Glossary

Plain-English explanations of the engineering words used on Lard Rocket.

A

• Acoustic impedanceAcoustic impedance describes how much a material resists being set into motion by a sound or vibration wave, equal to its density times its sound speed.

D

• DeratingDerating means using a component at less than its maximum rating because the operating conditions are harsher than the conditions it was rated under.
• DownwashDownwash is the column of air that a rotor, propeller or wing pushes downward to produce lift.
• Dummy loadA dummy load is a resistor or set of resistors that stands in for a real load, such as a speaker or antenna.

E

• Eccentric mass motorAn eccentric mass motor is a motor that spins a weight mounted off-center on its shaft.
• Electronic speed controllerAn electronic speed controller, or ESC, is a circuit that takes battery power and drives a brushless motor at whatever speed it is told to.

F

• Filter capacitorA filter capacitor is a large capacitor in a power supply that smooths the pulsing DC coming out of a rectifier into a steadier voltage.
• First bending modeA bending mode is one of the specific shapes a beam or bar flexes into when it vibrates at one of its natural frequencies.
• Flight controllerA flight controller is the small onboard computer that keeps a drone stable and steers it.
• FlybackFlyback is a sudden high-voltage spike produced when the current through a coil or transformer is interrupted.

I

• Icephobic coatingAn icephobic coating is a surface layer that ice bonds to only weakly, so it can be removed with little force.
• ImpedanceImpedance is the total opposition a circuit or component presents to alternating current, measured in ohms.

L

• LiPo batteryA LiPo, short for lithium polymer, is a type of rechargeable lithium-ion battery built in flat, flexible pouches instead of hard metal cans.

N

• NichromeNichrome is an alloy of nickel and chromium used to make heating elements.
• Nodal pointA nodal point is a spot on a vibrating object that stays nearly still while the rest of it moves.

O

• Output transformerAn output transformer sits between the power tubes of a tube amplifier and the speaker.

P

• Piezoelectric effectThe piezoelectric effect is the ability of some crystals and ceramics to produce a voltage when squeezed, and to change shape slightly when a voltage is applied.
• Pulse electrothermal de-icingPulse electrothermal de-icing removes ice by sending a short, very large burst of electrical power through a thin heater under the ice.

R

• Radiation shieldA radiation shield is a barrier, usually a shiny metal sheet, placed between a hot object and something that must stay cool to block heat traveling as infrared radiation.
• ResonanceResonance is the tendency of an object to vibrate with much larger motion when it is pushed at one of its natural frequencies.
• Resonant beam breakerA resonant beam breaker is a pavement-breaking machine that drives a long steel beam at its natural bending frequency.
• RMSRMS, short for root mean square, is a way of stating the effective value of a voltage or current that changes over time.

S

• Spark arrestorA spark arrestor is a fine metal screen or baffle that catches burning particles before they can escape from an exhaust, chimney or vent.

T

• Thermal massThermal mass is how much heat energy an object must absorb to raise its temperature, which depends on its weight and the material it is made of.
• Thermal runawayThermal runaway is a self-feeding failure in which a battery cell heats up, and that heat triggers internal chemical reactions that release even more heat.
• ThermocoupleA thermocouple is a temperature sensor made from two different metals joined at one end.
• Thrust-to-weight ratioThrust-to-weight ratio compares the maximum upward push an aircraft's motors can produce with the aircraft's own weight.
• TransducerA transducer is a device that converts one form of energy into another, such as electrical signals into motion or sound.

V

• Variable pitch rotorA variable pitch rotor can change the angle of its blades while spinning, which changes how much thrust it makes without changing its speed.

W

• Watt hourA watt hour (Wh) is a unit of energy equal to using one watt of power for one hour, or 3,600 joules.