Testimonials

Magazine: Test and Measurement
Issue Date: January 2003

Aeropropulsion Lab Relies on VXI Test Systems for Speed, High Channel-Count and Signal Conditioning

A couple of months ago, when a boat manufacturer was planning to buy surplus gas turbine helicopter engines from the United States government to power speedboat racers, he wanted to verify engine performance and evaluate the warranty being provided by the seller. The manufacturer’s solution? Engage the Aerpropulsion Lab in Ottawa, Canada.

Although testing helicopter engines for speedboats may not be an everyday occurrence, it highlights the versatility, flexibility and high performance testing the Aeropropulsion Lab is able to provide.

The Aeropropulsion Lab is part of the National Research Council of Canada’s (NRC) Institute of Aerospace Research (IAR), Canada’s national aerospace laboratory. IAR facilities include eight wind tunnels, air compressor/exhauster facilities, engine test cells, a full-scale structural fatigue rig, aeroacoustics chambers, a Flight Data Recorder Playback Centre, and a fleet of eight research aircraft.

The Laboratory provides consulting services, engages in collaborative research, and licenses its technology to a wide range of clients who need solutions in the areas of design, strength, durability, structural integrity and performance of aircraft, gas turbine engines and space structures.

The engine test cells of the Aeropropulsion Lab need the flexibility to test a tank engine one day, an after-burning turbojet the next and a helicopter engine after that. All high performance testing for the likes of blue chip corporate, as well as government, organizations.

As this article is being written, one of the engine test cells in the Aeropropulsion Lab, consisting of two test beds equipped with VXI systems, is measuring temperatures and pressures for a helicopter engine manufactured by General Electric. A second test cell with another VXI system is testing a new General Aviation turbo-fan engine manufactured by Pratt Whitney.

The engines destined for speedboats were Lycoming T53-L-13 1400 shp engines used in Huey helicopters designed for military and medical service during the Vietnam war. The engine is capable of producing 1400 shp (shaft horsepower) at 64 psi of torque on a standard day (59 degrees F) at sea level (29.92 HG). Applied to a helicopter, this provides enough power to carry up to 12 troops, with a crew of two. The UH-1D "Hueys" have a range of 293 miles (467km) and a speed of 127 mph (110 knots). These Hueys could be armed with M60D door guns, quad M60Cs on the M6 aircraft armament subsystem, 20mm cannon, 2.75 inch rocket launchers, 40mm grenade launcher in M5 helicopter chin-turret, and up to six NATO Standard AGM-22B (formerly SS-11B) wire-guided anti-tank missiles on the M11 or M22 guided missile launcher. The UH-1D could also be armed with M60D 7.62mm or M213 .50 Cal. pintle-mounted door guns on the M59 armament subsystem.

Brought into the NRC Aeropropulsion Lab engine test cells, the T53’s were hooked up to a dynamometer and VXI instrumentation, run up to power, and monitored with a full set of checkouts to verify engine performance.

According to Brian Barry, Technical Officer and Data Acquisition Specialist at the Aeropropulsion Lab, two of their facility’s test cells are equipped with VXI systems to provide the precision measurements and the level of confidence among clients who need high performance testing.

"When the clients see our VXI system, they know we’re in the big leagues," says Barry. "When I bid on a project, we can say we have VXI equipment and that benchmarks our ability."

When Barry first began working at the Lab in the 1990’s, test equipment consisted of DEC PDP-11 computers with a NEFF front end. Soon afterward, the Lab replaced the PDP-11’s with VAX 3100’s, retaining the NEFF front end. VAXs, of course, had PDP-11 compatibility mode built in. However, frequent changes in client testing requirements meant frequent reconfiguration of the VAXs. Says Barry, "It takes a lot of manpower to manage a bunch of VAXs. It takes considerable time to write the software, let alone do all the system management. So, I pushed for PC-based data acquisition."

Although the Lab first purchased PC-based SCXI (Signal Conditioning EXtension for Instrumentation) equipment, the performance level was not as high as VXI and SCXI was proprietary hardware built by a single vendor. "We have a van with SCXI testing equipment which we use for outside testing," says Barry. "VXI is our high-end; really high-end."

Why did the Lab consider VXI (VME eXtension for Instrumentation)?

"A lot of our clients were using VXI," says Barry. "You get more performance out of the VXI . . . If you look at the specs of VXI equipment, you’ll see temperature accuracy is better, channel rates are higher and reliability is presumably better. However, we’ve only had our VXI equipment since 1998, so I don’t consider that long enough on which to judge reliability. And at the end of the day, it’s a multivendor standard, so we’re not limited to vendors."

Nevertheless, the NRC Aeropropulsion Lab purchased KineticSystems VXI hardware exclusively. This decision was due primarily to a local sales representative whose fine track record and previous recommendations had successfully assisted the Lab with other equipment purchases. Among the representative’s product lines were VXI modules designed and manufactured by KineticSystems Company, LLC of Lockport, Illinois.

"The hardware is beautiful," says Barry. "There’s no knocking it. When KineticSystems says a module will scan at 100 kHz; it scans at 100 kHz. Signals are nice and clean.

"There are several features you don’t find with VXI equipment from other manufacturers. KineticSystems provides per channel amplifiers and permits more flexibility when you set up scan rates. For example, if you look at a 32-channel temperature module from another well-known VXI vendor, you can only read in groups of 10, 20 or 32 channels. You can’t read the first five, skip 15 and then read the next 10. You can’t have any one module’s address appear twice in the scan. KineticSystems lets you read in groups of 4.

"There are also pre- and post-filtering gains on KineticSystems signal conditioning modules. You can set prefiltering gain in groups of eight and post-filtering gain individually. And the filters tend to be better. Another VXI vendor limits setting the filter for the whole cart.

"So, there’s some tweak-ability you don’t get with other vendors. One’s a Chevy; the KineticSystems is the Rolls Royce."

According to Barry, few vendors have as wide a VXI product selection as KineticSystems. In fact, a provider of some of the Lab’s previous PC-based test equipment not only didn’t have much of a selection, Barry says, "It looked like they had taken their PXI equipment and soldered it onto bigger boards. So I figured I’d end up with all the limitations I already had."

Barry says KineticSystems VXI cards also provided several advantages unavailable from other VXI vendors, including:

• High channel count flexibility
• Fiber optic interface providing a fast, accurate and convenient alternative to thick cables.

The Aeropropulsion Lab installed one VXI system and now they have two. The first system consisted of the following components:

Computer: MO7-CYCLONE Pentium III-700 Mhz PC running Windows NT 4.0/SP6. The application software is LabVIEW Professional V6.0. The computer contains the following hardware:

• V122 – KineticSystems’ PCI (Peripheral Component Interface) host adapter providing
  an interface between the PCI bus and the fiber optic highway.
• 10 baseT network interface
• GPIB interface (for a pressure scanner)

Front End (all KineticSystems modules):

• V195 – 13-Slot, C-size VXI ac Mainframe with 1,000 W power supply.
• V120 – Slot-0 controller that interfaces a Fiber-Optic highway to one or more
  VXI mainframes (FOXI™). It is a slave device on the highway and receives its commands from the V122 host adapter. The fiber-optic highway supports distances between nodes up to 2 km (6,560 feet) with an I/O throughput up to 10 Mbytes/second.
• V208 – 16-bit Analog-to-Digital Converter that processes up to 100,000 samples/second with a 4 Mb buffer.

Modules cabled to test bed (all KineticSystems modules):

• V243 – 48-channel (high level) voltage measuring, signal conditioning MUX.
  Includes programmable gain per channel and 2-pole, active, low-pass Butterworth filters on each channel. Filter cutoff frequencies and pre-filter gains are software selectable.
• V243 – 96-channel (low-level) temperature measuring, signal conditioning MUX.

Same features as module above.

• V635 – 8-channel 100 kHz Frequency Counter.

Other Equipment:

• Pressure Scanner
• Barometer
• Frequency to voltage converter, 14 channels
• DC power supplies
• 28 dedicated wet pressure transducers
• 4 RF conditioners for flowmeters

Typically, the test cell reads voltages off engines, pressure transducers and thermocouple temperatures.

Reflecting on the VXI system, Barry singled out the V243, commenting, "The V243 is great because you can set gain per channel, you can set filtering in groups of 8 channels and you can vary the scan list. You can look at different groups of channels as you choose.

According to Barry, since one of the engine test cells was large enough to accommodate two engines, they divided the cell into two; creating both an East and a West test bed. By installing a separate counter card (V635) and two additional V243 MUXs, two test beds are fully instrumented within the cell using one mainframe. Although they cannot conduct testing in both test beds simultaneously, the Lab has significantly shortened configuration time between tests.

Typically, the engine test cells read less than 100 channels for any one test, often only 30 – 40 analog channels. However, Barry reports they will soon be using 300 channels requiring 100 kHz Analog-to-Digital conversion.

A second test cell at the same facility is also outfitted with a VXI test system. Chief differences between this cell and the East/West test bed previously described are:

1. Computer: M07-AVON Pentium III-700 Mhz PC running Windows NT 4.0/SP6
2. Pressure scanner that does not need a GPIB interface
3. Frequency to voltage converter – 7 channels
4. 14 dedicated wet pressure transducers
5. The same KineticSystems mainframe and modules are used in this cell as the previous dual test bed cell.

Says Barry, "With KineticSystems product, you can be sure it’s high-quality hardware with nice, tight specs. Of course, given the price of VXI, you expect the best. I think VXI is high-end and KineticSystems does a good job with the hardware. I have not been disappointed with their hardware at all."

So, should you ever witness the winning of a speedboat race by a boat featuring a powerful T53 gas turbine engine, you may recall the Canadian Laboratory and the VXI test system used to verify the engine performance.

This application note is provided "as is" without any warranties of any kind, either expressed or implied, including but not limited to the implied warranties of merchantability or fitness for a particular purpose. KineticSystems Company, LLC further does not warrant the accuracy and completeness of the material contained herein. KineticSystems Company, LLC may make changes to this material, or to the products described in it, at any time without notice.

Back to testimonials