Anatomy of a Moonbuggy: Give It a Brake
Posted on Mar 31, 2011 09:48:40 AM | Angela Storey
It is upon us! Buckle your seatbelts and give the team advisor a Maalox -- it's time to assault the course and go for the gold!
Registration began today for teams participating in the 18th annual NASA Great Moonbuggy Race. We'll hold our opening ceremonies tonight at the U.S. Space & Rocket Center in Huntsville, Ala.
Like all our teams, Huntsville Center for Technology racers Ezra Logreira and Karine
Wittenborg are itching to roll. Our unofficial "Face of the Race" duo for 2011,
they're both seniors, headed to the University of Alabama in Birmingham this fall.
But they want one more win for HCT before they go... (MSFC/David Higginbotham)
We'll welcome old friends and new, go over the guidelines and walk the winding, half-mile race course (which, as you read this, is getting the finishing touches today from the Space & Rocket Center's elite crew of groundskeepers and "moon mechanics," under the watchful eye of head axle-breaker Dennis Gallagher... who occasionally breaks into villainous MWAHAHA laughter, we kid you not).
And tomorrow, April 1, at 7 a.m. Central time, the buggies start to roll.
So let's wrap up our look at moonbuggy hardware with a few final elements -- some critical, some cosmetic, but every one of value to your performance. And possibly your posterior.
Steering configurations are as varied among moonbuggies as any other element, but the relative simplicity of the hardware -- upright or drop handlebars (or a simpler straight handle or riser bar, like that on a mountain bike) which turn the fork and front wheels via a stem rotating in the headset -- may mislead teams into giving it too little thought.
The design is paramount here. How are you configuring your riders -- side by side or one in front and one in back? Will they share steering duties, or does just one of them take on the responsibility of guiding the vehicle? Do the style and position of your handlebars match the seating angle of your riders? If they're seated low at a backward angle for better pushing power, for example, you don't want upright handlebars that force them to awkwardly lean up or forward to maintain control.
Look at a recumbent bike, with under-seat or over-seat steering. You may want to riff on that idea, and design a buggy with steering arms or joysticks positioned at the sides, permitting the riders the most aerodynamic profile and ergonomically satisfying ride positions possible. But testing must be rigorous. Does the system have the necessary responsiveness? How much power will it take to rake that speeding buggy around a sharp turn? Can "lowrider steering" measure up?
Race organizer Gallagher, a NASA astrophysicist who works at the Marshall Space Flight Center, is always quick to point to mountain bikes as a good jumping-off point for basic buggy design, and this is another area where they can give you some good ideas. Especially consider the wider widths of mountain bike handlebars or risers, he says -- which can dramatically improve handling.
"And be sure they have some play to them," he adds. "This terrain's really uneven, so they'll need to be able to handle a lot of hard jerks and jolts." (Mwahaha indeed.)
Dennis's fellow engineer and race planner Tom Hancock, chair of the American Institute of Aeronautics and AstronauticsAlabama/Mississippi section, agrees steering is important... but he's more concerned about brakes. He's one of the guys who's out there the night before the race, laying down something like 175 bales of hay -- to make sure careening buggies have something soft to run into when they get out of control.
See this? This is important. This is the thing that keeps your advisor's heart rate
down in a safe zone. Especially during that hairpin left turn right after Obstacle 3.
Hancock says brakes come in all flavors among buggies -- from the crude rim brakes found on regular bicycles; to internal hub or disc brakes for sturdier off-road or tandem bikes; to direct-pull or linear-pull brakes like the "V-brakes" found on many BMX and mountain bikes.
With rim brakes, friction pads are compressed against the wheel rims themselves. Among internal hub brakes, they're contained within the hub of the wheel. Your best options, our experts agree, are disc brakes, which have a separate rotor for braking, or linear-pull brakes, which seem to have the most hardware flexibility, work well with suspension systems based on more rugged off-road bikes, and stand up best to hard, abrupt braking.
Whatever your configuration, Hancock says, whether they're hand-operated or controlled by foot-pedals, the brakes are absolutely critical, and should be thoroughly tested repeatedly before race day.
"Buggies can pick up so much speed out there, and we're always surprised to see so many with brakes only on the front, or only on one side," he says. "That's because they've been salvaged off a regular bicycle, of course, and the end result is they drag really hard to one side."
And that's no good, especially if a large rider is paired with a small one. "We see guys close to 200 pounds matched with girls around 110-120," he says. "Add the weight of the vehicle, and a few critical heavy-side turns on the track where vehicles may pull three or four Gs..."
It's a recipe for trouble. "Your welds may be good, but they may not be that good," he laughs. "Or the center of gravity may be too high, and you risk tipping over."
Riders can offset those dangers -- pick a solid braking systems and train your drivers to apply them properly.
Don't settle for the cheap seats
Let's move on to one of the most memorable elements of the moonbuggy -- or it will be, after your riders disembark at the end of the course and discuss with you why you chose to skimp on seating.
"Bucket seats are the best," Hancock says. "Find something of quality that conforms, if possible, to the lower back and rear end. You want your drivers seated solidly to provide lots of lower-back pushing power.
The rear seat on a Huntsville Center for Technology buggy. Note the ergonomically
sound handlebar placement. (MSFC/David Higginbotham)
Simple folding seats can snap, Hancock warns -- all the riders' mass and energy is being centered in the lower back, and flimsy chairs won't hold up. Likewise, saddles -- simple bicycle-style seating -- won't suffice, because there's no lower-back pushing power there at all. "That's just asking for pain," he says.
He also advises against angled seatbacks. He's seen teams cant the back rests 15-20 degrees -- maybe in an effort to be more aerodynamic. "But depending on the configuration of the buggy, now you're expending a lot of energy just to stay up straight to pedal," he says.
Whatever your seat of choice, Gallagher reminds all racers to include strong, buckling seat belts. No Velcro, no rope, no duct tape. "Seat belts are NOT part of the façade," he says.
Finishing touches: The accessories
The façade is where we'll round out this exploration of the moonbuggy's inner workings. This race is a historic legacy, after all, celebrating the Apollo-era Lunar Roving Vehicles that rolled across the surface of the moon in 1971 and 1972.
It's been 40 years since those fabled moonbuggies raised the bar for off-road racing, and your buggy needs a few accessories that put the finishing touches on this homage to NASA ingenuity and can-do spirit.
According to the race guidelines, each buggy must have a simulated TV camera approximately 2 inches by 3 inches by 6 inches or so; a simulated high-gain antenna with a reflector approximately 2 feet in diameter; two simulated batteries (roughly 4 inches by 6 inches by 8 inches); "moon dust abatement" devices, better known as wheel covers (or sweet, sweet fenders); a simulated electronic-controls radio and display console (totaling an approximate 1 cubic foot in size); and a national or school flag. Items get checked before and after each run... and you want to have the same set of goodies at the end that you had at the start.
Secure your gizmos," says Hancock. "Otherwise, it can cost you. You lose a point for every piece that comes off. People drop fenders, cardboard instrument boxes and other things all over the track."
He suggests that new racers in particular keep everything simple to start. Try to keep accessories out of the way of the riders, so they don't inadvertently knock them loose. "Small, secure and out of the way," he advises, then chuckles. "One of the most novel approaches I ever saw was a team that just had a sign on the side of the steering column. It said, 'Our whole instrument system is on the side of the steering column.' " Not exactly kosher -- but it kept the teams' focus on the bigger challenges.
Huntsville Center for Technology keeps its accessories, such as this mini-camera,
anchored and out of the drivers' way. Don't get penalized when that fancy contraption
comes flying off! (MSFC/David Higginbotham)
Don't be afraid to get creative, though. "Some accessories are really great," Hancock says. "We've had kids make working displays. A lot of them will bring a video camera and mount it on the front end to tape their run." To get a look at what's possible, check out the buggy from last year's winning high school team, the International Space Education Institute. Their GPS tracking and other on-buggy hardware is mind-blowing!
And visitors can get an actual buggy-cam experience -- shot by high school racers in 2009 -- inside the U.S. Space & Rocket Center at the NASA Education Competition exhibit. Just look for the mini-moonbuggies.
Drivers -- to the starting line!
As the race draws ever nearer, Gallagher and Hancock reflect on what it offers -- practical, real world engineering challenges that may open new career doors for many of our intrepid racers.
"This is professional experience," Gallagher says. "Design work, specc'ing out your requirements, fabrication, welding, rigorous testing... This is the real deal, and it leaves an impact."
For his part, Hancock loves watching new teams tackle the course for the first time. "They may come from small towns, and their team may not have all the resources of bigger school systems," he says. "But so many show up with work that is just great -- intuitive, slick and well thought out. They may not have all the materials to take their ideas to the next level, but the spark is there. The flame is lit."
Expect that inventive flame to deliver no end of unique, unexpected moonbuggy designs and configurations when we take the course on April 1. We may see three-wheelers. TWO-wheelers. Anything is possible. One team years ago designed something that looked like an exercise machine -- both drivers were standing up. "Worked great til they hit the first obstacle," Gallagher laughs.
"We had a tank once," Hancock remembers. "It was eight feet long, it wasn't very well put together, it was dropping cleats all over the course..." He smiles. "But it was COOL."
Be safe out there, teams.
And be cool.
You're invited to watch live race coverage all day Friday, April 1, via UStream at http://www.ustream.tv/channel/nasa-msfc. The race is expected to start at 7 a.m. Central time. Our deepest thanks to Dennis Gallagher and Tom Hancock for their help in developing this blog series. For those interested in learning more about these good folks who help us execute the NASA Great Moonbuggy Race year after year, you can read more about them here.
Anatomy of a Moonbuggy, Pt. 3
Posted on Mar 28, 2011 09:07:35 PM | Angela Storey
Mere days remain until the 18th annual NASA Great Moonbuggy Race! As we continue our exploration of moonbuggy mechanics, we turn to the drivetrain. And immediately Dennis Gallagher, our race expert and NASA astrophysicist, puts a weary hand over his eyes.
"Chains," he says. It sounds like a curse word.
What it is, What it Does, What a Ride
What constitutes the drivetrain? Get on a bicycle or dirt bike and look down, Gallagher says. The drivetrain is basically everything between the rider's feet and the road, including pedals, gearing, axles, tires and wheels.
This Huntsville Center for Technology buggy puts the pedals high and forward
for extra pushing power… (MSFC/David Higginbotham)
Typically, moonbuggy drivetrains come in two flavors, says Tom Hancock, the chair of the American Institute of Aeronautics and Astronautics Alabama/Mississippi section and a longtime member of the Great Moonbuggy Race planning committee. There's the fancier, direct-drive system -- which employs a driveshaft and transmission to transmit torque and rotation -- or a simple series of gears.
The drivetrain system transmits human power from the riders' madly pedaling legs to the drive wheels of the vehicle. Most also have a gearing system to convert speed and torque.
Hancock has seen some pretty fancy rigs over the years, but says most dependable buggies use reliable gearing originally developed for dirt bikes or heavier off-road riders. "You'll see stripped gears, sure," he says. "But-"
"Chains," Gallagher repeats.
His lament is a common one on the track. Chains can spell doom out here, where drivers see the jut and angle of obstacles ahead and over-exert themselves. In recent years, one of the most common sounds on the course (after the fire-whistle wail of the starter's horn, the whoops of the kids from Lima and Middle Tennessee State, and the boogie-inspiring percussion of the Puerto Rico teams' drums) has been the grinding SNAP! of an over-tensioned chain breaking on the very first mound of thick, wet gravel. And if the chain hasn't snapped outright, chances are it was too loose… and slipped off the gear teeth. Goodbye, momentum.
A Delicate Balance of Speed and Torque
"You're putting a lot of stress on this system," Gallagher says. "The buggy is human-powered, but it's really not like a bicycle at all. A rider's legs can put upward of 300 pounds of force on each pedal with each stroke." Add a second rider, a lot of adrenaline and awesome prizes and bragging rights at the end of the track… and now there's nearly 1/2-ton of force hitting those chains on every obstacle.
"Standard bike chains cannot put up with that kind of force," Gallagher says.
Those guys in the bike-racing movie BREAKING AWAY were pretty amazing on a
flat, circular track. We're pretty sure our course and our racers would leave them
spitting dust. (MSFC/David Higginbotham)
"If you're using chains, make sure to use lots of tensioners and chain guards, particularly around the bottom of the vehicle where you contact the terrain," Hancock says. "Last year, the Huntsville Center for Technology buggies had three or four different tensioners and they really paid off."
Gallagher concurs. He also emphasizes caution to those teams who employ derailleur gears -- a kind of variable-ratio transmission system that includes a chain and sprocket system to change gears and widen the range of torque and power that can be applied.
But being able to change gears to increase speed shouldn't be the ultimate goal, he says. Because of all the turns and obstacles, the fastest buggies on the course usually only clock about 15 mph on straight sections.
"It's a challenge," he says. "On straightaways, you want gearing conducive to speed. On harder sections, you want gearing conducive to torque." But he believes the best vehicles maintain a fairly steady top speed across the course, without a lot of gear changes.
For others, their delicate drivetrain elements were never designed to take the kind of punishment doled out by the NASA Great Moonbuggy Race.
"Think beyond a regular bicycle," he says. "I like planetary gears, gearboxes designed specifically and fabricated by teams aware of the requirements of the course. Do it yourself!"
Hancock agrees, and offers this key pointer for teams building their own drivetrain -- or working on nearly any other element of the buggy. "Modular is key," he says. "Come up with a system where the hardware is nearly all modular, so you can easily and quickly pop out broken or damaged parts and pop in replacements."
Put this, as they say, to the metal. But know the strength of said metal when it meets
the force you're applying. Is your hardware up to the stress? (MSFC/David Higginbotham)
Pedals, Wheels and Tires
Rounding out the drivetrain portion of our buggy tour are the points where the rider meets the ride and the rubber meets the road: pedals, wheels and tires.
Don't shirk on good pedals, Hancock urges. Find quality pedals that have locks on them, the kind used by professional racers, to ensure your shoes don't slip off. "Velcro won't work. Toe hooks won't work," he says. "Your feet go through 40-60 degrees of motion and they'll just come off. You've gotta anchor the feet securely to maintain contact with the pedals."
And drivers need to be mindful of their choice of footware, he says. "Even if you spend money on those bike pedals with the little cleats, if you're wearing smooth-soled shoes… what was the point?"
Buggy wheels and tires need to be strong and durable. "Look at track bikes, ATV wheels," Gallagher suggests. "They don't have to be tall -- just wide."
Tall wheels can present their own brand of problems, Hancock agrees. "There's a tradeoff. On the undulating terrain found on the course, if a wheel is too big, it can end up spanning a small crater or rille and get stuck. If it's too small, it can't get up out of a gap. Wide wheels work best. Anyone who shows up with regular bicycle tires on their buggy is going to lose a wheel."
This never happened to those BREAKING AWAY kids… (MSFC/David Higginbotham)
Next time, we'll assess brakes, steering and seats, and talk about those clever, clever buggy accessories…
Ready to Defend Their Crown
Posted on Mar 28, 2011 08:06:34 PM | Angela Storey
International Space Education Institute, Leipzig, Germany
The International Space Education Institute is headed stateside as we post this. We're excited to see what Ralf Heckel's team brings this year, not just to the high school division -- which they won in 2010 -- but to the college division as well. Here's German high school racer Nadin Rössler with an update...
No. of teams in 2011: 2 (one high school team, one college team)
2010 rank: Finished 1st in high school division
Best score to date: 1st place, 2010, finishing in 3 minutes 37 seconds
International Space Education Institute racers train for the race near the
MDR Tower in Leipzig. (Ralf Heckel)
The NASA Great Moonbuggy Race is the chance for showing new possibilities and for showing a new way of thinking. It' also a great possibility for me to be a member of that great run. I'm Nadin Rössler, 17 years old, from Chemnitz, a German town between Leipzig and Dresden. There, I am a student of the Johann Wolfgang von Goethe High School, which also supports our project.
Certainly, everybody has to get a special feeling for the race. NASA and "moonbuggy" seem to be words which are far away from us normal scholars and students. It's crazy, to be a part of such a great chance. But for calming down and understanding, we also prepared mentally for the race -- we watched films of the moonbuggies, read articles and spoke with the "ingrained" members. It was a really good and important help to realize our potential, to see that the future needs young people like us who have new ideas and new ways of thinking. That's why it isn't impossible to take part in such great races. And that's a thing -- I'm really full of pride.
Buggy drivers Max and Nadin train on their tandem bicycle. (Ralf Heckel)
To find a design for our moonbuggy wasn't our most difficult job. Our team has taken part in the Moonbuggy Race for more than five years. But we had to perfect our buggy. And that doesn't mean to change design, color or structure -- we changed the weight, the wheels and the stability. All in all, we will have a very light and flexible buggy this year. And we're all very proud of the results of our work.
For building our buggy, we needed a lot of time. Every weekend we were in the International Space Education Institute for drilling and welding. Last year, our buggy reached a speed of 50 mph. That's why we did a crash test this year, to guarantee our safety on the buggy.
Now, after a lot of sweat and brainpower, we look forward to Huntsville and are excited to see the other buggies. We hope and believe it will be an unbelievable time for us.
The race is also a question of fitness. Our way of training included a lot of tours with bikes. But not just normal bicycles -- we also had a tandem for riding together and a recumbent bike for learning how to sit in a moonbuggy. The plan for our trips often was a tour to a lot of beautiful parts of Leipzig. Among them is a bicycle park with small hills specially made for passing on bikes. Some of us dared the course while the others cheered. We took countless photos and films. It was a lot of fun to watch the others and to try driving over the hills by myself. With that funny way of training we got not just healthier and more prepared for the event, but we also got team players.
To get prepared for the run doesn't just mean to train until the sun is setting. It also means to have fun with the group and to experience the world together. That's why we made more than 150 trips this year through Germany and Europe. We were in small towns such as Borsdorf, Eisenach and Peenemünde, and also visited great cities like Moscow. We took a lot of new memories with us, and it really helped turn us into team players.
The team! Clockwise from the top: Roman, Thommy, Max, Nadin, Krissi, Eric,
Marine and Evgeniy. (Ralf Heckel)
It's our aim to walk the same way together -- the way to the Great Moonbuggy Race in the USA. We are all very proud to be members of this fantastic competition. Everybody is excited, and each one wants to perform with excellence.
We are the only members from Europe who will come to the race this year, so it's our aim to attract more European students because the moonbuggy gives many scholars the chance to learn new ways of thinking. We learn working in a team, training with the team and exploring with the team. It's a chance to learn new things in science and engineering.
And we're all very excited about how our buggy will come through the race. Maybe ours is the fastest. Or the lightest.
No matter what happens -- for us, our moonbuggy is the best.
Team Update: Lima Gets Ready for Race Week
Posted on Mar 25, 2011 12:35:50 PM | Angela Storey
Lima Senior High School, Lima Ohio
We've got another update from the Lima Senior High Spartans!
No. of teams in 2011: 2
2010 rank: Finished 14th (Team 1) and 17th (Team 2)
Best score to date: 4th place, 2008, finishing in 7 minutes 23 seconds (Team 2)
The Lima Senior Moonbuggy Team has received a letter from the Lima Senior Spartan:
As the Spartan himself prepares for the trip, the moonbuggy teams are working hard, and it shows. Since our last update, both teams have been meeting for hours each day to work on the buggies. After a minor setback regarding a drill press, the teams are back on track and their determination is stronger than ever!
Lima Senior team member Nick Tarbet tackles some late framework.
(Bryson Tarbet, Lima Senior High School)
"The buggies need to be completed, tested and packed into the trailer by March 29," said Sarah Koza. "Between now and then, we really need to buckle down and get these buggies done." "We are on the final stretch," added Nick Tarbet. "We have less than a week to finish, so time is of the essence. If it weren’t for the determination of all of the team members, these buggies would not get done."
One of the goals of the NASA Great Moonbuggy Race is to inspire teams to share
their experiences and spread enthusiasm for math, science and engineering
in their community. Here, Lima Senior racers, from left, Aaron Snider, Kayla Lowry,
Sarah Koza and Aubrie Nuckles talk to students at Heritage Elementary School in
Lima about their GMBR adventures. (Bryson Tarbet)
"In the past few weeks, we have seen more determination than we have before from all of the team members," added Kayla Lowry. "The team members have been working constantly to get the finishing touches on the buggies and finalize the details of the trip."
The trip to Huntsville from Lima is about 8-1/2 hours long by charter bus. The team will meet at the school at about 4 a.m. on March 31. We will get on the charter bus and arrive in Alabama around mid-afternoon. Needless to say, iPods and DVD players will be a common sight on the bus!
After we arrive in Huntsville, we will check into the hotel rooms and get situated. Later that afternoon, we will meet as a team and walk the course. After we get a look at this year’s course, and the various meetings, we will all meet at the hotel to have some fun.
"Last year, we had a pretty epic game of Marco Polo," said Bryson Tarbet. "It’s nice to be able to relax after a day of being in a bus. Not only is it fun, but we get to reinforce the bonds between the members of the team. It is always nice to be reminded that even though we have two buggies and two designs, we are all part of the Lima Senior High Moonbuggy program."
The teams are excited to see the different designs and ideas brought by other competitors this year. It is hard to believe that after April 2, the race will be over. But that doesn’t mean we are done. As soon as we get back, we start working toward next year.
Go Spartans! Bring home the gold!
The Anatomy of a Moonbuggy, Pt. 2
Posted on Mar 23, 2011 10:18:47 AM | Angela Storey
With less than two weeks to go until the start of the 18th annual NASA Great Moonbuggy Race, we're discussing the engineering marvel that is the moonbuggy itself. A direct descendant of the original Lunar Roving Vehicle, racers' moonbuggies are built to take the worst our course has to offer.
Well… they're supposed to be built that way. =)
Experienced teams such as the Huntsville Center for Technology have
refined their designs based on practical course experience. New teams don't yet
know what's waiting for them… (MSFC/David Higginbotham)
That looked like it hurt. (MSFC/David Higginbotham)
The Suspension is Killing Me
Once you've got your buggy's chassis figured out, you've got to start thinking about protecting your own "chassis" -- with a good suspension system designed to take the punishment of the course so racers' backsides don't have to.
The suspension is the catch-all term for the simple or complex network of springs, shock absorbers and linkages used to connect a vehicle to its wheels. They contribute to good handling and braking and protect the vehicle's riders from jarring changes in the driving surface. Most standard suspension systems for moonbuggies employ passive springs to absorb impact and shocks to control spring motion.
Do you go with a standard beam suspension -- a simple cart axle that keeps each pair of wheels parallel and perpendicular to the axle -- or splurge and design an independent suspension system, giving each wheels a certain amount of self-governing rise and fall?
"Some buggies show up with no suspension at all," says race authority Dennis Gallagher (he's also a world-class astrophysicist, no matter what he looks like in that shady race-day hat of his). "I'm not sure why they'd make that particular choice. I guess they're interested in reliving the bone-crushing antique wagon or automobile experience circa 1905?"
Gallagher heartily recommends a sturdy independent suspension to brace drivers against the decidedly uneven terrain they'll face on the course. "Obstacles are definitely NOT uniform," he cautions. "Every wheel takes punishment individually, so you're going to get thrown to one side or the other."
Believe it. One late-race obstacle in particular causes all four wheels to seesaw violently, and separately, in truly queasy-fying fashion. If your vehicle has held up to that point, over some higher and steeper obstacles, you should be fine… but it has been known to deliver the coup de grace to wounded buggies, and taken the last ounce of strength out of already exhausted racers.
The strut for this wheel/axle mounting incorporates a lot of buggy
business,including suspension springs, steering and drive chain. HCT
knows how to build a better mousetrap! (MSFC/David Higginbotham)
Go for the suspension, Gallagher urges -- leave the butt-pummeling Americana to people peddling around flat tracks at classic-car shows.
Any typical off-road vehicle suspension system will provide a good jumping-off point. "If you've seen it on a dirt bike or an ATV, chances are you'll see it on a moonbuggy," he says.
The best suspension systems maintain a relatively even keel, keeping the frame fairly level, keeping most of the punishing action away from the buggy operators. Let the wheels bounce around all they want, Gallagher says -- the real challenge is to absorb the punishing shock of travel without losing control of the machine. "Springs work both ways," he says. "They load and they unload. So if you hit an obstacle, you're going to be thrown up and off."
He ponders the likelihood of that, ruminating on the possible buggy configurations heading his way April 1. "Please," he chuckles, "wear your seatbelts!"
No Dissembling: Everything Can Hinge on Your Folding Mechanism
Nobody wins this race based on course speed alone. Every team kicks off their run by demonstrating how quickly they can fold out, pop up or otherwise reconfigure their collapsed moonbuggy.
This is an historic aspect of the challenge, based on the need to fit the original Lunar Roving Vehicles in a cramped, 4-by-4-by-4 cube aboard the Lunar Excursion Module. That was all the room Apollo-era engineers could afford to devote to the rover, and the unfolded vehicle worked perfectly the very first time for Apollo 15 astronauts David Scott and James Irwin
It's too simple to call it a "folding mechanism," of course, but whether you use hinges; separate hardware elements and a handy batch of cotter pins; or a more elaborate pump system to collapse and then pop your buggy back into ready position, this is a unique and often perplexing moonbuggy element.
"It's contrary to the logic of the design requirements to have a frame that can fold," Gallagher says. "But it's all part of the magic of this race, just as it was part of the historic original design."
The folding mechanism for HCT's tri-tube truss configuration. Note thelatching mechanism, and particularly the hinge placement. It's on thebottom -- better ensuring it stays closed when it meets the punishingforces of the course. (MSFC/David Higginbotham)
Tom Hancock, the Huntsville-based chair of the Alabama/Mississippi section of the American Institute of Aeronautics and Astronautics and a longtime member of the Great Moonbuggy Race planning committee, says there's been no end to the innovative folding concepts teams have come up with for the last 17 races. They don't all fold. Some are hinged; some have a pivoting chassis frame. Some come accordion-style, with sliding sections and cotter pins to lock them down. Some get laid out in pieces, to be quickly transformed by hand when the clock starts -- robo-mobiles in disguise, some held together with a mismatched assemblage of bolts and the raw will of the team.
"Bolts reeeeeeally slow down assembly," Gallagher laments. The raw will sometimes helps more.
Hancock is always amused to hear modern buggy teams contemplating how to shave tenths of a second off their two-second assembly time. (That's right -- some teams can configure their whole rig in just one-Mississippi-two-Mississippi.)
"Two seconds!" Hancock laughs. "Back in 1994-1995, assembly times could be 20 minutes." He recalls an early Georgia Tech team sweating as the clock ticked, while they actually did an on-the-spot arc-welding job at the assembly line.
"We were all just watching the timer," he says, "shaking our heads and repeating, 'Do NOT look at the arc-welding light!'"
However fanciful or practical your plan for collapsing and reassembling the buggy, Gallagher points to the same, simple bottom line. "Just be sure the machine has sufficient strength to put up with the stresses caused by those hinge or fold points once the buggy is assembled or unfolded," he says.
He reiterates his earlier caution about chassis work here. "Know the strength of materials, the thickness strength of welds, and what kind of loads you're going to put on those hinges or joints," he says. "KNOW whether or not your bolts will shear off under stress. Know it before you get to the starting line."
He's excited by the race; Hancock is too. They both dig the rush of pure, youthful adrenaline it sparks in almost every racer, but more important, they say, is the professional experience students are gaining, the practical value that lasts long after the adrenaline has faded.
"They don't have that experience yet, for the most part," Gallagher says. "Most won't have computer modeling experience yet, or a background in stress analysis, or a thorough, professional understanding of how a certain tension steel will behave in a particular application.
"What the race experience gains them is a clearer understanding of the way engineers work," he adds.
Which isn't to say it's a clinical or dispassionate profession. Just like the engineers tapped to defy the odds and deliver the original Lunar Roving Vehicle in a mere 17 months between 1969-1971, today's moonbuggy racers come to recognize that a professional engineering challenge is PURE passion.
"I have yet to see a team come in here and get trashed by the course who didn't get fired up to come back and tackle it a second time," Gallagher says.
Editor's Note: Next time, we'll talk moonbuggy drivetrains -- including all those accursed snapping chains!
Team Update: Lima Senior High Preps Its 'Spartan Spirit'
Posted on Mar 21, 2011 09:54:11 AM | Angela Storey
The Spartans of Lima Senior High School are checking in again to update us on their progress -- and they are PUMPED. We won't be surprised if their cheering section shows up this year with vuvuzelas. When you're packing, guys, just don't forget the buggies!
Here's their latest report…
Lima Senior High School, Lima Ohio
No. of teams in 2011: 2
2010 rank: Finished 14th (Team 1) and 17th (Team 2)
Best score to date: 4th place, 2008, finishing in 7 minutes 23 seconds (Team 2)
Race day is getting closer, Spartan fans! Both buggies are in the final steps of the building process. The seniors have finished shopping for the supplies we will need to fulfill the promise of being "Loud Lima."
"We are going to win the spirit award this year!" said senior Kayla Lowry. "We have been close in the past, but this year we are going full force and leaving everyone else in our dust!"
This year, the teams will be bringing new posters -- and some we made last year -- down to Alabama. We even are bringing our own megaphone to support the teams! This year, technology coordinator Bryson Tarbet will be pumping up the drivers, as well as the crowd, as the Lima Senior Spartan.
"We decided to bring our own mascot down to Huntsville because we really want to spread Spartan Spirit, and boost the morale of all the competitors," said driver Sarah Koza.
Lima Senior team members test the folding mechanism for
one of heir buggies -- a critical component of GMBR, which
requires each buggy to fold, collapse or disassemble into
a 4x4x4 container, just like the original lunar roving
vehicles used on the moon! (Photo: Bryson Tarbet,
Lima Senior High School)
Lima racers, from left, James Luke, Candace Ramage and
Brady Shafer tackle chassis work. (Photo: Bryson Tarbet)
The Lima Senior Moonbuggy Team has been one of the teams that brings the most supporters to the race. This year, along with the current team and parents, we are proud to bring four alumni down to Alabama: Ashton Tarbet, Erika Lowry, Sarah Foltz and Jessica Bradley, all former participants in the NASA Great Moonbuggy Race, will be traveling to Huntsville along with the team.
Both Lima Senior teams want to grant each and every team competing good luck.
"Although we would like to win, we really don’t want to see a buggy break, or not complete the course," said Bryson Tarbet. "We all know how much work it is to design, build and test a buggy -- we don’t like to see anybody’s time and efforts wasted."
Racers Nick Tarbet, left, and James Luke put a Lima Senior moonbuggy
through its early paces. Helmets, y'all, helmets! (Photo: Bryson Tarbet)
Once again, we would like to invite you to follow us on twitter @LSHMoonbuggy -- or follow the Lima Senior Moonbuggy Team on Facebook!
Editor's note: Thanks, Spartans! But remember, even a broken moonbuggy is a learning experience like no other. It just spurs teams to come back and try even harder the following year. If only for the fun of hanging with Loud Lima!
The Anatomy of a Moonbuggy, Pt. 1
Posted on Mar 18, 2011 10:24:43 AM | Angela Storey
As we roll toward the 18th annual NASA Great Moonbuggy Race, set for April 1-2 in Huntsville, Ala., we know many of our race fans out there may have questions about the mechanics of the vehicles -- the inner workings of the buggies themselves.
The typical moonbuggy is designed by each team to take on the challenging GMBR course, which simulates some of the conditions the original lunar roving vehicles faced on the moon 40 years ago. And those buggies take a pounding. The course is unforgiving, littered with gravel and rock outcroppings, pits, sand traps, and simulated "lava rilles" much like those the original lunar explorers bounced and thumped across during the Apollo 15, Apollo 16 and Apollo 17 missions.
On our course, only the strongest buggies survive. The rest are dragged away in pieces. Chains break. Frames snap. Wheels buckle. And nearly every newcomer team, no matter the outcome for their buggy, exits the course saying the same thing: "That was a lot tougher than we expected."
One of the past GMBR entries from the Huntsville Center forTechnology sits idle in their machine shop, dreamingof race glories gone by… (MSFC/David Higginbotham)
So what does it take to conquer the Great Moonbuggy Race course? Over the next couple weeks, we'll take a closer look at the moonbuggy itself… and learn more about these amazing machines, and what it takes to win.
Working Your Core: The Chassis
Let's start with the core of the vehicle: the chassis, the framework or skeleton that supports the whole rolling structure. It is typically composed of a metal frame -- usually steel or a combination of steel and other metals -- supported on springs or some other type of suspension system, all of which holds the body of the vehicle and its occupants as they travel.
Your win or loss in the NASA Great Moonbuggy Race can be decided right here, says Dennis Gallagher, a supervisor and space physicist in the Marshall Center's Science & Exploration Research Office. Gallagher, who helps plan the race each year and shepherds teams from the staging grounds (the sprawling parking lots in front of the U.S. Space & Rocket Center) to the starting line on race days, has watched hundreds of buggies approach the course. More often than not he can tell from a walkaround and a shrewd visual assessment how the day is going to go for its drivers.
"How strong are those struts? How good is that weld?" he asks. "Loose chains? Bicycle tires?" He shakes his head and smiles wryly. He's seen it all before, and he's rarely surprised.
The frame or central truss requires some forethought, he says. Steel is strong and durable, but it's heavy, he says; aluminum is lighter, but requires reinforced, stiffened members to hold up to the abuse of the course. (There's no weight constraint among the design guidelines, but each pair of moonbuggy drivers must be able to pick up their vehicle and hand-carry it 20 feet, without assistance, during the initial assembly phase of the run -- reflecting the historic job undertaken by Apollo astronauts to unload, haul out and quickly assembly their lunar roving vehicle on the moon.)
"The challenge is understanding the loads and stresses the buggy will experience," Gallagher says, "and adequately planning for them in the design."
The chassis of this Huntsville Center for Technology buggyuses reinforced aluminum tubes. (MSFC/David Higginbotham)
Teams often look at a combination of steel and aluminum, using tube-shaped metal struts to fashion a conventional rectangular frame for four-wheeled vehicles or a more creative configuration for three-wheelers (Gallagher doesn't like three-wheelers; we'll hear more about that in future installments).
Of course, if your team has a sugar daddy (i.e., a reeeeeally good school or corporate sponsor!) you might always consider using composite materials to fashion your chassis. Gallagher recalls a university moonbuggy a few years back entirely fabricated with composites -- woven or wound material embedded with a hardened epoxy resin fill for high strength. That buggy earned the Best Design Award; it didn't win the race.
Because the frame alone does not make the machine. You've gotta wisely choose your suspension options -- and again, it's all about what buggies are going to face on the field.
We'll talk about suspension systems and the buggy's critical assembly/disassembly system -- a key requirement that will help you sail through or leave you spitting rock dust -- next time.