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A low-cost method for reducing the dispersion in the trajectory of an unguided, spin-stabilized sounding rocket is developed and presented. The method is particularly suited to scramjet flight experimentation because the approach increases the likelihood of meeting Mach number and dynamic-pressure objectives. The paper discusses the design and model of the scramjet payload, two-stage launch vehicle, and the nominal trajectory, as well as a Monte Carlo analysis to quantify the likelihood of a successful scramjet test. Using the results of this analysis, a method is presented for reducing the dispersion in freestream conditions during the scramjet test window. The dispersion reduction is accomplished by modifying the time delay between the burnout of the first-stage booster and the ignition of the second-stage booster based on the vehicle state measured during the interstage coast. This method increases the likelihood of a successful test from 71 to 99% without adversely affecting range safety. Because the design and implementation of a vehicle-guided control system is not required, this method is relatively inexpensive, making its use highly desirable for low-cost scramjet flight experimentation.

The application of nonlinear elasticity concepts to the mechanical modeling of soft biomaterials is currently the subject of intense investigation. For fibrous soft biomaterials, some specific strain-energy density models for anisotropic hyperelastic materials have been proposed in the literature that are particularly useful as they reflect the typical J-shaped stress–stretch stiffening response due to collagen fibers that is observed experimentally. These models have the feature of incorporating the increased stiffness of the collagen fibers with deformation and involve a maximum fiber stretch (or locking stretch). Here we apply such models to the analysis of the fracture or tearing of fibrous soft biomaterials. Attention is focused on a particular fracture test namely the trousers test where two legs of a cut specimen are pulled horizontally apart out of the plane of the test piece. It is shown that, in general, the location of the cut in the specimen plays a key role in the fracture analysis, and that the effect of the cut position depends crucially on the degree of strain–stiffening. This dependence is characterized explicitly for the specific strain–stiffening constitutive models considered. The effects of anisotropy and strain–stiffening on the fracture toughness (resistance to tearing) are also examined.