Notice

Windfarm Mitigation for UK Air Defence Phase 2: Competition Document

Updated 11 June 2021

1. Introduction

This Defence and Security Accelerator (DASA) competition is seeking proposals that can develop technologies to permit the coexistence of future offshore windfarms alongside UK Air Defence surveillance systems. This includes alternative technologies that could reduce radar clutter caused by offshore windfarms, ensure intruder detection in the vicinity of offshore windfarms and fill or remove gaps in radar coverage created by windfarms.

The competition is funded by the Department for Business, Energy, and Industrial Strategy (BEIS) Net Zero Innovation Portfolio; and is undertaken in partnership with the Royal Air Force (RAF), the Defence Science and Technology Laboratory (Dstl), and the Defence and Security Accelerator (DASA).

A total of up to £3.6m is available, intended to fund a number of contracts of up to £600K each.

Please note this is the 2nd phase of funding for a multi-phase competition. It is not compulsory to have been involved in previous phases to apply. You should however make yourself aware of the previous competition and the bids we funded. It is anticipated that work for this phase will reach higher maturity than work funded in phase 1.

2. Competition scope

2.1 Background

The UK’s need for Offshore Wind

The development of Offshore Wind in the United Kingdom (UK) has supported domestic energy demands and contributed to the decrease in cost of low-carbon generation technology. This Levelised Cost of Energy (LCOE) of Offshore Wind now makes it competitive with fossil fuel generation, paving the way for a new greener economy in the UK.

Her Majesty’s Government (HMG), under the Offshore Wind Sector Deal, plans to install 40GW of offshore wind electricity generation capacity (expected to represent ca 40% of the UK’s electricity need) from offshore windfarms in the UK by 2030. This deal has also set a target of supporting 60,000 jobs and £2.4bn per annum of exports by 2030.

In addition, under the 2019 ‘Net Zero’ legislation, the Committee on Climate Change (HMG’s advisory body) has predicted a requirement for at least 75GW of electricity from offshore wind by 2050. This would require a ten-fold increase of current offshore windfarm generation capacity. It is expected that this will be achieved by offshore windfarm developers and operators installing additional offshore windfarms around the UK, both fixed bottom structures and floating structures. It is likely that achieving these ambitious targets will require developers to utilise new and more advanced manufacturing techniques.

The impact of turbines on radar

The continued development of wind turbine sites has the potential to cause a number of negative effects for military air defence (and air traffic control) systems. Offshore windfarms, when in the line of sight of radar, have a detrimental effect on Ministry of Defence’s (MOD) primary surveillance radar capability used to deliver a ‘recognised air picture’ for Air Defence.

Radar returns from within-radar line of sight wind turbines comprise reflections from both the static and moving elements; providing different challenges for the radar operator. While reflections from the stationary elements of wind turbines can be removed by utilising stationary clutter filters, the rotating turbine blades impart a Doppler shift on the reflection that cannot be easily removed.

A number of recent trials have demonstrated the adverse impact that this has on the UK’s air defence capability. The Doppler shift on ground radar returns mimics the signals of fast moving aircraft, curtailing the RAF’s ability to detect incoming, low flying, aircraft threats.

Analysis of these trials has concluded that current mitigation methodologies are insufficient to meet the expected operational requirements. In addition, many of the mitigations applied to civilian radar systems cannot be applied to MOD Air defence primary surveillance radar assets. Further, Air Defence staff cannot rely on transponder data, standard flight paths, and standard flying heights of potential enemy aircraft who may intend to remain hidden.

It is to be expected that future windfarms will increase in size and number. Additionally, turbine blades are expected to increase in length to over 130 metres. The blade tip velocity is expected to increase further. All these developments will exacerbate the detrimental effect of offshore windfarms on radar systems.

Given these challenges, current windfarm developments are subject to objections from the aviation sector, preventing the development of windfarms within the radar line of sight of many air defence radar installations.

With accelerated deployment of offshore windfarms needed to meet the goals set out in legislation, there is a clear need to mitigate the impact of wind turbines on radar and allow the windfarm developments to go ahead. MOD’s objections to offshore wind facilities within radar line of sight are causing attrition in the deployment pipeline, which risks endangering the decarbonisation trajectory of the United Kingdom.

3. Competition Challenge: Maintain effective surveillance of airspace in the presence of larger windfarms

The fundamental challenge is to maintain the effective surveillance of airspace despite the presence of larger windfarms. Whilst the context must take into account current practices and the wide use of radar the enduring requirement is one of effective monitoring of airspace. This should be achieved without compromising the performance of offshore wind turbines in terms of energy output or reliability which are critical in the UK reaching its decarbonisation targets.

The following topics are not restrictive nor exhaustive but present areas upon which innovation may have an impact. Scenarios are given here as illustrations and are not to be considered as direct problems to be solved.

3.1 Reduction of clutter or the impact of clutter

Wind turbines have a large radar cross-section (RCS). The rotating turbine blades generate a Doppler frequency shift. The curved surfaces of the turbine blades scatters the returning signal from targets, potentially losing information such as time of return and hence distance and Doppler velocity information. Large offshore windfarms may cause saturation of the returned radar signal.

For example

Consider a low flying object near a windfarm. The ability to at first detect and then track is the major objective of air surveillance. Any disruption caused by excessive clutter may adversely affect national security and/or safety.

3.2 Ensuring efficient detection and tracking time

It will be appreciated that the generation of clutter may impact on the ability to detect intruders and to track objects in the vicinity of windfarms. Detecting, identifying and maintaining contact with objects after detection is important.

For example

Consider a fast flying jet making a sharp turn over a windfarm. The entry trajectory may not match the exit trajectory. Confirming the two signals apply to the same object is of paramount importance.

3.3 Technologies to mitigate against larger turbine blades and wider turbine spacing development

To meet the targets for offshore wind energy generation it will be necessary to build more and bigger windfarms. This will increase the affected areas both horizontally and in height. Minimising the gaps in surveillance coverage is required to maintain the ability to detect incoming threats. In addition, the possibility of interference caused by two separate windfarms in proximity, or in the same radar line of sight, has to be considered.

It is likely that floating structures will be used in the future meaning the horizontal vertical position (bob and sway) of turbines is not fixed. How can this lack of positional certainty be accommodated or mitigated?

3.4 Alternate methods of surveillance

It should be appreciated that the current air surveillance system is based upon conventional radar technology. This does not restrict potential solutions and innovations to radar technology and we would welcome proposals that consider alternative technologies that will complement or provide an equivalent level of air surveillance, for example synthetic aperture radars that overcome interference by using long baselines.

3.5 Clarification of what we want

What we are seeking are proposal to address the challenge of maintaining the effective surveillance of airspace, despite the presence of larger windfarms. Proposals may include, but are not limited to, use of:

• alternative turbine materials
• shaping of turbine blades
• next generation or novel signal processing techniques including those using increased Artificial intelligence / Machine Learning / Deep Learning (and potentially exploiting wind turbine data)
• alternative technologies or
• combinations of these that would maintain the effective surveillance of airspace despite the presence of larger windfarms

We want novel ideas to benefit users working in UK Defence and Security. Your proposal should include evidence of:

• theoretical development, methodological advancement or proof of concept research which can demonstrate potential for translation to practical demonstration in later phases
• innovation or a creative approach
• clear demonstration of how the proposed work applies to the given military air defence (and air traffic control) contexts (including non-cooperative aircraft within the recognised air picture)

3.6 Clarification of what we do not want

For this competition we are not interested in proposals that:

• deliver technologies below TRL 4
• do not offer realistic prospect of mitigating radar line of sight turbine impact on air surveillance
• constitute consultancy, paper-based studies or literature reviews which just summarise the existing literature without any view of future innovation (which therefore could not be developed into further phases)
• offer demonstrations of off-the-shelf products requiring no experimental development (unless applied in a novel way to the challenge)
• are an identical resubmission of a previous bid to DASA or MOD without modification
• offer no real long-term prospect of integration into defence and security/civil capabilities
• offer no real prospect of out-competing existing technological solutions

4. Exploitation

It is important that over the lifetime of DASA competitions ideas are matured and accelerated towards appropriate end users to enhance capability. How long this takes will be dependent on the nature and starting point of the innovation. Early identification and appropriate engagement with potential end users during the competition and subsequent phases are essential in order to develop and implement an exploitation plan.

All proposals to DASA should articulate the expected development in technology maturity of the potential solution over the lifetime of the contract and how this relates to improved operational capability against the current known (or presumed) baseline. Your deliverables should be designed to evidence these aspects with the aim of making it as easy as possible for collaborators/stakeholders to identify the innovative elements of your proposal in order to consider routes for exploitation.

This Phase 2 competition aims to identify novel technologies that could be further investigated and taken to field trials to inform BEIS and MOD strategy for offshore windfarm development.

A higher technology maturity will be expected in the future. You may wish to include some of the following information, where known, to help the assessors understand your exploitation plans to date:

• the intended defence or security users of your final product and whether you have previously engaged with them, their procurement arm or their research and development arm
• awareness of, and alignment to, any existing end-user procurement programmes
• the anticipated benefits (for example, in cost, time, improved capability) that your solution will provide to the user
• whether it is likely to be a standalone product or integrated with other technologies or platforms
• expected additional work required beyond the end of the contract to develop an operationally deployable commercial product (for example, “scaling up” for manufacture, cyber security, integration with existing technologies, environmental operating conditions)
• additional future applications and wider markets for exploitation
• wider collaborations and networks you have already developed or any additional relationships you see as a requirement to support exploitation
• how your product could be tested in a representative environment in later phases
• how your technology will work with wind turbine technology and will withstand operational conditions such as erosion/corrosion
• any expected impact on the performance of the wind turbine, for example due to changes in blade geometry or blade mass
• how you envisage your technology may work and integrate with sir defence systems and ATC systems
• any specific legal, ethical, commercial or regulatory considerations for exploitation

Longer term studies may not be able to articulate exploitation in great detail, but it should always be clear that there is some credible advantage to be gained from the technology development.

5. How to apply

Proposals for funding to meet these challenges must be submitted by midday BST on 17 June 2021 via the DASA submission service, for which you will be required to register.

The total funding available for Phase 2 is £3.6m (excluding VAT), with individual proposals not exceeding £600K (ex VAT). If successful, contracts awarded will complete no later than 28 February 2023. Additional funding for further development may become available in the future. Any further development will be subject to a separate procurement process.

Further guidance on submitting a proposal is available on the DASA website.

5.1 What your proposal must include

The proposal should focus on the Phase 2 requirements but must also include a brief (uncosted) outline of the next stages of work required for exploitation.

When submitting a proposal, you must complete all sections of the online form, including an appropriate level of technical information to allow assessment of the bid and a completed finances section.

Completed proposals must comply with the financial rules set for this competition. The upper-limit for this competition is £600k (excluding VAT) per proposal. Proposals will be rejected if the financial cost exceeds this capped level. You must include a list of other current or recent government funding you may have received in this area if appropriate, making it clear how this proposal differs from that work.

A project plan with clear milestones and deliverables must be provided. Deliverables must be well defined and designed to provide evidence of progress against the project plan and the end-point for this phase; they must include a final report. You should also plan for attendance at a kick-off meeting at the start of Phase 2, a mid-project event and an end of project event at the end of Phase 2, as well as regular reviews with the appointed Technical Partner and project manager; all meetings will be in the UK.

Your proposal must demonstrate how you will complete all activities/services and provide all deliverables (in the table below) within the competition timescales (ending no later than the end of February 2023). Proposals with any deliverables (including final report) outside the competition timeline will be rejected, having been deemed non-compliant.

5.2 Minimum Required Deliverables

In accordance with DEFCON 705, required rights are noted below.

Deliverable/Event:	Action of supplier:	MOD Rights under DEFCON 705
Project kick off meeting	Participated in, and attended by, the supplier	N/A
Monthly progress meetings with the nominated Technical Partner	Participated in by the supplier	N/A
Quarterly progress meetings with DASA, Dstl, the RAF and BEIS	Participated in, and attended by, the supplier	N/A
Demonstration of technique or technology at a demonstration event . Demonstration can range from software modelling to a scaled physical event but must be appropriate to the TRL level	Delivered by, participated in and attended by, the supplier	DEFCON 705 Full Rights
Pre-quarterly meeting progress reports (including detailed project plan, risk, and applicable literature review)	Delivered by the supplier, 2 weeks prior to each quarterly progress meeting	DEFCON 705 Full Rights
Final report on technique or technology developed (including both technical detail and applicability to current and future offshore wind); including provision of collected raw data and statistical analysis	Delivered by the supplier at the end of the Contract	DEFCON 705 Full Rights
User guide(s) (where applicable)	Delivered by the supplier	DEFCON 705 Full rights
Any data or algorithms used during the project (where applicable)	Delivered by the supplier	DEFCON 705 Full rights
Interface definition for technique or technology (where applicable)	Delivered by the supplier	DEFCON 705 Full rights

A resourcing plan must also be provided that identifies, where possible, the nationalities of those proposed research workers that you intend working on this phase. In the event of proposals being recommended for funding, DASA will undertake due diligence checks including the clearance of proposed research workers. Please note that this process will take as long as necessary and could take up to 6 weeks in some cases for non-UK nationals.

You must identify any ethical, legal, or regulatory factors within your proposal and how the associated risks will be managed, including break points in the project if approvals are not received. Ministry of Defence Research and Ethics Committee (MODREC) approvals can take up to 5 months; therefore you should plan your work programme accordingly. Further details are available in the DASA guidance. If you are unsure if your proposal will need to apply for MODREC approval, then please contact DASA for further guidance.

Requirements for access to Government Furnished Assets (GFA), for example, information, equipment, materials and facilities, should be included in your proposal. DASA cannot guarantee that GFA will be available and you should therefore show such requests separately within your proposal to show how you will deliver your proposal without GFA.

IMPORTANT

Failure to provide any of the above listed will automatically render your proposal non-compliant.

5.3 Cyber risk assessment (REVISED JUNE 11 2021)

DASA has completed a Cyber Risk Assessment (CRA) for this competition. In order to submit to this competition suppliers are required to work towards cyber resilience. If selected for funding, the supplier must prove cyber resilience before a contract will be awarded.

Suppliers must complete a Supplier Assurance Questionnaire (SAQ) here, using the DASA Risk Assessment Reference (RAR) for this competition: RAR-ZKY89CXT and answer questions for risk level “Very Low”.

The Defence Cyber Protection Partnership (DCPP) will review your SAQ submission and respond with a reference number within 2 working days. The completed SAQ form and resulting email response from DCPP must be downloaded and included within the DASA submission service portal when the proposal is submitted. Please allow enough time to receive the SAQ reference number prior to competition close at midday on 17 June 2021.

If the proposal is being funded, the SAQ will be evaluated against the CRA for the competition, and it will be put it into one of the following categories:

1. Compliant – no further action
2. Not compliant – if successful in competition and being funded, the supplier will be required to complete a Cyber Implementation Plan (CIP) before the contract is placed, which will need to be reviewed and agreed with the relevant project manager

Suppliers can enter a proposal without all controls in place, but are expected to have all the cyber protection measures necessary to fulfil the requirements of the contract in place at the time of contract award, or have an agreed Cyber Implementation Plan (CIP). The CIP provides evidence as to how and when potential suppliers will achieve compliance. Provided the measures proposed in the Cyber Implementation Plan do not pose an unacceptable risk to the MOD, a submission with a Cyber Implementation Plan will be considered alongside those who can achieve the controls. A final check will be made to ensure cyber resilience before the contract is placed. Commercial staff cannot progress the competition / procurement without it. This process does not replace any contract specific security requirements.

Further guidance for completing this process can be requested by emailing accelerator@dstl.gov.uk.

Additional information about cyber security can be found at: DCPP: Cyber Security Model industry buyer and supplier guide.

5.4 Public facing information

When submitting your proposal, you will be required to include a proposal title and a short abstract. The title and abstract you provide will be used by DASA, and other government departments , to describe the project and its intended outcomes and benefits. It will be used for inclusion at DASA events in relation to this competition and included in documentation such as brochures. The proposal title will also be published in the DASA transparency data on GOV.UK, along with the amount of funding and your company name.

5.5 How your proposal will be assessed

At Stage 1, all proposals will be checked for compliance with the competition document and may be rejected before full assessment if they do not comply. Only those proposals who demonstrate their compliance against the competition scope and DASA mandatory criteria will be taken forward to full assessment. Failure to achieve full compliance against Stage 1 will render your proposal non-compliant and will not be considered any further:

The proposal outlines how it meets the scope of the competition	Within scope (Pass) / Out of scope (Fail)
The proposal fully explains in all three sections of the DASA submission service how it meets the DASA criteria	Pass / Fail
The proposal clearly details a financial plan, a project plan and a resourcing plan to complete the work proposed in phase 2	Pass / Fail
The proposal identifies the need (or not) for MODREC approval	Pass / Fail
The proposal identifies any GFA required to support the delivery of your solution	Pass / Fail
The technology proposed will deliver output of technology readiness level ≥TRL 4	Pass / Fail
The maximum value of the proposal is £600k exclusive of VAT	Pass / Fail
The proposal demonstrates how all research and development activities/services (including delivery of the final report) will be completed not later than 28 February 2023	Pass / Fail
The bidders proposal includes provisions for attendance and participation in the meetings outlined in section 5.1	Pass / Fail
The bidder has obtained the authority to, and has provided unqualified acceptance of the terms and conditions of the Contract.	Pass / Fail
The bidder has completed and submitted a Supplier Assurance Questionnaire (SAQ) together with the outcome– See Section 5.2 above	Pass / Fail

Proposals that pass Stage 1 will then be assessed against the standard DASA assessment criteria (Desirability, Feasibility, and Viability) by subject matter experts from the MOD (including Dstl), other government departments, and front-line military commands. You will not have the opportunity to comment on assessors comments.

DASA reserves the right to disclose on a confidential basis any information it receives from bidders during the procurement process (including information identified by the bidder as Commercially Sensitive Information in accordance with the provisions of this competition) to any third party engaged by DASA for the specific purpose of evaluating or assisting DASA in the evaluation of the bidder’s proposal. In providing such information the bidder consents to such disclosure. Appropriate confidentiality agreements will be put in place.

Further guidance on how your proposal is assessed is available on the DASA website.

After assessment, proposals will be discussed internally at a Decision Conference where, based on the assessments, budget and wider strategic considerations, a decision will be made on the proposals that are recommended for funding.

Proposals that are unsuccessful will receive brief feedback after the Decision Conference.

5.6 Things you should know about DASA contracts

Please read the DASA terms and conditions which contain important information for suppliers. For this competition we will be using the Innovation Standardised Contracting (ISC) links to the contract here: Terms and Schedules. We will require unqualified acceptance of the terms and schedules

Funded projects will be allocated a Project Manager (to run the project) and a Technical Partner (as a technical point of contact). This technical partner may be a subject matter expert from outside of Dstl (another Government department or an independent consultant under a NDA). In addition, the DASA team will work with you to support delivery and exploitation including where appropriate introductions to end-users and business support to help SMEs develop their business.

DASA also collects information from projects after the project has concluded and you should expect to be contacted once your project has completed for measurement purposes.

We will use deliverables from DASA contracts in accordance with our rights detailed in the contract terms and conditions.

For this phase, up to £3.6m is currently available to fund multiple proposals. There may be occasions where additional funding from other funding lines may subsequently become available to allow us to revisit those proposals deemed suitable for funding but where limitations on funding at the time prevented DASA from awarding a subsequent Contract. In such situations, DASA reserves the right to keep such proposals in reserve.

In the event that additional funding subsequently becomes available, we may ask whether you would still be prepared to undertake the work outlined in your proposal under the same terms.

6. Phase 2 dates

Description	Date
Pre bookable 1-1 telecom sessions	05 & 07 May 2021
Competition closes	1200 midday BST 17 June 2021
Award Decisions released	August 08 2021
Contracts	Aiming for September 2021 and concluding by end of February 2023

6.1 Supporting events

Supplier 1 to 1 teleconferences

A series of 15 minute one-to-one teleconference sessions, giving you the opportunity to ask specific questions. If you would like to participate, please register on the 1-1s Eventbrite pages below.

May 05 2021

May 07 2021

Clarification questions and answers from the 1-1 sessions will be recorded, anonymised and shared with all bidders as an annex to this document

Collaboration Survey

For this phase we are encouraging collaboration between suppliers. To support this we have a short survey to collect details of suppliers and stakeholders who wish to explore collaboration possibilities.

7. Help

Competition queries and clarification questions should be sent to accelerator@dstl.gov.uk, by no later than 17 May 2021 quoting the competition title. If you wish to subscribe to further updates please email a request into the accelerator inbox, this will ensure you receive future updates on this competition.

While all reasonable efforts will be made to answer queries, DASA reserves the right to impose management controls if volumes of queries restrict fair access of information to all potential suppliers.

8. Clarifications Annex

8.1 General Questions

Q: Is collaboration welcome?

A: Yes. Collaboration is especially recommended when a single approach is not likely to deliver a complete solution. It is most likely that a successful approach will be a system of systems and collaboration can help facilitate this, by allowing a diverse approach and, ideally, some testing of the solution to help demonstrate it will work sustainably in an operational environment.

To help facilitate this, we have created a collaboration survey on the competition page here. After completing this survey you will receive an email every Friday with a list of the other suppliers interested in collaboration. There is no limit to the number of suppliers that you can collaborate with.

Q: Can I use a non-UK national research worker on my project?

A: Yes, it’s fine to use non-UK national researchers. Both UK and non-UK national researchers will need to complete a Form 388 that DASA will use to perform due diligence and obtain necessary clearances. A Form 388 will be sent to you if you’re successful under a DASA competition. The process can take up to 6 weeks.

Q: What is the proposal cost limit?

A: If a proposal exceeds £600,000 it will be pre-sifted out.

Q: Can we submit more than one proposal?

A: Yes, it is possible to submit more than one proposal but each must be self standing and will be assessed individually on its own merits.

Q: Can we submit a proposal in to Phase 2, even though we were not part of Phase 1?

A: Yes, you can. We would advise you to make yourself aware of what was funded in Phase 1.

Q: Are presentations from Phase 1 available to help guide bids for Phase 2.

A: At the moment, these are treated as commercially sensitive. We are investigating the possibility of sharing

Q: What Technology Readiness Level (TRL) are you looking for?

A: We are hoping for TRL 5 or 6 by the end of Phase 2, but if your TRL is higher that is not an issue. Phase 1 looked at unique solutions to parts of the problem. For Phase 2, we want to look at how we put those together to make a system of systems to overcome the challenge.

Q: Will test facilities be made available?

A: We do not expect to provide access to test facilities. If your proposal require Government Furnished Assets (GFX/GFA) it should be made clear within the proposal. You may wish to consider collaborating with other suppliers that might be able to help with testing of some description.

Q: If I use commercially sensitive third party information or Supplier Background information [data] to test my algorithm can I prevent this from being shared with other companies under DEFCON 705 terms?

A. If the data needs to be shared with the Authority, for example because it is essential to the understanding of the work, which would be the first question to be considered, then The Authority is likely to agree for a Limited Rights Version of a final report, containing this data, to be delivered in addition to the Full Rights Version final report. Limited Rights Versions are largely (see Clause 14 of Defcon 705) only available for use within UK Government.

8.2 Scope Questions:

Q: Is there a preference for a particular technology?

A: This competition is solution agnostic, we do not know what the right technology is at this stage. The solution could come from a system of systems and something contributing to this would be of interest. The offshore windfarm environment is very hostile; this needs to be understood and reflected in your proposal.

Q: Is an alternative to radar an acceptable approach?

A: Yes. Although we are not looking specifically for a radar solution, we are looking for any proposed solution to have comparable performance. Any shortfalls from that (e.g. reduced detection range, delay in detection) should be noted and an explanation offered as to how these might be overcome in an operational system.

Q: Is there a de-emphasis on materials for Phase 2?

A: Not at all. However, we want to move on to look at how innovative materials will be integrated into the system. Given the hostile environment the blades must remain durable (leading edge erosion is an issue). Give thought to the impact your material will have on them. A description of how you will determine that your coating fulfils operational requirements should be given in your proposal. It is not necessary to demonstrate in a real life environment at this stage.

Q: Are you seeking to only identify aircraft, or more than this?

A: At this stage the focus is on air defence, so aircraft of all types. However, if you can do more than that it would be interesting.

Q: What surveillance coverage are you looking for?

A: Within and above the windfarm (on- and offshore), covering up to 2,000ft, ideally 5,000ft. Their impact on radar can be measured as high as 10,000ft. Being able to expand to a couple of Kilometres beyond the windfarm would be useful.

Q: Is detection behind windfarms an issue?

A: Not so much, although it might depend on where the windfarm is. The main issue is being unable to detect targets over windfarms or in the vicinity of them.

Q: Shadowing behind the windfarm can create cumulative effects; how far apart are the windfarms?

A: The sites of windfarms, both built and consented, can be seen on the Crown Estates website (https://www.thecrownestate.co.uk/en-gb/our-places/asset-map/)

Q: If aiming to reduce Radar cross section (RCS) what reduction is sought?

A: No particular specification; the aim is not to constrain an approach. A system of systems could be a solution, with cumulative effects. Turbine blades could be 40dBsm; it will be important to demonstrate how the solution would work in an operational environment. A broadband reduction of 10 to 15dB would be a good result.

Q: Is a retrofitting approach or an approach for new turbines preferred?

A: The government has committed to tripling its existing wind power capacity by 2030, so there is scope for new windfarm development; there are likely to be more windfarms and larger ones (with 200 to 300 turbines). Wind turbines for the first tranche have already been designed but retrofitting existing ones would also be useful, especially if erosion at the leading edge of the turbine blades can be addressed. It is important to demonstrate how your solution can be integrated into a working system.

Q: What bandwidth would need to be targeted if seeking to remove radar signals – narrow band or broad band?

A: It needs to be broadband so it allows for the surveillance system frequency to be changed in the future. The band currently used will be a regularly used band, but this might change and the approach needs to be adaptable to future needs.

Q: What is the targeted frequency band - will the operating frequency be in the S band?

A: Most systems operate in the L and S bands, but keeping the solution as broad as possible would be preferred, to accommodate future changes in operating frequency.A multi-band or broad band approach is preferable.

Q: Is an acoustics-based approach acceptable?

A: A great deal of noise will need to be screened out; blades of turbines, which change in direction and speed and sea noise, which also changes. This should be addressed in your proposal.

Q: How high are the turbines?

A: Future turbines are expected to be up to 370m high.

Q: Where are new windfarms appearing?

A: New windfarms are appearing 100km offshore

Q: Where are air defence radars located?

A: Air defence radars are on land usually between 10-15 miles from the coast.

Q: What duration of solution is sought?

A: Any solution needs to be practical and sustainable due to leading edge erosion of the blades. The mitigation of radar should be stable over a number of years.

Q: Is lag an issue?

A: Yes we are looking for a solution with detection accuracy; lag is an issue.