Flippers and Lifters

Flippers and lifters get under an opponent and raise it. A lifter picks the opponent up in a controlled way, to tip it over, pin it or carry it somewhere. A flipper does the same thing fast enough to throw the opponent over or through the air. They're popular in insect classes, especially in sportsman classes that limit spinners. For a quick overview of every weapon type, see Weapons.

Safety: an arm that can lift a robot can also crush a finger. Fit a weapon lock and treat the arm as live whenever the robot is powered. See Safety and Failsafes.

Types

Single-pivot lifters

The simplest lifter is an arm or a pair of forks fixed straight to a servo or gearmotor output. In insect classes this is now the most common layout. As of early 2026, Team Run Amok says the trend favors compact single-pivot lifters that are strong enough to carry forks and survive spinner hits, and that take up less space than four-bar designs. Direct servo lifters such as the SSP kit and Jelly Baby are typical examples.[1]

Servo-driven: common at 150 g and 1 lb. The servo plugs straight into the receiver (see Servos).
Gearmotor-driven: common at 3 lb and up, where you need more torque than a hobby servo gives. The FingerTech Viper lifter add-on (servo) and the Just 'Cuz Robotics SSP beetleweight kit are popular starting points (see Kits).

Four-bar lifters

A four-bar lifter connects the motor to the arm through extra hinged links. (Builders sometimes call these "three-bar" designs, but the robot's frame counts as the fourth bar.) Team Run Amok lists the advantages:[2]

The arm can be shaped to move forward and up as it rises, instead of pulling back away from the opponent.
The linkage can be tuned to keep the motor load fairly even through the lift, so a smaller motor lifts faster.
It folds up compactly, out of reach of the opponent's weapon, but still reaches a good height.

The downsides are extra hinges to break and harder math. Linkages also take some impact load into the hinges instead of the servo, but the servo is still at risk.

Cam lifters

A cam lifter slides thin, wide blades under the opponent and then twists them 90 degrees to high-center it. The torque it needs depends on the blade width, not an arm length, so it can be much smaller than you'd expect.[3]

Electric "flippers" at insect weights

Many 150 g and 1 lb designs are sold or shared as "servo flippers". In practice most are fast servo lifters that tip a light opponent over rather than throwing it. An electric motor alone struggles to make a real flipper because flipping needs a burst of power, not just force. In one Ask Aaron example, a small geared motor was modeled to throw an antweight only about 3 cm high.[4] Turning an opponent over is still very useful, especially against robots that can't self-right.

Spring-powered flippers

To get a real throw without pneumatics, some builders use a motor or servo to slowly load a spring or elastic band, then release it suddenly. Team Run Amok's Spring Flipper Mechanisms page compares several winding and release designs, including one used in the BattleBots robot Tantrum and a servo latch from a UK antweight. These are advanced builds: they store energy that can be released by accident, and the SPARC rules on springs apply (see Safety). A few builders also use flywheels to power flippers; Ask Aaron calls them hard to get right.[5]

Pneumatic and hydraulic flippers ("launchers")

The big flippers you see on TV are mostly pneumatic, and the most powerful ones are called launchers.[6] This wiki doesn't give build instructions for pneumatic or hydraulic systems. They involve high-pressure gas or fluid and need specialist knowledge and mentoring.

There are no off-the-shelf pneumatic components that suit insect-class robots, so parts have to be adapted or made by hand. Ask Aaron says this is not a job for beginners.[7]
Section 8 (pneumatics) and section 9 (hydraulics) of the SPARC Robot Construction Specifications set requirements and pressure limits, with some exemptions for robots of 12 lb and under. Events may add their own restrictions. Talk to the event organizer before you start.[8]

Strengths and weaknesses

Strengths

Simple, cheap and less dangerous to test than a spinner. A good choice for a first weaponed robot.
Lifting the opponent's wheels off the floor takes away its pushing power and steering, so it's easy to drive into a wall, pit or push-out.[9]
Turning over an opponent that can't drive upside down wins the match outright.
The arm often doubles as a self-righting mechanism.
Scores well in judges' decisions for control (see below).

Weaknesses

Lifters do little real damage.[10]
Everything depends on getting under the opponent first. A lower wedge beats you.
Against invertible robots, flipping does little. You need hazards, walls or pins instead.
Servos and gearboxes break when a spinner hits the arm.

Matchups

General guidelines only – see also Driving Practice.

Against invertible wedges and pushers: a pushing match. Win on lower forks, more traction and better driving.
Against vertical spinners and drums: risky but winnable. Strong, low forks or a wedge in front of the arm can take the hit, and a lifted vert can't hit you. Lifting one side of a spinner also makes it unstable (see Spinner Design).
Against horizontal spinners: get under the blade and lift. Tipped horizontals can tumble out of control.
Against non-invertible robots (many hammers, shell spinners, some lifters): one good flip can finish the match.
Against other lifters: whoever is lower and gets under first usually wins.

Design considerations

Torque

For a simple single-pivot lifter, Team Run Amok's rule of thumb is:[11]

Stall torque needed = arm length × weight class × 1.67

The 1.67 factor keeps the motor at about 60% of stall when lifting the full weight, so it still moves at a useful speed. Values from 1.5 to 2.0 are fine. Measure the arm length from the pivot to where the opponent's center of mass will sit, not to the edge of the opponent. Design for the full weight of the opponent on the arm, because the arm tip often catches in gaps or ends up lifting against a wall.

Example: a 4-inch arm on a 3 lb (48 oz) beetleweight needs about 4 × 48 × 1.67 ≈ 320 oz-in of stall torque at the arm.

For four-bar lifters the math is much harder. Use the free Team Run Amok 4-Bar Lifter Spreadsheet (Excel), which plots the arm's motion and the torque it needs. A separate servo lifter version models Team Run Amok's compact "inverted" servo layout.[12] The same page has an electric hammer spreadsheet, which can also model how fast a flipper moves.[13]

Choosing and protecting a servo

See Servos for the basics. For lifters specifically:

Use metal-gear servos. Ask Aaron's priorities are speed, torque and metal gears.[14]
Don't let hits reach the servo. A servo will hold its position until its gears break. Add strong end stops so the arm rests on the frame, not the servo, and consider a spring "servo saver" on the output.[15]
Power: strong servos draw several amps, often more than the BEC in a drive ESC can supply. When the voltage sags, the receiver can brown out. Use a separate high-current BEC, or a high-voltage servo rated for your battery.[16]
Don't stall it for long. Servos overheat if they hold a full load for long, and a pinned opponent is a full load.
Set your transmitter's end points so "down" puts the forks just on the floor, not straining against it.

Getting under the opponent

Low, thin, hard forks or a scoop are the business end. Many lifters use fork tips or wedgelets in front of the arm (see Wedges and Control Robots).
Forks find low spots in an uneven floor better than one wide blade does.
Put strong, separate stops under the arm so a heavy opponent or a spinner hit loads the frame, not the motor.

Balance

Your opponent usually weighs as much as you do. When you lift it, that weight moves onto your front edge. Keep your center of gravity low and toward the back, and keep enough weight on the drive wheels to keep pushing while you lift.

How they win

Knockout by flipping: a robot that can't move in a controlled straight line after being flipped is counted out after 10 seconds under the standard SPARC Match Rules.[17]
Pits and push-outs: a lifted robot is easy to push into a hazard, and the first robot to enter an elimination zone loses. Make sure you don't fall in with it, or it counts as both robots entering.[18] A strong lifter can also lift a robot over a low arena wall.[19]
Pins: holding an opponent is limited to 5 seconds when stationary or 10 seconds when moving, then you must fully release it.[20]
Judges' decisions: under the SPARC Judging Guidelines, flipping the opponent and carrying it into walls or hazards count as control, and a flipper that flips its opponent reliably, without many misses, can earn the top control score. In the newer Damage and Engagement criteria, pinning, high-centering and inverting the opponent (if it affects how well it can fight) count toward engagement. Just lifting a robot without damaging it counts as trivial damage, so lifters rarely win the damage points.[21]

Safety

Weapon locks: SPARC requires a clearly visible locking device on any moving weapon that can cause injury whenever the robot is outside the arena, and the lock must be in place when weapon power is switched on. This applies to servo lifters too.[22]
Springs: large springs used to power a weapon must be loaded and fired remotely by the robot itself, must never be loaded outside the arena or test area, and must fail to a safe position if radio or power is lost.[23] An elastic band can still store a lot of energy, so treat a cocked flipper as dangerous.
Pinch points: keep fingers out from under the arm and forks, and make sure your power switch can be reached without reaching under the arm.
Test with the robot in a test box or arena, and check that the arm doesn't move on its own when the radio is turned off (see Failsafes).

Famous examples

Heavyweights mostly use pneumatic or hydraulic power, which this wiki doesn't cover in detail; they're listed here for inspiration.

Biohazard – Carlo Bertocchini's classic electric heavyweight lifter, which its builder says can lift 220 lb.[24]
Bronco (Inertia Labs) – listed by BattleBots as a launcher.
Lucky – a pneumatic four-bar flipper/launcher; Ask Aaron confirms it uses a true four-bar linkage.[25]
Hydra (Team Whyachi) – a hydraulic flipper.
Tantrum and Blip (Aren Hill) – Tantrum used a spring flipper and Blip uses a flywheel-powered launcher.[26][27]
Whiplash – an articulated lifter combined with a vertical disc spinner.

Designs you can print

These open-source designs are taken from the list on 3D Printing (links checked October 2026):

150 g: the 150g Flipper Battlebot (emancarrillo), the basis for many remixes; Firestorm, an antweight version of the Robot Wars flipper; the 6-Wheel Servo Flipper with a detailed guide; and The Poop Scoop with a step-by-step beginner guide.
1 lb: Plifter V2, a plastic ant servo lifter with a full parts list, and the 1lb Ant Weight Lifter (TPU parts).
3 lb: the printable parts for the SSP kit, Chonk 3.0, and AlexKorvin's budget training lifter.

Kits are another easy start. As of October 2026 these include the FingerTech Viper lifter add-on (about CA$65, servo-driven), the Palm Beach Bots Super Scooper plastic ant lifter (about $175–220 depending on options) and the Just 'Cuz Robotics SSP 2.0 beetleweight lifter (about $450). Prices and stock change often; see Kits.