Air Trajectory B/C

[bernard]

I have a question about the size requirements.

In section 3 of the rules it says that the device must fit within a 70cm cube in a ready-to-launch configuration.

In section 4 of the rules it says that the device must be placed within a 1m x 1m square on the floor.

So, does this mean that right before I launch, the device must be able to fit within a 70cm cube in any orientation, and that the device also must be within the 1m square on the floor, meeting both requirements?

Or does this mean that when they fill out the checklist, the device has to fit within a 70cm cube, but during the actual competition, the device only has to be within that 1m square, and can be taller than 70 cm?

Your device must fit in a 70.0 cm (Div. C) or 80.0 cm (Div. B) cube in ready-to-launch position, and this cube can be placed anywhere within the 1.00 m square marked with tape by the Event Supervisor. And ready-to-launch configuration can be thought of as the configuration of your device the instant before your trigger it.

[ft55555]

I've never not been allowed to...

you should be allowed to... just like if you're using 2L bottles, you should be able to change the bottle between launches.

It's part of re-adjusting your device before the next launch, just as necessary as re-aligning your machine or making sure there's a new ball in there

Correct. You might want to look at the bolded language in rule 3.c., which we added this year just for this purpose.

I see the new language. Thanks. At first glance, it seemed to contradict the "must automatically return to ambient air pressure", but I see this requirement is intended to prevent the use of a chamber that remains pressurized between launches.

[chalker]

I see the new language. Thanks. At first glance, it seemed to contradict the "must automatically return to ambient air pressure", but I see this requirement is intended to prevent the use of a chamber that remains pressurized between launches.

I don't see how it contradicts it at all. Think about a plastic 2 liter bottle setup like a 'stomp rocket'. The bottle gets crushed during launch, and doesn't return to it's original shape, however the inside of the bottle will definitely be at ambient air pressure since the projectile is no longer in the barrel and thus the bottle interior is exposed to the atmosphere.

[Whiteheat073]

So my trebuchet actually did very well. It was able to hit the far target both times and hit the close target both times as well. Last minute the falling mass broke, but thankfully I was able to fix it literally 15 seconds before performing. Unfortunately we forgot our graphs, but besides that it went well.

[Whiteheat073]

Although, I would not recommend a trebuchet to future participants.

[Fanglin]

you should be allowed to... just like if you're using 2L bottles, you should be able to change the bottle between launches.

It's part of re-adjusting your device before the next launch, just as necessary as re-aligning your machine or making sure there's a new ball in there

Correct. You might want to look at the bolded language in rule 3.c., which we added this year just for this purpose.

I see the new language. Thanks. At first glance, it seemed to contradict the "must automatically return to ambient air pressure", but I see this requirement is intended to prevent the use of a chamber that remains pressurized between launches.

I would just use a plain old stomp rocket bladder. It is allowed, and you don't have to blow it up after each shot. This would make the shots much more consistent.

[BananaPirate]

Quick Question: Can we have two barrels (pvc pipes) with our air trajectory during impound and switch them during our 8 minutes when launching? Our barrel is too long at certain angles of launch so we might need two. It should be fine as long as the barrel not being used (not attached) still fits in the 70 cm cube right?

[windu34]

Quick Question: Can we have two barrels (pvc pipes) with our air trajectory during impound and switch them during our 8 minutes when launching? Our barrel is too long at certain angles of launch so we might need two. It should be fine as long as the barrel not being used (not attached) still fits in the 70 cm cube right?

Yeah that should be fine assuming you can get all 4 launches as well as switching the pipe within the allotted time

[kdwood]

In 3d., it states that the mechanism must stay withing an 80 cm cube while in a launching position. Does that rule apply for when the mechanism launches, i.e. the arm goes over 80 cm high and then returns to the cube while launching?

By "ready-to-launch configuration," the device seems to only need to fit within an 80 cm cube at the start of launch, not after.

Actually, read rule 4c: "No part of the launching device may extend outside of the launch area before or after a shot. If part of the launching device extends beyond the launch area during the launching action, it must return to and remain in the launch area immediately after the launch without assistance of the competitors." So the device must start AND end within the launching area, though during the launch parts of the device can exit the area; they just need to come back into the launching area on their own.

[windu34]

In 3d., it states that the mechanism must stay withing an 80 cm cube while in a launching position. Does that rule apply for when the mechanism launches, i.e. the arm goes over 80 cm high and then returns to the cube while launching?

By "ready-to-launch configuration," the device seems to only need to fit within an 80 cm cube at the start of launch, not after.

Actually, read rule 4c: "No part of the launching device may extend outside of the launch area before or after a shot. If part of the launching device extends beyond the launch area during the launching action, it must return to and remain in the launch area immediately after the launch without assistance of the competitors." So the device must start AND end within the launching area, though during the launch parts of the device can exit the area; they just need to come back into the launching area on their own.

Yeah I knew that was in the rules somewhere, just couldn't remember. Anyways, I recommend not going outside launch area in the first place and avoiding this whole mess.