Electric Vehicle C

Post Reply
Protestant
Member
Member
Posts: 16
Joined: October 30th, 2007, 6:15 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by Protestant » September 21st, 2008, 3:16 pm

Did they release sample rules?

Where did you get the info that it's smaller this year, or that there's a bonus for mechanical brakes?

User avatar
sachleen
Exalted Member
Exalted Member
Posts: 215
Joined: April 10th, 2007, 8:31 pm
Division: Grad
State: CA
Has thanked: 0
Been thanked: 0
Contact:

Re: Electric Vehicle C 2009

Post by sachleen » September 21st, 2008, 3:20 pm

the rule books are out, you can order them from the SO store.

User avatar
Pleiades
Exalted Member
Exalted Member
Posts: 563
Joined: April 14th, 2008, 4:16 pm
Division: Grad
State: AL
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by Pleiades » September 21st, 2008, 3:21 pm

mooble117 wrote:
seth959ci wrote:speaking of making the car go straight, what do you guys use to keep the axles from sliding left and right? thanks for any help!
Superglue and ball bearings.
Where do you get ball bearings? Can you just use the ones they have for rollerblades? Those are very expensive!! At Modell's the cheapest is like 25 dollars for 16!! I dont even know if those would fit on my axles.

And yes, the official rules have come out and they are on sale at the soinc store. Or you could get them from your state.


mooble117
Member
Member
Posts: 10
Joined: February 28th, 2007, 4:05 pm
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by mooble117 » September 21st, 2008, 6:02 pm

http://www.vxb.com/page/bearings/PROD/1-8inch/R2ZZ-1
http://www.vxb.com/ballbearings.html?gc ... xwoduhxpeA
Thats the site where we bought our bearings last year.
tip: buy bearings with common outer diameters(3/4, 7/8), or else you won't be able to find a bit to drill the hole for the bearing (11/16 for instance).

User avatar
seth959ci
Member
Member
Posts: 15
Joined: September 4th, 2008, 7:32 pm
Location: So. IN
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by seth959ci » September 21st, 2008, 7:23 pm

yeah i have ball bearings too,i'm just having problems with the threaded axles fitting into the bearings correctly even though i have made spacers(they are a little screwy for now). it is also a pain to keep the bearings in-place in the plywood my car is made of. i think some glue or bolts is in order. can anyone tell me the new wheelbase length requirement?

also, i have not seen the new rules yet and i was just wondering if there is a limited amount of wheels you can use on the car. i have a 6-wheeled design idea. 4 wheel drive anyone? hehe....
when the fear of crashing is greater than the thrill of speed,BRAKE!

captbilly
Member
Member
Posts: 94
Joined: April 17th, 2005, 11:06 am
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by captbilly » September 22nd, 2008, 7:17 pm

At the National competition for electric vehicle the event coordinator will specify a travel time for the vehicle. How do you control the travel time of the car for the Nationals electric vehicle competition. Do you integrate acceleration over time and deceleration over time for the start and stop and then add in the travel time for the constant speed portion of the run. It seems like the math could get quite complicated. I guess you could use calculus to write an equation that would take all the factors into account, but it would be pretty complicated. Anyone out there feel up to writing the equation of motion for the electric vehicle? Variables would be acceleration (could be non-constant), deceleration (also could be non-constant), max speed (for constant speed portion of run, if any), total distance and total time. Presumably testing or design would give the acceleration and deceleration rates as well as the constant maximum speed, so these could be plugged in as constants. Then the acceleration time, deceleration time and constant speed time could be calculated to give the correct total time and distance.

How about it, some math wiz want to work the equation and post it here?

Protestant
Member
Member
Posts: 16
Joined: October 30th, 2007, 6:15 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by Protestant » September 26th, 2008, 4:18 pm

Capt:
Most of the time, the acceleration at the beginning and deceleration at the end take up roughly the same amount of time and distance each run, so you simply have to add them in if you need to be really exact. The difference they have for speeding up and slowing down to different speeds is negligible. You can also try making a chart of how long it takes to get to certain distances for each speed that you set it to.

captbilly
Member
Member
Posts: 94
Joined: April 17th, 2005, 11:06 am
Has thanked: 0
Been thanked: 0

Re: Electric Vehicle C 2009

Post by captbilly » September 28th, 2008, 1:19 pm

Protestant wrote:Capt:
Most of the time, the acceleration at the beginning and deceleration at the end take up roughly the same amount of time and distance each run, so you simply have to add them in if you need to be really exact. The difference they have for speeding up and slowing down to different speeds is negligible. You can also try making a chart of how long it takes to get to certain distances for each speed that you set it to.
I was looking for a way to use a formula that would give an exact speed that you would need to accelerate to (at a known acceleration and decelleration rate) to give the exact speed setting required to reach the required distance at the required time. The number of charts needed to come up with every possible combination of average speed selected by the event coordinator and total distance selected by the event coordinator would be huge. The range of average speeds that you need to be able to work with is 2.66 - 1. If we assume that we want 0.1 second accuracy (probably the best timing accuracy you can expect from the timers) then you would either need 250 charts (one for each 0.1 second interval at 10 meters) or you would have to do some interpolation between charts (difficult to do at all, but extremely tough at a national competition).

If we are talking about the Regional and State competition, where the competitor gets to pick the travel time, it is as you say a simple matter to find the acelleration and decelleration time and just add in time at a constant speed to come up with total travel time. The tough problem is comming up with a solution for the National competition where the Event coordinator picks the travel time and you need to adjust your vehicle to reach the required distance at that time. You will need to vary the amount of, or time of acceleration and decceleration, so those will no longer be constants.

nctarheel
Member
Member
Posts: 2
Joined: November 5th, 2008, 8:45 pm
Has thanked: 0
Been thanked: 0

Newbie

Post by nctarheel » November 5th, 2008, 8:54 pm

I am very new to the Electric Vehicle, as it was kind of thrust upon me this year by the club adviser. There are a few questions that I have about this event that I was not able to find answers to at the North Carolina and US Science Olympiad web pages:
1) Are you judged any at all on how fast your vehicle travels the assigned distance?
2) Would I be penalized for using 4 D Cell batteries?
3) What is a good way to brake the vehicle in a straight line? I was thinking a front-drive, rear brake system would be more stable, kind of like on bicycles (without the front-drive).
4) Is weight factored into the score?
5) Which of these combinations would work best?
-Low-riding body
-High-riding body
-Slender-width body
-Wide-width body
-Long-length body
-Short-length body
-Wide axle/tire track
-Slender axle/tire track

Thanks for the help!

Post Reply

Return to “2009 Build Events”

Who is online

Users browsing this forum: No registered users and 1 guest