Gravity Vehicle C

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Re: Gravity Vehicle C

Postby MTV<=>Operator » September 6th, 2019, 7:43 pm

I understand, thanks for the clarifications. I planned on launching the vehicle from the top of the ramp but adjusting the mass concentration on the vehicle to regulate how high the center of mass is.

My current ramp design features barriers on either side of the ramp that extend 1.5 cm above the surface. Would this hinder the ES's ability to measure the highest point of the vehicle? I've seen pictures of ramps with side barriers, and the rules don't specify that this would be a construction violation, but I don't want to cause any issues at a competition.
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Re: Gravity Vehicle C

Postby AngelMB » September 7th, 2019, 8:32 pm

I understand, thanks for the clarifications. I planned on launching the vehicle from the top of the ramp but adjusting the mass concentration on the vehicle to regulate how high the center of mass is.

My current ramp design features barriers on either side of the ramp that extend 1.5 cm above the surface. Would this hinder the ES's ability to measure the highest point of the vehicle? I've seen pictures of ramps with side barriers, and the rules don't specify that this would be a construction violation, but I don't want to cause any issues at a competition.
I don't think side barriers should pose a problem. I believe the rule that would apply most to your concern would be 3.f. "The Vehicle and Ramp, together, in the ready-to-run configuration, must fit within a rectangular box with a 50.0 cm x 50.0 cm base and a height of 100 cm." I don't think the ES should have a problem measuring the highest point of the vehicle and ramp system if you use rails on the side of the ramp.
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Re: Gravity Vehicle C

Postby windu34 » September 7th, 2019, 9:08 pm

I understand, thanks for the clarifications. I planned on launching the vehicle from the top of the ramp but adjusting the mass concentration on the vehicle to regulate how high the center of mass is.

My current ramp design features barriers on either side of the ramp that extend 1.5 cm above the surface. Would this hinder the ES's ability to measure the highest point of the vehicle? I've seen pictures of ramps with side barriers, and the rules don't specify that this would be a construction violation, but I don't want to cause any issues at a competition.
I don't think side barriers should pose a problem. I believe the rule that would apply most to your concern would be 3.f. "The Vehicle and Ramp, together, in the ready-to-run configuration, must fit within a rectangular box with a 50.0 cm x 50.0 cm base and a height of 100 cm." I don't think the ES should have a problem measuring the highest point of the vehicle and ramp system if you use rails on the side of the ramp.
You should be fine with what you described.
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Re: Gravity Vehicle C

Postby annabelle0308 » September 8th, 2019, 12:39 pm

Hi, I'm new to this event and had a few questions:

What are the vehicle and ramp supposed to be made out of?

Any resources on how to build a release mechanism?

How is the machine held vertically in the starting position? Does the release mechanism hold it up?

Any tips on how to get the vehicle to move as slowly as possible while still reaching as close to the target as possible?

Thanks!
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Re: Gravity Vehicle C

Postby MadCow2357 » September 8th, 2019, 1:51 pm

Hi, I'm new to this event and had a few questions:

What are the vehicle and ramp supposed to be made out of?

Any resources on how to build a release mechanism?

How is the machine held vertically in the starting position? Does the release mechanism hold it up?

Any tips on how to get the vehicle to move as slowly as possible while still reaching as close to the target as possible?

Thanks!
Annabelle
1. No requirements as long as it's nothing hazardous - I'd recommend a type of smooth material that you can bend into a curve like sheet metal, with wood for supports.

2. None that I could find, but depending on your design you can consider using a number two pencil to hold the car in place (drill some matching holes through the car and the release mechanism).

3. Yes, the release mechanism holds it up.

4. Why would you want it to move as slowly as possible? Speed is important!
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Re: Gravity Vehicle C

Postby Tendan » September 8th, 2019, 6:16 pm

Do you think there is any best size for the car to be? Old pictures seem to indicate a wide variety of dimensions. Some covered the whole ramp and others were probably not even 25 cm long.
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Re: Gravity Vehicle C

Postby AngelMB » September 8th, 2019, 7:51 pm

Do you think there is any best size for the car to be? Old pictures seem to indicate a wide variety of dimensions. Some covered the whole ramp and others were probably not even 25 cm long.
I believe any size vehicle has the ability to work out well, but personally I think bigger cars are the way to go. I recall Windu34's vehicle event video saying something along the lines of wanting to go as wide as possible while not sacrificing the bonus. Seeing as there is no bonus for a thin car this year and there is less of a weight restriction (like in MV), I don't see why you would really want to go for a thin car. Wide cars allow less variation between runs as slight offset angles should affect the path your vehicle takes less than if your car was thinner. You also don't want to make your car too wide, I think anything above 25 cm may be a bit excessive.
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Re: Gravity Vehicle C

Postby Unome » September 8th, 2019, 8:20 pm

Do you think there is any best size for the car to be? Old pictures seem to indicate a wide variety of dimensions. Some covered the whole ramp and others were probably not even 25 cm long.
I believe any size vehicle has the ability to work out well, but personally I think bigger cars are the way to go. I recall Windu34's vehicle event video saying something along the lines of wanting to go as wide as possible while not sacrificing the bonus. Seeing as there is no bonus for a thin car this year and there is less of a weight restriction (like in MV), I don't see why you would really want to go for a thin car. Wide cars allow less variation between runs as slight offset angles should affect the path your vehicle takes less than if your car was thinner. You also don't want to make your car too wide, I think anything above 25 cm may be a bit excessive.
It's also worth noting that being heavier isn't going to significantly affect your speed with Gravity Vehicle.
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Re: Gravity Vehicle C

Postby windu34 » September 8th, 2019, 11:09 pm

Do you think there is any best size for the car to be? Old pictures seem to indicate a wide variety of dimensions. Some covered the whole ramp and others were probably not even 25 cm long.
I believe any size vehicle has the ability to work out well, but personally I think bigger cars are the way to go. I recall Windu34's vehicle event video saying something along the lines of wanting to go as wide as possible while not sacrificing the bonus. Seeing as there is no bonus for a thin car this year and there is less of a weight restriction (like in MV), I don't see why you would really want to go for a thin car. Wide cars allow less variation between runs as slight offset angles should affect the path your vehicle takes less than if your car was thinner. You also don't want to make your car too wide, I think anything above 25 cm may be a bit excessive.
It's also worth noting that being heavier isn't going to significantly affect your speed with Gravity Vehicle.
Angel and Unome hit the bullseye on this one. The only thing I would add is that you do still want to be careful about adding weight as you increase width and length. You want the center of gravity of your device to be as close to the rear as possible, while still remaining between your front and rear axles. Ideally, you do not want to distribute mass throughout the body of the vehicle, but rather concentrate it near the rear.

This brings up an interesting point of discussion: would it be possible to move the center of mass during the run of your vehicle? In the ready to run position, Id estimate wanting about 90% of the mass in the rear, but after the vehicle has descended down the ramp, it is more advantageous to have about 60-70% of the mass in the rear to prevent significant understeer and to aid in uniform braking. Perhaps it is possible to actually have the center of mass MOVE during the run. This could potentially be done near the end of the run (after 6-7 meters have been traveled) as a means of reducing vehicle speed. I envision a simple string wrapping around an axle after a certain distance has passed that moves the center of mass forward.
Food for thought. Id be interested to hear others' perspectives on this.
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Re: Gravity Vehicle C

Postby SluffAndRuff » September 9th, 2019, 3:41 pm

This brings up an interesting point of discussion: would it be possible to move the center of mass during the run of your vehicle? In the ready to run position, Id estimate wanting about 90% of the mass in the rear, but after the vehicle has descended down the ramp, it is more advantageous to have about 60-70% of the mass in the rear to prevent significant understeer and to aid in uniform braking. Perhaps it is possible to actually have the center of mass MOVE during the run. This could potentially be done near the end of the run (after 6-7 meters have been traveled) as a means of reducing vehicle speed. I envision a simple string wrapping around an axle after a certain distance has passed that moves the center of mass forward.
Food for thought. Id be interested to hear others' perspectives on this.
What's the legality on this, given the phrase in 3.g. "All parts of the Vehicle must move as a whole"?
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