Bar spinners

Bar spinners
Arena Cleaner knocks The Cat out with its bar spinner
Weapon Category	Heavy rotating weapons
Robots
Pioneer(s)	Vicious-1 (spinning hammers, 1997 US competition) Hammertron (spinning hammers, televised series) Fluffy (bar spinner)
Notable Robots	Arena Cleaner, Carbide, Fluffy, Ironside3 (horizontal) Aftershock, IG-88 (vertical)

Bar spinners are a type of heavy rotating weapon found amongst robots appearing in Robot Wars. In televised series, they first appeared in Series 3, in the form of a spinning hammer wielded by Hammertron. Later on, bar spinners gained widespread recognition following Fluffy's appearance in Series 5, and would become one of the more common spinner types in the Revival Series.

In Robot Wars, the most successful robot to use a bar spinner was Series 9 champion Carbide. Other successful robots with this weapon type include Battle of the Stars co-champion Arena Cleaner and Series 9 third- and fourth-place finishers Ironside3 and Aftershock, whose bar spinner was interchangeable with a vertical spinning disc.

Prior to televised series, the spinning hammer concept was pioneered by 1997 US middleweight competitor Vicious-1, which utilised a double-ended "Spiked Hammer Arm" as part of its extensive weaponry. The weapon, capable of inflicting significant damage for the era, also earned major success, with Vicious-1 going on to win the Middleweight Face-Off championship that year.

Definition

Bar spinners are powered heavy rotating blades, designed to accelerate quickly and inflict damage through the kinetic energy stored within them. Bar spinners differ from flywheels and other spinning discs due to their shape - usually a long rectangular bar with blunt, bladed or spiked tips - which offer much more engagement with the blade as a result of their smaller but denser designs. Bar spinners can be similar in shape to lawnmower blades, but are distinguished by their generally heavier weight, and use for concussive blows over cutting.

Heavy rotating blades are very versatile weapons. Not only are their designs open to variation, but they can also be mounted horizontally or vertically, incorporated into an invertible design, and designed for either piercing or hammering other robots. Bar spinners must be equally weighted on both halves of the bar, but are not required to be symmetrical. Some are capable of operating bi-rotationally, as with the weapons of IG-88 and Tauron, while robots such as Ironside3 and Apex were designed to accommodate different types of bar spinner as interchangeable weapons.

Before bar spinners rose to prominence after first being used by Fluffy, Robot Wars previously saw competitors use spinning hammers as weapons, functioning much like a bar spinner, but with externally weighted tips. Robots such as Zorro also used triangular-shaped bar spinners with three blades, covering the entire surface of the robot in a similar manner to a full-body spinner.

Advantages and Disadvantages

"Bar spinners such as Carbide try to take engagement to the extreme. By compromising on the flywheel effect of having the mass on the outside of the spinner, having a rotating bar means you have literally no limits on the amount of engagement. This trade-off increases wind resistance of spinning bars, which in turn increases current draw for your motor and places more stress on your components."

— Robot Wars: Build Your Own Robot

Advantages

Fluffy cleaves Pussycat's blade from its mount

Carbide tears off Thor's front plate

IG-88's vertical spinning hammer rips away a panel from Scorpion

The gyroscopic forces acting on Carbide's bar spinner allowed it to remain upright even after it was thrown by Eruption's flipper

• As bar spinners do not require an outer ring, they can have a larger radius than a spinning disc. This is an advantage because it means a spinning bar will have a larger reach than an equivalent spinning disc.

• An additional advantage is that, unlike a flywheel, the smaller surface area of a bar spinner can also help minimise the potential of the weapon being damaged by opponents. It was with this rationale that Team Shock equipped Aftershock with both symmetrical and asymmetrical types, to counter the rival horizontal bars of Carbide and Ironside3.

• Depending on the design, lighter bar spinners offer greater allowances for heavier and more durable armour. Aftershock's 14kg bar configuration in Series 9 incorporated 6mm HARDOX panels in place of the polycarbonate equivalents paired with the regular 24kg disc.
• Because the weight of a bar spinner is distributed in a smaller but denser weapon than a disc, the attack zone can be greater whilst actually increasing damage output. Compare the weapons of IG-88 and Vader for example.
• Regardless of their orientation, bar spinners can be incorporated into invertible designs. Invertible robots with horizontal types proved to be especially successful on Robot Wars, including Carbide, Fluffy and Arena Cleaner. Meanwhile, Tauron demonstrated that a vertical bar could be incorporated with similar size and power to horizontal counterparts.
  • In common with horizontal flywheels, horizontal bar spinners on invertible robots can also operate equally as effectively upside-down without the need for a reversible speed controller. If designed to spin in one direction while upright, the weapon will keep spinning in the opposite direction once the whole robot is inverted.
• Like other vertical spinner types, bi-directional motion is possible for vertical bar spinners if designed to incorporate features such as a reversible speed controller. IG-88 and Tauron are two competitors whose weapons were intended to operate in forward and reverse directions; the latter to ensure compatibility with its invertible design.
• Depending on the weapon's size and power, the gyroscopic forces of a horizontal bar spinner can prevent the robot from being completely flipped over when the weapon spins at full speed. Carbide demonstrated this characteristic during two of its fights against Apollo in the Series 8 Grand Final, and in its Series 9 Grand Final battle against Eruption.
• Depending on the robot's design, a vertical bar spinner can also function as a self-righting mechanism, pushing or 'kicking' the robot back onto its wheels as the weapon makes contact with the arena floor or walls. Aftershock's asymmetrical bar spinner demonstrated this capability during its Series 10 Heat Semi-Final against Carbide.

Disadvantages

Fluffy was very unreliable, and often broke down even after dominating its battles

Carbide was vulnerable to attacks from TR2 and Apollo after its weapon clutch failed during the Series 8 Grand Final

An impact with Aftershock (left) causes Ironside3 to lift off the arena floor

Apex's shaft collar breaks off in recoil

Apex disassembles in mid-air

• Due to their increased wind resistance over flywheels, bar spinners require a lot of kinetic energy which draws more current into their motors and places more stress on their components. This can lead to various reliability issues, including malfunctions. Zorro was defeated in its first-round battle in Series 7 after its excessive energy consumption drained the robot's batteries of essential power to its weapon and self-righting mechanism. Fluffy and Carbide's blades were also susceptible to failure on various occasions, with the latter's defeats to TR2 and Apollo in the Series 8 Grand Final being partly blamed on a malfunctioning weapon clutch.
• As with other spinning weapons, the recoil from a bar spinner can also adversely affect the robot's reliability. Fluffy was notorious for breaking down as a result of its attacks on other competitors throughout its appearances, such as its Series 5 Heat Final battle against Pussycat.
• Furthermore, said recoil can also cause the robot to be launched in a different direction or even airborne, as shown in most of Carbide's battles during Series 8-10. This could also result in the robot somersaulting or being flipped upside down once the bar hits the floor or other robots, as shown in Ironside3's battles against Eruption and Aftershock in Series 9. The largest bar spinner in Robot Wars, Apex, lost its bar spinner entirely in a battle with Track-tion, catapulting the remaining robot across the arena, while the spinner broke through one of the inner bulletproof wall panels.
• As one of the heaviest weapons, very few robots with this weapon have a fallback in the event that the weapon breaks. Carbide struggled to respond to TR2 and Apollo's attacks in Series 8 once its weapon failed to work, and Das Gepäck was able to recover ground once Fluffy's weapon broke.
• Given that bar spinners were prohibited from most live events, it is very expensive to create one when chances of qualification are limited. As with other spinning weapons, their dangerous nature also restricts opportunities for testing outside of Robot Wars, potentially compounding the reliability issues discussed above.
• Unlike discs, which tear through obstructing objects due to the minimal surface area to be impacted, heavy rotating blades are easier to stop if a robot is heavy enough to absorb the impact. Fluffy's weapon was halted by Das Gepack in the UK vs Germany final, and was unable to start spinning again.
• The gyroscopic forces of a vertical bar spinner can adversely affect the robot's control as it turns round, often resulting in the robot lifting onto one side as with vertical flywheels and drums. This characteristic was noticeably demonstrated by Tauron during its Series 10 Group Battle, although with no significant effect on its performance in battle.
• The mounting for bar spinners often results in a robot's weapon chain or belt being exposed, which once allowed Nuts 2 to disable Carbide's weapon during the Series 10 Grand Final.
• Horizontal bars that break and become asymmetrical can cause major stability issues, both through weight imbalance and the gyroscopic forces generated from the damaged weapon. This is often manifested by the entire robot shuddering and shaking violently every time the weapon is powered up in this state.

List of robots with Bar spinners

Robots are listed in alphabetical order.

DESKTOP MODE ONLY: Robots from the 1994-1997 US competitions are listed with a purple background.

Robot	Series Appearances with Bar Spinner	Notes	Image
Aftershock	Series 9-10	Used a 14kg vertical spinning bar, interchangeable with 24kg (Series 9-10) and 30kg (Series 10 only) vertical flywheels. Bar spinner rotating at 3,000rpm. An 18kg asymmetric bar spinner was also created for Series 10, with self-righting capabilities. Finished fourth in Series 9.	Aftershock with its asymmetrical bar in the Series 10 arena
Ansgar 3	Series 7	Competed exclusively in The Third World Championship. Blade weighed 10kg.
Apex	Series 9-10	39.75kg (originally 37kg) horizontal bar which covered the robot's whole surface area, the heaviest bar spinner in Robot Wars. Could spin at 1,750rpm. Interchangeable with a 38.45kg asymmetrial bar spinner in Series 10. The symmetrical bar famously detached from the robot in battle.	Apex in Series 10 with the asymmetrical bar spinner
Arena Cleaner	Series 9	Competed exclusively in Battle of the Stars. A 20kg spinning bar with two spiked blades. Joint Battle of the Stars champion along with Kadeena Machina. Later repurposed to compete as Cathadh.
Axe-C-Dent	Series 5-6	Featured only one hammer on its vertical spinning blade, with the reverse serving as a counterweight.
Carbide	Series 8-10	Weapon weighed 25kg and spun up to 2,300rpm. Series 9 champion and runner-up of Series 8 and 10. Featured three interchangeable bar spinners for Series 10 - the original bar, a second 25kg bar with green tips and a heavier red bar with curved tips. The curve-tipped bar necessitated a lighter weapon shaft, and went unused after seizing up during a safety test, amongst various issues.
Cathadh	Series 10	Represented the United States of America in Robot Wars: World Series. Previously competed as Arena Cleaner.
Crank-E	Series 9	A 'vertical asymmetric spinner', weighing 22kg and rotating at 6,000rpm.
Crazy Coupe 88	Series 8	Bar spinner was placed at the front, accompanied by a rear vertical disc.
Chopper	Extreme 2	Overhead horizontal blade.
Donald Thump	Series 10	Vertical bar spinner, weighing 16kg and spinning at up to 5,000rpm.
Fluffy	Series 5-7, Extreme 1-2	A double-headed 'spinning axe' weighing 20kg. Series 5 Heat Finalist and joint winner of the UK vs Germany Special, along with Das Gepäck.
Frostbite	Series 9	Weapon spun at 2,000rpm, and was noted for its small dimensions compared to most other bar spinners.
Hammerhead	Dutch Series 1	Angled, double-ended 'spinning hammer'.
Hammertron	Series 3	A double-ended 'spinning hammer', mounted on a panel which lifted up to 90 degrees and was said to double as a self-righting mechanism.	Hammertron, the pioneer of this weapon type
I Bot One Beta	Series 7	Two small horizontal blades, referred to as 'discs' on its statistics board.
IG-88	Series 7	A double-headed 'bi-rotational axe', capable of spinning in both forward and reverse directions.
Ironside3	Series 8-9	Weapon weighed 18kg, spun at 1,500rpm and was one metre in diameter. Finished third in Series 9, equipped with interchangeable flat- and 'cutting-edge' bladed bars.
Killerkat	Series 7	Horizontal bar spinner.
Mobot	Series 7	An early attempt at an 'undercutter' spinner, weighing 20kg and spinning at up to 45mph.
Paul Bunyan	US Season 2	A four-bladed 'spinning cross'. Spun at only 230rpm.
Propeller-Head	US Season 2, Nickelodeon	US Season 2 Grand Finalist and Nickelodeon Mayhem Champion.
Shockwave	Extreme 1	Vertical spinning blade.
Tauron	Series 9-10	Weapon weighed 13kg and spun at approximately 3,100rpm in Series 9; later upgraded to an 18kg bar in Series 10 with a rotational speed of 3,600rpm and a tip speed of 244mph. The spinner was bi-rotational and mounted on a pivoting assembly, enabling it to maintain an upright position even when the robot was inverted.
Terror Turtle	10, Extreme 2	An overhead spinning bar in Extreme 2. After using a spinning disc in Series 7-8, Terror Turtle was equipped with a small horizontal bar spinner in Robot Wars: World Series.
The Alien	Series 5-7	Weighed in between 7-12kg and spun at between 1,000-1,300rpm. A 'spinning hammer' incorporating two 1.5kg lump hammers at the tips. Capable of flipping opponents over.
The Executioner	Series 7	Replaced the robot's spinning disc prior to competing in order to keep it within the 100kg weight limit.
The Kegs	Series 10	Twin clusterbots with horizontal bar spinners, each claimed to be capable of tearing a hole through a car.
The Swarm	Series 10	Bar spinner belonged to Blenda, one of the five clusterbots forming part of The Swarm.
Tornado	Series 6-7, Extreme 2	Horizontal bar spinner attached to a metal frame surrounding the robot's chassis. Formed part of an 'anti-crusher weapon' specifically designed for use against Razer. Converted into a vertical bar spinner for Series 7, but was never used in this form.	Tornado with its horizontal bar spinner from Series 6/Extreme 2
Twister	Dutch Series 2, UK Series 7	Triangular bar spinner, mounted at a horizontal angle in Dutch Series 2 and parallel with the floor to run an invertible design in UK Series 7.
Vicious-1	1997 US Championship	A double-ended "Spiked Hammer Arm" formed one of the robot's interchangeable near-horizontal spinners, likely the first 'spinning hammer' wielded by a competitor. 1997 Middleweight Face-Off Champion.
Vulture	Series 10	Two-toothed 'spinning bar head' mounted on an overhead arm, which also functioned as an axe and a self-righting mechanism. Weapon was capable of spinning at 6,000rpm and delivering 8kJ of energy with every hit. Referred to by Jonathan Pearce as an axe spinner; considered the first and only weapon of its kind to appear on Robot Wars, a weapon which would later be coined as a "hammer saw" by other shows.
Zorro	Series 7	Three interconnected bars with double-headed blades.