Questions and Answers about Combat Robotics from Team Run Amok.

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7759 Questions and Answers about Combat Robotics
from Team Run Amok

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Stubby Shaft Solutions
Q: I'm a new bot builder trying to build an ant for the first time entirely on my own. I'm planning on doing a servo four-bar lifter and I'm planning to use four 30.4mm diameter 14mm wide LEGO tires. I'm curious about what you'd recommend for the drive motors to go with those wheels, given that the robot is a control bot. I've only build heavily aggressive horizontals before so it's a little different.

I was thinking n20s/30s (but I could totally be wrong) but all the ones I can find that actually have specs have a mere 8.6mm long shaft. Is there a good way to use those short shafts in a wheel that is nearly double the width? I see people all over using them with little to no issues but every time I have tried to it has not gone well because the shaft was wobbly because it was just not long enough. [Purdue, University]

A: Mark J. Good quality N20 gearmotors would have ample power for your control ant, but the gearboxes are potato chip fragile. In the 150 gram class they're fine, but even with wheel protection they don't survive well in full combat one-pound ants. For full combat I can't recommend anything without a stout planetary gearbox -- something like the Repeat Robotics Brushed Mk2. They are larger and heavier than N20s, but two would be enough.

If you're building for the plastic ant class you could certainly give N20s a shot. If you do a web search for N20 long shaft you'll find multiple choices for both threaded and smooth shafts in assorted lengths. The pictured example (fingers for scale) from eBay has a 23mm long shaft. Cheap eBay N20s typically have low-power motors, but you can swap in the high-power carbon brush robot motors if needed.

I must note that it is unusual to first pick your wheels and then design the drivetrain around them.


Enter the Asymmetric
Q: Hey, I want to build an asymmetrical beater bar weapon. I plan to use a Badass 1360 Kv motor, 21.6 voltage battery, and a 2:1 ratio gearbox. Can you guide me through using the team amok spinner weapon calculator? I'm confused on how to use it to make an asymmetrical beater bar. [Miami, Florida]

A: Mark J. I'm curious about the weight class of your robot. At 6.56 ounces the BadAss 2825 1360 Kv motor is too small for a hobbyweight, but if you're building a beetle you'd do better with a smaller motor and a heavier beater.

The Spinner Weapon Kinetic Energy Calculator lets you assemble and model a symmetric design from the geometric shapes available in the calculator, but an asymmetric design requires specialized center of mass and rotational inertia functions that the calculator cannot perform -- you'll need a CAD program for that. When you have your asymmetric weapon design, here's how to enter it into the calculator for modeling:

  • The CAD program you use to design your asymmetric beater bar will be able to provide the weapon Moment of Inertia .
  • Enter that value into the Asymmetric: MOI field in the Weapon Elements section of the calculator and leave the other fields blank.
  • In the Brushless Weapon Motor section enter your 'BadAss' motor data:
  • Kv: 1360
  • Ri: 13 mΩ
  • Volts: 21.6
  • Reduction: 2 to 1
  • Click Calculate .
The calculator will not have enough information to calculate Weapon Mass or Tip Speed but will give Weapon Speed and Kinetic Energy. Your CAD program can provide weapon mass, and if you want tip speed go back up to Weapon Elements and enter your weapon radius in the Impactors field, leaving the mass at zero.
I have added the above Q&A to the Spinner Calculator: Example Analyses page.

Wants to Calculate by Hand
Q: What is the exact formula to calculate each of these for my weapon: spin up time, RPM, and KE? I know you guys have a calculator but I want to calculate by hand. [Chicago, Illinois]

A: Mark J. Yea, and I want a deep dish pizza -- but I won't write up a synopsis of the eleventh and twelfth weeks of Mechanical Engineering 230 to get one. I don't suppose you'd like to research by hand as well?

The problem with simply handing out equations is that you need background in the subject to understand when and how to apply them. Then you'll find out that you require additional equations to supply the inputs to the first set of equations, and then if your weapon is a complex shape you throw out the equations and integrate r2dm over the entire object. How good is your calculus?

Quick and dirty:

  • Moment of Inertia for your weapon plugs into the kinetic energy equation below. Here is a list of equations to obtain the the moment of inertia for basic geometric shapes. If your weapon can be represented as a combination of these shapes, calculate the MoI for each part and add them up: Moment of Inertia Formulas. Wait, those formulas leave out mass -- This link is better.
  • RPM is the speed constant for your motor (Kv) times the applied voltage divided by the reduction ratio of your weapon drive. This approximation does not consider aerodynamic drag, which increases with the cube of speed. Super high RPM will simply not be attained regardless of what this approximation says.
  • Kinetic Energy = 1/2 × I × ω2 where "I" is the Moment of Inertia of the weapon and "ω" is the weapon's angular velocity expressed in radians per second. Radians per second = RPM × 2π/60.
  • Spin-up Time is a calculus thing that I'm not gonna try to walk you thru here -- but there is a handy shortcut that relies on the relationship between joules and average watt-seconds of motor output. I've got a whole webpage that outlines that process with plenty of equations: Estimating Weapon Spin-up Time.
Whatever answers you get be sure to check them against one of our calculators, and make sure you give me credit on your homework.
Non-Parallel Problem
Q: In a 4-bar lifter, what would be the adverse effects if the pivots on my 2 pairs of bars are not on the same plane, like the servo is a few cm off the floor and the other 2 pivots are mounted on the roof? (This is not Iceywave, fyi) [Newton, Mass]

A: Mark J. It's very common (and often advantageous) for the base of a 4-bar lifter to set in a plane angled relative to the plane of the top bar. The image below shows the layout of the 4-bar lifter for our beetleweight 'Zpatula' as modeled by the Team Run Amok 4-Bar Lifter Spreadsheet. Note that the rear pivot on the base frame sets well above the front pivot; it is typically the rear pivot that is elevated.

I suggest that you download the lifter spreadsheet (requires Microsoft Excel) and use it to evaluate designs with differing element lengths and pivot positions. It takes a while to find a design that combines the desired lifter motion with a consistent motor torque requirement. Have fun.


Wired Remotes Rule
Q: Wired remote control different structure [Maharashtra, Bharat]

A: Mark J. Sure. Try this:


ASCII Art and HTML Don't Mix
Q: There's Big Brother, There’s BIGGER BROTHER, but where's
__ ____ ___ ___ ______ ___ ______
| \ | | / _ \ / _ \ |_____| / __\ |______|
|__/ | | | |_| | | |_| | |_____ | | | |
| \ | | \__ | \__ | |_____| \ \ | |
|__/ | | _ | | _ | | |_____ __/ / | |
_| |_ | \_/ / | \_/ / |_____| |___/ |_| BROTHER?
\__ __/ \__ __/

: ) Iceywave [West of San Antonio ✪]

A: Mark J. Nope, not gonna fix your ASCII art so that it will work on my adaptive HTML page. It's too wide and life is too short.


It's me, Rodger the Web Gerbil.

Mark J. is hopeless at Cascading Style Sheets. He only upgraded to HTML 4.0 'cause I made fun of his skills. I waited 'til your post scrolled down the page far enough that Mark won't notice before I fixed your ASCII and made it adjust for narrow screens. Nothing much to it. Cheers.

__ __ ___ ___ _______ ____ ______ | | \ \ | | / _ \ / _ \ | _____| / __\ |_ _| | |__/ / | | | |_| | | |_| | | |____ | | | | | __ ( | | \__ | \__ | | ____| \ \ | | | | \ \ | | _ | | _ | | | |_____ __| | | | | |__/ / |__| | \_/ / | \_/ / |_______| \ ___/ |__| \__ __/ \__ __/
BROTHER?


More Reduction Please
Q: Hello, I am trying to build a 30Lb combat robot and I am dipping into some new electronics I haven't used before. For my drive I have 2, Andymark 775 redlines, geared down by a ratio of 10. I am using 2 Vex Talon SRX ESCs for both motors. For the weapon system I am using a Castle 2028 800Kv brushless motor, with a Mamba monster X esc. My batteries are Powerhobby 4S 15.2V 4200mah 120C GRAPHENE + HV Lipo Battery.

I want to run these batteries in series to provide 8S for the weapons system, while allowing the drive motors to run off each individual battery at 4S. The talons can handle 4S but the redlines are 12V motors. So I'll just change the rate through my drone controller to output less voltage. The castle weapon system is kind of what I'm new at. I have never used it before and I don't want to fry anything with the power system I am trying to implement. Can you help with advanced wiring diagrams for this system? [Bloomington or maybe Hartford]

A: Mark J. I had a similar question two years ago from a builder using dual 3S LiPos for the same purpose. There are some options to consider and some things to watch out for when attempting this type of circuitry; I'll direct you to the original 2023 post for the full set of diagrams and a discussion of pros and cons. Just substitute your 4S batteries in for the 3S batteries in the diagrams. Note also that your Talon SRX ESCs do not have battery eliminator circuits to power your receiver, so you will use the 3-wire cable from the weapon ESC for receiver power. You didn't ask for comments on your components, but I will note that a 10:1 reduction for the AndyMark 775 Redline motors is low for a 30lb 'bot. With 3 inch wheels a 20:1 reduction would be about right: see Optimizing Combat Robot Drivetrains. The AndyMark Redlines are quite commonly run at 6S voltage in combat robots so you should have no issues running them at full 4S voltage if you run them with an appropriate gear reduction.


No Steering Wheel
Q: drive train [Madhya Pradesh, Bharat]

A: Mark J. I've never actually tried, but it shouldn't be very hard. You can only go where the rails go, so just give it a little throttle and toot the whistle once in a while.

 

One... Two... Three...
Q: On a previous post (can't remember which one) you said flippers like 'Lucky' and 'Ziggy' wouldn’t be classified as three-bar lifters. Where’s the fourth bar?

- sincerely, Iceywave [West of San Antonio ✪]


A: Mark J. The gif you sent along with your question does not accurately depict the flipper mechanisms of 'Ziggy' (pictured below) and 'Lucky'. Both use true four-bar mechanisms with a short rear element. Bar mechanisms have no sliding elements. More about 4-bar mechanisms.

From a 2015 post in part two of the Robot Weapons archive:

The internet is full of references to '3-bar' mechanisms, but this is a misnomer. What they're calling a '3-bar' is actually a '4-bar' in which they fail to count the base as the 4th bar. A true 3-bar mechanism forms a triangle and has zero degrees of motion freedom - it won't move at all. Lifters use a 4-bar mechanism. Don't spread the incorrect 3-bar usage.

Q: Ohhhhh… that makes sense. I've corrected my flipper animation to be more accurate. Thanks!

- sincerely, Icewave


P.S. did anyone win this year’s 'Most Prolific Contributor Award'?

A: Repeating the 'Most Prolific Contributor' award would be poor game theory - it would be expected. For 2024 I gave a "Most Prolific Answerer Award" - it was delicious.


Conditional Bests and Worsts
Q: A question I'm sure you’re used to getting is: "What's the best combat robot ever?" The answer is either redacted, redacted, or some obscure beetleweight that won a single tournament, then retired before it could rack up any losses. But something I've been wondering is: What's the best combat robot to NOT win a championship? (Best win/loss ratio, or most fights won total)

Another question: What robot has the worst win/loss ratio, or most losses total?
- sincerely, Iceywave [West of San Antonio ✪]

A: Mark J. I do get a lot of "Who's Best" questions, but I direct them to Reddit where such questions belong and are frequently discussed. I'm pleased that you deflected to questions with more quantitative answers.

It is a great shame that BotRank.com crashed and burned. For many years they kept by far the best records of combat robot tournament results and analysis -- until event organizers decided that it was too much bother to send in their tournament results. In 2021 the BotRank data base corrupted and, without new data being submitted, it just wasn't worth the effort to repair. A great shame that reflects poorly on event organizers.

Fortunately, the Wayback Machine has a working mostly pre-corruption copy of BotRank from May of 2021 that is useful for historical questions such as you pose. A few highlights:

  • Heavyweight (220) with the most wins: "Sewer Snake" (81)
  • Heavyweight (220) with the most losses: "Sewer Snake" (34)
  • Heavyweight (220) with the best win percentage (no title and 10+ wins): "Voltronic" (70.6% - 12 wins 5 losses)
  • Heavyweight (220) with the lowest win percentage (10+ matches): "redacted" (20.0% - 3 wins 12 losses)
  • Any Weight Class: highest win percentage (30+ matches): antweight "Dark Pounder" (87.1% - 81 wins 12 losses)
I'll let you sift thru the archived BotRank for other 'bests' and 'worsts'.
Side Note - Although Combat Robot Hall of Fame member 'Rust in Peace' does not appear in the BotRank database, it has a verified record of 45 wins and 2 losses for a 95.7% win percentage. If you are willing to judge a robot by its performance at the time and place of its career, that puts it in contention for the most dominant combat robot of all time.

Maybe a School Project
Q: Working on making a small battle bot that will fit within a cubic foot. Could you recommend a power supply to use if we need to power 2 motors of 12V and 2 Amps. [Lima, Ohio]

A: Mark J. I don't know of any robot combat event that requires a competitor to fit in a "cubic foot", so can I assume this is a low-budget school project?

Matching a battery pack to a combat robot requires more information than you have provided. I can only give you a couple of general options:

  • The limited motor specs you provide would be common for a one-pound 'antweight' combat robot. A typical antweight robot with such motors might use a rechargeable 3S Lithium Polymer battery of about 300 mAh capacity. Lithium batteries are both light and compact but they require a specialized charger and must be charged and stored with care to prevent spontaneous fires. The cost of such a battery plus an inexpensive 3S charger could be around $40.
  • Some budget minded robot builders run their antweight robots on an 9-volt alkaline battery via an adapter cable. Your 12-volt motors will run a bit slower on 9-volts but will operate well enough. Alkaline batteries cannot be recharged, but a good quality 9 volt battery might power a simple antweight robot for over an hour before replacement.
I will mention that combat robot motors are often "over-volted" to provide greater power and speed. If you switched to 6-volt motors, they would provide improved performance over equivalent 12-volt motors when run on a 9-volt battery. Most small 6-volt gearmotors will survive quite well at 9-volts for the short periods combat robots are operated -- if the wheel size and drive train gear reduction are reasonable.
The Brushless Version
Q: Humorous Post Is there a specific transmitter you recommend to help control the ludicrous speed of brushless drive motors used in insect-class combat robots? [Brushless Hipster]

A: Mark J. You're in luck. Check out the 'Master Speed Control' on the new FlySky FS-i6 'Brushless Version':


Flashback: an archived post from 2016
Very Specific
Q: when did 2.4ghz radios become popular? [Havertown, Pennsylvania]

A: Mark J. February 3rd, 2008 at 10:24 AM pacific standard time.

Q: that's very specific.

A: That's when RoboGames decided that tracking transmitter frequency crystals was too much bother and mandated spread-spectrum radios for their combat events. The 2.4 gHz radios would have taken over eventually, but RoboGames pushed the issue.

About that same time RoboGames also decided that the single most popular large combat class - Hobbyweight robots - was too much bother and dropped it. Superheavys and Feathers followed. Power corrupts.


Robotica Video Library
Team Run Amok's friend in Erskine, Scotland has gathered together dozens of 'Robotica' videos from UK and US sources for the Robotica Episode Anthology Library on YouTube. Playlists include full episodes, commercials, and individual matches culled from a variety of sources. Save as a bookmark or subscribe for future updates.

Check the Charge
Q: I'm wiring up a beetleweight Peter Bar Kit with Rectified Robotics 35A bi-directional ESCs and Repeat Robotics Max Drive motors. On power up the drive ESC lights go blue, then quickly solid red. The drive works but the throttle is inconsistent. Sometimes there is limited power and sometimes the motors will run full speed. Any thoughts in what is causing the solid red light? [Redacted] A: Mark J. Have you checked the charge on your LiPo pack? A red LED on those reprogrammed READYTOSKY ESCs is a low voltage warning: maybe reading voltage too low for a 4S but too high for a 3S. Put a full charge on your battery and give it another try.

You might also want to clean up those solder connections and remove the stray solder on a couple of your power chips. It looks like your soldering iron has too little heat for this type of work. Some soldering paste and pre-tinning the wires would help a good bit, as would some practice on something less sensitive and expensive than an ESC.


Gram-for-Gram
Q: You often mention garolite as a suitable material for a combat robot. I replaced a damaged 6061 aluminum panel on my beetle with G10 garolite but had it fail under similar conditions. Isn't garolite supposed to be stronger than aluminum? Am I using the wrong type of garolite or is it just used if you need to save weight? [The Other Windy City]

A: Mark J. I'm gonna guess that you replaced the failed aluminum panel with a garolite panel of the same thickness. Except for density (aluminum weighs 50% more than an equal volume of garolite) the physical properties of G10 and 6061 are similar. The failure modes of a metal and a fiber composite differ but if an aluminum panel fails, a garolite panel of the same thickness will likely fail as well.

Gram-for-gram, garolite is stronger than aluminum. A garolite panel 50% thicker than the failed aluminum panel would weigh the same while offering greater strength. For improved strength think equal weight, not equal thickness.


Raising the Roof
Q: How effective would adding spacers to shock mount the lexan top panel be to counter the new, devastating hammer saws like Strikepoint in the beetleweight class? (On a 4WD wedge) Although having the armor resting above the chassis would lead to a less than ideal outcome against horizontals that manage to rip into the gap, I figure that it would buy me a few hits against overhead disc spinners and saws by giving it some distance away from the electronics. [Behind a Cloudflare Curtain]

A: Mark J. Any specific guidance I might give would depend on design details you have not provided. Beetle, 4WD wedge, Lexan top panel -- are we talking about a BotKits D2? General comments:

  • Lexan (polycarbonate) gets much of its strength from its ability to flex and stretch. Think of it as stiffened transparent rubber.
  • Lexan cracks and fails when it is fastened in a way that concentrates the stress of flexing to a small area. I typically recommend oversized mounting holes with rubber grommet inserts to allow some 'give' around the fasteners.
  • Raising a top panel on small spacers removes the support of the chassis edges and increases stress around the fastening points. The added height also increases stress on the fastening screws. You haven't mentioned how much additional space you are considering.
Is damage from overhead weapons something your 'bot has actually experienced, or is this speculation on your part? If this is an actual problem I might suggest simply replacing the top panel with something that does not flex enough to endanger your internal components: carbon fiber, garolite, or perhaps thicker Lexan.
Antweights for Tots
Q: Recently, I remembered watching a lost (?) BattleBots related charity event. It was held (I think) in late 2018 and was live streamed on Twitch. It featured several builders from the show competing with antweight versions of their robots. The bots I remember seeing were:
  • Wrecks
  • Stinger
  • Yeti
  • Huge
  • Free Shipping
    ...and
  • Battle Royal with Cheese
I've tried searching for this event, but I can’t remember what it was called. Do you have any more info?

- sincerely, Iceywave [West of San Antonio ✪]

A: Mark J. Pretty obscure, Icey. That was the BotBash Toys For Tots Charity Tournament, circa 2019.

"The Bot Bash Charity Brawl invited many of Battlebots most renowned contestants to our shop to fight with MINIATURE BATTLEBOTS in a tournament format! Miniature versions of Skorpios, HUGE, Tantrum, Free Shipping and more were all featured in this all out micro-brawl."
Here's a link to a twenty match video playlist on YouTube.

Q: Thank you for the fight playlist!

One more thing. I’ve also recently remembered seeing a TV interview with Michael Mauldin around 3-6 years ago, where he talked about The Lazy Toad Robotic Club and Grille. I’m pretty sure it aired on my local PBS station, 'KLRN'. I know you live in Oregon, but I thought I might as well ask, since I can’t find it online.

- sincerely, Iceywave

A: I do have an informative lecture given by the venerable "Fuzzy" Mauldin from that period, but he does not mention the Robot Club and Grille and I'm fairly certain it never aired on any PBS station. I'm afraid it will have to do: Fuzzy's 2019 BattleBots Lecture.

Alexa... remind me to start charging for questions like this.

You Already Have Gearboxes
Q: I want to get my D2 beetle running again, but I want to use something stronger than the generic Botkits 22mm gear motors to stay competitive and I can't get the Botkits motors to last on 4S. The Just 'Cuz Dragon 22mm Dartbox Gearmotors look great, but the weird clamp drive motor mounting system the D2 uses won't work with a square Just 'Cuz gearbox.

Any alternate recs for good 22 mm brushed gearmotors? [Social Media]

A: Mark J. Let me save you some money. The motor bolt pattern on the BotKits 22mm gearbox is correct for 130-size Dartbox motors, so just remove the stock motors and bolt up any of the brushed Nerf/Dartbox motors you like. You may need to shorten the shaft just a bit and/or transfer the pinion gear from the old motor.

If you want to stick with the 4S lipo pack I'd suggest the Just 'Cuz Gecko replacement motors for the Dartbox Pro. They're dirt cheap, will run all day on 4S, and at 16 volts pull only 7 amps each at stall. The Dragon motors can pull two-and-a-half times that many amps at their 12 volt max, require extra heavy duty ESCs, and are complete overkill for a four-motor beetle.

Reply: Nice, thank you


Heat Kills Motors
Q: Are there any brushless outrunner motors in the 2822 size class that can handle 14.8 volts? (can't find any online) If not, what will happen if I try to spin one only rated for 11.1 volts with a 4S? I'm doing an antweight based on the Fingertech mini beater bar, and I want to use a 4S for more drive and weapon speed, but although the page for the beater bar electronics bundle claims that it can handle 14.8 volts, the page for the motor itself (2822 1100 kv) says it can only accommodate a 2S-3S lipo. [Close to D.C.]

A: Mark J. The maximum voltage a motor can handle depends in part on how much load is placed on it. Too much load will 'bog down' the motor during spinup, causing it to draw extra current over an extended period of time. Extra current means more heat, and heat kills motors.

The FingerTech antweight beater bar kit has a relatively small weapon spun via a 1.7:1 reduction timing pulley set. This reduction reduces the torque load on the motor, shortens spin-up time, and prevents overheating on a 4S battery. If the same motor was used with a 1:1 direct drive it would not be prudent to run it at 4S.

If you want more weapon speed I would suggest sticking with a 3S battery and selecting a higher Kv 2822 weapon motor. Greater drive motor speed can make a 'bot difficult to control and is rarely usable in an insect-size arena. See the post Traction and Reflex Limited in the archives.

Q: 1lb beater bot guy here. I found out that Fingertech sells 2600 kv 2822 motors, which should do nicely for increasing the weapon speed. However, the page for the motor says that the motor draws 24A, and "over double the power output [of the 1100 kv motor] requires a larger ESC." The 40A ESC is a full 6 grams heavier than the 20A ESC, which I also may or may not have already ordered, so I decided to seek a second opinion.

Palm Beach Bots appears to be reselling this motor with the claim that it is compatible with the 20A ESC, so I'm at an impasse here. Should I bite the bullet and grab the 40A, especially considering that I'm still planning to use the 14.8V battery which would probably draw more current on spinup? (since more weapon speed on a vert = good, and I drove a D2 kitbot at 4S for a couple years, so I'm reasonably confident that I can handle whatever speed two Silver Sparks can output) Or will the max current being above the ESC's rating be irrelevant since the motor will stop drawing a lot of current after spinup?

A: You're operating under a number of bad assumptions. Where to start...

  1. I don't know where you got: more weapon speed on a vert = good. More speed equals more stored energy, but more speed also equals less 'bite' -- and bite wins matches. I suggest you read the Ask Aaron Spinning Weapon FAQ with particular attention to the 'Rotational Speed' section. Running a 2600 Kv motor with the FingerTech antweight beater at 4S will have the two-impactor weapon spinning at a theoretical 22,600 RPM. The weapon will have almost no 'bite' and - unless you get very lucky - will just skitter across the surface of your opponent.
  2. The 2600 Kv 2822 motor Palm Beach Bots sells is "Viper compatible" but the specs and measurements do not match the motor sold by FingerTech. It is similar, but not the same.
  3. When a specification sheet for a brushless motor gives a "Max Current" it is NOT the greatest current the motor can draw; it is the most current it can continuously draw without failing from thermal overload. A typical 2600 Kv 2822 outrunner might have an internal resistance of less than 0.05 ohm and can draw more than 120 amps if bogged down into its mid-RPM range. This is why it is important to load the motor lightly and let it pass thru the lower RPM range quickly.
  4. Likewise, a "20 amp" hobby ESC can provide 20 amps of current for some (usually unspecified) period of time, and will provide much more for short periods.
  5. Yes, increasing voltage does result in a proportional increase in current draw, both during spinup and perhaps disproportionately at max weapon RPM with a weapon that has a lot of aerodynamic drag.
  6. Beater bar weapons have notoriously high aerodynamic drag. Attempting to spin one at well over 20,000 RPM will bog down your weapon motor enough to draw well more than 25 continuous amps of current and it will melt -- unless of course the brushless ESC fails first.
  7. Driving a weaponless four-wheel-drive beetle on 4S is a whole lot different from driving a two-wheel-drive ant on 4S with a very fast vert weapon adding very large gyro forces into the mix. You'll spend a lot of time sideways on one wheel -- see Designing Around the Gyroscopic Effect.
I gave my best advice in answering your first set of questions. I have now given the background on that advice. More is not necessarily better, and more may bring disasterous consequences. Proceed as you please.
Can You Trust the Gerbil?
Q: Hello, I am wondering what thickness of TPU I should use for my beetleweight minibot? I started off with quarter inch, but it turned out to be to heavy. What should I do? [South of Hartford, Connecticut]

A: Mark J. See Frequently Asked Questions #17.


Pssst! Down here... It's me, Rodger the Web Gerbil.

Mark is kinda touchy about questions that don't provide the silly little details that might give him a chance to come up with a quantified answer. This time though, I think he missed something. I have access to all of his notes and the exotic software that he doesn't share with the robot community, and I found this equation filed under "If All Else Fails":

cos2 (x) + sin2 (x) × (eix + e-ix )2 / 4 + sin2 (x) × (e2ix + e-2ix ) / 4 + e2ln(sin(x)) + 1/2 = What Should I Do?
Plugging your values into the equation I get: "Make it thinner 'cause making it thicker won't make it lighter."

They Don't Get It
Q: What do your combat robots think of the current COVID-19 pandemic? [Kansas City, Missouri]

A: Mark J. My robots don't care. My robots don't spread, suffer from, or die from Covid-19 -- but you can. Don't be selfish. Follow the science. Stay safe.


Two photos of Aaron Joerger Remembering Aaron Joerger, 1991 - 2013

The 'Ask Aaron' project was important to Aaron, and I continue the site in his memory. Thank you for the many kind messages of sympathy and support that have found their way to me. Aaron's obituary

- Mark Joerger   
Killer Robot drawing by Garrett Shikuma

Q: how can robots help us deal better with hurricanes and why? [Ontario, California]

A: [Aaron] Few people in Nebraska are threatened by hurricanes, so send a swarm of killer robots into low Atlantic and gulf coastal areas to drive the puny human inhabitants toward Nebraska. Problem solved.

Robot haiku:

That's obviously
A question from your homework.
Do your own research.

Aaron's Greatest Hits! More of Aaron's Poems Aaron at Nickelodeon Robot Wars Aaron's Minecraft High Dive Video Aaron's World of Warcraft Player Guide


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