Static Performance of a . . .

A m ultiaxis thrust-vectoring nozzle designed to have equal ow-turning capability in pitch and yaw was conceived and experimentally tested for internal static performance at Langley Research Center. The cruciform-shaped, convergent-divergent nozzle turned the ow for thrust vectoring by deeecting the divergent surfaces of the nozzle, called aps. Methods for eliminating physical interference between pitch and yaw aps at the larger multiaxis deeection angles were studied. These methods included restricting the pitch aps from the path of the yaw aps and shifting the ow path at the throat oo the nozzle centerline to permit larger pitch-ap deeections without interfering with the operation of the yaw aps. Two ap widths were tested at both dry and afterburning power settings. Vertical-and reverse-thrust conngurations at dry power were also tested. Despite the complex internal geometry, this cruciform nozzle had only slightly lower unvectored thrust eeciency than existing axisymmetric and nonax-isymmetric nozzle designs. Thrust losses in single-axis thrust vectoring were primarily the result of complex ow i n teractions between shearing ows within the nozzle. Splitting the ow, a consequence of the cruciform cross section, caused these interactions. Thrust losses in multiaxis thrust vector-ing were primarily the result of turning supersonic ow. More equal pitch and yaw thrust-vector angles were achieved by the nozzle with narrow divergent aps than by the nozzle with wide divergent aps. However, the narrow-ap nozzle had thrust losses 1 to 2 percent higher than those of the wide-ap nozzle. The shifted-throat nozzle design had larger thrust-vector angles at the nozzle pressure ratio of peak resultant thrust eeciency than the restricted-ap nozzle design but had 1.5-to 2.0-percent-lower peak thrust performance. The vertical-and reverse-thrust conngurations had performance similar to that of existing nozzles of similar design.