The F-22 is designed for stealth, but if you want to exploit this, you must carry only internal weapons and fly carefully around EWR and SAM sites. You can carry large loads of external stores, giving you more weapons and options. You give up stealth but gain in flexibility and game play options (the real F-22 has weapon-capable external hard points, but they are intended mainly for fuel tanks for long-range ferry flights). You can change weapon loadouts (and many other things) in campaign missions, but not in training missions.
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Related to stealth is EMCON (emissions control), with levels from 1 (no transmissions) to 5 (full radar and comms use). EMCON can be handled automatically or manually. The automatic system tries to use the minimum necessary transmissions based on the tactical situation. You need at least EMCON 2 to use the radio to contact your wingmen.