Originally Posted by
tottigol
Obviously there are the wings and the nacelles with engines/gearboxes, but aren't the rotor/propeller blades of composite material?
Primarily composite, but with other materials that are radar reflective:
"
The V-22 is equipped with two counterrotating three-bladed proprotors. The blades are constructed primarily of composite material with a metallic leading edge abrasion strip and integral de-ice blanket. "
V-22 Osprey
Each blade is also wired for green LED lights at the blade tips, for ground crew safety (you may have seen photos of the "green ring" on these things at night). So they're not 100% composite, and whatever metal is in there is spinning to form a disk in cruise mode. A metal leading edge strip would probably light up pretty good.
This was the only info I could find about the radar cross section, from "V-22 crew chief Staff Sgt. Brian Freeman’s letter to Gannett’s Marine Corps Times," quoted in defenseindustrydaily.com:
"
Nevertheless, the countermeasures dispensing system was found to have insufficient capacity for longer missions, and radar reflection from the V-22’s total propeller disc area of more than 2,267 square feet rivals that of two Boeing 707s in formation.146 (Given that situation, one can only wonder at the logic behind the development of top-secret "stealth paint" for the fuselage at a cost of $7,500 per gallon; the one aircraft they painted required 10 gallons for a paint job costing $75,000 -- but those huge, whirling discs were still there, bouncing back radar signals with gusto.)"
V-22 Osprey: A Flying Shame?
Maybe there have been upgrades since then, and I remember seeing something recently about Bell developing new prop/rotor blades. But I think that was mainly for cost-savings? Anyway, it's just something I find interesting when comparing tiltrotor, tiltwing, and more conventional designs for military use.