Aerodynamics Analysis of Solid Fuel Ramjet Projectiles
Abstract
The aerodynamic characteristics of several Solid Fuel Ramjet (SFRJ) projectiles are estimated by a combination of the NSWC-Aeroprediction code and a post-processing analysis that account for the effects of inlet and the buttress threads. Comparison between predicted and measured normal-force curve slope for two SFRJ-SPINNER configurations show good agreement in one case and 18%-23% analytical under-prediction in the other. The agreement in center-of-pressure location is very good in both cases. The analysis explains the unstable flight of the 60mm SFRJ-FINNER Projectile, having original fins. The analysis predicts, for the projectile with extended fins, a static margin of 0.5 calibers at low supersonic Mach numbers, marginal stability as Mach number approaches 4.3 and instability at Mach numbers larger then 4.3. Wind-tunnel tests of this configuration show that the open inlet contributes more normal-force than accounted for in the analysis and that contribution of the fin set is slightly underpredicted by the NSWC code. The predicted normal-force curve slope is up to 11% smaller than experimentally obtained and the center-of-pressure location is in good agreement with test results. The experimentally obtained contribution of the buttress threads to the axial-force coefficient is in good agreement with the predicted value. No effect on the threads on the stability of the projectile was observed under the wind tunnel flow conditions.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1988
- Accession Number
- ADA196755
Entities
People
- Asher Sigal
- James E. Danberg
Organizations
- Ballistic Research Laboratory