While the team members rolled up their sleeves with CAD tools from the get-go, an on-site disaster with their 2008 catapult entry (the machine broke apart at the competition) prompted them to go back to the drawing board and design a next-generation catapult that would not be subject to the same structural failures.
"Based on that lesson, which was embarrassing, we wanted to see what we could do," Mollenhauer told us. What they did was come up with several designs for the catapult, which encompasses a siege engine that relies on torsion power to hurl the pumpkins, using simulation capabilities to understand how the machine would perform under real-world operating conditions.
SolidWorks Simulation was used to virtually test weights, motion, clearances, stress, and dynamic analysis, Mollenhauer says. "We really put simulation into play, doing fit checking, dynamic motion testing, and stress testing," he explained.
Team ETHOS's redesigned catapult, called Phoenix, took first prize in the 2009 Punkin' Chunkin' competition with a throw of 2,088 feet.
The team also used SolidWorks Simulation to verify the materials -- a combination of composites, steel, and aluminum -- since that was a sore spot with its 2008 disaster. Based on Mollenhauer's knowledge of composites (that's his day job, after all), the team built the arm out of carbon fiber. "It's the only material you can use to build something this lightweight and strong," he said.
Now heading into this week's competition, Mollenhauer feels pretty confident about the further refinements made to the Phoenix catapult that the team worked on this year. Based on last year's performance where the machine performed well, but the sling design was faulty, the team revamped its sling design, again using SolidWorks Simulation to verify the changes.
"Our goal this year is to break 3,000 feet," Mollenhauer said. That's quite a chunkin for an eight-pound pumpkin.
I haven't attended an event, but I've been following this competition for a while now. It's a great time and exposes the general public to the process of engineering and use of scientific tools to solve and optimize complex problems. Now that our public maned space program has been scrapped, it's awesome that engineering gets a chance to be put on public display in such a fun, positive light.
Thanks for wading in, William. It does seem like a pretty cool event and one that can showcase a lot of great engineering prowess at a variety of levels. There are grade school students, university students, hobbyists, and like this team, professional engineers, all participating in the same event. And I don't think this is the only one--there are several others held around the country.
While I think the contest is more than admirable to showcase mechanical engineering ( I do love pumkin chuckin by the way). I certainly hope that the enginerring team from Wright Patterson were doing this on their own time. In this time of fiscal frugality one would hope that all federally subsidized programs would keep a short leash on their budgets to ensure no more waste is going on. At least no more than usual.
I likewise hope thet the Wright-Patterson team did it on their own time.
In this corner of Michigan there has been a competition that seemed a bit looser in the requirements for the launching system. The very best that I am aware of was quite a bit farther than the 2000 foot mark, somthing over three thousand feet, which was obtained by means of a fairly complex compressed air system. The very most complex setup had a secondary air insertion mechanism partway down the barrel, which overcame some of the thermodynamic limitations of the more standard approach.
My own speculation has been that some sort of mechanical launcher that used an air cylinder as the energy supply could beat a similar unit using only gravity for power. The serious problem is that compressed air can store and deliver a vast amount of energy, which in a failure mode could injure a whole lot of participants and bystanders. So while it has a tremendous potential, the compressed air approach would add enough to the safety requirements aspect to reduce the fun aspect quite a bit.
MY own, fairly safe, air launch experiments were able to deliver about a pound a distance of about 300 feet. Of course, this was from a hand-held launcher that was a lot smaller than these wonderful pumpkin launchers.
We used to have a low key punkin chunkin contest in Raleigh, North Carolina. There was usually a team of students from NC State there as well as a lot of local groups like Boy Scouts and church groups. It was great to see some raw engineering at work. The funny thing was that the college students usually used all steel construction while older groups used a lot of wood in their constructions. Engineering and designing with wood seems to be a learned task that is not taught much in school.
From Dell / Intel® New Paradigms in Design Work Scott Hamilton, vertical market strategist for Dell Precision workstations, 5/2/2013 5
Early in my career, I worked as a draftsman and remember the days of drawing on vellum with numbered pencils and Mylar with plastic lead. This was a fun experience in the sense that I ...
I've been using workstations for more than 10 years and love finding ways to get more performance from my system. With demanding professional applications that require more power each ...
A lasting memory from my first job as an engineer in an auto assembly plant is standing on hard concrete at six in the morning, vending-machine coffee clutched in hand, listening to ...
For industrial control applications, or even a simple assembly line, that machine can go almost 24/7 without a break. But what happens when the task is a little more complex? That’s where the “smart” machine would come in. The smart machine is one that has some simple (or complex in some cases) processing capability to be able to adapt to changing conditions. Such machines are suited for a host of applications, including automotive, aerospace, defense, medical, computers and electronics, telecommunications, consumer goods, and so on. This radio show will show what’s possible with smart machines, and what tradeoffs need to be made to implement such a solution.
To save this item to your list of favorite Design News content so you can find it later in your Profile page, click the "Save It" button next to the item.
If you found this interesting or useful, please use the links to the services below to share it with other readers. You will need a free account with each service to share an item via that service.
Tweet This
16 
