Wind tunnel models are cast around core consisting of array of tubing. Principal advantage of technique is that greater number of pressure orifices are easily installed, without compromising aerodynamic shape of model. Technique reduces construction cost by about 50 percent

Jackson, C. M., Jr.

Summerfield, D. G.

English

NASA Technical Reports Server

JuI 1971	 Brief 71-10247 
NASA TECH BRIEF 
Langle y Research Center 
NASA Tech Briefs announce new technology derived from the U.S. space program. They are issued to encourage 
commercial application. Tech Briefs are available on a subscription basis from the National Technical Information 
Service, Springfield, Virginia 22151. Requests for individual copies or questions relating to the Tech Brief program may 
be directed to the Technology Utilization Office, NASA, Code KT, Washington, D.C. 20546. 
Technique for the Integral Casting of Pressure Instrumentation
in Wind-Tunnel Models 
The problem: 
The aerodynamic characteristics of wings or other 
surfaces are evaluated by wind-tunnel tests on small 
scale models. Much of the experimental data are 
pressure measurements taken through an array of 
orifices in the aerod y namic surface. 
After the model is cast, it must be modified to 
allow the installation of tubing which connects each 
individual orifice to a pressure sensor. Machining 
channels to receive the tubing relieves internal 
stresses in the metal and results in warping and 
degradation of the specified aerodynamic shape. 
Alternately, the tubes serving the orifices in one 
surface of a model can be extended through the 
opposite surface, but this results in a model with 
only one useful surface.
The solution: 
Cast the wind-tunnel model around a core con-
sisting of an array of tubing. 
How it's done: 
The tubing array is designed to satisfy the instru-
mentation and the physical dimensions of the wind-
tunnel model. The model (see fig.) is cast around 
the array core and finished to specifications. The 
model is then X-rayed to establish the precise loca-
tions of the individual tubes. Finally, using the X-ray, 
a template is constructed to assist in drilling the ori-
fices. 
In constructing the template, it is necessary to 
compensate for parallax in the X-ray. In addition, 
prior to drilling the orifices, the gap between the 
model and the template must be filled with a 
polyester resin to provide lateral support for the 
drill. 
The principal advantage of this new technique is 
that a greater number of pressure orifices can be in-
stalled easily, without compromising the aerodynamic 
shape of the model. Initial feasibility studies indicate 
that this new technique can be used to reduce con-
struction cost by approximately 50 percent. 
Note: 
No additional documentation is available. Specific 
questions, however, may be directed to: 
Technology Utilization Officer 
Langley Research Center 
Hampton, Virginia 23365 
Reference: B71-10247 
This document was prepared under the sponsorship of the National 
Aeronautics and Space Administration. Neither the United States 
Government nor any person acting on behalf of the United States
Government assumes any liability resulting from the use of the 
information contained in this document, or warrants that such use 
will be free from privateiy owned rights.
https://ntrs.nasa.gov/search.jsp?R=19710000246 2020-03-17T02:19:54+00:00Z
Patent status: 
Inquiries about obtaining rights for the commercial 
use of this invention may be made to: 
Patent Counsel 
Mail Code 173 
Langley Research Center 
Langley Station 
Hampton, Virginia 23365 
Source: C. M. Jackson, Jr. and
D. G. Sum merfield
Langley Research Center
(LA R-10812)
. 
C 
Brief 71-10247	 Category 08


Technique for the integral casting of pressure instrumentation in wind-tunnel models

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