Compact Boost Motor Propellant Stabilizer Sensor

Navy SBIR 22.2 - Topic N222-126
SSP - Strategic Systems Programs
Opens: May 18, 2022 - Closes: June 15, 2022 (12:00pm est)    [ View Q&A ]

N222-126 TITLE: Compact Boost Motor Propellant Stabilizer Sensor

OUSD (R&E) MODERNIZATION PRIORITY: General Warfighting Requirements (GWR)

TECHNOLOGY AREA(S): Materials / Processes; Sensors

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a compact sensor(s) that will collect the data which is used to infer the stabilizer content as well as other energetic, low molecular weight, organic compounds from the propellant in a solid rocket motor assembly.

DESCRIPTION: Solid rocket motors used by the Navy have propellant formulations that contain highly energetic materials. The formulations contain inorganic and organic solids, plasticizers and an elastomeric polymer. Stabilizers are employed to protect the polymeric structure used in the propellant formulations. The stabilizer content changes with age and environmental exposure. The Navy has a need for a compact sensor or suite of sensors that can collect data that can be used to infer the stabilizer content of solid rocket motor propellant in a non-destructive manner. The sensor would be used to inspect a suitably prepared propellant surface or subsurface in a rapid fashion. Knowledge of the stabilizer content and some of the other energetic components allows for a better evaluation of the health of the propellant. In addition to the sensor(s), an insertion system that is capable of positioning the sensor at a variety of difficult to reach locations within the solid rocket motor assembly will need to be designed. The needed R&D effort is the miniaturization of the sensor head (on the order of inches) and the development of an insertion system capable of moving the sensor into hard to reach areas within the rocket motor.

A sensor or a sensor suite that can perform the required measurements will address the difficulty of non-destructively evaluating the stabilizer content of the propellant grain in areas that are difficult to access. This technology will avoid the need to extract samples, potentially rendering the asset unusable, or dissecting an asset which forces the need for a replacement. The technology will avoid the need to disassemble and reassemble the solid rocket motor and minimize or eliminate the need to attach the equipment to the solid rocket motor. The capability the technology provides will allow measurements to be taken on substantially more assets.

This SBIR topic is focused on a sensor or multiple sensors that have the ability to collect the data needed to determine the stabilizer content, concentration, of the two stabilizers present, as well as the concentration of the energetic, low molecular weight plasticizer. Current non-destructive approaches employ an Ultra-Violet Visible (UV-Vis) light technique to determine stabilizer content. Laboratory methods typically employ high performance liquid chromatography techniques to determine stabilizer content. Future approaches may employ a miniature version of these techniques or leverage a completely different method. In the current approach, the operator manually places the sensor head into position. Fiber optics are used to expose the sample area to UV-Vis light. Some of the light is absorbed by the sample and the remainder is reflected off of the surface. The intensity of the reflected light is measured as a function of wavelength. Through calibration and data-processing, the stabilizer and plasticizer concentration is determined. The propellant surface is typically slightly oxidized or has a surface finish and may need to be prepared before surface measurements can be made. The sensor should meet low power, low voltage and HERO (Hazards of Electromagnetic Radiation to Ordnance) requirements for on-shore use [Ref 4]. The sensor should be capable of being able to pass through the confined area of the nozzle and be used at locations in the interior of a solid rocket motor. The sensor must be capable of being calibrated prior to use. The insertion system must be capable of placing the sensor at multiple locations, up to several meters from the exterior of the solid rocket motor assembly or preferably a mobile system capable of moving to the correct location for measurement. The sensor and insertion assembly must be capable of intermittent usage for a period of ten years.

PHASE I: Develop a technical concept for a propellant stabilizer sensor. Proposed design concepts should be completed during Phase I. Laboratory-scale demonstrations to verify the proposed sensor concept(s) can meet size constraints while provide the correct data. The laboratory testing must be satisfactorily completed to transition from Phase I to Phase II. Identify risks to the technical approach and develop/evaluate plans to mitigate those risks for Phase II. Laboratory-scale demonstrations to verify the proposed insertion system should be completed. The Phase I Option, if exercised, will include the initial design specification and capabilities description to build a prototype solution in Phase II.

Coordinate with Navy SBIR liaisons on key technical requirements data to be measured, size of the sensor, size of the insertion system, application method, power, and data storage/transmission needs.

PHASE II: Design and develop a prototype of the propellant stabilizer sensor based on the concept(s) from Phase I. Ensure the design has the ability to collect the data that can be used to measure the concentration of the two stabilizers and the energetic plasticizer. Ensure the design is sized such that it can pass through the throat of a Third Stage solid rocket motor nozzle and fit within the confined spaces of the propellant grain geometry. Ensure the design is capable of performing the measurements at multiple locations. Ensure the insertion system is capable of moving the sensor to the desired location. Complete testing of the sensor prototype to validate operation and feasibility. Design the testing to emulate the installation, sensing, data collecting/storage, and removal. Test material compatibility to ensure survivability and compatibility with solid rocket propellant during the inspection process.

PHASE III DUAL USE APPLICATIONS: Update the sensor from Phase II efforts. Support the development of an instruction manual for use. Manufacture an updated prototype and demonstrate use on an identified asset that is considered representative. Provide the necessary support for certification and qualification of the system for deployment and use at fleet facilities and/or facilities where fleet assets are located. This technology has the potential to be used commercially in any industry that has a need for stabilizer monitoring of materials in areas of high hazards.


  1. Roth, Milton. "Determination of Available Stabilizer in Aged Propellants Containing Either Diphenylamine or Ethyl Centralite." Technical Memorandum 1107 Ammunition Group, Picatinny Arsenal, February 1963.
  2. Moniruzzaman, M. and Bellerby, J.M. "Use of UV-Visible Spectroscopy to Monitor Nitrocellulose Degradation in Thin Films." Polymer Degradation and Stability 93(6), 1067-1072 June 2008.
  3. Graves, E.M. "Field-Portable Propellant Stability Test Equipment." Army Logistician 40 (4), July-August 2008.

KEYWORDS: Stabilizer Measurement; 1.1 Propellants; Compact Ultra-Violet/Visible Light Spectrometer; UV-Vis; Low Molecular Weight Aromatic Compounds; Compact Multi-Spectral Spectrometer; Non-Destructive Measurement


The Navy Topic above is an "unofficial" copy from the overall DoD 22.2 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its 22.2 SBIR BAA pre-release on April 20, 2022, which opens to receive proposals on May 18, 2022, and closes June 15, 2022 (12:00pm est).

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** TOPIC Q&A **
Questions answered 05/31/22
Q1. Will the Navy provide access to representative samples with different levels of stabilizer content to be measured in Phase I laboratory testing?
A1. No, the Navy will not provide access to any samples, but will assist when possible and necessary information wise, to help the team conduct representative laboratory testing and measurements
Q2. Should the sensor system perform any surface preparation alluded to in the topic? Or is it only intended to measure a suitably prepared surface / subsurface?
A2. The Surface layer may be resin rich or oxidized, either condition will lead to inaccurate measurements, so this will may to be addressed before measurement. If the sensor system could address this surface preparation it would be highly beneficial. It is not required but, definitely should be taken into consideration especially when in respects to accuracy of measurements
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