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illusionist wrote:I'm guessing some sort of plastic, but I can't think of any material that would be able to bend in order to fit the curve of the ramp... Or BalsaMan, if you dont mind, are you guys using straight rails (I don't want to be too nosy into your design, as you've already shared quite a bit with us)?

No problem, up to a point, for now, of course....

The rail is straight on the upper, flat section of the ramp, and follows the curve all the way to the bottom; 29cm radius on the curve. Some plastics do have a very low coefficient of friction...

fishman100 wrote:Agreed with Balsa Man; I've only seen a few teams without a "guide rail" system of some sort. Some use tape, others have the guide rails as part of the ramp, etc.

Can you explain what you mean by "tape"? I currently do not have guide rail system and I'm looking for a method that is very simple.

Faustina wrote:

fishman100 wrote:Agreed with Balsa Man; I've only seen a few teams without a "guide rail" system of some sort. Some use tape, others have the guide rails as part of the ramp, etc.

Can you explain what you mean by "tape"? I currently do not have guide rail system and I'm looking for a method that is very simple.

The simplest method would be to put markings on your ramp and line up the tires of your vehicle with those marks. You could also have two paperclips (in the front and rear) pointing down (not to be confused with the one on the side for measuring), to line up with a line in the center of the ramp. That's probably the simplest method as it requires two paperclips and a sharpie.

sachleen wrote:

Faustina wrote:

fishman100 wrote:Agreed with Balsa Man; I've only seen a few teams without a "guide rail" system of some sort. Some use tape, others have the guide rails as part of the ramp, etc.

Can you explain what you mean by "tape"? I currently do not have guide rail system and I'm looking for a method that is very simple.

The simplest method would be to put markings on your ramp and line up the tires of your vehicle with those marks. You could also have two paperclips (in the front and rear) pointing down (not to be confused with the one on the side for measuring), to line up with a line in the center of the ramp. That's probably the simplest method as it requires two paperclips and a sharpie.

That wouldn't necessarily ensure that the vehicle leaves the ramp at the same angle/direction each time though. It's definitely better than nothing, but I still think a guide rail system would be better (however, there is a large amount of friction that comes with a rail system unless the proper materials are used).

illusionist wrote:That wouldn't necessarily ensure that the vehicle leaves the ramp at the same angle/direction each time though. It's definitely better than nothing, but I still think a guide rail system would be better (however, there is a large amount of friction that comes with a rail system unless the proper materials are used).

Right. there's no doubt that a rail to guide the car would be the best solution but it's not easy to pull off.

You could also use the release mechanism to hold the car straight and in the same position every time. Maybe have the flat rear of the car against the mechanism so you really just have to push it up against it and it'll get lined up. Has anyone tried anything like that?

Edit:
Also, don't you think there could be instances where a slight misalignment with the rail system cause the car to slow down a lot and miss the target distance? The whole point of the rail is to prevent this, but if it was slightly off the rail would try to correct it but we also use long cars that don't turn easily and that would just slow it down. In cases like that, you'd rather have the car be off the center a bit than not go very far.

Faustina wrote:

fishman100 wrote:Agreed with Balsa Man; I've only seen a few teams without a "guide rail" system of some sort. Some use tape, others have the guide rails as part of the ramp, etc.

Can you explain what you mean by "tape"? I currently do not have guide rail system and I'm looking for a method that is very simple.

I took Gorilla Tape and tore off strips and taped them to the ramp. Since one strip of tape wasn't thick enough to ensure that the wheels would follow the guide rails I made, I took several pieces of tape and placed them on top of the existing tape.

luckisdedication wrote:What is everybody doing to ensure that their vehicle comes off the ramp perfectly straight?

We have a track/rail on our ramp, with a small guide wheel on the front and back of our vehicle that rides the it down. Works okay, a few days ago we noticed it lifting the front wheels off the ramp... which was very bad of course =/ But we got it mostly fixed

Half-Blood-Princess wrote: We have a track/rail on our ramp, with a small guide wheel on the front and back of our vehicle that rides the it down. Works okay, a few days ago we noticed it lifting the front wheels off the ramp... which was very bad of course =/ But we got it mostly fixed

.
That's a good way to get tracking with low friction. Lifting the front wheels sounds like the front guide wheel is/was mounted in front ot the front axle. If so, as you go into your transition curve, distance down to the ramp surface will reduce (from what you have in flat section), pushing the wheel up. If mounted directly under the axle, that distance won't change in a curve. You may have figured that out already......

We got the gravity supercharger working at full power over the weekend for the first time; some new dilithium crystals arrived by shuttlecraft; a little more speed now. 5 days to Regionals

sachleen wrote: You could also use the release mechanism to hold the car straight and in the same position every time. Maybe have the flat rear of the car against the mechanism so you really just have to push it up against it and it'll get lined up. Has anyone tried anything like that?

Edit:
Also, don't you think there could be instances where a slight misalignment with the rail system cause the car to slow down a lot and miss the target distance? The whole point of the rail is to prevent this, but if it was slightly off the rail would try to correct it but we also use long cars that don't turn easily and that would just slow it down. In cases like that, you'd rather have the car be off the center a bit than not go very far.

Using the release mechanism as a consistent position holder is indeed a very good, and easy to implement way to get some alignment. On rail misalignment, as long as the rail is a) straight, b) aligned along the "fall line (the "straight way down - line a marble would take), and c) the guides that track the rail are aligned with the wheels (so the car's not "crabbing- the wheels not trying to run a different line than the rail runs), the interaction of rail and guides will be minimal.

Balsa Man wrote:

Half-Blood-Princess wrote: We have a track/rail on our ramp, with a small guide wheel on the front and back of our vehicle that rides the it down. Works okay, a few days ago we noticed it lifting the front wheels off the ramp... which was very bad of course =/ But we got it mostly fixed

.
That's a good way to get tracking with low friction. Lifting the front wheels sounds like the front guide wheel is/was mounted in front ot the front axle. If so, as you go into your transition curve, distance down to the ramp surface will reduce (from what you have in flat section), pushing the wheel up. If mounted directly under the axle, that distance won't change in a curve. You may have figured that out already......

We got the gravity supercharger working at full power over the weekend for the first time; some new dilithium crystals arrived by shuttlecraft; a little more speed now. 5 days to Regionals

Yeah that's exactly right, it's still mounted in front of the front axle. But now we have it bent up wards just a tiny bit, so it's not lifting it up anymore

Cool,
Good luck at your Regionals.