# Project 3 — B-21 IR/RCS Signature Trade Study

Group projectDue Lesson 3030% deliverable category

## Background Block 3 taught you to read and shape every band of an aircraft's signature: the infrared spectrum and its seekers (L21–L24), radar cross-section as an aspect pattern (L25–L26), the materials and discipline that buy the last decibels (L27), and the fusion rule that ties them together (L28) — detection is a union, so you are found at the range of your **loudest band**, R_det = max_b R_b. This project turns that toolkit into an acquisition decision. Your group is the B-21 design cell: a fixed budget buys a package of signature-management investments — planform realignment, structural low-band treatment, radar-absorbing coatings, plume suppression, low-emissivity skin, DIRCM, emission discipline — and each cuts some bands and not others, at a cost in money and weight. Against a three-band threat — a VHF surveillance radar, an X-band fire-control radar, and an IR MANPADS — you must choose the package that minimizes the loudest-band detection range without exceeding the budget. The trap is that the loudest band, the low-frequency VHF radar, is the one that radar-absorbing material barely touches, so the obvious buy spends money and moves nothing. Finding the package that spends *at the limiter*, and knowing when the limiter jumps to another band, is the project. ## Materials Project 3 handout (PDF) — the authoritative tasking, deliverables, and rubric B21_SignaturePattern.csv — B-21 baseline VHF / X / IR signature vs aspect SignatureMenu.csv — the seven signature-investment options The MATLAB starter `code/L29_Project3Starter.m` is bundled in the [course code download](../downloads/Download_Course.md) with both CSVs beside it — it scores the baseline and one example package against the three threats, so your group starts at the trade study, not the file I/O. ## Explore the trade study Toggle investments on and off and watch the budget and the three threat ranges update; then rotate the aircraft to see which threat holds a track at each aspect. This is an explorer, not the deliverable — the PDF handout is the tasking. Open in full screen
## Schedule - **L29** is a dedicated in-class work day — see [L29 — Project 3 Work Day](L29_Project3WorkDay.md). - **L30**: slides (PDF) and code due before class; 10-minute presentation + 5 minutes Q&A, every member speaking — see [L30 — Project 3 Presentations](L30_Project3Presentations.md).