Mousetrap Vehicle C

[Balsa Man]

Balsa Man, what design are you using? (One mousetrap each way or both mousetraps connected with with a rotation in the string around the axle halfway)

Two traps-one driving each axle

[packer-backer91]

Balsa man what is your avg total score, ...I know you said you had trouble stopping yours accurately but how bad are you talking about 10+ cm away? Also one more question do you rely on the mouse trap to propel your vehicle both ways or do you use the mouse trap to power it one way and use a secondary scores of energy to get it to come back [like a rubber band or spring that is stretched out as the mouse trap goes forward?]

Actually, I just said we had to work on distance - a problem with getting all the power available on the return trap to the wheels. At Regionals, it ran out of go a little over a meter short of getting back - not a braking issue. Power is all trap- no secondary source

Really with that speed your vehicle could not cost to the finish? Because you said distance problem I thought that you had a stopping problem because of your high speed. So your vehicle is not under power as it comes back [accelerates then coast to a stop?] for mine is the vehicle is under power for up to last 3 feet [this was the plan to get the most out of the mousetrap]. I like your Idea of having 1 trap per axel would provide great acceleration I will try to see if I can replicate this, did you extend the kill bar any [attach a rod to it to make them longer? ]

[masterhat]

Balsa Man, what design are you using? (One mousetrap each way or both mousetraps connected with with a rotation in the string around the axle halfway)

Two traps-one driving each axle

we tried that but we had a bit of trouble with activating the second mousetrap. We tried a wingnut but it did not work very well. We also could not get the string to wind nicely around the axle on the way out. Do you use a ratchet? How do you do it?

Ours has been pretty bad (>40 seconds) so we would appreciate the help

[Balsa Man]

I want to be a little careful - with State a few weeks down the line. Also, I'm in the process of getting a better understanding of exactly what the problem we have is, so we can fix it. Fairly early in the season, we worked through a prototype chassis - proof of concept on various things, then our two teams put together lighter versions. They worked pretty much by themselves; I kept getting reports of things going well, issues to work through. It wasn't till 2 weeks before Regionals that it became clear they were having a significant problem.

Tripping the second trap is done with a momentum-activated (activated by the brakes going on) lever arm. We have a collar- a piece of tube that rides on the front axle (the axle that becomes the rear on the way back). Power string is pre-wrapped around it. Its held to one side, and kept from rotating, by a little piece of tape. One end has cuts in it that engage a little pin in the axle. The trap is positioned such that the string is running at, oh, a 45-degree angle, so the pull has both a rotational and sideways component, and its the sideways component that pulls the tube over- along the axle- to engage the pin. It worked fine on the prototype..... (3.5 sec down, 5.5 sec back)

At Regionals, I only got to watch one of ours. It appeared that a number of winds were wound off before engagement; much less than full power being applied to drive; coasted to a stop 1m+ short of the finish line. The other didn't get back quite as far.

[packer-backer91]

Bulsa Man, I like your design but all my thoughts going into the how your vehicle works, I had an idea to use yours and incorporate an idea I had but like many great ideas that people think of they don’t always work the same way in real life as they do when you come up with them, so today I went of CAD and starting to come up with a rough sketch of how I would make the vehicle it came apparent what I wanted to do is not possible. I wanted to have 4 wheel drive but the design I came up with would be impossible to work. Does anyone have true 4 wheel drive [4 wheel drive going Both ways]? I came up with a good idea to make the mousetraps operate it was coming up with a way to have two mousetraps work independently operating two arms pulling string off both axels but there is no way to get the string to be pulled of the one of the axels the way I drew it up. Anyway a long story short if anyone does this I would like to know how you did it.
The two problems I found in my drawing were:
The String can’t pull off one of the axels
There would be two different amounts of pull on each rod [has to due with angle of string and distance of arm from the axels] thus causing the potential for some weird stuff to happen. This may seam unclear to some people reading this but I know it would fail [this was the first problem that my vehicle had].

Does anyone use an arm extension under 30cm’s on their mousetraps. Just a question I have time at school dedicated to SO so I go through many thing to see how to maximize my vehicles potential and experimenting with arm length was one of the things I never tested.

[bwy]

The manual doesn't cover these questions, so I'm hoping they're okay but I want to make sure:
The way my car's brakes work (which isn't actually very well, and I could use some tips), the mousetrap stops but then starts moving back again toward the 7m line. Is that okay?
Also, I was wondering if we had to actually use the mousetraps' built in release mechanism, or if we could just let go of the lever bar to start the car.
With all of that, how decent is a distance score of about 20 cm and a time of about 26 sec with the lane bonus for an overall of 26?

[packer-backer91]

The manual doesn't cover these questions, so I'm hoping they're okay but I want to make sure:
The way my car's brakes work (which isn't actually very well, and I could use some tips), the mousetrap stops but then starts moving back again toward the 7m line. Is that okay?
Also, I was wondering if we had to actually use the mousetraps' built in release mechanism, or if we could just let go of the lever bar to start the car.
With all of that, how decent is a distance score of about 20 cm and a time of about 26 sec with the lane bonus for an overall of 26?

really the part about the car traveling back toward the 7m line is a venue specific call as I interpret the rules you are fine actually this is kind of a handicap. The best thing to do is to alert the judge doing the event what is going to happen so they are not surprised [this is always a good thing to have good communication with judges it was saved me at State just by alerting them of a function that may not be similar to other people
Yes, use the mousetrap release, somewhere in the rules it says that they must function as intended and making own release to me does not keep the same function of the mousetrap. The time score is good, the distance is not so good try to improve that but a time of 26 is a decent time.

[Balsa Man]

Does anyone use an arm extension under 30cm’s on their mousetraps.

We're using arms about 7cm long.
As to the rest of your discussion, I'm sorry, I don't follow.

[winneratlife]

Does anyone use an arm extension under 30cm’s on their mousetraps.

We're using arms about 7cm long.
As to the rest of your discussion, I'm sorry, I don't follow.

One thing:
7 cm...NO WAY it's coming back with a classic string pull-axle design...Maybe a string pull-hook-turn axle design, which is hugely inaccurate... (The short arm also explains the fast car)

Basically when it comes to extension, shorter arm = faster, longer arm = further...
Or at least that's what I've heard...

The two problems I found in my drawing were:
The String can’t pull off one of the axels
There would be two different amounts of pull on each rod [has to due with angle of string and distance of arm from the axels] thus causing the potential for some weird stuff to happen. This may seam unclear to some people reading this but I know it would fail [this was the first problem that my vehicle had].

The fact that the two mousetraps can't be in exactly the same place does create a lot of weird stuff...not really much you can do about that...
The string not pulling off of one of the axles? Huh? If the mousetrap triggers, either the string pulls off or breaks... I think your analysis might be wrong and that won't be a problem, unless I'm misunderstanding

Overall, this design has so many variables that the only way to make it work is build it, test it, adjust it, test it, etc. A sheet of paper doesn't do much...

[Balsa Man]

Does anyone use an arm extension under 30cm’s on their mousetraps.

We're using arms about 7cm long.
As to the rest of your discussion, I'm sorry, I don't follow.

One thing:
7 cm...NO WAY it's coming back with a classic string pull-axle design...Maybe a string pull-hook-turn axle design, which is hugely inaccurate... (The short arm also explains the fast car)

It goes out on a 7cm arm - in about 4 sec. It stops, and heads back. In early testing, the prototype was coming all the way back - in about 5 sec on a 7cm arm. The issue we're working through is getting the come-back to engage quickly, like it once was. Speed is a function of both arm length, and wheel/axle size ratio.