The robot could definitely handle turbo on 4" wheels. At a certain point it just becomes a nuisance to drive for not much benefit. The 3.25" wheels are also much nicer and more convenient to use and the grip wheels are about 10x better than the 4" variety (we didn’t have any on hand or we would have used them on the middle wheels).
Rubber bands lose a decent portion of the energy stored due to hysteresis. I am curious to see how efficient these rubber bands are at storing and releasing energy. Would you maybe be up for some testing in your free time? For science and such 
This place has the cheapest rubber bands that I have found, and they have the Alliance brand ones: http://www.bulkofficesupply.com/plasticrubberbands.aspx?p_331793=%252364
They have the “Sterling” type that Cameron posted the link to for $5.15 per 1lb box (they’re the same, just not blue), and “Pale Crepe Gold” ones that are supposedly even better for $6.66 per 1lb.
I believe the ones VEX sells now (for IMHO a crazy price) are the Alliance latex free type.
When I get a chance, I will record the tension of new rubber bands on the shooter, then shoot 200 shots or so and record the tension again.
I have finally finished the short documentary for the ri3d: VEX Nothing but Net Robot in 3 days documentary - YouTube
The cut-out template for the nautilus gears should be attached to this.
You guys are amazing. :eek:
Can this shoot all the way from one corner of the field to the high goal? Thanks for sharing this!
Yup! It is designed to fire user loads from the tile accurately into the goal.
In the video you said that your flywheel launcher with a lot of backspin wasn’t shooting the distance needed to reach the goal. About how far was it actually launching? Would it make it from midfield?
Have you tried it on the field yet? It looks great.
Have you guys ever tried the latex tubing from vex? I’ve heard that it’s more consistent in elastic force over time than the rubber bands. This is the year to test that idea.
The flywheel with a lot of back spin shot around 13ft, this would be more than enough to shoot from midfield.
No, we don’t have a field yet. Thanks for the suggestion, i will definitely try it!
Did you guys think of any elevation ideas?
I wasn’t referring to the decay of a rubber band’s properties over repeated use (although I am interested in that as well). Instead, I meant how you may put 2 Joules of energy into stretching a rubber band but will only get 1 Joule back out when you release it with the rest being lost due to hysteresis.
6 motors with turbo gears is different to 4 motors with speed gears. They have the same stall force, but the 6-motor drive has a higher maximum speed (of course) and also takes longer to accelerate to its maximum speed. That means each individual motor is drawing more current for more time while the robot accelerates, so the 6-motor drive is more likely to trip motor PTCs than the 4-motor drive. (Of course the 6-motor drive is also more likely to trip cortex or power expander PTCs, both for this reason and because there are more motors).
I half-wrote a post about this exact thing a couple of years ago that went through the theory in detail, but I never finished or uploaded it. If I get some time after exams I will.
Yes, we have thought of self elevating system, and a few ramp ideas.
Yes, I was talking about torque. I made an oversimplification which Oliver later clarifies
Was that actually tested, or are you just using experience?
That makes sense. I knew torque was related to current, which is related to the rate it overheats, but my train of thought was oversimplified because I forgot to consider time to accelerate to full speed. I don’t want to hijack the thread with theory, but could you PM me or upload it to a new thread if you decide to do it?
On a side note, are you approximating the 2:1 speed ratio, or am I derping on math?
I’m getting an output of about 24.5 with your set up and a 25.1 with a 4" on 2:1 (ignoring the torque-speed curve)
We did not have time to test it, however the robot had plenty of torque and it only weighs 11.5lbs. Based on these, we assume that it would be fine on 4" wheels and turbo.
I just approximated. I think it came out to 1:1.95 or something when we calculated it.
Based on your current experiences with these systems, what are your thoughts on them?
We did not have a lot of time to experiment however, we decided that the hanging type which is compatible with all robots would be the most ideal. With that being said, if self hanging is legal and easy to accomplish, then that is the best. However, if this is a very complicated design, then I would go with a ramp…