Effect of Hinge-Moment Parameters on Elevator Stick Forces in Rapid Maneuvers
Abstract
The importance of the stick force per unit normal acceleration as a criterion of longitudinal stability and the critical dependence to this gradient on elevator hinge moment parameters have been shown in previous reports. The present report continues the investigation with special reference to transient effects for maneuvers of short duration. The analysis made showed that different combinations of elevator parameters which give the same stick force per unit acceleration in turns give widely different force variations during the entries into and recoveries from steady turns and during maneuvers of short duration such as abrupt pull ups. A combination of relatively large negative values of the restoring tendency C sub h delta and the floating tendency C sub h alpha t approaching those of an unbalanced elevator, results in a stick force that is high during the initial stage of a pull up and then decreases, and may even reverse, as the acceleration is reduced at the end of the maneuver. The stick force per unit acceleration is greater for abrupt than for gradual control movements. If the negative value of C sub h delta is reduced so that the corresponding value of C sub h alpha t becomes slightly positive, the reversal of force may be eliminated and the force may be brought nearly in phase with the acceleration. There is a limit to the permissible reduction of the value of C sub h delta however, because as C sub h delta approaches zero the stick force per unit acceleration may become lower for abrupt than for gradual maneuvers and may thus lead to undesirably low stick forces at the beginning of the maneuver.
Document Details
- Document Type
- Technical Report
- Publication Date
- Oct 12, 1944
- Accession Number
- ADA298236
Entities
People
- Harry B. Greenberg
- Robert T. Jones
Organizations
- National Advisory Committee for Aeronautics