REDUCING TRAILING EDGE FLAP DEFLECTION REQUIREMENTS IN PRIMARY CONTROL THROUGH A MOVEABLE HORIZONTAL TAIL

Open Access
Author:
Bluman, James Edward
Graduate Program:
Aerospace Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
None
Committee Members:
  • Farhan S Gandhi, Thesis Advisor
Keywords:
  • trailing edge flaps
  • elevons
  • primary control
  • horizontal tail control
Abstract:
Achieving primary control of helicopters through the use of trailing edge flaps holds significant promise in eliminating the swashplate and related controls—a system that is complex, heavy, a significant source of drag, and subject to demanding maintenance requirements. However, the predicted deflections that trailing edge flaps serving in this role must reach to achieve high speed trimmed flight are currently beyond the stroke and authority of current smart-material actuators that could be used. A method of reducing the required trailing edge flap deflections through fixed frame moments input via a moveable horizontal tail is developed and demonstrated to significantly reduce the required trailing edge flap deflections on a UH-60 helicopter. Expanding on previous work which demonstrated the ability to reduce cyclic pitch requirements in high speed flight through moveable horizontal tail inputs, this study presents a 2-DOF flap-torsion rigid blade trim analysis utilizing linear inflow and advanced UH-60 rotor and fuselage geometry in conjunction with the moveable tail. Parametric studies are performed on the effect of blade root torsional stiffness and rotor blade pitch indexing on the required flap deflections. A moveable horizontal tail is added and demonstrated to reduced required cyclic elevon deflections on a UH-60 with non-dimensional rotating natural frequency (νθ) of 2.1 and pitch index (θPre) of 20° at a forward speed of 130 knots (μ = 0.3) to deflections with the capability of current actuators (±5°) without prohibitive vehicle attitude and performance penalties.