Contribution of body-mounted fins and tailplanes to lateral derivatives due to sideslip at subsonic speeds for general body width to height ratio.
Abstract:ESDU 93007 applies to single or twin fins on aircraft at angles of attack up to 5 degrees and angles of sideslip up to 4 degrees. It treats a wider range of body height/width ratios than ESDU 82010 which deals with the single body-mounted fin for geometries typical of transport aircraft where body height/width ratio is close to one. The fin sideforce is calculated by applying a semi-empirical interference factor to a basic lift-curve slope estimated from ESDU 70011 for the wing obtained when the fin is reflected about its root chord. The interference factor takes account of body, wing and tailplane interference, and three factors are provided depending on the relative positions of all lifting surfaces. For twin fins a further empirical factor is applied. Yawing and rolling moments follow once the point of action of the sideforce is known; the point empirically determined in ESDU 82010 based on an assumed elliptical loading along the fin quarter-chord line was found to be satisfactory here as well. Methods are also given for estimating the small contributions to the yawing and rolling moments from a body-mounted tailplane. Plots of predicted results against experimental data extracted from 24 sources in the literature (together with some unpublished results) show the sideforce, yawing moment and rolling moment derivatives to be estimated within 0.08, 0.04 and 0.02 respectively. The ranges of geometry covered by the test data are tabulated, and two fully worked examples illustrate the use of the methods.
- Rolling Moment Due To Sideslip (Lv or Cl β)
- Sideforce Due To Sideslip (Yv or Cy β)
- Yawing Moment Due To Sideslip (Nv or Cnβ)
|Data Item ESDU 93007|