120 pounds of TTATT or Sting'Em

Huh, didn't know they had made that alteration but when I say throw I mean THROW. Touro still runs at only 6,000 rpms with a very small weapon. We'll be running at similar (crossing my fingers for higher) speeds but with a much larger weapon (better moment of inertia). This is primarily because we also have to use crappy batteries - budget constraints won't allow for them to be replaced.

The point of what I've been saying is no robot in the 120 lb class has yet pushed drums to their limit. When that happens, you're going to see a lot of old approaches fly out the window, just like they did with 15s.

And yes, Sum of All Fears will hold up to its own weapon. We've been making sure of this the whole time we've been working on it.

Highschool 120 class still has a limit on tip speed...at 300 it's almost a joke on a drumbot, compared to our 3 and 15 pounders.

Now full bodied spinners is a different story

That's still about 8000-9000 RPM for a 7" tip-to-tip diameter weapon (or 6" OD, .5" teeth), and I've not yet heard of a 120 that even approaches that. A couple thousand RPM more makes a LOT of difference; at 6,000 RPM, our drum would store around 40-50 kJ, while at it's top theoretical speed of 9167 RPM (which is what our budget next year is partly going towards) it stores nearly 110 kJ. Copperhead could store a similar amount, if it was run at the 300 fps limit.

1/2" blades on a 120 ???? sounds VERY tiny...I have 1/2" blades on my 3 pounder....

It's just different philosophies...if you guys get your NEW tech drumbot together, our OLD school TTATT clone with 1/2" or better Ti wedge will be happy to test its ability to NOT be a 1 hit wonder.... and our ability to take a hit and keep on going....

Actually...maybe there is no tip speed limit in college class...???? haven't checked.

If Sting'Em's drum were scaled up to a 120, tip speed wpuild be insane.....we can easily exceed 400 on the 15 pound version. If we convert to a hammerhead drum, blade width would be 1" or better.

Nope, there's a speed limit in our class... but it's higher: 400 fps . So redoing my calculations... we've got a ceiling of 11,800 RPM, tooth height of 1" over a 5.75" OD drum with 1/2" thick walls (total diameter 7.75"), total final weight of approximately 15 kg/30 lbs. With those specs, we'll have around 200 kJ as our peak storage.

EDIT: I did check, and HS still has a 300 FPS limit.

ps: I honestly forgot what our exact tooth height was - I've been busy the past few weeks. And now, back to studying for my Differential Equations final, which will likely eat me alive and everyone I know as well.

Jeff, Fluffy is 5.5" dia with 1/2" teeth. it's supposed to go 13k-14k. seriously. the limits are small.

Of course the limits are small, I'm just pleased to find that they're higher than I thought they were.

On the topic of the armor though, so long as it is made to take worst-case scenario hits (ex: somehow being prevented from moving and taking most of the energy from a weapon strike) it should be fine. It's just that 120s will need a little more on the calculation side going forward.

Jeff L wrote:

Of course the limits are small, I'm just pleased to find that they're higher than I thought they were.

On the topic of the armor though, so long as it is made to take worst-case scenario hits (ex: somehow being prevented from moving and taking most of the energy from a weapon strike) it should be fine. It's just that 120s will need a little more on the calculation side going forward.

Out Ti bots are not like that AT ALL....We hardly absorb ANYTHING. WHen you hit us, both bots will feel the worse case scenario.

Why should we give our opponent a freebee. If they are going to hit us, then their structure and all electronic and mechanical components had better be able to take it.

and they should hjope that the one hit destroys our TTATT stytle bots, otherwise we'll just do it again and again and again.

There are not many moving components in a TTATT style bot as compared to a spinner.

Spinners have parts that need to rotate at speed and with reasonable balance, motor, shaft, bearings other joints that are not hard fastened, etc plus much higher battery capacity, esc, belts .....

Here's a taste of what to expect as our 3 pound TTATT clone fights a drum on wheels...and we couldn't hit water if we fell out of a boat. WHile this one went the distance, by the end, the drum bot was pretty much trashed.

https://www.youtube.com/user/mspurk#p/u/12/t-qRG-xV0y4

Now we know that as you scale things up, material size to strenght is not linear.

Son of Thump is .1 Ti held together with 75 to 100 2.5mm screws

TTATT is .220" Ti held together with 75 to 100 10-32's

120 lbs of TTATT would be almost 1/2" Ti held together with 75 t0 100 3/8" screws.

No, I mean "Calculate the material required/dimensions/etc to have your robot survive if it was somehow magically welded to the floor and then took a hit from a drum that was a nearly perfect transfer of energy to your robot. Assume the magical welds do not break." That way, the robot really will never break. (this scenario could happen, but you'd have to do some funky stuff to get wedged into the arena wall/I-Beams with spikes before you'd be pinned sufficiently)

Needless to say if a bot gets ejected from the arena, and can't get back in, then it looses

Your drumbot and our brick stand a fairly equal chance of that happening.

Now if you magically transfer all your perfect energy to us, remember that our wedge is bearing on the ground, while your drum is on top of it.So who's gonna fly further? Ask Fluffy and numerous others.

I've been on both sides of the coin and here's another problem

As the match wears on, the spinner isn't creating near the energy that it was at the debut, unlees you have totally oversized your batteries.

A smart driver will bait a drum and avoid head ons for a bit, just to wear down the batteries.

TTATT style bots require almost ZERO battery power to keep the wedge down, which along with keeping the front facing the drum , is the only thing needed to help drumbots destroy themselves with their own energy.

Here's an example of the worse thing a wedge bot can do against a drum with decent power..charge a fully charged battery...lol

This version of Sting was creating 1k joules in a 3 pound bot....drum was at just over 3/4 speed

https://www.youtube.com/user/RattlerRobots#p/u/7/JJey-GVyL1s

On the down side, with a TTATT style bot, 1 mistake and you could be orbiting the planet

well, first off, copperhead didn't take any vertical hits with Ti, so it didn't get much of any air.

And richard, the drum bot that fell apart after fighting your TTATT beetle was probably a Sethbot, right? Built by Seth? From what I remember hearing about that fight, Uber Platypus was built in like three days, so I'm not sure that's the best example of what you'll be going up against...

Dan Curhan wrote:

well, first off, copperhead didn't take any vertical hits with Ti, so it didn't get much of any air.

And richard, the drum bot that fell apart after fighting your TTATT beetle was probably a Sethbot, right? Built by Seth? From what I remember hearing about that fight, Uber Platypus was built in like three days, so I'm not sure that's the best example of what you'll be going up against...

I agree 300% that uber was a drum on wheels, with no structure.

But the track record and my points to jeff and others sre:

1) SOT walks away with no damage...the motors shook loose, so I defaulted, but that was NOT with our new gbox setups as in Sting

2) TTATT 15 took Fluffy's hit and pretty much disabled it and every other bot it fought and didn't even blink...repairs consisted of watching paint dry.

3) Uber was ALL drum, which if the 15 and 120 builders go that route, then their structures will be nowhere near as solid as a ttatt clone.

Remember, ttatt ,SOT, 120 lbs ttatt and the 12 that we are currently working on are all CLONES. Nothing has been or will be compromised.

So, scaling up or down, and in analyzing the few fights that we've had, I think that we have a design that can be scaled and remain competitive in all classes.

This is why we built the 3's and now the 12...R & D which will hopefully lead to a final tweaked 15 and 120 for our educational purposes, which is what all this is about.

We are under no illusion that these are indestructible and we know that the future competition will be against proven and much sturdier bots than uber P.

This is why we are making the trip to Moto. Not cause we have nothing better to do....our goal is to arrive at BOTSIQ in SF with tested and proven or refined bots...It's a long, expensive trip to make , especially with untested bots.

Does this make sense to anyone??

Thanks for the input Dan.

Probably the area where I've put in the most confusion concerning Tech's line of thinking is we're doing this new 120 on a very tight budget, so went with a design paradigm that should give us very good survivability with much cheaper materials. Sure it'll look like hell by the end of a tournament, but the cost of replacing the aluminum is not a great concern to us.

The second area is in planning for future opponents with much greater capacity to do damage - it looks like TTATT/Sting'Em are mostly there already, but it would still be a good idea to check any areas where plates are joined or where fasteners are used when it's being scaled up. 120's will eventually pull far ahead of 15's proportionally where energy is concerned, so strengthening in at least those areas is a good idea for the 120 lb version.

I agree

Fortunately, scaling up 10-32's = 3/8" hardware..the strength difference is much greater than the actaul scale.

i.e 3/8 shcs's are exponentially stronger than 10-32's

OOPS..actually the opposite is true.....per size, the smaller screws hold more ...hmmmm....must be brain overload...we'd probably have to go up to 1/2" hardware...wow....mins you all the 10-32's are overkill in the 15.

Dowel pins on the other hand get stronger as size goes up unlike screws

Finally some progress on the 120...

Only alu in this bot, are some pullies and 2 inner frame rails....the rest is tool steel from 3/4" to 2" thick

I don't know if you already thought of this but another option than the 2 short mags powering the weapon is 1 long mag with a pulley on both ends of it. Similar to the way that falcon did it. It saves some space weight and a little less wiring to do, and is a bit simpler. Just a thought.

I don't think that they would be lucky enough that the belt spacing would work.....they opted for a belt on either end, with the belt pullies being part of the single piece drum

Also, to get the anticipated drum speed, the smaller motors would be a better choice...

Actually the inside scoop is that they are looking for some brushless motors that will do the job.

While still gathering feedback from nat's, a few NEW things have come up. 1 is a kind of neat setup that could allow this drum to spin well over 20k, possibly even 30k, which while WAY too fast, would sound pretty awesome in a 120.....

Thanks for the input....funny that I happen to have that pic somewhere.....how did that bot do? curious

I believe that it won in both the HS and college divisions when it competed. As for belt placement shaft extenders will do the trick. will that rpm keep you in the fps rules

30k in a 120lbs bot?!

I will pay my way down to Miami to see that in person.

im pretty sure falcon owned when it has competed

Falcon is one of the most impressive robots I've ever seen in person - I believe it won the HS championship twice, was retired, then brought out of retirement almost unchanged four years later and won the 2009 college championship.

EDIT: In addition, the whole thing is titanium (excluding the drum, I believe).

Found the pics...here's another good one

So what do you guys think about wheel placement on a 2 wd bot?

Falcon has them very far back, as do this year's shock bots....

ntertainment, and the touro bots have them much further forward.

mlec's can be placed just about anywhere, but they chose closer to the middle ala riobotz.

I think that mid placement helps with driveablility, while further back = obviously more nose weight which might possibly help vs wedges???

what say you??

What i have seen with the wheels in the back is ALOT of gyro when turning and a lack of traction to boot. I would keep the wheels in the middle if you stay with the 2wd. I don't understand why you are going 2wd from what i saw at nats your 4wd system was very effective. And you look to have the space for it

but weight may be another thing.
I also remember copperhead being to gyro flip itself over with its wheels all the way in the front