Engine – hayyavionics.com

ENG.01Working principle

Thrust from an oscillating plate — not a rotating part.

Inside a sealed casing, high voltage between fixed and moving electrode surfaces creates electrostatic attraction. The moving dish is pulled down, the flexure hinge springs it back, and rhythmic AC drive keeps the oscillation alive. Every stroke draws air through a one-way valve and presses it out through the perforated base — thrust comes from the momentum of the expelled air, not from the internal force between the plates.

The five building blocks

01

Electrode pair

Fixed base electrode + moving dish, both faces coated with a thin PVDF-class dielectric film — suppressing electron emission and lifting the working field far above bare metal's practical limit.
02

Flexure hinge

No sliding or rotating bearings: the plate translates on the elastic flex of spring-steel arms. Zero friction, zero wear — arm stiffness and plate mass form the mechanical resonator.
03

Valve plate

Multiple mini reed tongues — or a valveless nozzle-diffuser geometry — diode the flow into one direction.
04

Perforated base

Exhaust is distributed across the entire base; air travels millimetres at most, so exit velocity stays low and the flow stays quiet.
05

Resonant drive

Cell capacitance + transformer inductance are driven at LC resonance — reactive energy is recovered every cycle; the source supplies only real work and losses.

Nothing rotates anywhere — outside or inside. The moving parts of the cell are exactly three: the plate, the flexure arms, and the valve tongues.

The calculation chain — every family value derives from it

Electrostatic pressure: P = ½ · ε₀ε_r · E²; The ceiling of force density; E chosen below the material limit
Voltage: V = E · d; Gap ≥ stroke + safety margin — stroke is bought with voltage
Flow rate: Q = A · stroke · f · η_vol; Volumetric efficiency (valve quality), Phase 1 target ≥ 70%
Thrust: F = ṁ · v = ρ · A_exit · v²; Thrust is born from momentum; ṁ = ρ·Q
Thrust efficiency: F / P_jet = 2 / v; Halve the exit velocity → double the N/W. Wide base, low v
Peak acceleration: a = (2πf)² · x; Draws the mechanical forbidden zone; x = stroke/2
Resonance: f = √(k/m) / 2π; Flexure stiffness k, plate mass m — the drive sits here

Two free design decisions — exit velocity (v) and working field (E) — and everything else follows. Constants: ε₀ = 8.854×10⁻¹² F/m · ρ(air) = 1.225 kg/m³ · PVDF: εr ≈ 10, strength ~200 MV/m.

Why the capacitor regime?

The upper limit of electrostatic force per unit surface is the same in every geometry: P = ½ε₀εr·E². The only thing that sets this ceiling is the field strength the material can carry. Open-sphere or far-electrode arrangements demand thousands of times higher potential for the same force (V = E×d) — a narrow-gap capacitor stack puts every field line to work and produces the same force in the kilovolt band. Hayy's multi-plate, thin-gap architecture is the direct consequence of that choice.

ENG.02Cell family

Three scales. One architecture.

Cell-S — the proof cell

The base unit of the family and the subject of the Phase 1 validation program. It powers Hayy Mini and Mini XS — and every larger size is derived from this cell's measurements.

The 3 mm stroke is where "shallow oscillation, deep breath" meets the voltage budget: deeper strokes make the supply expensive (V = E×d), shallower ones inflate frequency and valve load. At 500 Hz the valve window is 1 ms — comfortable territory for reed tongues.

Open risk: volumetric efficiency (the valve reflex) is the single unmeasured critical link — the design's takeoff margin depends on it. Secondary: flexure fatigue life (10⁹+ cycles) and film temperature plateau, both verified in the Phase 1 endurance run.

Dish dia / active area: 95 mm / 71 cm²
Stroke / plate gap: 3 mm / 3.5 mm
Frequency: ~500 Hz (tuned to resonance)
Working field E: ~7 MV/m — 7× safety vs PVDF limit
Voltage: 25 kV (28 kV with margin)
Nominal thrust (target): 1.8 N (at η-vol = 75%)
Input power / specific: ~40 W / ~45 N/kW
Cell mass (target): ~60 g → thrust/weight ≈ 3:1
Valve / drive: Multi reed (A/B: nozzle-diffuser) / resonant AC

Cell-M — the commerce cell

The core of the "Hayy M" product sold to OEMs — a packaged, standalone thrust module with flange, HV connector and control interface. An 8-cell array carries a 10 kg-class cargo drone; a 48-cell array carries a 60 kg-class platform.

~3× the size of S: area ×10, thrust ×10. Peak acceleration halves, so the stroke doubles and frequency halves — the scale rule's first application. 42 kV stays within the single-layer limit, so the module remains simple: no layering needed at this size. Since thrust follows V² in milliseconds, differential thrust delivers roll, pitch and yaw with no propeller inertia.

Open risks: cell-to-cell flow and acoustic interference only appears in array testing — a single cell can't catch it. In a 48-cell array, losing 2 cells must not break the flight. The 42 kV source is not a shelf product — a special but known class; supply + isolation mass must stay inside the module budget.

Dish dia / active area: 300 mm / 0.07 m²
Stroke / plate gap: 6 mm / 7 mm
Frequency: ~250 Hz
Working field E: ~7 MV/m
Voltage: 42 kV — single layer
Nominal thrust (target): 18 N — 1.8 kg lift per cell
Input power / specific: ~350 W / ~51 N/kW
Cell mass (target): ~1.2 kg → thrust/weight ≈ 1.5:1
Valve / drive: Reed array / resonant AC

Cell-L — the vehicle cell

The carrier unit of the Hayy V/T vehicle program — and the first application of the layered "accordion" architecture. A single layer would need ~110 kV, so it is built as a 3-layer stack: the patent's multi-plate group structure becomes mandatory at this size.

Parallel-bus layering: intermediate dishes work double-faced and connect to alternating buses. Every layer sees the same 37 kV — no point in the system ever exceeds layer voltage; megavolts never arise. Force adds up with layer count. Odd and even dishes oscillate in anti-phase (the accordion): gaps breathe alternately, the mass centre stays fixed, vibration self-cancels. Vehicle integration: Hayy V (300 kg) ≈ 12 × L plus redundancy; for Hayy T (1,200 kg) the footprint constraint raises layers from 3 to 8 (the L8 variant, ~950 N on the same base).

Open risks: pressure-wave synchrony enters the design math at 900 mm / 120 Hz — exhaust-hole phasing matters. The 37 kV inter-layer bushings are a known but meticulous transformer-craft item. The valveless geometry's net efficiency per layer is settled only by test.

Dish dia / active area: 900 mm / 0.64 m²
Stroke / layer gap: 12 mm / 14 mm
Frequency: ~120 Hz
Working field E: ~8 MV/m
Layer structure: 3 layers × 37 kV — parallel bus
Nominal thrust (target): 360 N — 36 kg lift per cell
Input power / specific: ~9 kW / ~40 N/kW
Cell mass (target): ~25 kg → thrust/weight ≈ 1.5:1
Valve / drive: Valveless nozzle-diffuser (candidate) / resonant AC — pulsed (Marx) option at vehicle scale

ENG.03Family comparison

S is measured. M is derived. L is validated.

	Cell-S	Cell-M	Cell-L
Dish diameter	95 mm	300 mm	900 mm
Active area	71 cm²	0.07 m²	0.64 m²
Stroke / gap	3 / 3.5 mm	6 / 7 mm	12 / 14 mm
Frequency	500 Hz	250 Hz	120 Hz
Voltage	25 kV	42 kV	3 × 37 kV
Nominal thrust	1.8 N	18 N	360 N
Input power	40 W	350 W	9 kW
Thrust / power	45 N/kW	51 N/kW	40 N/kW
Mass (target)	60 g	1.2 kg	25 kg
Thrust / weight	3 : 1	1.5 : 1	1.5 : 1
Peak acceleration	~1,500 g	~750 g	~350 g
Layers	single	single	3 — parallel bus
Product	Hayy Mini / XS / XL	Hayy M module	Hayy V / T

Each size sits at roughly 1/10 the thrust scale of the one above it. Test data ties the family into a single extrapolation chain — the larger sizes are derivations from measurement, not claims from zero. Larger cells breathe "slow and deep", smaller cells "fast and shallow"; where a single cell hits its scale limit, the answer is cell count, not a giant cell.

ENG.04Design rules

The rules every cell obeys.

d ≈ stroke + margin

The gap must not exceed the stroke

Extra gap is only dead volume and a voltage bill. Flow comes from A × stroke × f — not from channel width.

V = E · d

Stroke is paid in voltage, area in material

A deeper stroke makes the supply expensive; a wider dish only asks for material. The design swells toward the cheap resource — in this machine, that is area.

F / P = 2 / v

Keep the exit velocity low

Pushing the same thrust slowly through a wide perforated base is both efficiency and silence. A fast jet from a narrow mouth is the jet regime: inefficient and loud.

a = ω² · x

Respect the acceleration wall

Frequency punishes quadratically, stroke linearly; large amplitude at high frequency is the mechanical forbidden zone. Sitting on the resonator is mandatory, not decoration.

n × V(layer)

Answer the voltage ceiling with layers

When one gap's voltage becomes uncarryable, intermediate dishes are stacked in. With the parallel bus, no point exceeds layer voltage — force adds with the layer count.

service cartridge

Design the surface renewable

Dielectric life and contamination are the cell's real aging mechanisms. Film + valve + wiper live in one sealed cartridge — maintenance happens at the dealer, by swap, not in the field.

T(film) → plateau

Thermal equilibrium must be proven

Heating doesn't stop; it balances. The acceptance test: at target power, film temperature settles on a plateau below the material limit. No plateau means leakage — cut power or add surface cycling.

ENG.05Phase 1 — validation

The whole family stands up with one experiment.

A Cell-S benchtop rig. Because voltage and frequency are adjustable, the same rig measures both the shallow-fast regime (0.5 mm / 3 kHz) and the deep-slow regime (3 mm / 500 Hz) — the bench referees the two design philosophies.

CURVE 1

Thrust – voltage

Verification of F ∝ V² and the absolute thrust level, measured on a load cell.

CURVE 2

Thrust – frequency

How volumetric efficiency moves with frequency — the valve reflex's report card. Reed and nozzle-diffuser plates are A/B-swapped in the same cell.

CURVE 3

Temperature – time

Film temperature plateau at target power, with simultaneous partial-discharge inception voltage (PDIV) tracking as the early indicator of cell life.

Acceptance criteria

Volumetric efficiency η ≥ 70% at nominal frequency — the design's takeoff margin hangs on this number
Repeatable, measurable net thrust — target band 1.4–2.0 N
Film temperature ≤ 80% of the material limit, settled on a plateau
50 hours cumulative run with no dielectric or structural failure; PDIV curve flat
Fowler–Nordheim sweep: the operating point stays at least 3× below the surface's real field limit

2026 Q3

Test rig

Single-cell benchtop rig with high-voltage AC drive, thrust stand and load cells — alongside the patent + PCT filing.
2026 Q4

The three curves

Thrust–voltage, thrust–frequency and temperature–time measurements, acoustic characterization, and the open Phase 1 technical report.
2027

Multi-cell & ground

Phases 2–3 in parallel: multi-cell hover demo and the ground-mode crank / track-wheel chassis.

The technology is at patent-application stage. Every performance value in this document is a physics-derived target; none has been measured yet. Thrust density, volumetric efficiency and dielectric endurance are Phase 1's open questions — the first investment is spent on proving these three numbers, not on marketing.

Technical documents — Library Talk to the founding team

The Hayy Cell family.