The objective of the proposed work is to obtain European experience in propellant composition, handling, operating and integration of NOFB propulsion technology by:

  1. Developing a propellant formulation and prepare the NOFB.
  2. Performing preliminary engine testing. This includes ignition conditions testing, mapping for combustion stability and investigate basic combustion parameters like flow properties, combustion stability mapping.
  3. Establishing procedures to safely handle the NOFB propellant and evaluate basic propellant properties and material compatibility.
  4. Performing a subsystem impact assessment.

A literature survey is included in the activities within Task 1 and results in to a candidate fuel blend for Breadboard testing and a test propellant specification.

The activities within Task 2 are focused on testing NOFB in a breadboard engine of a representative size for Large apogee engine, in a European test facility of known provenance, to assess the technical feasibility of this technology against the current engine options. The identification of a suitable breadboard thruster for the test campaign is the first activity within Task 2.

Before and during the course of engine testing significant experience will be gained in handling NOFB and is reported within Task 3.

A preliminary plan for implementing an NOFB propulsion system is the outcome of Task 4.

The AEL 600 N test engine selected for the test activities


Safety is the main challenge within this project.

Mixing of an oxidiser and fuel within its flammability limits is per definition a potential hazard. To develop a NOFB blend with excellent performance characteristics and manageable handling and safety characteristics is key to the success of this project.

The potential hazards of the NOFB mixture limits the engine testing to a test setup in which the NOFB will be mixed just before injected in to the test engine. This, and use sufficient safety measures as flame arrestors, prevents a catastrophic event in case of a flash back. The challenge during tests is to obtain viable test data in a representative and safe test setup as much as possible.

The outcome of both, the handling & safety characteristics and the NOFB performance characteristics in the test engine dictate the practical use of NOFB and with this the success of the project.


NOFB propellant, if proven that the potential hazards with this propellant are manageable, offers the potential of bi-propellant performance with mono propellant system complexity. Nitrous oxide and the potential fuels that makes NOFB are all considered ‘green’ and the chance that the use of these components will be restricted by REACH legislation is negligible.

NOFB is in potential an excellent low cost and durable replacement for hydrazine and may strengthen the competiveness of European SatCom industry.


The beneficial features of NOFB that makes this propellant attractive for space propulsion systems are:

  • Nitrous oxide and the potential fuels that make NOFB are all considered ‘green’ and the chance that the use of these components will be restricted by REACH legislation is negligible.
  • The price of Nitrous oxide and the potential fuels that makes NOFB is low compared to the current storable propellants
  • NOFB is self-pressurizing, no pressurization gas or pumping system is required
  • The Isp out-performs that of hydrazine and approaches that of the current storable bi-propellant engines

System Architecture

A NOFB propellant will be defined, this propellant includes:
• Nitrous oxide
• A fuel, for example a hydrocarbon as ethylene
• Additives to stabilize the mixture if needed


The work in the project plan is organised in four technical tasks being:

          -      Task 1: Propellant definition                           Nov. 2015 – Mar. 2016

          -      Task 2: Engine testing                                     May 2016 – Jan. 2017

          -      Task 3: Propellant handling study                 Mar. 2016 – Jun. 2016

          -      Task 4: Sub-system Impact Assessment       Nov. 2016 – Mar. 2017

The project milestones are the following:

          -      NOFB Propellant Formulation and preparation report   (Mar. 2016)

          -      The test readiness review                                                   (Sep. 2016)

          -      Engine Test Report                                                              (Jan. 2017)

          -      Sub-system impact report                                                    (Mar. 2017)

          -      Final presentation                                                                (May 2017)

Current status

The kick-off of the project was on the 13th of November 2015. The activities within Task 1 are in progress. The literature study is approaching its finalisation and propellant selection criteria are being defined. 


ESA Contacts

Status date

Tuesday, March 15, 2016 - 09:27