exasun systems
exasun systems

Eight and a half hours on one battery.

Fixed-wing and rotary UAVs for defence, energy, survey and patrol. Designed, printed and assembled in New Delhi.

{{ heroTime }} {{ heroLine }}
The line

Nine aircraft.
Two families.
One interface.

Four fixed wings that fly a working day, five rotary platforms that go vertical from wherever the team is standing. The payload plate, the power rail and the ground station are the same on all nine, so a sensor qualified on one flies on the rest.

Fixed wing

All four airframes →
{{ m.name }} {{ m.alt }} {{ m.name }} {{ m.alt }} {{ m.time }} {{ m.summary }}

Rotary

All five platforms →
{{ x.name }} {{ x.alt }} {{ x.name }} {{ x.alt }} {{ x.time }} {{ x.summary }}
Endurance is battery-electric with no payload, at each aircraft's own cruise speed. Full specifications on each platform page.
Propulsion

The hours are built, not bought.

A long-endurance aircraft is not one with a bigger battery. It is one where the propeller, the motor and the wing are matched to the speed the aircraft actually flies at — because that is where two thirds of the power in this class is currently thrown away.

Induced and profile power against airspeed for the HLF-4
Where the watts go on an HLF-4. Below about 55 km/h the power is buying lift; above it, pushing through air. Cruise sits just past the crossover, where the total is flattest — which is why the endurance figure and the survey speed are the same number.

The class norm is a seven-inch propeller turning fast enough to move air at thirty metres a second, on an aircraft that flies at eighteen. The mismatch is not a rounding error; it is most of the energy budget.

We size the propeller, the motor and the pack for the cruise point rather than the peak, then take the mass back out of the structure. The same airframe, the same cells, a working day instead of an afternoon.

44 W
Electrical power an HLF-4 needs to hold level flight at 65 km/h.
20 : 1
Lift-to-drag at cruise, from the wing rather than from the motors.
0.85
Usable fraction of the pack every published figure is calculated on.
Hydrogen · development programme

A stack instead of a pack, on the two airframes built for it.

A proton-exchange stack turns hydrogen into electricity with water as the only output. It refuels in minutes rather than charging in hours, and its power-to-weight is what turns long endurance from a battery order into a design choice.

The HLF-1 and the HLX-1 take a stack and a tank in place of the pack — the bay on both was sized for it from the first revision. Every endurance figure on this site is battery-electric; the stack is quoted separately.

The propulsion programme →
Proton-exchange fuel cell stack
Proton-exchange stack. Cell count sets the voltage, active area sets the current.
Common to every aircraft

One fleet, not nine products.

A crew learns the line once. A sensor is qualified once. A spare is a file, and the aircraft that took the strike is flying again the same week.

{{ f.h }}

{{ f.p }}
Applications

Where a working day changes the job.

Each line is an aircraft in the line doing a task it can fly today, with the figure that makes it possible.

{{ a.k }}

{{ a.v }}

{{ a.pf }}

Tell us the mission. We will tell you the aircraft.

Give us the sortie length, the sensor and where you fly it. You will get the platform that meets it, its full specification, and a straight answer if we do not have one yet.

Registered name
Exasun Systems LLP
LLP identification
AAR 987
Registered office
New Delhi, India
{{ formRegarding }}
{{ formNote }}
The line

Nine platforms, one interface.

Pick the hours the task needs. The payload plate, the power rail and the ground station do not change between them, so the choice is about the mission and nothing else.

Designation Airframe Endurance Payload Launch and recovery Field assembly
{{ r.name }} {{ r.name }} {{ r.alt }} {{ r.type }} {{ r.time }} {{ r.pay }} {{ r.launch }} {{ r.asm }}
Light under 500 g · Medium to 1 kg · Heavy above. Rated mass per airframe ships with the datasheet. Endurance is battery-electric, no payload. Request the datasheets →

The fixed wings, by the hour

Battery-electric, no payload, at each aircraft's own cruise speed. Endurance falls with payload on the curve beside it — a quarter-kilo costs the Zenith about forty minutes.

Endurance of the four fixed wings, 6 h 15 m to 8 h 30 m Endurance against payload for the four fixed wings

The line, as built

The four fixed wings, the HLX-3, HLX-5 and HLX-6 are rendered from their own geometry, part for part. HLX-1 and HLX-2 are shown as design renders.

Common to all nine

One payload interface
Quick-release plate, power rail and data bus are identical across the line.
One ground station
Crews trained on any platform can fly the rest without new software.
Open firmware
Pixhawk-standard autopilot, auditable by the buyer.
Propulsion

Endurance is the whole design brief

It is decided by two numbers, and most of the industry works on only one of them.

HLF-1 Meridian · the hydrogen-ready airframe Live model. Drag to orbit.
01

Energy on board, divided by power required

There is no third term. Every extra minute in the air comes from raising the numerator or lowering the denominator.

On a fixed wing, power required falls with induced drag, so span and cruise speed dominate. On a multirotor it falls with disc area, so the largest propeller the airframe will carry does more for flight time than any battery.

02

Sized for the mission, not the datasheet

A pack specified for peak current carries mass it never uses. A propeller specified for maximum thrust wastes power at cruise. We size both for the point the aircraft actually flies at, then take the mass back out of the structure.

Development programme · HLF-1 and HLX-1

The bay the stack goes in

A pack has a hard ceiling: once the cells are as dense as cells get, the aircraft stops improving. A fuel cell moves the ceiling, because the energy sits in the tank and the tank is refilled rather than recharged.

Highlighted in the model is the mounting pad in the HLF-1 centre bay. Two airframes take a stack in place of the pack. Every endurance figure on this site is battery-electric.

Nothing but water
No combustion, no exhaust.
Refuel, not recharge
Swap a cylinder and launch again.
Cold-weather margin
Output holds where pack capacity falls away.

What a stack is made of

Cell count sets the voltage, active area sets the current, and the plate pattern decides how evenly either arrives. None of it is exotic; all of it is geometry.

Fuel cell pack, exploded
One cell is about 0.7 V. Endurance is a stack height problem.
Bipolar flow plate
Flow plate. The serpentine channel feeds hydrogen across the active area.
Air-cooled stack, 14 V
Air-cooled bench unit with its tank regulator.
03

39 minutes to eight and a half hours, battery-electric

What the approach produces across the line. Fixed wing in ink, multirotor in olive; no payload.

{{ p.name }} {{ p.alt }} {{ p.time }}
Ask what it would carry for you
{{ pf.kicker }}

{{ pf.desig }} {{ pf.alt }}

{{ pf.time }}

{{ pf.lead }}

{{ pf.note }}
{{ c.k }}
{{ c.v }}
Propulsion

{{ pf.planH }}

{{ pf.planP1 }}

{{ pf.planP2 }}

{{ b.label }} {{ b.time }}
Performance

{{ pf.perfH }}

{{ pf.perfP }}

{{ pf.perfCap }}
{{ pf.perfCap }}
{{ partsKicker }}

Every part, and why it is that part

Assembled Apart
{{ hoverLabel }}
  • {{ f }}
    •

Drag the slider or keep scrolling to separate the airframe. Hover a group to isolate it. Component makes and part numbers are supplied with the bill of materials under NDA.
Serviceable groups {{ partsLabel }}

{{ pf.payloadH }}

{{ pf.payloadP }}

Mount
Common quick-release plate
Power rail
not published
Data
Serial and Ethernet
Ground station
One application, all platforms

Specification

Where a field reads not published, the number exists — it goes out under NDA rather than on a web page.

{{ m.k }}
{{ m.v }}
{{ s.k }} {{ s.v }}
Request the datasheet
Fixed wing

Four airframes, one build method

Six and a quarter to eight and a half hours on station, hand or bungee launched, belly recovered. Every one is a set of printed parts on a placement table, so a spare is a part and a change is a file.

Common to the fixed wings

One interface, four airframes

Payload plate

The same quick-release plate on every nose, so a sensor qualified on one platform flies on the rest without rewiring.

Ground station

Pixhawk-standard autopilots and open firmware across the line. A crew learns the fleet once.

Printed part sets

36 to 47 parts per airframe. Spares are prints, and a strike costs the part that took it.
Rotary

Vertical, from wherever the team is standing.

No runway, no launch crew, no prepared site. Five airframes that go up from a compound, a road head or a rooftop — on the same payload plate and the same ground station as the fixed wings.

Anywhere it stands
Launch and recovery inside the aircraft's own footprint.
Airborne in a minute
Folding arms and printed hubs, out of a case or a backpack.
3 h 30 m
The Anvil holds one point for a shift, with the largest bay in the line.
{{ rt.kicker }}

{{ rt.desig }} {{ rt.alt }}

{{ rt.time }}

{{ rt.lead }}

{{ rt.note }}

HLX-1 Anvil HLX-2 Cirrus HLX-3 Ember
{{ u.h }}

{{ u.p }}
HLX-1 with payload case Rotary platform airframe HLX-3 Ember plan view
{{ c.k }} {{ c.v }}
Specification

{{ rt.desig }} in numbers

Where a field reads not published, the number exists — it goes out under NDA rather than on a web page.

{{ s.k }} {{ s.v }}
{{ m.k }}

{{ m.v }}
Support

Printed part by part, supported part by part

{{ support.lead }}

{{ b.h }}

{{ b.p }}
At a glance

What comes with an aircraft

Ask us about a fleet →
{{ s.k }} {{ s.v }}
About

We re-engineer endurance

{{ about.lead }}

{{ b.h }}

{{ b.p }}
The company
{{ f.k }} {{ f.v }}
The team

Three disciplines, one airframe at a time

{{ t.k }}

{{ t.v }}