Scrambler C

[iwonder]

Use math tags, it's standard LaTex math.

[magicalforest]

iwonder, how come you can get a higher velocity using a spring? Aren't you still working with the same amount of potential energy? Or is it because with the falling mass launcher, the potential energy is converted into kinetic energy for both masses (falling and vehicle)?

And how can you calculate the exit velocity of a spring launcher?

Thanks!

[olympiaddict]

That's exactly why, magicalforest. When you use a falling mass launcher, this heavy mass falls and hits the ground, and any kinetic energy it had left is converted into sound/shock waves in the ground/air/etc. and since the mass is heavy, this is not negligible.
With a spring launcher, the difference is that the spring stops the mass (or nearly stops it) before it hits the ground, meaning that all of its energy (PE=mgh) is converted into energy stored in the spring. Then the spring releases and this launches the vehicle, converting to kinetic energy of the vehicle.

Theoretical exit velocity can be calculated using:

Mgh = (1/2)mv^2
Where M is falling mass
g is accel due to gravity
h is displacement of mass over the fall
m is mass of egg transport
v is exit velocity

Obviously you could calculate a theoretical maximum velocity, but eh, I'd be pretty impressed with a device that is 80% efficient (super rough estimate!) because your mass can't fall a whole meter, there's friction, there's the kinetic energy of the spring assembly as it accelerated the car (small since it's low mass but still there), other losses due to imperfect construction etc. so take this into account when calculating. The 80% number isn't based on any calculation, I just estimated so I could mention this.
You can add a factor for efficiency expressed as a decimal (e=.80 for example) by using:
eMgh = (1/2)mv^2

Good luck!
I personally didn't build a spring launcher last year, anyone who did, mind sharing some of their experiences? I know they're something like trade secrets so I understand if not

[iwonder]

Yup. My initial statement that the velocity of the mass and car are equally launch doesn't work for a spring launcher, so the weight doesn't take any energy from the system.

I had a spring launcher last year that did a 1.2s time at states, I've heard of some doing a little faster. The real hang up is stopping the mass as much as possible, while still making it consistently set off the second trigger to release the vehicle. Also our vehicle was something like 500g with an egg I think, so it had a lot of issues going in a straight line, but we got that fixed too.

[bernard]

A FAQ has been posted on the official Science Olympiad website:

Is a single team allowed to impound and use more than one ETV for the two runs?
No, Rule 2a & 2b refer to a single ETV not multiple ETVs.

[chalker]

A friendly reminder to all. SO has 2 ways of 'clarifying' the rules: rules clarifications and FAQs. Rules Clarifications actually change the wording in the rules and are rarely issued (typically only a handful per year). FAQS help interpret specific situations or meanings and are much more common. These are listed in 2 different locations on the website. The above mentioned content is a FAQ, not a clarification.

[Signet]

What sort of steering mechanisms would be good for the bonus?

Given a 4-wheel vehicle with 2 axles, I can envision teams simply rotating one of the axles about its midpoint, but would they have to deal with the resulting scrub with something like Ackermann geometry?

[iwonder]

Since turning the axle is pretty simple on most vehicles, I'd just try that before worrying about more complex linkages.

[A Person]

What sort of steering mechanisms would be good for the bonus?

Given a 4-wheel vehicle with 2 axles, I can envision teams simply rotating one of the axles about its midpoint, but would they have to deal with the resulting scrub with something like Ackermann geometry?

I doubt you would need a complex steering system like the one above. What I believe you to think the pro of the complex steering system, that the car would have all four wheels spinning with good, solid contact with the ground constantly to have that certain point that the car rotates around, is not needed as there is the fact that the car, even with the more complex steering system, is probably going to have some problems with your light vehicle not pressing down hard enough for the wheels not to drift or slide, if those are the right terms. Because the lightness of the vehicle and what we're using it for, it means that the car would be affected by smaller things like dust of the floor.

[ByronClaw]

Wait how is a spring launcher better than just a mass launcher? I mean, the force and work being applied from the falling mass will decrease by being transferred to the spring. Unless I'm missing something?