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150HFE
Twin-Boxer, Ultra-Smooth
150cc Opposed two cylinder 2-stroke FlexDI™ Fully Integrated HFE Propulsion System for UAVs
Built on the proven 75cc architecture, the 150cc twin-boxer HFE delivers ultra-smooth heavy-fuel power - 11.9 hp, <340 g/kWh efficiency in a 10.4 kg system. Qualified to MIL-STD-810H and proven through 25,000 operational hours in the field.
Plug-and-fly integration, faster to flight
Compact form, direct coupling and integrated Engine Management System mean faster install, cleaner wiring and lower integration risk.
Endurance
efficiency
FlexDI™ heavy-fuel combustion at <330 g/kWh extends range and offers superior fuel consumption.
Ultra-smooth power
Twin-boxer layout delivers >11.9 hp with low vibration for cleaner data and reduced airframe fatigue.
Mission-grade durability
MIL-STD-810H qualified; FAR 33.49(b) 3×150 h back-to-back plus 500 h mission-profile testing - confidence from dyno to field.
FlexDI™
Fuel Injection
Orbital’s FlexDI™ atomises fuel to ~8 µm droplets (vs ~120 µm conventional), delivering a cleaner, more complete burn. The result is >30% lower cruise fuel use, high specific power (>70 kW/L), and assured starts in –30 °C conditions with automatic altitude compensation to high density altitudes.
FlexDI™ runs JP-5/JP-8/Jet A/Jet A-1 or gasoline with no calibration change, meets MIL-STD-1474D noise targets, and uses electronic oil metering for consistent lubrication.
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FlexECU™
Intelligent electronic propulsion management system
Hardware designed and validated for aero applications
Black-box logging
Fault monitoring and “return to base” logic
Anti-stall
Power management
Speed control
Engine protection
Textron Aerosonde 4.8HQ
The Textron Aerosonde 4.8HQ uses Orbital's 150HFE Integrated Propulsion System. Orbital worked closely with Aerosonde team to design and engineer to meet their exacting performance and reliability standards.
Proven Over Decades
Optimised for Today
CPI from 30+ years of missions
Lifetime Value
Engineered In
Designed for UAV duty cycles (not repurposed motorcycle engines):
thrives in high-hot-heavy profiles; higher MTBO → fewer removals, fewer spares, less downtime.
Lower fuel burn (FlexDI™ / OCS):
30%+ cruise reduction unlocks longer missions on the same fuel or more payload - compounds across time.
Proven reliability, engineered improvement:
30+ years of data driving Continuous Product Improvement (CPI); essential for single-engine platforms and BVLOS/LoS extensions.
Mission Assurance, not ad-hoc S&R:
spares, overhaul, diagnostics, and SLAs sized to your tempo - shifts lifecycle risk off your team and protects availability.
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How we reduce total cost
of ownership
Fewer removals & teardowns:
Long MTBO from UAV-specificarchitecture → lower maintenance labour and logistics.
Lower fuel burn (FlexDI™ / OCS):
FlexDI™ efficiency → reduced opex or increased commercial yield (more data per tank).
Faster integration, fewer surprises:
IPS + EMS + diagnostics → compressed development costs and quicker time-to-revenue.
Predictable sustainment:
Support packages align cost to use; overhaul cycles planned, not reactive.
Integrated Propulsion Systems
From 50–350cc FlexDI™ heavy-fuel engines and PMS, Orbital delivers proven reliability, efficient combustion, and straightforward integration - backed by decades of mission experience
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150HFE Specifications
Why Heavy-Fuel
Wins for Payload,
Endurance & BVLOS
Orbital’s FlexDI™ heavy-fuel engines give you the payload headroom, endurance, and mission assurance electric struggles to match
When range, uptime and mission assurance matter, Orbital’s FlexDI™ heavy-fuel engines deliver higher energy on board, faster turnarounds, and proven reliability in harsh theatres.
Proven reliability and consistent power delivery across heat, cold, dust and wet - critical when crews lose direct visual control giving higher mission assurance for BVLOS corridors, maritime legs and remote operations.
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More Payload on
Board & Endurance
That Scales
ISR payloads are getting heavier and smarter. BVLOS routes are longer and harsher.
Higher energy density per kg than batteries means you can carry more sensors, comms and compute - or keep the same payload and fly longer. Orbital’s FlexDI™ Integrated Propulsion Systems with superior fuel efficiency allows for bigger ISR packages, cleaner data, and less compromise on airframe weight balance. Fly further and smarter with Orbital.
Explore the 3 Ways
to Work with Orbital
All options deliver Orbital’s proven reliability, FlexDI™ efficiency, and mission assurance across
all engines. Choose the engagement model that fits your programme, timeline, and budget.
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Strategic
Partnership Programme
For OEMs who need a system-level advantage with co-engineered propulsion that wins programmes.
We embed with your team to design and execute a bespoke Integrated Propulsion System (IPS), optimised for your airframe and mission profile - from requirements capture to flight test and beyond, we’re with you for the long run mission after mission.
Includes:
- Dedicated engineering squad
- Bespoke calibration & integration
- Platform-specific packaging
- Test campaign support
- Roadmap co-development
- Priority sustainment
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Mission-Ready
Engines
Orbital’s renowned power, efficiency, and reliability - ready to deploy.
Standardised configurations of Orbital’s renowned Integrated Propulsion Systems with the same reliability and performance built on a 20 year pedigree - delivered faster and at a lower price point for OEMs seeking market leading Over Line of Sight (OLS) propulsion. Configure from proven options and ship.
Includes:
- Pre-qualified configurations
- Standard harnesses & mounts
- Documented performance maps
- Accelerated lead times
- Fast online ordering
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Mission
Assurance Support
Keep your fleet flying - every mission, every theatre.
A stand-alone benefit for all Orbital customers, Mission Assurance ties our performance and reliability DNA to day-to-day operations - so your UAVs become global leaders and stay that way.
Availability-first SLAs:
Targeted response and resolution times sized to your tempo and theatres.
Diagnostics that prevent downtime:
In-/post-flight telemetry, health monitoring, and black-box logging to spot issues early.
Planned sustainment:
Scheduled overhauls, component refresh, and firmware updates to keep engines at spec across life.
Spares & repairs, ready to go:
Kitted spares, repair logistics, and AOG escalation to shorten mean-time-to-restore.
Field support & training:
Remote assist and on-site options; operator and maintainer training with clear documentation.
Performance reporting:
Fleet-level insights and recommendations to lift availability and reduce through-life cost.
Newsroom
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The Role of Metrology in Orbital UAV’s Engine Crankcases
In the world of unmanned aerial vehicles, reliability begins long before the first flight.
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At Orbital UAV, combustion efficiency begins with precise fuel atomisation
Our FlexDI™ air-assisted direct injection system atomises fuel to ~8 µm droplets, compared to ~120 µm in conventional systems.
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Built for Extreme UAV Performance: OptiProp
Tactical UAVs are flying higher, faster, and into increasingly contested environments - leaving no margin for inefficiency
Let’s chat about your airframe
and mission requirements?
Sales
Share timelines, quantities, and target budgets - we’ll map the best path (Partnership or Mission-Ready).
Technical
Bring your platform specs, payloads, and constraints - we’ll recommend the right engine/PMS configuration.
Brochures & Technical Downloads
Access product brochures, platform overviews, and key technical documents in one place.
Download the files you need to compare configurations, review specifications, and share internally with your team.
Contact Orbital
