Project CALLISTO (PROPULSION) · UK public procurement notice

The UK MOD will be holding a Project CALLISTO Challenge Session on the afternoon of the 18th June 2025 in London, UK. Industry partners, particularly those currently established or planning to be established in the UK, are invited to attend to provide feedback on Project CALLISTO’s proposed scope, timescales and feasibility. Additional information: The User requires a low-cost, 1.2-2kN propulsion system to power a UK MOD development programme (Proj BRAKESTOP) for a heavy One Way Effector (OWE). The propulsion system could be used for other applications e.g. cruise missiles, other OWEs.

Project BRAKESTOP has highlighted limited availability of the class of propulsion systems needed. Therefore, MOD wishes to increase the availability of this class of propulsion system.

Technical Propulsion Engine Requirements

The engine shall:

• Be a 1.2 – 2kN single engine propulsion system (Sea Level Static Maximum Thrust)

o Low end for least amount of ancillary cost (facilities, fuel, equipment, build material, machine size, test cell etc)

o Could then be iterated for enhanced capability.

• Be designed to be easily manufactured at scale using widely available manufacturing methods/machinery.
• Manage at least 5 hours component life; this provides confidence in managing the expected application life, but also pushes the materials technologies to low cost.
• Be able to reliably start rapidly (ideally < 30 seconds) and accelerate to high power (ideally <10 seconds).

o Reduced warfighter exposure is important.

• Demonstration within 9 months ready for Q1 2026.

o Demonstrate to then iterate pushing the competitor’s ability to learn and adapt to risks arising given engine testing.

• Within 12 months, be prepared for full rate production of 20 engines a month.

It should:

• Be resilient to -15 to +40 degrees.
• Be resilient to fuel type.
• Be readily adaptable for spiral development towards enhanced capability.
• Be cost effective against equivalent market competitors in this thrust class.
• Be resilient to typical transport vibration.

Procurement Approach and Timeline

MOD’s preferred approach is to purchase a proven, off-the-shelf propulsion system of the desired technical and cost characteristics from a supply chain which can guarantee security of supply of the quantities required Q2-Q3 2026.

Currently, there are several different consortiums building a range of solutions against the BRAKESTOP requirement. The technical requirements are therefore deliberately broad at this stage but will be refined as BRAKESTOP solutions are eliminated from the competition over late 2025 and into 2026.

Pricing Information

Target (Propulsion System) Unit Price: £75K

Target (Propulsion System) Volume: 20 units per month from Q2/Q3 2026 to support Project BRAKESTOP

If there is no off-the-shelf solution that meets this requirement, MOD is willing to consider additional funding for development of a new propulsion system(s).

Challenge Day Information

The Authority will be holding a Project CALLISTO Challenge Day on the afternoon of the Wednesday 18th June 2025 in the STADIUM room at Scalespace in London, UK.

Please use the following link to submit a request form to attend the Challenge Day. MOD will consider the track record of companies of designing and/or manufacturing propulsion systems will be allowed to attend the event – it is therefore key that you provide examples of your expertise.

Please note that responses must be submitted by 10th June 2025.

Due to capacity limitations, this Challenge Day will be limited to 4 personnel from each company. In the event of the location’s capacity being exceeded, the MOD will restrict down to 1 person from each company.

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