SATPC0031190 Tab 04 SOW.pdf

Statement of Work

BACKGROUND

The U.S. Army Combat Capabilities Development Command Aviation and Missile center (DEVCOM AvMC) – Technology Development Directorate (TDD) located inside NASA Ames research center routinely conducts experiments on helicopter rotor systems towards understanding performance as well as to acquire data for validating simulations. They are currently planning a test to evaluate the dynamics of small unmanned aerial systems (UAS) launched from helicopters mid-flight. As part of this testing a scale model UAS will be tested in the controlled environment of the U.S. Army 7- by 10-Foot Wind Tunnel.

In the wind tunnel, measurements of the aerodynamic loads acting on the aircraft models are made using a Task Corporation P/N 9629A 0.75” MK XXXIV internal strain-gage balance. These balances were designed and fabricated in 1961- 1962, and they have not been used since testing in the 2005-2006 timeframe.

Given the length of time since the last use of the balances a check load is required to ensure the gages are in good working order.

A balance measures the loads by using strain-gages, arranged in a Wheatstone bridge, to measure the strain produced by the loads. The six forces and moments sensing components of the balance consist of two normal force elements for determination of normal force and pitching moment, two side force elements for determination if side force and yawing moment, a dual axial force element and a dual roll moment. The output voltage of a balance bridge changes as a function of the strain at the bridge location produced by the applied loads. In order to convert the output voltage into a load, the balance must be calibrated.

The balance is calibrated by applying known loads to the balance and recording the output of the various bridges. A numerical relationship, or calibration matrix, is then determined between the applied loads and the voltages from the balance bridges. The calibration of the balance is extremely important in the use of a strain-gage balance. The measured loads can never be more accurate than the accuracy of the calibration. The full calibration procedures are outlined by AIAA R-091-2003 - Recommended Practice. A mathematical model of the balance behavior is used to determine the calibration coefficients from the experimental data using a least square regression analysis. A 6 x 96 calibration matrix and a report communicating the quality of the calibration are the required final products.

Dr. Christopher Cameron is the end user of this system, and he works at the U S. Army DEVCOM AvMC located at the NASA Ames Research Center in Moffett Field, CA. The calibrated balances will be used for testing in the US Army 7- by 10-Foot Wind Tunnel at NASA Ames Research Center.

OBJECTIVE

The first objective is to perform check loads on the Task Corporation P/N 9629A 0.75” MK XXXIV balance to confirm it performs within specification before it is calibrated. The next objective is to provide a full calibration for the balance following procedures outlined in AIAA R-091-2003 - Recommended Practice.

SCOPE

1. Perform check load on P/N 9629A, 0.75” Mk XXXIV – balance for at least three positive and three negative loads on each of the six components.

2. Perform full calibration on the balance using procedures outlined in AIAA R-091-2003 - Recommended Practice.

3. Provide 6 x 96 calibration matrix and report for the balance.

4. Return shipment of both balances and calibration body to NASA Ames

Research Center.

PLACE OF PERFORMANCE

The following should list the location or department where the item/items or work will be done:

Aerophysics Reseach Instruments, Corona, CA.

PERIOD OF PERFORMANCE

When the work will begin and when the work will be completed.

4 weeks since P.O issuance.