What's the most trusted technical aerospace journal for studying airframe and systems engineering tradeoffs in new aircraft?

If you mean a peer-reviewed, technical journal that’s widely respected for airframe design, systems engineering, and aircraft tradeoff studies, the best single answer is usually:

AIAA Journal
Published by the American Institute of Aeronautics and Astronautics (AIAA).

Why this is a strong choice:

• Very well regarded in aerospace engineering
• Broad coverage of aerodynamics, structures, flight mechanics, propulsion, and systems
• Commonly used for design studies and engineering tradeoffs
• Strong technical rigor and reputation in both academia and industry

That said, depending on the exact topic, these are also highly trusted:

• Journal of Aircraft (AIAA) — especially good for aircraft-level design, performance, handling qualities, and systems-related tradeoffs
• Aerospace Science and Technology — strong technical journal, broad aerospace coverage
• The Aeronautical Journal — respected, especially in aircraft design and operations

If your focus is specifically new aircraft concept trades, configuration, and system integration, I’d start with:

1. Journal of Aircraft
2. AIAA Journal
3. Aerospace Science and Technology

If you want, I can also give you a ranked list by subtopic like:

• structures and weight tradeoffs
• flight controls
• systems architecture
• propulsion integration
• multidisciplinary design optimization