V–22 LOW-SPEED/HIGH RATE OF DESCENT (HROD) TEST RESULTS

An extensive flight test program has been conducted to evaluate the effects of Vortex Ring State (VRS) on the V-22. Since there was no existing flight data on tiltrotors with respect to VRS, a methodical buildup approach was used during the test program. Over a three year period, the V-22 Integrated Test Team (ITT) conducted progressive flights of the V-22 deep into fully developed VRS. Initial testing involved defining the static, or, steady state VRS boundary. During this test phase, aircraft controllability well beyond typical operational limits and a consistently effective recovery technique were demonstrated. Subsequent testing demonstrated dynamic maneuvers that penetrated the steady-state VRS boundary by first expanding to aggressive single axis maneuvers, and then progressing to multi-axis maneuvers. Test results show that the V-22 provides increased sink-rate margin for avoiding VRS, when compared to conventional helicopters.