Vladyslav Berehovyi, Head of Programs at the Defence Builder Accelerator, and Anatolii Khrapchynskyi, Strategic Advisor, took part in the European Defense Tech Festival in Berlin as mentors.

The event ran for four days in one hangar and combined prototype demonstrations, pitch sessions and mentoring work with European and Ukrainian teams. Alongside the mentoring sessions, the team met colleagues from 17Tech and several Ukrainian companies that Defence Builder is now following up with.

Across the four days, Vladyslav worked through five points with the teams he mentored.

The first concerned testing with end users, which he described as an input to R&D rather than a milestone. Without it, a team builds against its own assumptions, so testing has to run as a continuous process feeding each iteration rather than as a one-off event before release.

The second was validating the need before committing resources to development. The technology a team is planning may already be deployed in Ukraine without the team knowing, because of information security, or there may be a reason it is not in use at all.

The third concerned usability: how quickly an untrained end user can operate the product effectively. If it depends on frequent consultations or on the developer team being present, that is a question about the design rather than about support.

The fourth addressed production readiness. TRL indicates technical readiness but not the ability to produce at scale — each stage requires its own human, capital and production resources, and the supply chain has to be assessed with disruption scenarios accounted for, because investors are evaluating a long-term view rather than a prototype.

The fifth was regulatory: working through defence regulations in the team's own country, export control included, and preparing a roadmap covering the full path from import through to retrieval or donation where testing in Ukraine is planned.

Collaboration across teams at the event was substantial, but there is still limited understanding of what validation and testing mean in practice, and that gap accounts for a significant share of wasted engineering effort in the sector.