Cranfield, 2024

The Photon Racing P-One is a road-legal, single-seater series-hybrid electric race car designed to compete in the Grand Tour of a Small Island motorsport event. This project aimed to be a well-rounded challenge of design, innovation, engineering skills application and real-life application, following FIA/legal restrictions, as well as environmental challenges.

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The project brief was to design a 2-, 3-, or 4-wheeled road-legal vehicle to compete in the Grand Tour of a Small Island, a motorsport event held in the UK. The event included:

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• 4× Rallycross heats (Lydden Hill, Kent)

• 3× Drag runs (Santa Pod Raceway, Northamptonshire)

• 2-hour endurance race (Trac Môn, Anglesey)

• 3-hour endurance race (Cadwell Park, Lincolnshire)

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In addition, the car had to complete 630 miles of public road travel between events, with a 150 mi range using 30 L of fuel and one refuel stop allowed.

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The design constraints for this project were as following:

 

Powertrains: Mandatory use of the AIE 650S Wankel rotary engine as ICE, fuel must be commercially available & sustainable (>50,000 L/year production), fuel allocation of 30 L (for 4 wheels, 25 L for 3 wheels), and 20 L for 2 wheels), and hybridisation (motors + batteries) allowed, but battery SoC must be 0% at the start of the first rallycross heat.

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Setup: 10 minutes allowed pre-event to change setup; 20 minutes post-event to make the car road-legal, support limited to a 3.5-ton Sprinter van for tools, crew, and spares, and maximum tyre mass of 200 kg for the whole event.

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Chassis and Safety: Chassis (spaceframe or monocoque) must pass FIA-equivalent structural load tests, exotic materials are banned (titanium, magnesium), the bodywork must protect the energy storage unit, survive 2 minutes of fire exposure, and ensure safe venting/disconnection of storage in case of overpressure or crash, and if the chassis has the lowest embodied energy out of all the teams, a 10% fuel boost is awarded.

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Electrical: All >60V HV conductors must be double-insulated with leakage monitoring for automatic safe isolation.

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Legal: Vehicle must pass UK road regulations (IVA M1) for lights, mirrors, seatbelts, emissions, and safety, as well as comply with noise limits: ≤100 dBA (Lydden Hill), ≤105 dBA (Santa Pod, Anglesey, Cadwell Park).

 

Such constraints and regulations drove the decisions over the design of the vehicle. 

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The whole process for the culmination of the vehicle took somewhere along the 3-4 month mark, starting first with a small team of 8, to later be merged with a secondary team. The details of the final vehicle are as shown below:

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Chassis

• Designed a natural flax-fibre reinforced with carbon fibre composite monocoque for sustainability and stiffness.

• Final chassis weight: 66.9 kg with integrated steel rollover structures.

• Achieved torsional stiffness of 13 kNm/deg and bending stiffness of 1609 N/mm, exceeding targets.

• CAD-driven design included demoulding considerations and ergonomic cockpit packaging.

• Structural FEA validated against FIA safety load cases (roll hoop, side, and frontal impacts) .

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Aerodynamics

• Developed modular CFD-validated aero package tailored for rallycross, drag, and endurance events.

• Delivered peak Cl = −2.4 at 40 mm ride height in track setup.

• Explored active systems such as Drag Reduction and variable-angle wings.

• Sensitivity studies showed lap times were more dependent on downforce than drag.

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Powertrain

• Series-hybrid configuration chosen for efficiency and simplified packaging.

• ICE: AIE 650S rotary engine driving a Helix SPM 150-88 generator (~130 kW continuous).

• Drive: Four in-wheel Helix SPX 88-120 motors, peak system output 480 kW / 3500 Nm.

• Energy storage: Skeleton SuperBattery D60 modules (174s1p), ~9 kWh, 225 kW discharge, 165 kg.

• Battery thermal management via ethylene glycol cooling; motors air-cooled.

• Radiator sizing determined via hybrid ε-NTU/LMTD method, with ~3.95 m² heat transfer area.

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Vehicle Dynamics

• Suspension tuned for high stiffness with anti-roll bars, using Brembo GT braking system.

• Custom wheel hub integration for in-wheel motors and gearbox packaging.

• Final setup allowed peak lateral acceleration of ~4G and standing ¼ mile in 8.8 s.

• Tyre and suspension models validated via quasi-static whole-car simulation with load transfer and Pacejka tyre model.

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Performance and Simulation

• Built lap-time simulation tools (point-mass and whole-car QPMLTS/QWCLTS).

• Simulations predicted:

  • Top speed: 270 km/h

  • Endurance pace optimised by hybrid ICE operation

  • Quarter-mile: 8.69 s at Santa Pod – faster than a 1600 bhp tuned GT-R, close to MotoGP performance .

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Thanks to the inmense effort and dedication of the whole team, we were awarded the "Most Credible Engineering Solution" out of all the teams.

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Please find attached below the relevant documents to this project.