Title of Invention	"A DEVICE FOR MEASURING AERODYNAMIC LOADS ON AFTERBODY OF AEROSPACE VEHICLES"
Abstract	1. A device for measuring aerodynamic loads on afterbody of aerospace vehicles which comprises an annular cylindrical body having a mount (non-metric) end (1), one end of the said mount end having an integral axial force unit (2) characterized in that the said integral axial force unit (2) consisting of plurality of longitudinal peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral extensions (2C) having an integral rig end, the said intermeshed longitudinal extensions (2A and 2C) being interconnected by means of a plurality of transversal flexures (2B), the ring end of peripheral extensions (2C) being integrally connected to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures (3A), the said longitudinal flexures being connected integrally to load (metric) end (4), the said transversal flexures (2B) being provided with one or more strain gauges at each location (AF), the longitudinal flexures (3A) of the said force/moment cage (3) being provided with one or more strain gauges in each location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and RM).

Title of Invention

"A DEVICE FOR MEASURING AERODYNAMIC LOADS ON AFTERBODY OF AEROSPACE VEHICLES"

Abstract

1. A device for measuring aerodynamic loads on afterbody of aerospace vehicles which comprises an annular cylindrical body having a mount (non-metric) end (1), one end of the said mount end having an integral axial force unit (2) characterized in that the said integral axial force unit (2) consisting of plurality of longitudinal peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral extensions (2C) having an integral rig end, the said intermeshed longitudinal extensions (2A and 2C) being interconnected by means of a plurality of transversal flexures (2B), the ring end of peripheral extensions (2C) being integrally connected to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures (3A), the said longitudinal flexures being connected integrally to load (metric) end (4), the said transversal flexures (2B) being provided with one or more strain gauges at each location (AF), the longitudinal flexures (3A) of the said force/moment cage (3) being provided with one or more strain gauges in each location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and RM).

Full Text	The present invention relates to a device for measuring aerodynamic loads on afterbody of aerospace vehicles The main usage of the device of the present invention is for measuring forces and moments on the afterbody of aerodynamic configurations with jet on or off condition accurately without causing any obstruction to the airflow. Prior art by literature and patent search through world databases reveal that earlier used balances were different in design from the one referred here. However, the earlier designs of balances have certain drawbacks such as long sensing element, needs isolation of the balance from high jet pressure and free-stream airflow, and system features complicated jet air supply hardware. For example, NAL report "Measurements Related to Afterbody Studies on A Thrust-Minus-Drag Rig", AE TM 4-82, August 1982, stated that a six component balance is used for measurements of loads. This balance has long sensing element resulting errors in measurements due to deflection and effects of thermal gradient. Balance needs isolation from high-pressure air of jet as well as free stream. Force isolation of the metric afterbody from non-metric forebody was achieved by stainless steel bellows and Teflon ring, which adds the complexity and calibration of balance in-situ. In another example referred in, AIAA-88-2059 "Development of a New Flow-through Force Measurement Balance with Improved Accuracy for Use in Powered Wind Tunnel Model Testing ", AIAA 15th Aerodynamic Testing Conference, May 18-20, 1988/ San Diego, California, the drawbacks of the system were complex configuration of balance, balance needs isolation from high-pressure air of jet as well as free stream. Force isolation of the metric afterbody from non-metric forebody was achieved by stainless steel bellows and Teflon ring, which adds the complexity and calibration of balance in-situ. The design of the two opposing longitudinal bellows results in a cumbersome arrangement, The main drawbacks of the earlier system are - 1. Indirect measurement of loads 2. Calibration of balance in-situ. 3. Long sensing elements causes non-linearity in outputs and thermal gradient effects. 4. System has complicated jet air supply hardware. The main object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which obviates the drawbacks as detailed above. Another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which facilitate to test short-after body models. Still another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which facilitate to test models with free stream flow with jet off/on conditions. Yet another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which is also used in other tunnels as internal/external mounted balance. In the drawings accompanying this specification, figural of sheet 1 of 3 represent constructional details of the device, wherein (1) is mount (non-metric) end, (2) is axial force unit consisting of 2A longitudinal peripheral extensions of fixed end, 2B are the interconnecting transversal flexures, 2C are the longitudinal peripheral extensions of force/moment cage end, (3) is force/moment cage; 3A are the longitudinal peripheral flexures, (4) is load (metric) end. Figure 3 of sheet 2 of 3 shows the wiring diagram and bridge formation for different elements, in figure 2A to 2D of sheet 2 of 3 of the drawings is shown the locations of the strain gauge. Figure 2A of sheet 2 of 3 shows the plan view of device of the present invention and shows the location of strain gauges (AF1 to AF8) measuring axial force, figure 2B and figure 2D of sheet 2 of 3 are the section views of the force/moment cage, where the location of strain gauges for normal force, side force and rolling moment are shown. Figure 2C of sheet 2 of 3 represents the location of the strain gauges for measuring pitching moment and yawing moment. Accordingly, the present invention provides a device for measuring aerodynamic loads on afterbody of aerospace vehicles which comprises an annular cylindrical body having a mount (non-metric) end (1), one end of the said mount end having an integral axial force unit (2) characterized in that the said integral axial force unit (2) consisting of plurality of longitudinal peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral extensions (2C) having an integral rig end, the said intermeshed longitudinal extensions (2A and 2C) being interconnected by means of a plurality of transversal flexures (2B), the ring end of peripheral extensions (2C) being integrally connected to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures (3A), the said longitudinal flexures being connected integrally to load (metric) end (4), the said transversal flexures (2B) being provided with one or more strain gauges at each location (AF), the longitudinal flexures (3A) of the said force/moment cage (3) being provided with one or more strain gauges in each location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and RM). In an embodiment of the present invention a device for measuring aerodynamic loads on after body of aerodynamic configurations, mount (non-metric) and load (metric) end geometry is selected to suit the testing models. The novelties of new invention are as follows; a) Direct measurements of the loads. b) High Normal to axial load capacity and very rigid compared to other configurations. c) Linear and nonlinear interactions are negligible. d) Visual inspection and repairing is easy. e) Short lengths of force/moment cage and axial force unit minimize the thermal gradient effects. The following examples are given by way of illustration and therefore should not to be construed to limit the scope of the present invention. The following examples of loads in kgs applied to the balance during a trial calibration and corresponding outputs in mV per volt of excitation in main element as well as secondary elements. Example 1 Loading: Normal Force +ve (Table Removed) Example 2 Loading: Pitching Moment +ve (Table Removed) Example 3 Loading: Rolling Moment +ve (Table Removed) Example 4 Loading: Axial Force 1 +ve (Table Removed) All the above examples and illustrations indicate that the calibration data obtained by using this device has a good linearity in the main component as well as secondary components interactions. The main advantages of the present invention are: 1) It is a compact device compared to earlier balance configurations. Hence the error in measurements due to deflections is reduced. 2) The device configuration is such that the entire strain gauge networks are located in small volumes thereby avoiding thermal gradient effects. 3) In this device, respective bridges directly measure aerodynamic loads/moments. 4) Eliminates drawbacks as support system interference in aerodynamic loads. 5) Allow bigger diameter of jet airflow. 6) Obviates long length of sensing element. 7) Allow higher normal force to axial force capacity. We Claim: 1. A device for measuring aerodynamic loads on after body of aerospace vehicles which comprises an annular cylindrical body having a mount (non-metric) end (1), one end of the said mount end having an integral axial force unit (2) characterized in that the said integral axial force unit (2) consisting of plurality of longitudinal peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral extensions (2C) having an integral rig end, the said intermeshed longitudinal extensions (2A and 2C) being interconnected by means of a plurality of transversal flexures (2B), the ring end of peripheral extensions (2C) being integrally connected to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures (3A), the said longitudinal flexures being connected integrally to load (metric) end (4), the said transversal flexures (2B) being provided with one or more strain gauges at each location (AF), the longitudinal flexures (3A) of the said force/moment cage (3) being provided with one or more strain gauges in each location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and RM). 2. A device for measuring aerodynamic loads on after body of aerospace vehicles substantially as herein described with reference to the examples and drawing accompanying this specification.

Full Text

The present invention relates to a device for measuring aerodynamic loads on afterbody of aerospace vehicles
The main usage of the device of the present invention is for measuring forces and moments on the afterbody of aerodynamic configurations with jet on or off condition accurately without causing any obstruction to the airflow.
Prior art by literature and patent search through world databases reveal that earlier used balances were different in design from the one referred here. However, the earlier designs of balances have certain drawbacks such as long sensing element, needs isolation of the balance from high jet pressure and free-stream airflow, and system features complicated jet air supply hardware. For example, NAL report "Measurements Related to Afterbody Studies on A Thrust-Minus-Drag Rig", AE TM 4-82, August 1982, stated that a six component balance is used for measurements of loads. This balance has long sensing element resulting errors in measurements due to deflection and effects of thermal gradient. Balance needs isolation from high-pressure air of jet as well as free stream. Force isolation of the metric afterbody from non-metric forebody was achieved by stainless steel bellows and Teflon ring, which adds the complexity and calibration of balance in-situ.
In another example referred in, AIAA-88-2059 "Development of a New Flow-through Force Measurement Balance with Improved Accuracy for Use in Powered Wind Tunnel Model Testing ", AIAA 15th Aerodynamic Testing Conference, May 18-20, 1988/ San Diego, California, the drawbacks of the system were complex configuration of balance, balance needs isolation from high-pressure air of jet as well as free stream. Force isolation of the metric afterbody from non-metric forebody was achieved by stainless steel bellows and Teflon ring, which adds the complexity and calibration of balance in-situ. The design of the two opposing longitudinal bellows results in a cumbersome arrangement,
The main drawbacks of the earlier system are -
1. Indirect measurement of loads
2. Calibration of balance in-situ.
3. Long sensing elements causes non-linearity in outputs and thermal gradient
effects.
4. System has complicated jet air supply hardware.

The main object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which obviates the drawbacks as detailed above.
Another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which facilitate to test short-after body models.
Still another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which facilitate to test models with free stream flow with jet off/on conditions.
Yet another object of the present invention is to provide a device for measuring aerodynamic loads on after body of aerodynamic configurations, which is also used in other tunnels as internal/external mounted balance.
In the drawings accompanying this specification, figural of sheet 1 of 3 represent constructional details of the device, wherein (1) is mount (non-metric) end, (2) is axial force unit consisting of 2A longitudinal peripheral extensions of fixed end, 2B are the interconnecting transversal flexures, 2C are the longitudinal peripheral extensions of force/moment cage end, (3) is force/moment cage; 3A are the longitudinal peripheral flexures, (4) is load (metric) end. Figure 3 of sheet 2 of 3 shows the wiring diagram and bridge formation for different elements, in figure 2A to 2D of sheet 2 of 3 of the drawings is shown the locations of the strain gauge. Figure 2A of sheet 2 of 3 shows the plan view of device of the present invention and shows the location of strain gauges (AF1 to AF8) measuring axial force, figure 2B and figure 2D of sheet 2 of 3 are the section views of the force/moment cage, where the location of strain gauges for normal force, side force and rolling moment are shown. Figure 2C of sheet 2 of 3 represents the location of the strain gauges for measuring pitching moment and yawing moment.
Accordingly, the present invention provides a device for measuring aerodynamic loads on afterbody of aerospace vehicles which comprises an annular cylindrical body having a

mount (non-metric) end (1), one end of the said mount end having an integral axial force unit (2) characterized in that the said integral axial force unit (2) consisting of plurality of longitudinal peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral extensions (2C) having an integral rig end, the said intermeshed longitudinal extensions (2A and 2C) being interconnected by means of a plurality of transversal flexures (2B), the ring end of peripheral extensions (2C) being integrally connected to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures (3A), the said longitudinal flexures being connected integrally to load (metric) end (4), the said transversal flexures (2B) being provided with one or more strain gauges at each location (AF), the longitudinal flexures (3A) of the said force/moment cage (3) being provided with one or more strain gauges in each location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and RM).
In an embodiment of the present invention a device for measuring aerodynamic loads on after body of aerodynamic configurations, mount (non-metric) and load (metric) end geometry is selected to suit the testing models.
The novelties of new invention are as follows;
a) Direct measurements of the loads.
b) High Normal to axial load capacity and very rigid compared to other configurations.
c) Linear and nonlinear interactions are negligible.
d) Visual inspection and repairing is easy.
e) Short lengths of force/moment cage and axial force unit minimize the thermal
gradient effects.
The following examples are given by way of illustration and therefore should not to be construed to limit the scope of the present invention.
The following examples of loads in kgs applied to the balance during a trial calibration and corresponding outputs in mV per volt of excitation in main element as well as secondary elements.
Example 1 Loading: Normal Force +ve

(Table Removed)

Example 2 Loading: Pitching Moment +ve

(Table Removed)
Example 3 Loading: Rolling Moment +ve

(Table Removed)
Example 4 Loading: Axial Force 1 +ve

(Table Removed)
All the above examples and illustrations indicate that the calibration data obtained by using this device has a good linearity in the main component as well as secondary components interactions.
The main advantages of the present invention are:
1) It is a compact device compared to earlier balance configurations. Hence
the error in measurements due to deflections is reduced.
2) The device configuration is such that the entire strain gauge networks are
located in small volumes thereby avoiding thermal gradient effects.
3) In this device, respective bridges directly measure aerodynamic
loads/moments.
4) Eliminates drawbacks as support system interference in aerodynamic
loads.
5) Allow bigger diameter of jet airflow.
6) Obviates long length of sensing element.
7) Allow higher normal force to axial force capacity.

We Claim:
1. A device for measuring aerodynamic loads on after body of aerospace vehicles
which comprises an annular cylindrical body having a mount (non-metric) end (1),
one end of the said mount end having an integral axial force unit (2) characterized
in that the said integral axial force unit (2) consisting of plurality of longitudinal
peripheral extensions (2A) and corresponding intermeshed longitudinal peripheral
extensions (2C) having an integral rig end, the said intermeshed longitudinal
extensions (2A and 2C) being interconnected by means of a plurality of transversal
flexures (2B), the ring end of peripheral extensions (2C) being integrally connected
to a force/moment cage (3) essentially consisting of longitudinal peripheral flexures
(3A), the said longitudinal flexures being connected integrally to load (metric) end
(4), the said transversal flexures (2B) being provided with one or more strain
gauges at each location (AF), the longitudinal flexures (3A) of the said
force/moment cage (3) being provided with one or more strain gauges in each
location in multiple longitudinal positions (NF, SF, PM, YM and RM), the said string
gauges being connected in Wheatstone configurations (AF, NF, SF, PM, YM and
RM).
2. A device for measuring aerodynamic loads on after body of aerospace vehicles
substantially as herein described with reference to the examples and drawing
accompanying this specification.

Documents:

275-del-2001-abstract.pdf

275-del-2001-claims.pdf

275-del-2001-correspondence-others.pdf

275-del-2001-correspondence-po.pdf

275-del-2001-description (complete).pdf

275-del-2001-drawings.pdf

275-del-2001-form-1.pdf

275-del-2001-form-19.pdf

275-del-2001-form-2.pdf

275-del-2001-form-3.pdf

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Patent Number

230950

Indian Patent Application Number

275/DEL/2001

PG Journal Number

13/2009

Publication Date

27-Mar-2009

Grant Date

28-Feb-2009

Date of Filing

12-Mar-2001

Name of Patentee

COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH

Applicant Address

RAFI MARG, NEW DELHI-110001, INDIA.

Inventors:

#	Inventor's Name	Inventor's Address
1	RAM SINGH VERMA	NATIONAL AEROSPACE LABORATORIOS, POST BAH NO-1779, BANGALORE-560017, INDIA.
2	RAMA RAO RAMESH	NATIONAL AEROSPACE LABORATORIOS, POST BAH NO-1779, BANGALORE-560017, INDIA.
3	NARENDRA BEHARI MATHUR	NATIONAL AEROSPACE LABORATORIOS, POST BAH NO-1779, BANGALORE-560017, INDIA.

PCT International Classification Number

G01M 9/00

PCT International Application Number

N/A

PCT International Filing date

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1			NA