Technology for Pressure-instrumented Thin Airfoil Models, Phase 1
1985 - 56 pages
A network of channels was chemically milled into one surface of a pair of matched plates having bond planes which were neither planar or profiled to match the contour of the trailing edge of a supercritical airfoil for testing in cryogenic wind tunnels. Vacuum brazing bonded the plates together to create a network of pressure passages without blockages or cross leaks. The greatest success was achieved with the smaller samples and planar bonding surfaces. In larger samples, problems were encountered due to warpage created by the relief of residual stresses. Successful bonds were formed by brazing A286, Nitronic 40 and 300 series stainless steels at 1065 C using AMS 4777B brazing alloy, but excessive grain growth occurred in samples of 200 grade 18 nickel maraging steels. Good bonds were obtained with maraging steel using a 47 percent Nickel-47 percent Palladium-6 percent Silicon alloy and brazing at 927 C. Electro-Discharge-Machining was an effective method of cutting profiled bond planes and airfoil contours. Orifices of good definition were obtained when the EDM wire cut passed through predrilled holes. Possible configurations for joints between small segments and the larger main wing were also studied.
What people are saying - Write a review
We haven't found any reviews in the usual places.
18 nickel maraging 304 stainless Aggression Grain Structure airfoil contours airfoil surface BASIC CHARACTERISTICS blind holes bond line braze alloy braze foil BRAZING CYCLE Combination Channels Holes Aggression CHARACTERISTICS & INITIAL Chem-mill chemical milling chemically-milled channels cross-leaks CYCLE Combination Ident Details of PITACT docking ports DS2 and DS3 EDM wire EDM wire-cut EXAMINATION Channels Holes Faying Surface Channels ferric chloride grain boundary grain growth Hastalloy Holes Aggression Grain INITIAL PREPARATION Material Langley Research Center lower surfaces Material & Origin MBF20 AMS METALLURGICAL EXAMINATION Channels Metglas n/a n/a n/a NASA Nickel maraging steel Nitronic 40 offcut parent metal Phase pilot hole PITACT program PITACT Samples planar pressure orifices pressure-tight profiled bond planes residual stresses samples DS2 segment 3F segment 4M shown in Fig stainless steel supercritical airfoil Surface Channels Holes thick tongue and groove trailing edge segments vacuum brazed Vascomax 200 view in Fig warpage