Engineering / Entertainment / Media

Missile defense physics from MD Discovery Channel contestants [VIDEO]

Maryland contestants Andrew Stroup and Corey Fleischer live to compete another day after Episode 2's missile defense challenge on the new Discovery Channel TV show "The Big Brain Theory: Pure Genius." Here, get the detailed physics behind the proposals to fight off projectiles with just five days of planning.

This is a guest post from Andrew Stroup, an entrepreneur and cast member of a new Discovery Channel show called "The Big Brain Theory: Pure Genius," that highlights engineering talent.

Every Friday, Andrew Stroup and Corey Fleischer will recap the latest episode of “The Big Brain Theory: Pure Genius.” Stroup and Fleischer are the two Maryland contestants competing on the new Discovery Channel show that airs Wednesdays at 10 p.m. Stroup and Fleischer hold weekly viewing parties starting at 9 p.m. at PBR Baltimore.
Episode 2 summary:
This week’s challenge was to design a system that would stop an incoming projectile with a projectile — missile defense, in other words. We had only five days and $20,000.
The BLUE team implemented a launching propeller design, while the RED team used a spray-and-pray shotgun method (with a backup VOODOO gun). Ultimately, both teams failed at taking down the projectile in the air, but in the end, the BLUE team was selected to be the losing team because they were never able to launch their countering projectile.
It was sad to see Joel get eliminated, but the RED team, and more importantly I, was saved for another day.
(And for those who saw Episode 1: Joe was indeed eliminated after the first round, but he was back on the Red Team competing for a wild card spot to re-join the competition at a later date.)
Watch the Episode 2 recap here.

Episode 2 in-depth coverage (for those interested in the physics behind the Red Team’s design, and the behind-the-scenes “dirt”):
THE THREE AMIGOS: You may be starting to pick up on this, but within the RED team, there was a subgroup that earned the title “the three amigos,” which consisted of Eric, Corey and me. Time will do us justice as to why we were called this, but when we were all together, nothing could stop our momentum.
MY PROPOSED DESIGN: My blueprint challenge design included a three-phase “shotgun” approach. Three barrels, loaded with projectiles of increasing size, would fire in sequence at the target as it travels to the bunker. My two biggest concerns were:

  1. Hitting the target (not your textbook physics problem)
  2. Destroying the target (clearly made out of light foam material).

As I developed my initial design, I tried to cover both issues by using a “shotgun” approach and shooting multiple rounds at the target, hopefully breaking up the target after the third round hit it.
RED TEAM DESIGN: We ultimately agreed upon a modification of the shotgun design PLUS the VOODOO gun (see below for details on the VOODOO gun). The design required a lot of steel as we originally planned for 100 barrels, but ended up only being able to fabricate 60 within the allotted time.
To account for lateral drift of the incoming projectile, Corey designed and fabricated a linear rails system that was powered by an electrical motor that would move the entire rail gun. Additionally, all this design doesn’t just appear out of nowhere. A lot of math and physics were involved to make this happen, to include finite element analysis by Corey and discrete models by Eric to calculate the time frame to launch.
THE VOODOO GUN: Beyond the shotgun design, we came up with a backup system which started from an idea I had late the first night, during our team meeting at the house. “What if we all had turrets with cameras, firing at the target?” (Think Millennium Falcon from “Star Wars.”) Although ditching our current design path was not feasible, we decided to create a one-off to see if it’d work and have a “backup” system.
With the help of Eric’s controls expertise, we came up with the VOODOO gun. The design included 5 barrels, each sourced with compressed air by an isolated accumulator for each barrel. Each accumulator had a solenoid mounted at the exit port, which, when energized, would release the compressed air, firing the projectiles.
The barrels were controlled by a wooden toy shotgun model (thanks, Corey) that was connected to two string potentiometers, wired into an Arduino. The gun was placed in front of a monitor, which displayed the site down the barrels, due to a video surveillance camera mounted on the barrels (thanks, Joe). Based on the input of the potentiometers, the barrels were controlled by two electrical linear actuators, matching the movement and position of the toy shotgun.
Bottom line: toy shotgun moves, giant robot turret outside moves = VOODOO GUN!
FLUID POWER: The entire system (both the shotgun and the VOODOO gun) was hinged on my pneumatic system design. Both systems required a significant amount of design, parts and plumbing, which took a lot of my time for the first couple of days just getting everything laid out and ordered.
Unfortunately, the fact the fluid power design and pneumatic setup came from my efforts wasn’t clearly articulated in the episode. The distribution of airflow, the balance of accumulator size versus barrel volume, and parts selection were all part of the design and I was and still am extremely happy with the performance within our time and money constraints.
TRIGGER MECHANISM: One of the biggest challenges that led to a couple of heated arguments was the trigger mechanism. Due to budget constraints (mainly because of how much ammo cost), we weren’t able to procure individual solenoid valves for each barrel, which severely impacted the original design and configuration. Ultimately, we settled on a pneumatic actuated linkage system (not without lots of arguing between this and a spring design) to open all the manual valve handles at the same time.
With the resources that we had left, I was able to come up with a balanced design between a pneumatic actuated system and an even distribution of pressure across all barrels. We actually had to fabricate a complete second pneumatic system for the trigger mechanism, which pretty much took me up until the very last minute of the build (with a couple of minutes to test).
Based on the performance of the system on competition day, the largest variance was based on how we packed each cylinder, which was limited based on time and resources.
THE BEHIND THE SCENES: Between rounds, we were given a 15-minute window to reload and pressurize the system, which took a lot of planning on our part to ensure our system was ready. However, part of the problem that we faced was the inconsistent packing and loading across the 60 barrels, which was an impact of the time constraints we faced.
PACKING UP: At the end of the night on the last build day, we had to move our design out of the shop onto a flatbed truck for transfer to the competition site. Our design was SO massive and SO heavy that it took us four hours to get it out and onto the truck (wrapping up at 3 a.m., and having to get up at 6 a.m. for the competition). Not only that but we BARELY fit through the garage door (literally an inch of clearance).
COMPETITION DAY: We were given only 30 minutes to set up our system. HOWEVER, because of Dan’s blowup of “never screwing up” yell-fest at Corey and his “ownership” of that part of the design, it took us over 2 hours to set up because the system wasn’t safe. Also, the fuse problem, which Dan so readily blamed Eric and myself for (always pointing the fingers to someone else), was because the generator we ordered, which ran on independent fuses, couldn’t be delivered in time — so we had to downgrade to a smaller generator the day of the competition.
BOTTOM LINE: I was ready to be the team that was eliminated. Dan may be an engineer, but he didn’t know how to work in the team dynamics of people as smart or smarter than him and lived in this perception he was always right, never wrong, and carried the team. Without Corey, Eric, Joe, and my contributions to the physics/math, design and fabrication, it never would have worked and we did that while working together as a team, not having to fight each other every step of the way.
Case in point, here’s a behind-the-scenes look of Dan blowing up over a table order mishap (seriously?) and my having to step in and mediate.
RESULTS/STRATEGY: My personal opinion: the captain goes down with the ship. Gui implemented a monarchy and in that construct, the leader should be held accountable for the results. Sad to see Joel go, but there may be a reason why I’m still hanging out in the background. Also, this won’t be the last time you’ll see me stretch my fluid power knowledge to help solve the design challenge problem.


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