NACA Research Memorandums

Report discussing an investigation of the stability of a series of flared-body and blunted-cone models at a range of Mach numbers. Increasing the flare length was found to increase static stability and the damping in pitch. The Reynolds number was found to have a large effect on static stability at lower Mach numbers, but little effect on the higher end of the range covered in testing

Free-Flight Test of a Technique for Inflating an NASA 12-Foot-Diameter Sphere at High Altitudes

A free-flight test has been conducted to check a technique for inflating an NASA 12-foot-diameter inflatable sphere at high altitudes. Flight records indicated that the nose section was successfully separated from the booster rocket, that the sphere was ejected, and that the nose section was jettisoned from the fully inflated sphere. On the basis of preflight and flight records, it is believed that the sphere was fully inflated by the time of peak altitude (239,000 feet). Calculations showed that during descent, jettison of the nose section occurred above an altitude of 150,000 feet. The inflatable sphere was estimated to start to deform during descent at an altitude of about 120,000 feet

Minimally invasive total knee replacement : techniques and results

In this review, we outlined the definition of minimally invasive surgery (MIS) in total knee replacement (TKR) and described the different surgical approaches reported in the literature. Afterwards we went through the most recent studies assessing MIS TKR. Next, we searched for potential limitations of MIS knee replacement and tried to answer the following questions: Are there selective criteria and specific patient selection for MIS knee surgery? If there are, then what are they? After all, a discussion and conclusion completed this article. There is certainly room for MIS or at least less invasive surgery (LIS) for appropriate selected patients. Nonetheless, there are differences between approaches. Mini medial parapatellar is easy to master, quick to perform and potentially extendable, whereas mini subvastus and mini midvastus are trickier and require more caution related to risk of hematoma and VMO nerve damage. Current evidence on the safety and efficacy of mini-incision surgery for TKR does not appear fully adequate for the procedure to be used without special arrangements for consent and for audit or continuing research. There is an argument that a sudden jump from standard TKR to MIS TKR, especially without computer assistance such as navigation, patient specific instrumentation (PSI) or robotic, may breach a surgeon's duty of care toward patients because it exposes patients to unnecessary risks. As a final point, more evidence is required on the long-term safety and efficacy of this procedure which will give objective shed light on real benefits of MIS TKR

NACA Research Memorandums

Report presenting a free-flight investigation over a range of Mach numbers at a range of lift coefficients to determine the aerodynamic characteristics of an airplane-configuration model with a 52.5 degree delta wing and a low, swept horizontal tail. Results regarding time history, longitudinal trim, lift, drag, longitudinal static stability, side-force characteristics, and theoretical comparisons are provided

NACA Research Memorandums

Report presenting a free-flight investigation of the zero-lift rolling effectiveness of air-jet spoilers on an unswept flexible wing over a range of Mach numbers. Testing was made to determine the relative effectiveness of air-jet spoilers at leading-edge and trailing-edge locations. The leading-edge jet spoiler exhibited near-zero effectiveness at transonic speeds and had a roll reversal between Mach numbers 0.93 and 1.35