Arnold Engineering Development Center, Attn: AEDC PKP, 100 Kindel Drive, Suite A332, Arnold AFB, TN 37389-1332

66 -- INTERNAL STRAIN-GAGE BALANCES SOL F40650-98-R-0012 DUE 040198 POC Rick Stewart (931) 454-7844 E-MAIL: Click here to contact the contracting officer via e-mail, stewarwr@hap.arnold.af.mil. The Arnold Engineering Development Center (AEDC) is interested in contracting with vendors who are currently using the most advanced technologies and methodologies in the design, fabrication, and gaging of internal 6-component strain-gage balances. The advanced technologies and methodologies should include but are limited to the following: finite element analysis, material selection and heat treatment, gage selection and attachment, fabrication techniques, flexure designs to increase sensitivity while reducing stress levels, temperature compensation (where most of the improvements have been produced in research for cryogenic balances), and calibration techniques including multiple component calibrations and methods to reduce hysteresis. The experience and performance of the vendor in producing 6-component internal wind tunnel balances which have accepted for use in wind tunnels comparable to AEDC Tunnel 16T will be very significant in the vendor selection. Comments concerning the vendor's capability aswell as on the requirements of the RFI are solicited. Interested sources should respond to the contracting officer with a brief summary of technical capabilities and any comments on our requirements. The balances shall be of single piece design cylindrical cross section with attachments to the sting support and test article designed to AEDC specifications and with deflections kept to a minimum. The AEDC is interested in balances ranging from 0.3 to 4 inches in diameter with the following approximate capacities: Smallest: 0.3 inches diameter; 13 in-lbs normal force at 0 pitching moment; 10 in-lbs pitching moment at 0 normal force; 13 lbs side force at 0 yawing moment; 10 in-lbs yawing moment at 0 side force; 3 in-lbs rolling moment and 6 lbs axial force. Largest: 4 inches diameter; 8,000 in-lbs normal force at 0 pitching moment; 70,000 in-lbs pitching moment at 0 normal force; 8,00 lbs side force at 0 yawing moment; 70,000 in-lbs yawing moment at 0 side force; 15,000 in-lbs rolling moment and 1,000 lbs axial force. These above loads are for Pitching Moment and Yawing Moment referenced to the balance center. The balance must be designed for a safety factor of at least 3.0 on yield if failure would result in the model separating from the sting and at least 2.0 on yield if failure would not result in the model separating from the sting, assuming simultaneous application of the rated full scale loads on all components. As a minimum the balance calibration will be accomplished by applying known loads in precise locations to achieve full range loads. Each component will be loaded in 4 to 5 increments from zero to a full load condition. Normal and Side Forces will be loaded at several locations in both the positive and negative directions and include locations that are forward and aft of the Balance Moment Center (BMC) and at the BMC. Axial and roll will be loaded in both the positive and negative directions. All other loadings which might be necessary to fully characterize the balance will be included in the calibration ( ie. combination loads). The calibration data will be used to derive the calibration matrix for converting the data to engineering units and should include all necessary terms (ie. at least first and second order interactions). If the balance has been calibrated completely, the calibration data including all combinations of loadings will be used to compute load values which will be compared to the applied loads. A state-of-the-art balance should be able to provide standard deviation of the errors, computed from the back calculated calibration data, of approximately 0.05% of full range load for each component under all combination of loadings. If not included in the calibration, loadings which represent the combination loads expected during the wind tunnel test will also be included in the accuracy assessment of the balance and calibration. The balance must perform to the accuracy requirements while at stabilized homogeneous conditions over the range of 60 to 160 degrees F. The integrity of the balance will not be compromised when exposed to sustained temperatures of 160 degrees F. (0064)

Loren Data Corp. http://www.ld.com (SYN# 0355 19980309\66-0018.SOL)