Shape-Changing Aircraft Need to Know Wing Position

Position Measurement & Control - Issue 49

TECHNICAL FOCUS

Shape-Changing Aircraft Need to Know Wing Position

Position Transducers Help Ensure Stability of Wings During the Morphing Process

Shape-changing planes: science fiction or science fact? Thanks to a California company called NextGen Aeronautics -- with a little help from Firstmark Controls components -- what once sounded like something from the mind of George Lucas or Steven Spielberg is now a reality. NextGen Aeronautics's design, funded by Boeing's Phantom Works division, uses a material dubbed "flexible skin" that conforms to the wing's changing skeleton. When a series of linear actuators mechanically change the shape of the wing skeleton, the flexible skin stays with it, offering a protective shell that maintains integrity even at high speeds. Part of the success of this design comes down to the quality of components used -- the material for the flexible skin, the durability of the linear actuators, and, of course, the accuracy and repeatability of Firstmark Controls position transducers.

Figure A1: A computer simulation of the MFX-1 shows how much its wings can change in shape. Position transducers provide valuable data to keep wings stable during this process.

For the MFX-1 project, which showcased its morphing wing capabilities in August 2006, NextGen Aeronautics used Firstmark Controls position transducers to monitor status. The position transducers measured the linear separation of the wing spars, then sent feedback to the wing's structure controls to alert systems of current positions. The reliability and accuracy of the Firstmark Controls position transducers gave the NextGen Aeronautics team the confidence that even their most precise needs would be fulfilled. "We chose Firstmark Controls for the high precision and quality of their products, as well as their light weight, small packaging, and ease of use," says Dana Patrick Howard of NextGen Aeronautics. "We have found that the Firstmark Controls products have met our needs and exceeded our expectations as has the customer service."

With Firstmark Controls position transducers providing real-time data of vital measurements to ensure stable changes mid-flight, the MFX-1 was able to accurately demonstrate its full capabilities: area changes of 40%, span changes of 30%, and sweep variation from 15° to 35°, all while traveling at speeds of nearly 124 mph (200 kph).

NextGen Aeronauticsis now focused on the bigger, more powerful MFX-2. Some Firstmark Controls products have already made it into the design -- for flight control and telemetry, and more position sensors for displacement feedback. To learn more about morphing wing technology and Firstmark Controls products, contact Firstmark Controls.

IN ACTION

Minimizing Drag, Maximizing Speed: The North American Eagle Landspeed Project

North American Eagle Uses Firstmark Controls Products to Help Break the Landspeed Record

Culling engineering talents from all across Canada and the United States, the North American Eagle team works tirelessly to create the world's fastest automobile. The goal? Go 764 mph (1230 kph)) or faster to best the landspeed record set on 15 October 1997. To get there, the team will need to ensure the vehicle's components maintain the most precise level of integrity to maximize speed -- and that's where Firstmark Controls position transducers come into the picture.

Data acquisition engineer Steve Wallace noted two critical areas that required monitoring were suspension compression and canard position. For suspension compression, the goal is to achieve aerodynamic neutrality so no additional forces adversely affect vehicle acceleration. To keep this in check, Steve and his crew mounted one position transducer to the front wheel well. For the canards, North American Eagle needed real-time data for canard control, and a second position transducer was mounted on the front canard for angle measurement with data sent back to the canard control mechanism.

Figure B1: The North American Eagle.

The vehicle's top speed is 312 mph (502 kph) and work continues to perfect the vehicle design. It's clear that Firstmark Controls position transducers are doing their job in helping the team out. "The reason for using position transducers instead of accelerometers or rate gyroscopes is the simplicity of their output. No double integration or expensive gyroscope controllers required...(the transducer measurements) confirmed that we are close to aerodynamic neutrality up to 300 mph," Wallace says.

Wallace believes despite the extreme conditions, Firstmark Controls components are more than up for the task. Wallace states, "The environment is 100° to 150° F, extremely, if not obscenely, dusty, and subject to shaking. We have had flawless performance to date with these position transducers."

Figure B2: North American Eagle's Steve Wallace mounts a position transducer by the vehicle's cockpit to help measure for aerodynamic neutrality.

To learn more about breaking the landspeed record, visit North American Eagle's website.

APPLICATION FOCUS

Birthing Simulator Benefits from Reliable Position Feedback

Johns Hopkins Researchers Use Position Transducer Data To Develop New Solutions For Birthing Complications

Position transducers have a wide variety of applications, but can they help doctors save lives? At Johns Hopkins University's Department of Biomedical Engineering, Firstmark Controls position transducers are doing just that. Led by JHU's Dr. Robert Allen, a team of biomedical engineers have designed and patented a simulator to help medical students and researchers study and practice on difficult situations that may arise during labor. The birthing simulator has two parts: a female lower body complete with pelvis and legs with realistic joint movement and a fetal model with a moveable neck, shoulders, and arms.

While birth is a natural process, there are many instances where complications may arise. These unique, and often dangerous, circumstances are difficult to prepare for; the birthing simulator provides a workable model for new techniques and emergency situations without ever putting a human life at risk.

Figure C1: The simulated baby. The three items labeled 270 are Firstmark Controls position transducers.

Part of the process is keeping live data of how the different simulator components are positioned. Firstmark Controls sensors provide a variety of measurements, including rotary (attached to the pelvic shaft for pelvic rotation) and angular/position sensors (attached to both the female model and the fetal model for different component position status and measurement). Data from each sensor is sent out to a data acquisition unit and converted and stored into a data recording module. This data provides valuable analysis on how doctors should handle different situations, including positioning the legs and adapting to different fetal head positions.

The birthing simulator is just another example of how critical measurement data can be in a critical medical situation. Without accurate data that allows doctors to repeatedly test procedures, an emergency operation could be off by an inch - an inch that could mean the difference between life and death.

To learn more about the Johns Hopkins birthing simulator, visit the university's Biomedical Engineering home page.

ISSN 1527-5108 • Document Number S050AI(061107)