DARPA-PS-26-136.pdf

Program Solicitation (PS) Fox Tail

DEFENSE SCIENCES OFFICE

DARPA-PS-26-136

September 24, 2026

OVERVIEW INFORMATION:

• Federal Agency Name: Defense Advanced Research Projects Agency (DARPA), Defense

Sciences Office

• Funding Opportunity Title – Fox Tail

• Announcement Type – Initial Announcement

• Funding Opportunity Number – DARPA-PS-26-136

• Assistance Listing Number: Not applicable

• Dates/Time - All Times are Eastern Time Zone (ET):

o Classified Proposers Day: August 31, 2026 o Posting Date: September 24, 2026 o Requests for Security Classification Guidance (SCG) and Classified Addendum may be made immediately after PS posting. Note that proposers should allow at least 10 business days for processing requests and delivery of the SCG and Classified Addendum.

Proposers are encouraged to make this request early, as response times may vary.

DARPA is not responsible for abstract or proposal submission delays due to late requests.

See Section V for additional details.

o Deadline to Notify Security of Intent to Submit Classified Abstracts: October 30, 2026 o Proposal Abstract Due Date: November 13, 2026, at 4:00 p.m.

o Question Submittal Closed (Classified and Unclassified): January 13, 2027, at 4:00 p.m.

o Deadline to Notify Security of Intent to Submit Classified Proposals: January 16, 2027 o Proposal Due Date: January 29, 2027, at 4:00 p.m.

• Anticipated individual awards: Multiple awards are anticipated

• Period of Performance: Fox Tail is an 18-month effort, with a 12-month Base period and a 6-month Option period.

• Types of instruments that may be awarded: Other Transaction Agreements for Prototype

• Fox Tail is a classified program operating at the SECRET level. Security classification guidance via a Security Classification Guide (SCG) and DD Form 254, “DoD Contract Security Classification Specification,” can be requested along with the Classified Addendum per the instructions below in Section V.

• NAICS Code: 541715

• Agency contact:

The PS Coordinator for this effort may be reached at:

FoxTail@darpa.mil

DARPA/DSO

ATTN: DARPA-PS-26-136

675 North Randolph Street Arlington, VA 22203-2114 mailto:FoxTail@darpa.mil

SECTION I: FUNDING OPPORTUNITY DESCRIPTION

INTRODUCTION

The Defense Advanced Research Projects Agency (DARPA) is soliciting innovative proposals in the general area of extreme-scale hydrodynamics, including, but not limited to, high amplitude wave propagation, very high Reynolds number flows, and abrupt phase changes. Proposed research should investigate innovative theoretical and computational modeling approaches relying on first principles-based closures of the governing laws of fluid motion under such conditions.

BACKGROUND

Prediction and understanding of extreme-scale events in seawater requires the development of first-principle-based models capable of capturing anomalous thermo-fluid-dynamic conditions. To model these events, research should focus on developing thermodynamically consistent closures for potential local thermodynamic non-equilibrium (LTNE) effects while balancing disturbance energy budgets—including mechanical power, formation enthalpy, and phase transformations.

PROGRAM STRUCTURE

Program Metrics

Proposals must explicitly address the metrics specified in the classified addendum, with a detailed justification involving the use of calculations, theory, and data. Proposals that do not have sufficient data, analyses, referenced proof, or other forms of evidence to support their plans to meet the metrics may be considered non-conforming and removed from consideration.

Program Schedule Details on the program schedule are included in the classified addendum.

Milestones and Deliverables Details on milestones and deliverables are included in the classified addendum.

SECTION II: EVALUATION CRITERIA

Proposals will be evaluated using the following criteria listed in descending order of importance. Overall Scientific and Technical Merit; Potential Contribution and Relevance to the DARPA Mission; and Cost and Schedule Realism.

• Overall Scientific and Technical Merit: The proposed technical approach is innovative, feasible, achievable, and complete. Detailed technical rationale is provided delineating why the proposed approach can achieve the program goals and metrics. Task descriptions and associated technical elements provided are complete and logically sequenced with all proposed deliverables clearly defined so the final outcome of the award’s work achieves the program’s goal. The proposal identifies major technical risks and planned mitigation efforts that are clearly defined and feasible.

• Potential Contribution and Relevance to the DARPA Mission: The potential contributions of the proposed effort bolster the national security technology base and support DARPA’s mission to make pivotal early technology investments that create or prevent technological surprise. The proposed intellectual property restrictions (if any) will not significantly impact the Government’s ability to transition the technology.

• Security: The proposed activities are consistent with the Security Classification Guide (SCG) provided for the Fox Tail program. Proposer has a clear understanding of how they and their subcontractors will handle sensitive and/or classified information. The proposer documents their facilities as capable of handling Fox Tail information at the appropriate level and in the appropriate environment. Publication strategy, conference attendance, and any related publicity activities are clearly anticipated and compliant with the Fox Tail SCG.

• Cost and Schedule Realism: The proposed costs and schedule are realistic for the technical and management approach and accurately reflect the technical goals and objectives of the solicitation. The proposed costs are consistent with the proposer's Task Description Document (TDD) and reflect a sufficient understanding of the costs and level of effort needed to successfully accomplish the proposed technical approach. The costs for the prime proposer and proposed sub-awardees are substantiated by the details provided in the proposal (e.g., the type and number of labor hours proposed per task, the types and quantities of materials, equipment and fabrication costs, travel and any other applicable costs and the basis for the estimates). The proposed schedule aggressively pursues performance metrics in an efficient time frame that accurately accounts for the anticipated workload. It is expected that the effort will leverage all available relevant prior research in order to obtain the maximum benefit from the available funding. For efforts with a likelihood of commercial application, appropriate direct cost sharing may be a positive factor in the evaluation. DARPA recognizes that undue emphasis on cost may motivate proposers to offer low-risk ideas with minimum uncertainty and to staff the effort with junior personnel in order to be in a more competitive posture. DARPA discourages such cost strategies.

Unless otherwise specified in this announcement, for additional information on how DARPA reviews and evaluates proposals through the Scientific Review Process, please visit: Proposer Instructions: General Terms and Conditions.

https://www.darpa.mil/work-with-us/proposer-instructions

SECTION III: SUBMISSION GUIDELINES

This section provides general guidance for all potential proposers. Detailed instructions, formats, and submission requirements for the technical proposal are located in the classified addendum.

Instructions for requesting the SCG, classified addendum and classified proposal templates are in

SECTION V.

All UNCLASSIFIED technical, contractual, and administrative questions regarding this notice must be emailed to FoxTail@darpa.mil. Emails sent directly to the Program Manager, or any other address, may result in a delayed or no response. DARPA will attempt to answer all questions in a timely manner and post a “Frequently Asked Questions” document on the DARPA website. This will be updated on an ongoing basis until the closing date listed above.

Instructions for submitting classified questions are in the classified addendum.

• Proposers must review the following links:

o Proposer Instructions: General Terms and Conditions:

https://www.darpa.mil/about/offices/contracts-management/proposer-general-terms o Other Transaction Agreements: https://www.darpa.mil/about/offices/contracts-management/proposer-transactions

• Award Instrument: This solicitation will use an Other Transaction (OT) for Prototype agreement. A model OT agreement is provided as part of this solicitation (Attachment G).

• Abstract Submission: Proposers are strongly encouraged to submit a classified abstract.

Proposers must send an unclassified email to FoxTail@darpa.mil notifying security of their intent to submit a classified abstract by the date and time specified in the Overview section.

Use the subject line “DARPA-PS-26-136 Notification of Intent to Submit a Classified Abstract.” DARPA will review the abstracts and provide feedback as to whether a full proposal submission is encouraged. Abstracts are due no later than the date and time specified in the Overview section. Abstracts received after this time and date may not be reviewed. Detailed instructions for abstract content and submission are provided in the classified addendum.

• Proposal Submission: Proposers must send an unclassified email to FoxTail@darpa.mil notifying security of their intent to submit a classified proposal by the date and time specified in the Overview section. Use the subject line: “DARPA-PS-26-136 Notification of Intent to Submit a Classified Proposal.” Full proposals are due no later than the date and time stated in the Overview section. Proposals received after this time and date may not be reviewed. A conforming proposal consists of multiple volumes and attachments. The technical core of the proposal submission will be classified. Specific templates, content requirements for the technical volume, and classified submission instructions are provided exclusively in the classified addendum.

• Unclassified Submission Components: The following attachments must remain unclassified and be submitted via the DARPA Broad Agency Announcement Tool (BAAT) no later than the proposal due date and time stated in the Overview section. For instructions on how to mailto:FoxTail@darpa.mil https://www.darpa.mil/about/offices/contracts-management/proposer-general-terms https://www.darpa.mil/about/offices/contracts-management/proposer-transactions https://www.darpa.mil/about/offices/contracts-management/proposer-transactions submit to BAAT, visit the “Unclassified Submission Instructions” section at Proposer Instructions: General Terms and Conditions.

o Cost Proposal (Volume II): Includes Proposal Volume II Instructions (Attachment E) and the completed DARPA Cost Proposal Spreadsheet (Attachment F).

o Schedule of Milestones and Payments (Attachment I): Proposers must submit their proposed payment schedule. Note: Milestones must only be listed by number.

Detailed technical success criteria for these milestones must be reserved for the classified Technical Volume and must be easily corelated to the unclassified milestone number.

o Completed/Redlined Model OT (Attachment G): Proposers must submit any proposed redlines or changes to the model Other Transaction agreement.

o Representations and Certifications (Attachment J): Must be completed and submitted.

• COST SHARING: Cost sharing is not required unless the proposer is a traditional defense contractor, who is not working with a non-traditional defense contractor to a significant extent.

o Proposers must include a statement that identifies and substantiates which of the following condition(s) are met to permit use of OTs for Prototypes in accordance with 10 U.S.C. § 4022(d)(1): (A) There is at least one nontraditional defense contractor or nonprofit research institution participating to a significant extent in the prototype project; (B) All significant participants in the transaction other than the Federal Government are small businesses (15 U.S.C. § 638) or nontraditional defense contractors; (C) At least one third of the total cost of the prototype project is to be paid out of funds provided by sources other than the Federal Government; or (D) The senior procurement executive for the agency determines in writing that exceptional circumstances justify the use of a transaction that provides for innovative business arrangements or structures that would not be feasible or appropriate under a contract, or would provide an opportunity to expand the defense supply base in a manner that would not be practical or feasible under a contract.

Cybersecurity Maturity Model Certification Requirements

As codified in 32 CFR Part 170, the Cybersecurity Maturity Model Certification (CMMC) Program is designed to ensure Department of War (DoW) performers are properly safeguarding Federal Contract Information (FCI) and Controlled Unclassified Information (CUI) that is processed, stored, or transmitted on performer information systems. FCI and CUI must be protected to meet evolving threats and safeguard nonpublic, unclassified information that supports and enables the warfighter. The CMMC Program provides a consistent methodology to assess a defense contractor's implementation of cybersecurity requirements. Proposers are encouraged to visit the DoW Chief Information Officer CMMC Resources & Documentation site for more information on CMMC: https://dodcio.defense.gov/cmmc/Resources-Documentation/.

This provision outlines the CMMC requirements pertaining to this solicitation, to include the required CMMC level and the corresponding proposal requirements. All DARPA-awarded https://www.darpa.mil/work-with-us/proposer-instructions https://www.google.com/url?q=https%3A%2F%2Fdodcio.defense.gov%2Fcmmc%2FResources-Documentation%2F

Procurement Contracts and Other Transactions, including those involving Fundamental Research, at a minimum require prime performers and subcontractors to demonstrate compliance with CMMC Level 2 (Self), which focuses on the protection of FCI and consists of the security requirements that correspond to the 15 basic safeguarding requirements specified in 48 CFR 52.204-21.

1. Required CMMC Level

The required CMMC level for this solicitation is:

• CMMC Level 2 (Self-Assessment). Level 2 focuses on the protection of CUI and incorporates the 110 security requirements specified in NIST SP 800-171 Rev 2.

2. Eligibility for Award

To be eligible for award under this solicitation, the CMMC Unique Identifier (UID) associated with the prime proposer must reflect a current CMMC status (representing either Final or Conditional status) posted in the Supplier Performance Risk System (SPRS) indicating compliance at the required level above. Additionally, the proposer must have a current annual CMMC affirmation, submitted by an authorized Affirming Official, posted in SPRS. Further, as some entities may have multiple business segments, multiple CAGE codes, etc., DARPA must reasonably be able to relate the CMMC UID in SPRS to the proposing entity.

(Note: SPRS is housed within the Procurement Integrated Enterprise Environment https://piee.eb.mil; an additional resource on SPRS is located here:

https://dodcio.defense.gov/Portals/0/Documents/CMMC/CMMC-SPRS.pdf)

3. Subcontractor Flow-Down

Prime proposers are responsible for verifying subcontractor compliance. In the proposal, the prime proposer must attest that all subcontractors who will process, store, or transmit FCI or CUI under a resultant award will meet CMMC Level 2 (Self). The proposal must also describe the verification method the prime proposer will use to ensure subcontractors have the required CMMC status in SPRS prior to subcontract award.

Specifically:

If the Subcontractor will process, store, or transmit...

...the Subcontractor's Minimum Required CMMC Level is:

Federal Contract Information (FCI) only CMMC Level 2 (Self-Assessment)

Controlled Unclassified Information (CUI) The CMMC Level required by this solicitation

4. Intellectual Property and Technology Transition

Intellectual Property (IP)

The Fox Tail program, as described in the Classified Addendum, intends to transition beyond R&D into meaningful Government utilization and operational application. As such, the Government seeks to ensure the continued availability of capabilities and technical data https://piee.eb.mil/ https://www.google.com/url?q=https%3A%2F%2Fdodcio.defense.gov%2FPortals%2F0%2FDocuments%2FCMMC%2FCMMC-SPRS.pdf developed under this program that requires Intellectual Property (IP) rights sufficient to operate, maintain, modify, reproduce, compete, manufacture, and transition the prototype and associated deliverables, as applicable. Accordingly, IP license rights and transition planning are material requirements of this solicitation.

The Government’s objectives are to:

• Articulate the Government’s baseline licensing requirements to ensure successful technology transition, which include the ability to use, integrate, modify, sustain, transition, and further develop program results

• Understand proposer’s IP concerns through the proposal process, and negotiate mutually beneficial solutions

Baseline licensing requirements. The following table describes the Government’s minimum licensing requirements for acceptance of proposed technology solutions:

IP Category Definition Baseline Requirement

Foreground

IP (FIP)

First conceived, created, developed, or reduced to practice under this effort.

Government Purpose Rights (GPR) to items developed, generated, or delivered under the agreement

Background

IP (BIP)

Pre-existing privately funded IP, including pre-existing software, technical data, designs, tools, interfaces, documentation, or know-how that is incorporated into, required to operate or maintain, or otherwise necessary to manufacture, reproduce, modify, or transition the prototype.

GPR where available or a special negotiated license enabling the Government to transition the technology.

No Blocking Rights

The Government will not accept restrictions associated with Background IP, proprietary limitations, or other IP interests in a manner that unreasonably prevents, delays, or materially impairs the Government’s ability to:

• Utilize program results generated, developed, or delivered under this program for integration into 3rd party technologies developed by multiple performers.

• Transition capabilities to operational users and maintain/sustain resulting capabilities without significant additional licensing costs.

A performer shall not incorporate Background IP into a deliverable in a manner that prevents achievement of program objectives unless specifically identified and accepted by the Government prior to award.

SECTION IV: SPECIAL CONSIDERATIONS

• This solicitation, stated attachments, and websites incorporated by reference constitute the entire solicitation. In the event of a discrepancy between the announcement, attachments, or websites, the solicitation takes precedence.

• Non-U.S. organizations and/or individuals cannot participate in this solicitation. All other responsible sources capable of satisfying the Government's needs may submit a proposal that shall be considered by DARPA. Historically Black Colleges and Universities, Small Businesses, Small Disadvantaged Businesses and Minority Institutions are encouraged to submit proposals and join others in submitting proposals; however, no portion of this announcement will be set aside for these organizations’ participation due to the impracticality of reserving discrete or severable areas of this research for exclusive competition among these entities.

• Due to their specialized roles and longstanding regulatory relationships with the Government, Federally Funded Research and Development Centers (FFRDCs), University Affiliated Research Centers (UARCs), and Government Entities to include National Laboratories present potential conflicts and advantages that would compromise fair and open competition.

These entities typically may only receive funding through existing awards they hold with their sponsoring agencies. If these entities are proposed as subawardees, their costs must be clearly segregable in cost proposals. If scientifically merited, DARPA may fund work proposed by these entities with the following caveats:

o FFRDCs: (1) FFRDCs must clearly demonstrate that the proposed work is not otherwise available from the private sector. (2) FFRDCs must provide a letter, on official letterhead from their sponsoring organization, that (a) cites the specific authority establishing their eligibility to propose to Government solicitations and compete with industry, and (b) certifies the FFRDC’s compliance with the associated FFRDC sponsor agreement’s terms and conditions. DARPA, under this solicitation, will not award separate contracts to FFRDCs as prime or subawardees but will instead leverage their existing sponsors' agreements.

o UARCs: While UARCs typically have statutory authority to compete with industry, internal DARPA policy views them as trusted advisors who are only eligible to act as performers in fields where they do not serve in an advisory role. Even in those situations, DARPA still considers UARCs as having organizational conflicts of interest (OCI) when applying for a performer role. Proposals with UARCs as prime or subawardees must include an OCI mitigation plan.

For this solicitation, DARPA will not establish new contractual agreements for their participation. Accordingly, any proposal submitted directly by these entities in a prime contractor capacity may be deemed non-conforming and not evaluated. Proposals that include a UARC, FFRDC, Government entities, or National Laboratory as a subcontractor may also be deemed non-conforming unless: (1) their role is clearly defined in the technical proposal with a point of contact, and (2) a rough order of magnitude cost is provided in the technical proposal only—cost proposals must exclude their funding, as DARPA will not fund them through the prime. It is important to note that if funded, these organizations will be required to share their work and findings with other performers also supporting the same program. Additionally, DARPA may contact these entities directly to discuss proposed activities.

• As of the date of publication of this solicitation, the Government expects that program goals as described herein either cannot be met by proposers intending to perform fundamental research or the proposed research is anticipated to present a high likelihood of disclosing performance characteristics of military systems or manufacturing technologies that are unique and critical to defense. Therefore, the Government anticipates restrictions on the resultant research that will require the awardee to seek DARPA permission before publishing any information or results relative to the program. For additional information on fundamental research, please visit Proposer Instructions: General Terms and Conditions.

o Proposers should indicate in their proposal whether they believe the scope of the research included in their proposal is fundamental or not. While proposers should clearly explain the intended results of their research, the Government shall have sole discretion to determine whether the proposed research shall be considered fundamental and to select the award instrument type. Appropriate language will be included in resultant awards for non-fundamental research to prescribe publication requirements and other restrictions, as appropriate. This language can be found at Proposer Instructions: General Terms and Conditions.

o For certain research projects, it may be possible that although the research to be performed by a potential awardee is non-fundamental research, its proposed sub-awardee’s effort may be fundamental research. It is also possible that the research performed by a potential awardee is fundamental research while its proposed sub-awardee’s effort may be non-fundamental research. In all cases, it is the potential awardee’s responsibility to explain in its proposal which proposed efforts are fundamental research and why the proposed efforts should be considered fundamental research.

Other Resources Available:

• The APEX Accelerators program, formerly known as the Procurement Technical Assistance Program (PTAP), focuses on building strong, sustainable, and resilient U.S. supply chains by assisting a wide range of businesses that pursue and perform under contracts with the DoD, other federal agencies, state and local governments, and government prime contractors. See www.apexaccelerators.us/ for more information.

APEX Accelerators helps businesses:

o Complete registration with a wide range of databases necessary for them to participate in the government marketplace (e.g., SAM).

o Identify which agencies and offices may need their products or services and how to connect with buying agencies and offices.

o Determine whether they are ready for government opportunities and how to position themselves to succeed.

o Navigate solicitations and potential funding opportunities.

o Receive notifications of government contract opportunities on a regular basis.

o Network with buying officers, prime contractors, and other businesses.

https://www.darpa.mil/work-with-us/proposer-instructions https://ddmdraft.darpa.mil/work-with-us/proposer-instructions https://www.apexaccelerators.us/ o Resolve performance issues and prepare for audit, only if the service is needed, after receiving an award.

• Project Spectrum is a nonprofit effort funded by the DoD Office of Small Business Programs to help educate the Defense Industrial Base (DIB) on compliance. Project Spectrum is vendor-neutral and available to assist businesses with their cybersecurity and compliance needs. Their mission is to improve cybersecurity readiness, resilience, and compliance for small/medium-sized businesses and the federal manufacturing supply chain. Project Spectrum events and programs will enhance awareness of cybersecurity threats within the manufacturing, research and development, and knowledge-based services sectors of the industrial base. Project Spectrum will leverage strategic partnerships within and outside of the DoD to accelerate the overall cybersecurity compliance of the DIB.

• www.projectspectrum.io is a web portal that will provide resources such as individualized dashboards, a marketplace, and Pilot Program to help accelerate cybersecurity compliance.

• DARPAConnect offers free resources to potential performers to help them navigate DARPA, including “Understanding DARPA Award Vehicles and Solicitations, “Making the Most of Proposers Days,” and “Tips for DARPA Proposal Success.” Join DARPAConnect at www.DARPAConnect.us to leverage on-demand learning and networking resources.

http://www.projectspectrum.io/ http://www.darpaconnect.us/

SECTION V: REQUESTING THE SECURITY CLASSIFICATION GUIDE

AND CLASSIFIED ADDENDUM

A formal request for the Security Classification Guide (DARPA-CG-1253), classified addendum and classified proposal templates may be submitted by filling out Attachment K CLASSIFIED ADDENDUM AND SECURITY CLASSIFICATION GUIDE REQUEST FORM and emailing the Request Form to FoxTail@darpa.mil with subject line titled, “Request DARPA-PS-26-136 Security Classification Guide and Classified Addendum.”

The DARPA-PS-26-136 Attachment K CLASSIFIED ADDENDUM AND SECURITY CLASSIFICATION GUIDE REQUEST FORM is the only method of request that will be accepted. Security classification guidance via a Security Classification Guide and a DD Form 254, "DoD Contract Security Classification Specification," will be provided with the classified addendum and classified proposal templates.

Requests for the classified addendum should include, at a minimum, the company name, Technical POC name and phone number, Facility Security Officer (FSO) name and phone number, CAGE code, statement of facility clearance and safeguarding capability, and a valid U.S. Postal Service address for receiving classified material at the SECRET level. If requesting receipt via classified email, include the network (i.e., SIPR, DSWAN, JWICS, or SAVANNAH/ ASCEND, and a valid email address. DARPA will verify the facility clearance and the clearance of the recipient before e-mailing via secure system or mailing the classified material.

It is the proposer’s responsibility to ensure that they fully familiarize themselves with the Security Classification Guide prior to reading the classified addendum and preparing abstracts and/or proposals for submission.

Requests for the classified addendum should be received by no later than the due date and time specified in Part I: “Overview Information” to allow adequate time to have classified material provided to them in support of DARPA-PS-26-136. Proposers should allow at least 10 business days for processing requests. Requests will be handled on a first-in, first-out basis. Incomplete or inaccurate request forms will be returned to sender along with a notification of what needs to be corrected. Any new request will be processed based on the date of when the revised request form is received.

Proposers choosing to submit classified information from other collateral classified sources (i.e., sources other than DARPA) must ensure: (1) they have permission from an authorized individual at the cognizant Government agency (e.g., Contracting Officer, Program Manager); (2) the submission is marked in accordance with the source Security Classification Guide (SCG) from which the material is derived; and (3) the source SCG is provided along with the submission.

Proposers submitting classified information must have, or be able to obtain prior to award, cognizant security agency approved facilities, information systems, and appropriately cleared/eligible personnel to perform at the classification level proposed. This includes ensuring all industrial, personnel, and information systems processing security requirements are in place and at the appropriate level (e.g., Facility Clearance Level, Automated Information Security, Assessment and Authorization). Furthermore, all proposed personnel who will be performing Information Assurance (IA)/Cybersecurity related duties on classified Information Systems shall meet the requirements set forth in DoD Manual 8570.01-M (Information Assurance Workforce

Improvement Program).

Additional information on the subjects discussed in this section may be found at https://www.dcsa.mil/.

https://www.dcsa.mil/