Scrambler C

[InfiniCuber]

Just submitted a question (Can rubber bands be stretched (e.g. stretched rubber bands used to secure objects) as long as they do not contribute to the energy used to propel the ETV?) to the FAQs because I could see the rubber band FAQ affecting teams that use rubber bands or similar elastic materials as tires.

My guess is that it will be legal because I believe they are talking about potential energy that can be used to propel the vehicle, but it's good that you are posting the question, this is very helpful!

[wx4caster]

Regional thoughts and impressions:

We just had out regionals in SC KS this past weekend and i wanted to pass along my thoughts and our experiences from the event. First off the track was laid out great with the CAN firmly in place halfway down the track as the rules specify (distance 9 m.). But read the rules very closely if you make an attempt at the curve. The can is "centered" on the 0.5 m. point. So with the radius of the can, you do not have a full 0.5 m (more like 45 cm) to work with on the left side to get by. So with a wide vehicle you have absolutely NO chance to make the curve and stay in bounds. With that said, our team members attempted to "shoot the curve", which went horribly wrong as the ETV picked this time NOT to curve. It went out of bounds and suffered a competition penalty (tiered). Run one was dead. So the plan for the second run was to adjust the ETV and go straight down the course (NO curve) and get a good run in. The second run appeared to go great, stopping less than 10 cm short of the wall, dead on straight. This run would have won the competition, but controversy ensued. Our team uses a push lever for its energy propulsion, with a wire to keep the rod from hitting the ground once the car is pushed out and launched. The push rod does have some "bounce" after the launch which gives the perception of the rod hitting the ground. Well the judges ruled that our rod DID hit the ground, which is a construction violation (tiered again). We had video proof that we took to an arbitrator, and showed them how our push rod works, but were denied our appeal. They said the video was unclear. Also they said our run took 24 seconds to make it to the wall. 24 seconds??? We are sure the photogate system was tripped by our team during launch setup and not reset before we said 3,2,1,GO. Video again showed a 4.8 second run. This is pure incompetence by the judges to not realize this mistake. NO ETV takes 24 seconds. (BTW, a judges kid was manning the photogate timer).

This is going to read like "sour grapes", but we are pretty sure the judges had an "ax to grind" with our team, as we took 1st in state with this exact same scrambler last year (NO violations!!). They were going to find any violation they could to get us tiered. So we are certainly going to tweak some things to remove all doubt.

My suggestion for all scrambler teams, video everything. If there is any kind of uncertainty, have video proof to back it up. there are great slow-mo video apps out there. We plan on using them at state, as our team qualified for state.

[InfiniCuber]

Regional thoughts and impressions:

We just had out regionals in SC KS this past weekend and i wanted to pass along my thoughts and our experiences from the event. First off the track was laid out great with the CAN firmly in place halfway down the track as the rules specify (distance 9 m.). But read the rules very closely if you make an attempt at the curve. The can is "centered" on the 0.5 m. point. So with the radius of the can, you do not have a full 0.5 m (more like 45 cm) to work with on the left side to get by. So with a wide vehicle you have absolutely NO chance to make the curve and stay in bounds. With that said, our team members attempted to "shoot the curve", which went horribly wrong as the ETV picked this time NOT to curve. It went out of bounds and suffered a competition penalty (tiered). Run one was dead. So the plan for the second run was to adjust the ETV and go straight down the course (NO curve) and get a good run in. The second run appeared to go great, stopping less than 10 cm short of the wall, dead on straight. This run would have won the competition, but controversy ensued. Our team uses a push lever for its energy propulsion, with a wire to keep the rod from hitting the ground once the car is pushed out and launched. The push rod does have some "bounce" after the launch which gives the perception of the rod hitting the ground. Well the judges ruled that our rod DID hit the ground, which is a construction violation (tiered again). We had video proof that we took to an arbitrator, and showed them how our push rod works, but were denied our appeal. They said the video was unclear. Also they said our run took 24 seconds to make it to the wall. 24 seconds??? We are sure the photogate system was tripped by our team during launch setup and not reset before we said 3,2,1,GO. Video again showed a 4.8 second run. This is pure incompetence by the judges to not realize this mistake. NO ETV takes 24 seconds. (BTW, a judges kid was manning the photogate timer).

This is going to read like "sour grapes", but we are pretty sure the judges had an "ax to grind" with our team, as we took 1st in state with this exact same scrambler last year (NO violations!!). They were going to find any violation they could to get us tiered. So we are certainly going to tweak some things to remove all doubt.

My suggestion for all scrambler teams, video everything. If there is any kind of uncertainty, have video proof to back it up. there are great slow-mo video apps out there. We plan on using them at state, as our team qualified for state.

Oh wow. That's pretty frustrating, I gotta say. Yes the bonus can be difficult to get but once you get it, its great! That small gap is supposed to be a challenge, lol. But the fact that you had a potentially competition-winning run and they docked you even WITH video proof... a bit sketchy.
Sorry bro. Happens to the best of us. Some ES are better than others, and sometimes they just won't budge on decisions!

[bernard]

Just submitted a question (Can rubber bands be stretched (e.g. stretched rubber bands used to secure objects) as long as they do not contribute to the energy used to propel the ETV?) to the FAQs because I could see the rubber band FAQ affecting teams that use rubber bands or similar elastic materials as tires.

Not sure why it isn't posted publicly since I think the previous FAQ response about rubber bands wasn't entirely accurate, but here's what I got in an email today in response to my question:

Can rubber bands be stretched (e.g. stretched rubber bands used to secure objects) as long as they do not contribute to the energy used to propel the ETV? (section: 2 / paragraph: c / sub-paragraph: / line: 1)
Yes

[dhudes]

I'm a Dad. My daughter is competing in the Yeshiva league for Science Olympiad. Just got the assignment this past Wednesday and the competition is next Sunday March 8th. I've been working this with her and she wants to go with a pulley launcher. I appreciate the simplicity compared to a spring launcher but the use of a string or worse, a pulley belt, seems an inferior approach due to elasticity. Normally, we want a pulley belt to have elasticity to stay snug on the pulley wheel but here we don't have a closed loop -- at least the usual design shown is a string with one end on the mass and the other threads through 3 pulleys and ends in a hook that pulls the ETV. So if you have 8% elasticity, you lost 8% of your potential energy unless you do a real good job of securing that belt. Even twine stretches. If you use a pulley and string, even a 1" pulley, seems to me you have some wiggle as the line is pulled. Wouldn't it be better to use a chain and sprockets? The servocity plastic chains, for example? You would need 9 or 10 1 foot segments. A Shimano 11 speed bicycle chain is 116 links at 4.8 ounces I believe you'd need at least 2 of them but they can link together with a master link readily enough.
If you used a bicycle chain you could then use bicycle sprockets.
The advantage of bicycle components is also they are readily available off the shelf in numerous shops in NYC and from numerous sellers online whereas servocity is about the only source for their pulleys and sprockets and so on.
Mind you bicycle components are not cheap, a Shimano 11 speed chain is $35.40 on Amazon (although with Amazon Prime shipping is free).

Beyond price and availability, it comes down to the most efficient solution. Which is really "build a spring launcher" but my daughter is reluctant due to complexity.

[dhudes]

What to use for the trigger mechanism that is pushed by a #2 pencil? I saw a recommendation of an archery trigger but those don't look like something you can depress with a #2 pencil.

[bernard]

What to use for the trigger mechanism that is pushed by a #2 pencil? I saw a recommendation of an archery trigger but those don't look like something you can depress with a #2 pencil.

An archery trigger has a switch that you can flip with a a #2 pencil. Here's a picture of my release mechanism. There is a a loop of wire attached to the cotter pin, and the pencil goes into that and is pulled. If you use this approach, make sure your pin won't touch the ground after being pulled otherwise its a competitive violation.

[dhudes]

thanks for the picture Bernard. I see you are using a 2" pulley rather than a 1". I'm putting together an order to servocity, was going for 1" pulleys since I though we don't need extra torque of a larger pulley.

[InfiniCuber]

What to use for the trigger mechanism that is pushed by a #2 pencil? I saw a recommendation of an archery trigger but those don't look like something you can depress with a #2 pencil.

You can really use the pencil in whatever way you want to release your mechanism, so setting off an archery trigger shouldn't be a problem. Use it to pull, push, press, whatever, it should work and give you consistent and accurate results. That's from my experience anyways!

[bernard]

thanks for the picture Bernard. I see you are using a 2" pulley rather than a 1". I'm putting together an order to servocity, was going for 1" pulleys since I though we don't need extra torque of a larger pulley.

I got my pulleys from McMaster-Carr for about $6-10 each. My pulley doesn't really turn, its just a smooth surface for my string to pull along.