Spinner Energy

**stinger** · 12th January 2004, 19:56

Elsewhere on the FRA site, you may have seen that Im working with James Baker on some guidelines for Spinning Weapons. We have a neat way of assessing the Kinetic Energy in your designs which shows how fast we would let you run. We only need to make a crude assessment of Style (mass distribution) + measured figs for actual Mass & Dia.

Now, at present the FRA are NOT sanctioning use of spinners except under controlled conditions in Class 2 arenas. James and I want to set sensible rules that will allow more spinners, albiet with a limit on permissible rpm.

We suggest that you start designing them with alternative drive systems - one geared down for live events, and another geared up for serious combat. You never know, the reduced spin-up time with a low ratio might even be an advantage ! Please note, that we do not anticipate permitting electronic speed limiters (but would allow reduced voltage).

We need to collect as much data as possible to decide where we should set the level for different arenas. For example we believe the most aggressive spinner is up at around 38KJ, with the most well know in the region of 16KJ, and Feathers peaking at 5-6KJ.

We have some experience of 6KJ in Jonnos arena, and want to collect as much additional info as poss to help establish challanging, but manageable poower limits.

Please post details here, or if you dont want to go public, then send them direct to me or James.

We would like to see Basic Dimensions of the spinning element plus its Mass and anticipated RPM. If you have a calculation for KE - then please post that as well.

Thanks,
Kevin S

**ThreeFingeredJack** · 31st August 2016, 21:04

So this is an old thread which I'm digging up in the aftermath of the recent new series. I've a few questions about vertical spinners which I'm hoping 9 years of experience can answer.
1. Are they legal or not? I'm getting mixed messages across the forum, the "rules" and what I've seen on the show. I appreciate the arena operator has the last say but the TV series was PACKED with spinners which seemed to violate 2 if not 3 of the rules applying to spinners.
2. This energy calculator on the teamchaos site- do they have a version in metric, or at least specifying what units are being used? Has this calculator been proved to work, what margin of error have people observed?
3. Earlier in this thread Richard from 13B appeared to basically justify why spinners should not appear at all...which is concerning. I want one. He predicted the possibility for a spinner to damage the arena and or send shrapnel at polycarbonate piercing speeds. At least one of these came true during the recent series, (see how I avoided the spoiler there), on this note, are they being considered for banning/regulating further to the '3 Rules'?
4. If I went with a 700mm disk diameter saw...that allowed or not? If not technically storing kinetic forces for impact purposes, but instead a glorified circular saw blade...still counts as a spinner, or a saw? Loophole?
5. Anything else anyone can give in terms of advice. Disk-edge mph optimums, material choices (hardox for everything?), motor protection tips etc.

**Garfie489** · 31st August 2016, 21:18

1) Spinner Rules are in context of the arena they are run in. Grade 2 and above has no stated limit, other than what the EO sets. Grade 3 is 500rpm, or what the EO sets - best advice is to read the rules carefully and in detail, and learn how they apply to different EOs and events.

2) Its always best to double check your figures from a unrelated source if unsure on the calculation. However that sites confused me aswell as it appears to be american, and thus imperial - yet gives the answer in metric. This is why you shouldnt use imperial for anything scientific :P

3) No, tip speed may be limited by EOs (EO has final discretion and may vary between). However youll likely still get over 200mph before they start getting cautious.

4) There is no difference between blade type, if it rotates its a spinner. Some robots have bars, beaters, ect - they arnt discs but come under the same regulations. Best advice is to not try finding loopholes in the regulations as the EOs will likely see through that and ban it anyway. If your defence is that its in the wording of the rules, tough - they decide if you enter their arena or not.

5) Build it at featherweight scale first. That way you can learn the technology and structural requirements needed whilst also not breaking the bank

**typhoon_driver** · 1st September 2016, 21:09

The team cosmos calculator gives accurate figures but they are only as accurate as the info you provide. It's obviously very simple so can't help you with complex curves etc. The most accurate method is to model the spinning mass in CAD and get your moment of inertia from there. Use that with the formula and you will have a bang on answer (assuming you ever reach the rpm you assume).