Thanks to all who took part in our Trebuchet Contest! We had perfect weather and all involved had a great time. With nine people competing on six teams, we saw a wide variety of designs and lots of experimentation.
Each team fired three shots, which were analyzed for efficiency and for accuracy. The efficiency score is calculated as the length of the best shot divided by the mass of the counterweight – to discourage anyone from using small cars as counterweight and hurling the projectiles all the way to Dodge Street. The accuracy score is the standard deviation of the three shots. To combine these into a final score, each category was normalized to 5 points for the best team in that area, with proportionally fewer points going to every other team. As a result, the best possible score is ten points, which would only be awarded to a team winning both categories.
|Rank||Team||Efficiency (ft/lb)||Accuracy (St Dev)||Score|
|4th||Kyle and his Dad||7.9||18.3||4.0|
|6th||Don, Stephanie, and Sarah||6.2||31.2||3.2|
Ben, competing with a trebuchet constructed years before and “conveniently” fitting the contest requirements, had the longest throw of the day at 214 feet, but the use of a rather large counterweight dropped his efficiency to mid-pack, though not nearly low enough to offset his astonishing repeatability and accuracy.
Dave, winner of the “Least Effort Possible” award which nobody has bothered to create, gave a spectacular performance, particularly considering that his machine was constructed and tested in under fifteen minutes.
Eric nearly forfeited the contest after some mysterious last-minute bugs, but came back with a very solid 94-foot throw. Unfortunately, with two of his three shots launching backwards, his accuracy score reminded everyone to stand well to one side of a firing trebuchet.
Kyle and his Dad arrived with the only machine too large to be assembled indoors. Installing a competitive amount of counterweight earned them a respectable score, but before and after the contest, their 50-lb maximum capacity gave the neighbors something to think about.
Kevin competed with the only machine requiring three hands to safely load, and was also the only entrant to attempt self-amputation during testing. Despite this, the device proved acceptably reliable and fired many shots without incident.
Don, Stephanie, and Sarah may have earned the lowest score, but they were also the only team to compete with no prior testing. Their trebuchet was not completed until several minutes after the start of check-in and was immediately put to the test with none of the tinkering and tweaking afforded by the other teams.
Once again, a huge thanks to everyone who took part in this contest! We know it was the most difficult challenge we’ve yet conceived, and everyone who took part worked extremely hard to make the firing line yesterday. We promise the next event will carry wider appeal – more on that in the coming weeks.
This is your chance to build the best miniature siege engine in Omaha. Â Work by yourself or in a small group to make the best golf-ball*-throwing device you can imagine. Â We will then compete for range and accuracy to crown a champion. The contest will take place at the Makery on September 21st.
Although the competition is called â€œTrebuchet Contest,â€ your device does not need to look like something out of the middle ages. Â You can use any design, any materials, any construction techniques, and in fact anyÂ launchÂ techniques youâ€™d like. Â We want to keep things interesting, so the rules for this contest are very lenient:
The energy used to launch the projectile may come only from the gravitational potential energy of a mass falling no greater than 16 vertical inches.Â Â No explosives, precompressed springs, compressed gasses, batteries, or any otherÂ sourcesÂ of energy. Â Gravity only. Â However, you can use all those things as intermediate steps if youâ€™d like – if you use gravity to compress a spring, or use electronic timing to coordinate the firing, thatâ€™s just good Maker spirit. Â Just be prepared to prove that youâ€™re not contributing any extra energy to the projectile.
Your siege engine requires a remote triggering mechanism.Â Â Mechanical, electronic, whatever. Â You need to be ten feet from the firing position during your shots, and away from the most likely misfire direction (for example, on a standard trebuchet you need to be off to the side, out of the plane of the arm). Â We want to keep things safe.
You cannot aerodynamically assist the projectile in any way.Â Â If you need wadding to seal the projectile in the barrel of your gravity-charged pneumatic cannon, thatâ€™s fine. Â If you want to use a sling which stays attached to the projectile instead of the trebuchet, well, youâ€™re the one who thinks itâ€™ll be competitive to throw more weight than anyone else. Â But whatever you do, the projectile has to take a ballistic trajectory once it leaves your machine.
Weâ€™re trying to keep things interesting and attract the widest range of designs by keeping the rules loose. Â Please donâ€™t abuse this privilegeÂ – nobody wants to read a ten-page rule book covering every possible situation. Â Tech inspection is going to have a â€œspirit of the rulesâ€ philosophy, and you should keep that in mind while working on your design. Â If you have a creative idea or think youâ€™ve found a loophole in the rules,Â please bring it up with Ben as soon as possible. Â Most likely it will be allowed, but if you show up on competition day with something ridiculous, having never discussed it with the organizers, you might find yourself disqualified. Â We promise flexibility and absolute discretion – if we allow your cunning plan, its secret will be safe, and we promise not to steal it for our own designs.
*Golf balls makeÂ idealÂ trebuchet projectiles. Â Unfortunately, theyâ€™re a bit dangerous and bouncy. Â To dramatically increase the chances of scoring each shot by ensuring we can actuallyÂ findÂ each projectile, we wonâ€™t be using golf balls. Â Competition projectiles will be approximately equal in size and exactly equal in mass to a golf ball. Â Projectiles will be supplied for scored shots, although you may test with anything you like.
Competitions and Scoring:
The exact equations used for scoring will be revealed the day of competition, to prevent any rules-lawyering and to allow us more time to perfect them.
You will be scored on your ability toÂ efficientlyÂ throw the projectile as far as you can. Â The mass of your power weight will be taken into account, so if you decide to increase performance with extra weight, make sure youâ€™re getting a proportional gain in range.
You will be scored on your ability to hit a predetermined target at a distance of your choosing. Â The main goal is accuracy, but your chosen range will also affect your score – a 10-foot miss from 100 feet isnâ€™t as impressive as a 10-foot miss at 200 feet.
As part of the recent OMGWTFBBQ festivities9, a contest was held, pitting the forces of gravity against the weight of cold hard cash (pennies, to be specific). Â The goal of the contest was to use soda straws to support as much currency as possible in as high of a position as possible, thus racking up the most “inch-cents” of score.
As it turns out, we ended up going to “foot-dollars” and using weights that weren’t exactly copper, given the engineering of some of the entries. Check out the results below.
|Stephanie & Cait||8.25||2898||23908.5||19.92|
|John & Don||11.25||271.5||3054.38||2.55|
|Claire & Dad||7.5||271.5||2036.25||1.70|
|Jess & Company||14.25||45||641.25||0.53|
|Patrick & Travis||19.375||14||271.25||0.23|
|Ben & Dave||11.5||0||0||0|
RedBull Creation challenge entry. It’s a brain-wave game. The players stand on opposite sides with wireless headsets that measure brain waves. One of them presses the big red button on the back, and then as they focus the power of their minds, the arm responds to their brain wave readings, and moves back and forth according to who is focusing best. After 10 seconds the Bullduino (visible at the front in the window) checks whether the pointer is in one of the green scoring zones. If it is still in the yellow zone, it’s a tie and it just returns to center. If it is in one of the green zones the player on that side is the loser, and the ball sprays that player.
After a run up of making throughout the week, the bridge competition began at the Makery last Sunday to test the designs of our participants.Â In all, there were 9 entries (some last minute).
In short, the rules:
Bridge:May contain only balsa wood and Titebond 2 wood glue.Must fit within a 50 x 20 x 10 cm rectangular volume.May not contain more than 6oz of glue by wet volume.Must have a smoothish road deck no less than 6cm in width.Â – suitable for a HotWheels-style car to easily roll overDeck ends must contact the upper surface of the test rig support planks.Deck must have no more than a 10% grade (where grade = 100 * (rise/run))Deck must accommodate the load plate.Some part of the load plate must fall across the midpoint of the span.There are no limits on construction tools or technique.Scoring:The load plate is 10 x 5 x 1 cm, and has a loading hook extending from the center of the bottom surface which requires 1 cm annular clearance through and below the bridge deck.Bridges will be loaded progressively (w/ minimum shock load), starting at 5kg and progressing in 1Kg increments to 10Kg.Upon reaching the maximum load, the bridge must hold for 1 minute.Â – Disputes as to whether a bridge ‘held’ will be resolved by voteBridges that fail will be ranked by the weight carried without failure and bridge mass.Bridges that do not fail will be ranked by the mass of the bridge.Testing:The open span between the support planks is 30cm.The open span is betweenÂ rectangular,Â fixed, smooth, level, coplanar planks with a thickness of ~2cm.The bridge may touch the top or inner surfaces of the supporting planks, but may not touch any other surface, nor be affixed to any surface.The load plate will support a wire or rod from which the test load will be suspended.
By now you may have worked out that there is a category in the results called “Fail Weight.”Â Well, we at OMG like to test to the limits of design.Â Also, we’re all about 8 years old at heart and like to break things, filming the results in slow motion video if at all possible.Â So, without further ado…every last bridge getting destroyed/max tested to sexy music:
Join us for our next competition, to be held this Sunday!Â See the forum for details.
Last Sunday (April 1st) was the first Omaha Maker Group Egg Drop. Â The competition was much in the same style as the Nerf Gun Mod Contest run last fall; This competition had a lower entry barrier, and thus far greater turnout, with 10 total entries (Eric entered twice). Â All the eggs survived the drop, but Stephanie was the big winner, with a score that bested the next entrant by a factor of 4. Click through for full results, and a little high-speed video, thanks to Ben. Continue reading
Last night, the Makery hosted a Nerf Gun Mod contest, previously announced here. Â We had 5 total entrants, after a few people had things come up at the last minute, and about twice that many spectators.
Only Brandon and Eric made an attempt in this category; Â Brandon did a functional “pseudo-steampunk” mod (with an extended brass barrel and integrated laser sight), while Eric gave his Nightfinder a complete color revamp using Sharpie markers (Which did come off on his hands). Â Â Eric won almost unanimously, earning him an extra 10% in the distance competition.
The accuracy contest was run next, in a series of 8 rounds, with a point going to the entrant who could hit a whiteboard (At about 15 feet) closest to the center mark. The entrant with the most points won this category. Â The contest itself came down to a shootout between Brandon and Dave, (2.5 points each) with Brandon emerging victorious. Eric (2 pts) and Kevin (1 pt).
This contest measured total distance to rest, thereby including any beneficial or harmful rolling or tumbling that a dart did. A slight accuracy component was involved, in that if a dart went more than 75 feet or so, it had to clear a 5 foot wide doorway. Â The low ceiling also proved challenging to some contestants, as it limited the amount that a dart could be arced.
Distance was scored as “best of 8 darts”, with each entrant shooting all 8 in succession. Â Brandon’s was the only dart to clear the doorway, making him the winner. Â A few darts bounced off the wall, though. Â Eric’s 10% bonus (2.2 paces, very scientific) was enough to propel him into 3rd place over Dave, leaving the results Brandon, Kevin, Eric, Dave, Patrick.
Overall, Brandon was the supreme winner, having taken first place in both categories. Â Even with a smaller-than-expected field, everyone involved had a great time. Â Thanks to all involved for making last night a success!Â A few photos from the event are below.