Acroflight was invited onto the RR ACCEL program by Stjohn Youngman and Roger Targett of Electroflight (www.electro-flight.com) in 2018.  However, the story begins some years before when Ultraflight supported the initial design analysis of Roger's brainchild that was to become the P1E.  This was an attempt to start a one-design series of single-seat, electric racing aircraft. 

 

From 2018 Acroflight's role was to contribute to the aircraft design, perform engineering analysis (stress) and create verification reports to enable Ash Owen (the E-Conditions Competent Person) to gain confidence in the airframe and commit to releasing the flight readiness documents (or equivalent in RR terminology).  The basic airframe started kit 10/10 of the small batch of NXT designed by Jon Sharpe.  Stjohn had carefully selected an airframe that could accommodate the large battery system envisaged, it's Reno Air Racing pedigree confirming that it had the capability to become a very fast electrically powered aircraft.

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Acroflight's scope of work increased, eventually including the major modifications to the airframe - a major fuselage joint to enable transportation, a complete re-design of the front end of the fuselage to accommodate the large battery system and ancillary equipment.  Due to a 6% increase in MTOW (and therefore max landing weight), the main gear was modified to make it lighter whilst still having sufficient strength to cope with the calculated loads.

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As the airframe is composite the modifications made had to take into consideration the compatibility of the existing material system.  Electroflight demonstrated a highly adaptable working practice - obtaining a medium temperature oven and configuring the workspace to suit the operational needs.  For example, the entire workshop was used to post-cure the structure - highly effective, if not the cheapest option!

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Towards the end of construction, RR engineers began the oversight process, critiquing the work and providing valuable comments and feedback on the numerous technical reports.  To add an additional layer of compliance oversight RR/Electroflight commissioned Cranfield Aerospace Solutions who also commented on our reports.

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The E-Conditions project enabled the relevant regulations to be used as program requirements.  This cherry-picking process created a set of requirements that are below those required for a full Certification program but are adequate for the specific function of the ACCEL.

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Acroflight's MD John Wighton added; " We are immensely proud to have been involved in the RR ACCEL project.  To achieve World Records using a highly innovative, novel feature-laden, aircraft is a testament to the engineering excellence present in the UK.   In particular, the vision of Roger Targett, the gutsy determination and efficient program management by Stjohn Youngman made this project a success.  The selection of a small group of experts in their respective fields showed RR how much can be done by so few.  We look forward to future projects in collaboration with Electroflight and Rolls Royce."

 

Acknowledgements to RR Press Dept. for descriptive extract:

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We believe our all-electric ‘Spirit of Innovation’ aircraft is the world’s fastest all-electric aircraft, setting three new world records. We have submitted data to the Fédération Aéronautique Internationale (FAI) – the World Air Sports Federation who control and certify world aeronautical and astronautical records – that at 15:45 (GMT) on 16 November 2021, the aircraft reached a top speed of 555.9 km/h (345.4 mph) over 3 kilometres, smashing the existing record by 213.04 km/h (132mph). In further runs at the UK Ministry of Defence’s Boscombe Down experimental aircraft testing site, the aircraft achieved 532.1km/h (330 mph) over 15 kilometres – 292.8km/h (182mph) faster than the previous record – and broke the fastest time to climb to 3000 metres by 60 seconds with a time of 202 seconds, according to our data. We hope that the FAI will certify and officially confirm the achievements of the team in the near future.

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During its record-breaking runs, the aircraft clocked up a maximum speed of 623 km/h (387.4 mph) which we believe makes the ‘Spirit of Innovation’ the world’s fastest all-electric vehicle.

Warren East, CEO, Rolls-Royce, said: “Staking the claim for the all-electric world-speed record is a fantastic achievement for the ACCEL team and Rolls-Royce. I would like to thank our partners and especially Electroflight for their collaboration in achieving this pioneering breakthrough. The advanced battery and propulsion technology developed for this programme has exciting applications for the Advanced Air Mobility market. Following the world’s focus on the need for action at COP26,  this is another milestone that will help make ‘jet zero’ a reality and supports our ambitions to deliver the technology breakthroughs society needs to decarbonise transport across air, land and sea.”

Business Secretary Kwasi Kwarteng said: “Rolls-Royce’s revolutionary Spirit of Innovation aircraft is yet more proof of the UK’s enviable credentials when it comes to innovation. This record will show the potential of electric flight and help to unlock the technologies that could make it part of everyday life. The government is proud to back projects like this to leverage the private investment necessary to unlock cleaner, greener aircraft which will allow people to fly as they do now, but in a way that cuts emissions.”