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Thread: Unlimited Rotational Kinetic Energy Storage?

  1. #11
    Guest
    Right, and the name is just as clever as the design! But because it is a spinning weapon, it is limited by the rules of a spinning weapon.

    Regards,
    Mack

  2. #12
    There was a time when someone was talking about having a vertical flywheel which would hook onto an axe, thus providing the axe with a lot of kinetic energy. Did this ever get built? Another related idea which Ive not seen implemented is to spin up an internal flywheel and hook onto an external disk/bar once up to speed - which means youre not quite so constrained when shoved against a wall (see Hypno-disk vs Tornado). You could do a CO2-less flipper the same way, possibly with a Cassius III-style (when it was still going to have it) vertical flywheel at the back as an exposed weapon as well, although the engineering would be... challenging.

    Ive often wondered about the idea of two counterrotating flywheels mounted above each other on a common axis, thus avoiding torque steer. The effect would be to chew into a relatively limited area on the opponent rather than to throw panels off, but it would stop the robot with the disks being thrown around the arena so much (although of course it puts more pressure on the axle). Is this a bad idea? Not that, for the same philosophical reasons as Mario, Im ever likely to build a spinner...

    If youre talking about maintaining the KE in the flywheel for the whole fight (not powering it from batteries or similar) then I think thats more of a challenge; the buffering needed to survive the various forces to which the robot would be subjected would make it very difficult to do anything useful, and youd need a *lot* of energy to be up there with the amount stored in CO2, petrol or even batteries.

    Just my tuppence.

    --
    Fluppet

  3. #13
    we did toy with the idea of having a second flywheel inside the shell to give a boost to the spin up but it would have taken too much weight away from the actual weapon and it would have been difficult to effectively transfer the energy.

    I also thought about the axe idea however the forces involved would require very well mounted components etc and prob in the end wouldnt be any easier than CO2.

  4. #14
    Guest
    I think I wrote something on the last forum about an axe like that. However, it was just an idea and never anything I had planned to build.

  5. #15
    Guest
    If all of the kinetic energy stored in a flywheel could be transferred into the opponent in one shot, Im sure that this would be more effective than a gas system. I agree that it may be difficult to design an energy transfer linkage that would be able to withstand the material stresses involved, but Im curious how much energy could be transferred with reasonable linkages (materials and geometry) without them yielding or quickly fatiguing. Transferring some fraction of the energy would simply mean that the unused kinetic energy of the flywheel would be left over for another shot or that it would take less time to spin the flywheel back up to speed.

    In theory, you could hook any weapon to the flywheel and could even link the drivetrain as well for bursts of speed for ramming or evasion. Perhaps a flipper *and* an axe/hammer could go into the same design (simultaneously, not as interchangeables), but space would surely get cramped.

    Fun to think, about, though! I think itd be fantastic to have a tossbot rather than a flipper that heaves the opponent vertically several meters. Getting under their center of gravity would be the challenge there, but seems possible.

    I think that gas systems are a bit of a cheat because they enter the ring with huge quantities of energy that was stored prior to the match. Non-gas systems must convert chemical energy into kinetic energy no sooner than the start of the match. But given that those are the rules, it does seem quite wise to take advantage of this inconsistency.

    Mack

  6. #16
    thats a good point Mack, never thought about it like that with the stored energy arguement........ hehe, fully spinning typhoon 2 entering the arena....... o the possibilities!

  7. #17

  8. #18
    Sorry for the above post.. it was posted before I realized that it was gone.Normaly the draft of the later part of this message.

    All experiments concerning energy storage in flywheels are done at ridiculous rpm like 100000 +. Even faster than turbos on cars.It is also the only way to put in enough energy in a limited weight. Using a 30 kg energy storage flywheel beats the purpose, as you can do that a lot easier with batteries. And before you say thats limited, look how hard Beta can hit.

    And for beating the other robot. Most flipperfights are over quickly but spectacular, even in arenas without moat around between inner and outher screen. How many times I have seen champions stacked against the sidewall of the RR arena, its about uncountable.
    You dont have to disassemble the opponent.It looks like fun, until you see your own machine scattered around the arena.-This is something you say yourself Mike.

    Now the mechanical systems to couple a flywheel to an axe, weapondisk or even flipper. The simplest,most weightefficient system I can imagine is the dry plate coupling from a Ducati.

    Forget anything with interlocking teeth or gears.The moment is way to big to distribute in a reasonable weight.

    And CO2, or other compressed gas feels like cheating?0.5L Gasoline is more calorierich than any CO2 bottle useable in RW.So thats also unfair.
    No the rules allow both, and it is up to the builders to use those unfair tricks as best as possible. Storm II (and 1) or Tornado neither use CO2 or gasoline, and still they are very competitive.Is the use of batteries then unfair?

  9. #19
    Guest
    Actually, the compressed gas in a CO2 bottle takes a fraction of a second to activate a weapon (for all intents and purposes, immediately after the match starts, the weapon can be used). The pressure drop of the escaping CO2 in the process will cause it to cool, but the energy is immediately available regardless of this cooling. To prove my point, consider that you vented all of your pressure in one strike/flip/etc. This could be done immediately.

    A gasoline engine cannot burn up all of the chemical energy stored in its fuel tanks all at once and transfer that energy into the opponent. A battery cannot drain all of its power through a motor in a single, quick burst either.

    The gasoline and battery powered systems are limited by their horsepower or voltage/current limitations, respectively.

    The appropriate analogy between a CO2 system and a gas or electric motor system would be entering the match with the chemical (gasoline or battery) energy pre-transformed into immediately usable energy such as kinetic energy (spinning disk) or potential energy (compress a huge spring such that it stores kJ-order energy).

    As for the amount of energy that can be stored in a flywheel, if you get a dense enough material positioned at the maximum radius your design wants to armor (tungsten is a very dense possibility), and you connect this with a lightweight set of spokes or slotted disk, you can store a tremendous quantity of kinetic energy at a few thousand rpm. You dont need 100000 rpm.

    Did some scavanging to collect the info, and if you had a tungsten ring that was 3cm thick, had an inner radius of 37.5cm and an outer radius of 40cm, it would have a mass of 35.1kg. If you then spun this ring up to 1000rpm, youd have 29kJ of energy. If you dumped all of this into a 100kg bot straight up, itd go 29.5 meters straight up!! And what goes up...

    This is a bit unrealistic, because it would take quite a long time to spin this disk up to 1000rpm, but you get the point; this would fit in a bot.

    I have an idea of how to get the energy out of the disk into whatever needs it, but I have to do a bit of research to determine if my approach would work...and then there is the minor detail of actually building it ;-)

    Mack

  10. #20

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