibalized" from other sources.

• The weight of the vehicle, including batteries, must not exceed 4 pounds (1.8 kg).

• The vehicle must have a “reference point” for judging its position on the hill. This point must be chosen by the team and marked with a colored, adhesive dot (supplied by the judges). The dot must be placed on the rigid body of the vehicle, not on any extension, jettisoned object, or flexible string or wire. The dot must be visible from above. The position of the dot can be changed from round to round but must remain in the same place during a given round against another vehicle. The dot will be verified by the track judge before each round.

• The vehicle must use a momentary switch of the “normally closed” type to activate the vehicle at the start of each run. An additional toggle switch may also be used in the circuit to turn off the vehicle when not competing. No “hot starts” (running the motor before the start signal) will be allowed. Normally closed switch

POWER:

• Power to propel the vehicle may be derived only from two standard-size 9-volt batteries (e.g., approximately 2" x 1" x 0.7"). Rechargeable batteries meeting these specifications are acceptable. Note: Only 9-volt batteries may be used for propulsion. Combinations of lower-voltage batteries (for example, six 1.5-volt AA batteries) are not acceptable. No additional power sources may be used to propel the vehicle. However, additional power may be derived from other batteries for the purpose of powering any on-board electronics. Only springs, rubber bands or the 9-volt propulsion batteries may be used to power any deployed appendages.

• The vehicle must not use CHEMICALS or DANGEROUS SUBSTANCES. No rocket-type devices, CO 2 propulsion cartridges, or chemical reactions are allowed (fire is considered a chemical reaction).

We get one point for getting on top of the hill, another for knocking off the flag, and a third for being closest to the middle line against an opposing vehicle. Any help would be greatly appreciated

[GAHD]

riiight, I'd just say canni balise the motor and batteries out of an onld 18V dirill for your drive train, and use a silicone or rubber cement coating on your tires for good grip. Pick up som "mechano' or whatever to build the chassies if you don't know how to or can't manufacture a chassies out of, say, roundbar steel. ALso remember that torque is your freind in a 'sumo' or tug of war style competition, have a good downshifted gearbox to maximize your force.

Other motors can include old power window motors (can pillage a 'junked' car at the autowrecker for those) Don't worry too much about supplying different voltages to the motor then it's specs, but if you do it 'can' burnout. If you're really industrious, wind your own motor right and you'll smoke the competition.

If you incorporate the ideas, let me know how it turns out.

[Barry]

hey im in year twelve and i do physics and recently we were playing aorund with flywheels and stuff, when someone was genius enough to build a car that went on the stored charge of a capicitor thingy they found in the lego, this could be a good way of getting the right amount of disatnce to be on top of the hill at the end, because u could pre-determin the exact amount that needed to be stored

[aubman247]

Wow thanks for the Ideas, I already have all the moters I need though from all my old remote control cars but i'll play around with that torque idea.

Hmm I was thinking of depolying some sort of appendage that would block the other vehicle from reaching the top and knocking down their flag within the first 15 seconds. Me and my partner made a little apparatus thing that when the vehicle is tilted a dangling piece of aluminum closes the circuit and runs the motor. Maybe I could use a capicator to depoly the appendage - I think this would work since if our car gets knocked back from the hill it'll activate the moter again

[GAHD]

RC car motors suck, you can stop them with your hands. Simply put, they're toys. But with down-shifted gearing it might be ok.

[aubman247]

Yeah they do suck, you need atleast two of them to climb the hill

[GAHD]

Get someone to take ya to an autowrecker with a ratchet-set, you can strip down a few cars for their power window motors, usually pritty cheap. Trust me, you ,won't be dissapointed by their power.

[aubman247]

Wow great idea car window motors... radio shack had nice electrical motor and gear set for sale for about 12 bucks each...

Hmm anyways I connected the all wires up with that dangling thing and the car has problems getting up the hill. I think its because there isn't enough surface area or the way the thing oscillates. Whenever the circuit connects I can see blue sparks flying out.. Is this bad? .. I hope I can fix it in time the competition is this sunday, or maybe should i just scrap this design?

[GAHD]

Hmm, if you can post schematics of your car, perhapse that'll help.

[aubman247]

Well I brought it in my physics class today and me and my partner tried it out with 3 batteries instead of the 2 allowed directly wired. The car doesn't even go up the hill anymore. Apparently the motors are damaged so we decided to scrap that car and focus on the backup...

At this point I don't think i have a chance in the competition anyways So i'll just study for the SATs and try to make a new one for my physics grade in 2 weeks

Well thanks for your help gahd its been a crazy one