Scaled Composites In-Flight Data Monitoring

A business address on Flight Line, Mojave, implies a close relationship with experimental aircraft. Just like the one Scaled Composites, Inc. has -- it makes them. Right there on Flight Line. And it has pioneered the use of Microstar Laboratories DAPs for in-flight data monitoring.

Proof-of-Concept

The people at Scaled get called in when someone has a concept to prove. Scaled Composites designs and builds Proof-of-Concept (POC) prototypes that run anywhere from 18% (radio-controlled) to full size. Check out www.scaled.com for a Web site that has some great images of POC prototypes and related project write-ups.

New Class of Aircraft

The illustration shows a VisionAire Vantage proof-of-concept demonstrator. This full scale prototype, developed, built, and test flown by Scaled Composites, Inc. under contract to VisionAire Corporation, proved -- in flight -- a design for an entirely new class of aircraft: the single-engine business jet.

Proof of Concept (POC) Testing at Scaled Composites

Each test flight, as usual, expanded the performance envelope of the aircraft in predetermined ways. Analog inputs to the DAP included conventional instrument readings of air temperature, airspeed, altitude, angle of attack, sideslip, fuel levels, etc., as well as not-so-conventional readings of control surface positions, and vibration that pilots call “flutter.”

Flutter matters. Control surfaces can vibrate to the point of structural failure. When the DAP reports unacceptably low damping of vibrations, the pilot stops pushing the envelope.

The DAP dramatically reduces turnaround between test flights. Rick Lee, an engineer at Scaled, said that the DAP performs, in flight, real-time computations that, when he started out in this line of work, “would take data technicians a week and a half of postprocessing before the next flight.”

DAPs help Scaled bring projects in on time and under budget.

The fuselage has an airframe structure formed entirely of carbon fiber as a grid-stiffened stressed skin, made and cured in one piece. The wings have a composite sandwich structure of carbon fiber skins and spars, with a sealed-foam PVC core surrounding the fuel tanks.

Real-Time Analysis

The prototype had a DAP in a mid-height tower PC bolted to the floor on the copilot side of the cockpit; the DAP communicated with the copilot through DASYLab, running on the PC, with virtual instruments displayed on an LCD monitor. The copilot used a trackball -- built into the seat armrest -- to interact with the displays.

The DAP continuously monitored over 70 inputs, and analyzed the incoming data in real time. Each test flight, as usual, expanded the performance envelope of the aircraft in predetermined ways. Analog inputs to the DAP included conventional instrument readings of air temperature, airspeed, altitude, angle of attack, sideslip, fuel levels, etc., as well as not-so-conventional readings of control surface positions, and vibration that pilots call "flutter."

Vibration

Flutter matters. Control surfaces can vibrate to the point of structural failure. When the DAP reports unacceptably low damping of vibrations, the pilot stops pushing the envelope.

In some test flights, the pilot "raps the stick" -- pilot talk for abusing the flight controls -- to deliberately excite vibration. The DAP records this moment and monitors all resulting vibration in the aircraft so that engineers can assess how quickly this damps out.

Reduced Turnaround

The DAP dramatically reduces turnaround between test flights. Rick Lee, an engineer at Scaled, said that the DAP performs, in flight, real-time computations that, when he started out in this line of work, would take data technicians a week and a half of postprocessing before the next flight.

Expansion

To instrument a typical POC demonstrator aircraft, Scaled has to monitor around 70 analog inputs -- so the built-in DAP I/O expansion for high-channel-count applications comes in useful.

Filtering

To take out noise, after signal conditioning through a 50 Hz lowpass analog filter, Scaled oversamples on many inputs and then has the DAP perform data reduction in real time; onboard intelligence -- unique to a DAP -- does this averaging before it passes filtered, reduced data to the PC.

Graphical Interface

To make changes to the instrumentation from one flight test to the next, Scaled depends on a quick and easy graphical interface to programming the DAP. DASYLab software on the PC provides this through the Microstar Laboratories DAP driver for DASYLab and the DAP PowerDLL.

To implement a "glass cockpit" for test instrumentation, Scaled now uses the multiple screen display feature of DASYLab to take advantage of the multitasking operating system on the DAP, and to display the real-time response of several virtual instruments at once. The copilot can zoom in on any instrument at any time -- on a whim or on a preprogrammed alarm level -- using the trackball built into the seat armrest.

DAP Features

Many Microstar Laboratories customers report these four DAP features as the most important:

Conclusion

So if, like Scaled Composites, you see one or more features from either group that can help you bring your projects in ahead of schedule and under budget, contact Microstar Laboratories now.

Afterword

Scaled Composites completed the POC Vantage on time and under a fixed-price contract. In spite of early interest from potential customers, Visionaire Corporation never took off as a business. Another company, Eviation, bought the assets, and has substantially redesigned the Vantage as a larger, twin-engine jet with 8-10 seats, the EV-20 Vantage Jet, expected to make its first flight in Q4, 2006. A subsidiary, Eviation Jets Brazil, headed by Guido Pessotti, retired president of Embraer, plans to obtain certification first with the CTA in Brazil by Q4, 2007. The FAA and CTA have a reciprocal agreement, which could speed up subsequent FAA certification.

Scaled Composites, meanwhile, continues to use DAP boards on projects for other ventures, notably for The Spaceship Company, formed by Sir Richard Branson (Founder, Virgin Group of Companies) and Burt Rutan (President, Scaled Composites).