1st/block 0 modification
The vulnerability of helicopters became apparent during the gulf war while the success of the F-117 stealth fighter was overwhelming.
It was a logical decision to start work on making the special operations helicopters more survivable and stealthy.
With the ever small Army budget it was necessary to keep costs low with modifications rather than a new design costing billions in development and not getting anywhere.
The decision was made to produce modification kits that simply replaced the regular fuselage with RAM treated composites.
As such the kits could be shipped easily and secretly by C-130 or C-17 transports to the site of operation where they could be put on existing helicopters.
This would keep movement of such modified helicopters secret since they never actually move as such themselves.
Several MH60K helicopters were modified to be used with the kits.
As the modification resulted in a higher weight their General Electric T700-GE-701C engines were tuned for more power.
modifications included:
wire cutting blades
a swing-out hoist
encrypted satellite radio equipment, Inertial Navigation System (GPS-INS)
trapezoid countermeasure boxes
stealth engine inlet box
stealth air stream inlet for exhaust cooling/mixing
tail rotor blade with anti-erosion ram treated tape.
folding of main rotor was retained with removable hudcap system
RWR in tail cone
boxed-in main gear
additional internal tanks
2nd/block 1 modification 2004-6
After the cancellation of the Comanche project, part of its staff and budget was directed for a more extensive update and modification
of the radar-evading helicopters.
The increased weight & power of the helicopters required higher lift, which would require a complete new rotor system with vibrations control, drive train, new software etc.
This would have been expensive and was equal with developing a complete new helicopter.
It was decided to adapt the rotor system, controls, and drive train from the Sikorsky S-92.
The main blades were a shortened version of the S-92 blades. The new wide-chord, composite rotor blades to provided improved performance, particularly under "hot and high" conditions.
With increased lift it was possible to reduce the main rotor rpm and lower its noise.
modifications included:
stealth engine inlet barrier filter variant
doppler navigation system
Hover Infra-Red Suppression System
3rd/block 2 modification 2013+
modifications to include:
new engines
new blades
featuring retractable gear
ejectable ESSS or ETS stub wings
