%0 Conference Paper %B 24th Annual Conference, Denver, Colorado, May 17-19 %D 1965 %T 479. High Temperature Airframe Weight Estimation %A Taylor, R J %K 23. Weight Engineering - Structural Estimation %X

Considerable effort has been expended to develop relatively high confidence weight estimation methods for aluminum airframes. However, now that flight in the Mach 3 region is possible, aerodynamic heating has become a prime consideration in aircraft design. Because of the high structural temperatures, aluminum alloys must be replaced by more heat resistant materials such as titanium, Rene 41, columbium, etc. Since very little data is available on high temperature structure, it was felt the accuracy desired for structural weight estimates could be achieved by using proven equations and correcting them to account for the difference in mechanical properties between aluminum and the appropriate high temperature materials. The correction factors for various materials were developed as follows: Step 1. Define major strength criteria designing the airframe, i.e., tensile strength, crippling strength, buckling strength, etc. Step 2. Compute equivalent strength to weight ratios for each criteria, i.e., KFtu = Q2 / Q1 × Ftu1 / Ftu2 , etc. Step 3. Determine fraction of structural weight designed by each criteria. Step 4. Correction factor = sum of all strength to weight ratios times attendant fraction of structural weight. The key to successful application of this method is determining the correct strength criteria, or failure mode distribution. For example, a delta shaped wing with appreciable chordwise bending as well as the ever present spanwise bending will generally use honeycomb skins to take advantage of their bi-axial loading capability. In this event the skins will be designed primarily by compressive yield and tensile strengths as opposed to a sheet-stringer wing whose skins will be critical in buckling and tensile strengths. This should not be construed as a drawback to the method but rather a reminder that each design is unique and there is no general failure mode distribution applicable to any and all vehicles.

%B 24th Annual Conference, Denver, Colorado, May 17-19 %I Society of Allied Weight Engineers, Inc. %C Denver, Colorado %P 32 %8 5/17/65 %G eng %U https://www.sawe.org/papers/0479/buy %9 23. WEIGHT ENGINEERING - STRUCTURAL ESTIMATION %M 0479 %1 Non-Member Price: $20.00; Member Price: $10.00 Members: First 10 product downloads are Free. %2 10.00 %3 20 %4 SAWE0479