Engineering News 7325

Technology under the tree
Compaq unveils 'Professional Workstation'
Sealing element improves tiller life
Plastic gives screwdriver a new twist
Roller-gate dam chain passes 'giant' test
Low-pressure shower saves water
Nylon sheaves help stabilize mobile mining drill
Vision system checks cholesterol kits
VR reveals Stonehenge, from a distance
Tripartite unravels auto-seal obstacle
French firm offers 'custom' satellites

WE ARE HERE!!!Technology under the tree

Engineers used everything from PCs to aluminum suspension systems to create this year's top high-tech holiday gift ideas

Newton, MA--Has Santa left too many ugly ties, questionable art items, or lame software packages under your tree?

As in past years, engineers are working overtime developing high-tech toys that adults can enjoy. Using powerful microprocessors, flash memory, CCDs, digital signal processing, and solid-modeling tools, these Santa's helpers have come up with some nifty items for your holiday wish list:

Kodak DC25 digital camera--CompactFlash removable flash-memory cards from SanDisk, Sunnyvale, CA, serve as the "film" for Kodak's new DC25 digital camera. The $499 point-and-shoot camera lets users view their pictures immediately through an integrated color LCD. Photos can later be viewed on a PC, transmitted to other PCs, inserted into documents, or printed out as standard, hard-copy pictures. CompactFlash cards are rugged, solid-state, PCMCIA-compatible storage devices you can use repeatedly to take hundreds of thousands of digital pictures. If you fill a card and don't have a spare, you can use the camera's 2 megabytes of internal nonremovable memory to store 14 or 29 pictures, depending on the resolution, in 24-bit color.

Bose Acoustic Wave Music System--For $1,079, you (or someone on your gift list) can be the proud owner of an Acoustic Wave portable music system from Bose. This all-in-one stereo system produces deep, rich bass from a small enclosure, thanks to the company's award-winning waveguide speaker technology. The technology uses controlled interaction of acoustical waves with a moving surface. This takes place inside the precision waveguide--a mathematically formulated tube containing a loudspeaker. The waveguide of the Acoustic Wave unit is nearly seven feet long. Other features include: a CD player, AM/FM stereo tuner with 10 presets, and credit-card-size remote. A continuous music option plays the radio after a CD finishes, and an optional pedestal has inputs for VCR, cassette deck, other music sources, and a microphone for use as a portable public-address system.

IBM Aptiva Model S78 PC--This sleek machine has all the features you've been longing for: 200-MHz Pentium, 3.2-gigabyte hard drive, 32 megabytes EDO memory, 2 megabytes video memory, 256 kbytes level 2 cache, 8X CD-ROM drive, 33.6-kbps DSVD data modem, cordless mouse, and joystick. And it's black. RingCentral software lets the Aptiva serve as communications central for telephone, speakerphone, answering machine, advanced Caller ID, FAX machine, address book, e-mail, and paging. Home Director home-control software uses a dwelling's existing powerline network to control lights and appliances, almost acting as a "home server." You can even program these functions from across the country with a phone call. This computer could provide some serious fun for someone wanting to experiment with home automation. System prices range from $2,499 to $3,099; monitors range from $499 to $799, depending on display size.

Sharp VL-DC1U digital Viewcam--A quarter-inch CCD (charge-coupled device) gives Sharp's latest Viewcam high-resolution pictures and CD-quality sound. The $3,595 camcorder also boasts a 4-in. color LCD viewscreen that absorbs 99% of all reflective light, 410,000-pixel-resolution recording, and a 30X digital zoom lens. The unit takes a 60-minute DV (digital video) cassette, and its lithium-ion battery lets you record up to an hour at a time.

Nintendo 64 video game system--For $200 you can buy a video game whose 3-D graphics rival those of high-end workstations. At the heart of the game is a 93.75-MHz MIPS 64-bit R4300i RISC microprocessor and a 62.5-MHz MIPS "Reality Co-Processor." Combined, the two chips let you interactively navigate a 3-D virtual space with real-time, high-resolution realistic scene rendering. The first two games available are Super Mario 64, featuring everybody's favorite plumber, and Pilot Wings 64, a flight simulator that lets players control a hang glider, mini-copter, or rocket belt. Star Wars: Shadows of the Empire, scheduled for a December 2 release, combines a flight simulator with the first-person viewpoint of a game such as Doom--this should be the killer app.

Brother Kitchen Assistant--For the chef--or would-be cook--this $350 interactive cookbook uses computer technology to access recipes at the touch of a button. You can print out recipes and shopping lists--for one meal or for a whole week's worth. Seventy-five recipes are included, and you can add--and have the device automatically sort--your own recipes. Cookbook Resource USA Ltd. is developing cookbook memory cards, with titles that range from basic cooking to exotic cuisines. Novice cooks at a loss can enter the ingredients on hand, and the Kitchen Assistant will find a recipe that works. An added bonus: five built-in timers.

Roland VG-8 V-Guitar System--Instead of buying a new guitar, try getting Roland's VG-8 V-Guitar System for $2,695. It'll make the guitar you already have sound like virtually any guitar and amplifier, no matter which guitar or amp you are physically playing. Roland uses digital signal processing to implement its COSM (Composite Object Sound Modeling) technology. In VGM (Variable Guitar Modeling) mode, the VG-8 uses electronic modeling to reproduce sound characteristics associated with such electronic circuits as vacuum tubes or transistors. Magnetic modeling reproduces the characteristics of such magnetic components as pickups, transformers, and speakers. By combining different elements, you can reproduce the total sound of Jimi Hendrix's Stratocaster, a Les Paul, or even 12-string guitars. HGM (Harmonic Restructure Modeling) takes the guitar waveform and restructures the harmonic content in real time, providing all sorts of unique synth-type sounds.

Dodge Viper--Voted the "Dream Car" by Design News readers in our 1996 auto survey, the Viper's latest incarnation is the $70,000 GTS Coupe. If this is your dream car, get one soon--Dodge is selling only 1,700 of the '97 models. Compared with the Viper roadster, the coupe's V10 engine has 450 hp versus 415 and a rise in torque to490 lb-ft from 480. The coupe's new aluminum suspension, rigid frame, and composite skin give it 12% more torsional rigidity than the roadster and is 60 lbs lighter. Also, you can adjust the pedals for leg stretch--an especially useful feature for those of us 5'4" and under. dn

--Julie Anne Schofield, Associate Editor

WE ARE HERE!!!Compaq unveils 'Professional Workstation'

Houston, TX--Compaq Computer Corp. has unveiled its first entry aimed specifically at the technical desktop: the Compaq Professional Workstation line, ranging from $43,00 to $10,200.

The new workstations incorporate one or two Pentium Pro processors, up to 6.4 Gbytes disk space, ECC DIMM memory expandable to 512 Mbytes, optional 3-D graphics acceleration, and five ports (2 serial, 1 SCSI, 1 keyboard, 1 mouse, and 1 microphone). The system is rated at 8.2 SPECint95 (floating-point figures were unavailable at press time). A modular design uses three thumbscrews for simple disassembly, if users want to add or swap components inside.

Compaq officials say they merge technical expertise from building high-powered servers for commercial customers with cost-cutting knowledge from the hotly competitive, low-margin PC industry.

WE ARE HERE!!!Sealing element improves tiller life

Troy, NY--For years, Troy-Bilt(R) tillers from Garden Way Inc. were plagued with oil leakage from the transmission. Now, thanks to a pre-applied sealant from Macomb, MI-based Nylok Fastener Corp., the tillers' weakest link has been eliminated.

"Because a tiller's transmission is constantly exposed to the earth, oil in the transmission becomes heated, builds up added pressure, and is forced up against the mounting screws," explains John Durrant, design engineer at Garden Way. "Over the years we have tried a variety of fastener and sealant products to prevent oil leakage from the transmission, but never had complete success."

At first, Garden Way applied gasket seals and sealant compounds to the fastening screws during assembly. But the installation proved messy, time consuming, and inconsistent, and never adequately solved the leakage problem. Then the company tried a pre-applied sealant, which eliminated the messy assembly but didn't seal the fasteners. Looking for a single fastener that not only worked but also saved installation time and costs, Garden Way turned to NYSEAL sealant.

NYSEAL is a fused sealing element that covers the bearing surface of the fastener's head and down the shank for two to three thread pitches by 360 degrees. The coating is permanently fused on the surface of the fastener. As the screw is seated to its final position against the mating part, the NYSEAL element compresses slightly and fills the void under the bearing surface of the head and the countersink, or bore.

"We used Nylok in a test program to make sure it performed as well as we thought it would, and we weren't disappointed," says Durrant. "Since it is pre-applied to the fastener threads, there is no mess or loss of installation time on the assembly line, and the cost difference is only pennies," he adds.

Although tillers operate at only 7 psi, NYSEAL screws were tested at 50 psi for two hours, and at temperatures up to 400F, without lessening sealing effectiveness.

WE ARE HERE!!!Plastic gives screwdriver a new twist

Kenosha, WI--With just a twist of the wrist, Snap-on Tools' new five-inch-long Mini Ratcheting screwdriver makes light work of attaching small screws. The secret: a one-inch-diameter reverse cap on the end of its handle.

Made of a long-glass, fiber-reinforced polypropylene composite from LNP Engineering, Exton, PA, the cap's 30-degree rotation provides directional control for tightening or loosening screws. It snap-fits over the handle.

"We just assumed we could use our standard material in this application," says Joe Hoepfl, senior project engineer at Snap-on. "However, de-velopment tests showed significant shrinkage resulted."

This presented a major pro-blem. "It was essential that no shrinkage occur in the cap or else it would prevent it from turning--in effect, causing it to lock up," Hoepfl explains.

When Snap-on began looking for a material to solve the shrinkage problem, it tested various types of nylons, cellulose acetates, butyrates, and polypropylenes. "The only material that elminated the problem was Verton(R) MFX materials," says Hoepfl.

Because screwdrivers are frequently used in automotive applications, it also proved important that the material stand up to corrosive fluids. "Verton structural composites are extremely resistant to fluids like battery acid, brake fluid, and gasoline," Hoepfl adds. "From experience, we know that if a tool works in the harsh automotive environment, it's going to work in a nice, clean factory."

WE ARE HERE!!!Roller-gate dam chain passes 'giant' test

Apple Grove, WV--A monster chain that looks like it could be a bicycle chain for King Kong recently went into service at the nation's largest roller-gate dam. The chain measures 165 feet in length and weighs 110,000 lbs. It had to be transported from the fabricator, ESG Co., Long Lake, MN, to the Ohio River on three flatbed trucks. A towering barge-mounted crane positioned the chain on the second of eight roller gates at the Robert C. Byrd Locks and Dam, operated by the U.S. Army Corps of Engineers.

Fru-Con Construction Corp., St. Louis, deactivated the old locks, replaced the roller gates, and installed the new chain. The chain raises and lowers the 300-ton, barrel-shaped roller gate, helping to maintain a navigable channel in the river.

The giant chain consists of two dissimilar metals. All the roller pins (weighing up to 550 lbs each), collars, spacers, and washers were made of Custom 450(R) stainless steel, a specialty alloy from Carpenter Technology Corp., Reading, PA. The end links and link bars were made of aluminum bronze.

The Corps of Engineers presented some stringent performance criteria for the metals. The engineers wanted to avoid past chronic problems that had plagued the gate's operation, as well as lowering maintenance over a 50-year period.

The original carbon-steel roller-gate chains corroded so badly that movement between the links and pins submerged in the water had become seriously restricted. Chain links traveling over the roller-gate sprocket would sometimes fuse together from corrosion buildup and pop out of alignment, frequently damaging the chain guards. At times, a sledge hammer had to be used to free moving elements.

Greases and lubricants proved impossible to apply on inaccessible sections and failed to last long on submerged chain sections. The problem arose from the original design, which did not leave enough clearance between the links and pins for the links to rotate freely. Therefore, the design was changed, along with the materials, to improve the clearance.

For example, zebra mussels, which would become crushed between the chain and gear track, binding the gate machinery, found the aluminum bronze components in the new chain design distasteful. This metal also proved to be compatible with Carpenter's Custom 450 stainless steel. Both materials have provided the bearing properties and non-galling characteristics that allow the pins and links to move freely.

The stainless steel, a martensitic age-hardenable material, has corrosion resistance similar to that of Type 304 stainless, enough for the grimy river water, and three times the yield strength--a tensile strength of 125,000 and yield strength of 100,000 psi in the annealed conditions. It is also ductile, tough, and durable.

Dimensional tolerances on the 22.75-inch- and 25.50-inch-long pins are held to plus or minus 0.001 inch for length. Tolerances of +0.000/-0.005 inch are maintained on the finished diameters of 6.483 and 10.983-inch. The total length tolerance for the 165-foot-long chain is only 5/16-inch.

The Byrd Locks and Dam, completed in 1937, is one of only four roller-gate dams in the U.S. During rehabilitation, each of the eight spillways will be equipped with a new roller gate and chain. Work is scheduled to be completed in 1998.

Low-pressure WE ARE HERE!!!shower saves water

Modesto, CA--Developed by Energy Technology Laboratories (ETL), the Universal Spa^TM AE 2001 shower head employs a flow-accelerating nozzle to generate a "brisk" spray at input pressures as low as 3 psi. The new shower head makes it possible for people living in areas with low-pressure water supplies, including those that rely on simple gravity-driven water systems, to enjoy a shower while saving water.

Most low-pressure shower systems rely on allowing large volumes of water to fall through a spray head, according to Walter Nelson, who designed the AE 2001. This approach works, but it consumes a lot of water. Applying fluid mechanics to the shower-head design enabled Nelson to accelerate water flow and cut the volume of water required for a shower.

Basically, the nozzle consists of a venturi with a stationary set of six semi-helical blades near its entry. The blades set up a left-handed vortex and help minimize resistance to flow, Nelson says. Fluid movement draws air into the flow through four orifices located near the beginning of the exit nozzle, producing a well-aerated liquid stream.

Given that the shower head's internal flow accelerator inherently limits flow to about 1.5 gallons/minute, the AE 2001 allows a person to take a good shower while using less water than would be consumed by a simple camp-type shower.

Engineers at ETL use Delrin(R) 500P from DuPont to injection-mold many of the shower head's parts: valve plug with integral control arm; locking ring for the plug; collar, ball, swivel, and orifice insert; and spray nozzle.

DuPont claims that Delrin 500P, part of the new Delrin P performance acetal resin family, provides faster mold cycling and lower mold deposit than earlier acetals.

WE ARE HERE!!!Nylon sheaves help stabilize mobile mining drill

South Milwaukee, WI--Bucyrus-Erie Co.'s newest mobile, diesel-hydraulic ro-tary-blast hole drill features a stable mast that can create holes from 9 to 121/2 inches in diameter at -5 to 30 degrees off center.

Helping make that possible are twin nylon guide sheaves that move up and down the unit's mast as they feed hydraulic and air hoses to the rotary head. The 42-inch-diameter sheaves weigh about 485 lbs, a fraction of the weight of same-size steel sheaves.

The lighter weight of the sheaves, made from Nylatron(R) GSM nylon by DSM Engineering Plastic Products, Reading, PA, gives the 39R drill good mast stability. Since the diesel-hydraulic units can drill holes off center, and must move over terrain with grades up to 25%, stability was a critical design factor.

In addition, the lightweight sheaves result in less stress on the mast and less maintenance. To eliminate loose, dangling hoses, all the hydraulic hoses are protected in a single, 10-inch-diameter rubber sleeve. The sleeve runs over the nylon sheave, which moves up and down inside the mast. Likewise, the large air-discharge hose runs over a similar sheave.

The lubricity and smoothness of the Nylatron GSM sheaves reduce surface friction between the rubber sleeves and the sheaves. Unlike metal sheaves, the nylon counterparts do not impede sleeve motion. They also won't develop sharp nicks that can abrade the sleeves, nor will they corrode.

And, the nylon sheaves cost about a third less than metal sheaves. With typical use, Bucyrus-Erie expects the sheaves to last three years.

Vision system checks WE ARE HERE!!!cholesterol kits

Natick, MA--To accurately measure the position of critical components of its cholesterol home-screening kit (recently approved by the FDA), Actimed Laboratories Inc., Burlington, NJ, relies upon the Checkpoint 800 machine-vision system from Cognex Inc.

Actimed's device consists of a sample well housing four pads that contain proprietary biochemicals. A user pricks his or her finger and places a drop of blood in the sample well. After blood reacts with the biochemicals, the device produces a cholesterol readout in a capillary channel that runs along its length. If a pad moves even a few mils from the back of the well, the device won't work properly.

Actimed needed a system that could inspect the devices during production. The New Jersey company sought help from Xyntek Inc., Yardley, PA, a provider of turnkey machine-vision systems. Xyntek then brought the Checkpoint 800 from Cognex to the attention of Actimed's engineers.

Designed to use a Windows-based environment for application programming, the Checkpoint 800 consists of processing hardware in a NEMA-rated enclosure, vision tool software, cameras, and a monitor. Employing the Checkpoint 800, engineers from Xyntek and Actimed designed an inspection system to measure pad location in three axes.

On the production line, an indexed conveyor moves a plastic web carrying six devices into the inspection station. At the station, the system acquires images from six cameras. (The cameras and 12 visible red lasers are located two feet above the web.) Using its search tool, application code finds two fiducial marks stamped onto the front of each device.

After acquiring all six camera images, the inspection system performs a normalized correlation to match what it sees to a model installed during development. This data determines the rotation and placement of the web.

A pair of laser beams are projected as line segments onto each device. The system then inspects each device by measuring where the laser-generated lines intersect. By using its edge-detection tool, the system matches the pixel image of each 2-D image with the known angle of each laser beam to perform triangulation, and thus determine X, Y, and Z dimensions. Doing so determines the placement of the pads in each device's well. System resolution is 1.4 mils per image pixel. After the system sends a pass-fail signal to a host computer, the computer marks failed devices for later removal. Each inspection cycle requires about 0.5 second for a six-device web.

VR reveals WE ARE HERE!!!Stonehenge, from a distance

Salford, U.K.--Bonaparte's soldiers scraped the French equivalent of "Kilroy was here" on some of Egypt's monumental ruins with bayonets. In the United Kingdom, English Heritage, a government-sponsored preservation society, is employing virtual reality in an attempt to deny future visitors of Stonehenge--a contemporary of the Great Pyramid--the necessity of pondering the value of messages from our time. The project also demonstrates how virtual reality can be used to develop realistic, interactive simulations with digitized objects.

In 1995, English Heritage completed an exhaustive study of Stonehenge and its environs. Archaeologists scanned each of the 80-plus stone blocks with a laser system that recorded surface features with 2-cm resolution, generating a database of approximately 48,000 points for each block. Several hundred photographs were also taken to record subtle surface details, such as small cracks, lichens, and fungi.

According to VR application developer Andrew Dennison, the data describing each stone had to be optimized through polygon reduction because no commercial surfacing algorithms could handle the required level of detail. Dennison used digitized photographs to texture map details accurately onto each surface model. The entire Stonehenge simulation contains 50,000 polygons--40,000 for the stones and immediate terrain and the rest representing more distant terrain.

The Stonehenge and terrain models were loaded into the WorldToolKit from Sense8 Corp., Mill Valley, CA, running on an Intergraph TDZ400 graphics workstation. The WorldToolKit library contains over 1,000 high-level function calls for configuring, interacting with, and controlling real-time simulations.

One of the most interesting features of Virtual Stonehenge is that it recreates a visit to the megalith during the Summer Solstice--appropriate since archaeologists say the site is essentially a four-million-pound clock designed by its builders to note that auspicious annual event. VR application developer Jason Buksh downloaded from the Internet right ascension and declination information for all stars with an apparent visual magnitude brighter than 3.55 (the larger the magnitude number, the dimmer the object). Buksh used this information to model an accurate star-field.

The stone circle out on the Salisbury Plain of Wiltshire has such historic and mystic resonance that visitors flock to see it, which is just the problem from English Heritage's point of view. Virtual Stonehenge permits people to examine the finer points of the megalith without doing it any harm.

WE ARE HERE!!!Tripartite unravels auto-seal obstacle

St. Paul, MN--A three-way relationship among a major materials supplier, rubber processor, and quality-conscious end-user can prove complicated. However, opportunities for success also exist. That's what happened when the 3M Specialty Fluoropolymers Department (now called Dyneon as a result of a joint venture between 3M and Hoechst AG), Acadia Polymers, and Chrysler put their collective resources together.

"It was how things are supposed to work, but seldom do," relates James Jacks, senior staff chemist for Acadia. "The turnaround on this project is just unheard of in our industry."

The venture, which began in early 1995, involved upgrading the elastomer used in transmission lip seals and D-rings for the 1996 Chrysler minivans. As part of its continuous project improvement program, Chrysler wanted to enhance the performance of transmission seal materials. Gary Binienda, manager of automotive transmission development for Chrysler, contacted Acadia, a rubber products company that focuses on automotive and sealing applications, to request an upgrade from ethylene acrylic to a fluoroelastomer material for the seal.

Acadia tried a standard FKM fluoroelastomer in its molding plant. However, temperature swings during the compression-molding process resulted in shrinkage variations that were unacceptable. Acadia witnessed a significant loss of material due to scorching, as well as other processing problems.

At that point, and just weeks before Chrysler needed the parts, another option emerged. 3M's Specialty Fluoropolymers Department had recently introduced L12896A, an experimental fluoroelastomer. Acadia had done some lab work with the material and found it to be very robust. However, at the time, Acadia didn't need large quantities of the material until its evaluation was complete.

The fluoroelastomer, part of a new FE-5000 series from 3M, had been designed specifically for improved scorch resistance. It also had demonstrated better mold release characteristics. Although based on the same polymer as 3M's standard fluoroelastomer, the new material incorporated a proprietary cure system.

Chrysler wanted assurances from 3M that it could provide the raw material to Acadia in time to meet its testing and production deadlines. Adding to the time crunch: Many of the people who needed to approve the contents of 3M's commercialization manual were out of the country.

"My first job was to assure Chrysler that we could deliver," recalls William Donahue, 3M's market development manager for new products. "We put it together in four or five days."

Significant time delays and the high cost of a mold redesign were averted, those on the team report. In effect, a project that would typically take 18 months was completed in about eight weeks.

"Each party carried out its task without a hitch," says Tom Bibby, vice president of quality and technology at Acadia. "Chrysler defined the criteria, 3M supplied the material and technical support, and Acadia handled the compounding. From my vantage point, this is a textbook case of excellent teamwork."

French firm offers 'custom' WE ARE HERE!!!satellites

Toulouse, France--Car buyers are long accustomed to selecting options packages to customize standard models. These days, satellite buyers are doing much the same. Matra Marconi Space, Europe's leading satellite maker, offers its Mark II line of Earth-observation craft to customers in diverse fields. In order to optimize its product for specific missions--and attract new buyers--the company relies on CAD, CAE, and mission-simulation software.

The Mark II is designed as a common platform to which an array of mission-enabling attachments can be added. These might include infrared sensors, cameras, radar imaging systems, specialized communications, solar cells, and batteries. The Mark II features a number of improvements over its predecessor: operational lifespan has been increased from three years to five; the satellite can be configured for a wider variety of missions; and it incorporates more advanced on-board processors and other technologies. Matra Marconi's first Mark II model, Helios 1A, was launched in July 1995 for the French military. The company currently is fitting the SPOT-4 satellite with an enhanced IR imaging system for launch late in 1997. A number of other programs based on the Mark II platform also are under way.

Using a standard platform reduces manufacturing costs, but each satellite has unique characteristics; weight can vary from two to eight tons. Jean-Michel Darroy, manager of Matra Marconi's space engineering tools division, indicated design, analysis, and simulation software play significant roles in configuring a Mark II satellite, planning its mission, and operating it once aloft. "We use software throughout the satellite's life cycle as design tools and to communicate with customers," Darroy said.

The space engineering tools division developed Systema, a family of analysis packages intended to help designers predict a spacecraft's thermal, electromagnetic, and mechanical loads. Systema modules run as a compliment to Euclid, a CAD/CAM system from Matra Marconi's sister company Matra Datavision in Paris (US headquarters: Andover, MA). The satellites are designed using Euclid, and models can be loaded directly into Systema for analysis. The thermal module is used to determine heat levels and distribution from the satellite's systems and solar radiation. The electromagnetic compatibility module shows how materials and configurations will affect sensors and communications. The mechanical module is used to analyze stress and check interference between satellite components.

Darroy said a series of other tools developed by the division--collectively known as Ops-ware--are used to prepare, validate, and execute mission operations and procedures. Such software is important for developing orbit plans for a satellite of a given configuration and weight so that it will be able to carry out its intended function. A system simulator allows users to visualize a mission on a computer-generated map and even simulate the end products of a mission by displaying images that have been collected on previous flights over a desired location. Ops-ware also includes modules for developing mission time lines, analyzing telemetry data, and automating spacecraft operations.

Competition among satellite makers for business is fierce. Increasingly, commercial satellite buyers are organizations with little or no past experience in space operations and cannot exactly kick the tires of models in a showroom. According to Darroy, mission simulators are useful tools for showing a customer exactly what his or her satellite will be up to up there.