Jay: Doug Malewicki is the first judge I've spoken to about his Junkyard experience. Doug, let me cut right to the chase. At some point during the actual race of the collapsible cars, you ran in with a rule change that they could power their cars with their feet/hands. Did you really get to make that decision?
Doug: No way. As the drive traction problems became apparent, the main director got on the radio with me and asked if I had any ideas how to quickly salvage the mess. I threw out maybe we could simplify the original rules to allow the hand and feet propulsion that we already saw both teams resorting to. He said OK - go out and make that announcement. So while running from the finish line gate crossing to the stalled area I was formulating what I was going to say. Yelling “Gentlemen STOP your engines” came out of the blue only because the Cruisers chain saw engines were screaming so loud. Explained the change, made it official and scooted out of the scene.
J: How long did it take to decide that this was the best course of action?
D: I am estimating the director got on my radio within 10 seconds of observing that neither the Cruisers nor the Wenches were able to make any more forward progress. That was followed by probably another 10 seconds of discussion between us followed by another 20 seconds to jog over there. All happened pretty fast. Pretty much an ad-lib situation.
You may not have noticed it on TV but the entire course was a slight uphill to the crossing gate at the finish. They would have had a much better chance at the appearance of a powered race if they reversed the course and used the advantage of that slight downward slope.
J: Makes sense, but I suppose the damage to the machines was already done. How did you become a judge?
D: Segment producer Tristan Chytroschek found www.CanoSOARus.com - the website discussing all my inventions. He then EMailed me about the show and asked if I would like to be on as one of the experts. Wanted to see some video of me also (checking to see if I was a dull, boring or totally weird engineer stereotype?). Sent him an old (short Robosaurus TV News interview). Tristan then started explaining the challenge and asked for ideas as to what I might design. I kept EMailing him back questions about specific aspects of the challenge. I.E.: The typical engineering strategy is to get someone to make "official rules" on different subtleties, than one can start “cheating” with physics. Basically, as soon as someone makes a stringent technical rule about mechanical equipment, then the smart people go to work and figure ways around it. NASCAR, Indy racing, Bonneville Land Speed machines, NHRA drag racing, Bicycle racing etc. all do it ALL the time and continuously.
Anyway, Tristan's boss wanted to see a bit more video of this Malewicki guy. My daughter Michelle became my off camera interviewer as to "Why I wanted to be on Junkyard Wars". We did it in short pieces on one of our regular 7-mile hill runs in Laguna Niguel, CA. After tossing some ideas and a series of questions about, we got to the trail and started filming the first segment. Ran a bit, while discussing the next idea, stopped and filmed some more, etc. Came out very funny... plus the day was absolutely clear with terrific ocean views way below. Half a dozen questions from Michelle, with half a dozen super scenic different backgrounds had to make for some interesting video for the producers to watch! Michelle is as good as Cathy Rogers in terms of voice presence. We had a lot of fun and actually changed the theme to "why I wanted to be on the SURVIVOR TV show" for some of the first questions - just as a way to pick on Tristan. Ended it all with that I am ready to "Outwit, Outplay and Outlast". Funniest bit in between was when I said “I knew that Angelina Jolie was a huge fan of Junkyard Wars and this could be my way to get to meet her - maybe she would dump Billy Bob after seeing me on Junkyard Wars” - HAH!
So, a few days later Tristan called and said that the producers watched the little video that they would really like to switch me to being the judge. What? He told me the bosses felt I had charisma (read that most of the judges are boring). Huh - I am an engineer. Engineers don't do charisma. Oh well. Be a judge? Why not?
After the fact, I am very glad I was switched to judge. It is the easy job. No frustrations, no worries, no intense power brainstorming, no dirt, no sweat. The experts, Hanz and Jim went through the meat grinder that day while I got repeated bribery hugs from Wenches, Geri and Pammy, whenever they passed me searching for goodies in the junkyard! Life couldn't get any better!
J: What's that saying? It's good to be the king? What about your day on set...was it spent sitting around in that truck/throne all day?
D: Very early in the morning, both teams and their experts were picked up from the Hotel that RDF Media had us all staying at and carted them off to the junkyard in a big van. I got to sleep in and wasn't picked up until 9 AM! Once at the junkyard, I was escorted to the dressing room trailer and put on my official Junkyard Wars judge jumpsuit. Then to the radio trailer where I was wired. All day long you could tune to different channels and eavesdrop on what each team was saying to each other or to what the hosts Tyler and Karyn were saying and on another channel the directors and producers. When needed, they just called for me on my radio: "Doug, time for another Judge Chat" and then told me where and how quickly they wanted me.
I spent quite a bit of time up on the observation post platform above and centered between the two build areas. That is where a safety person continually observes the teams and talks to them (directly to their radio headsets) if somebody on a team forgets to put on gloves or a welders hood, etc. when getting ready to use a potentially dangerous tool (which can happen a lot due to the pressure and rushing to get things done fast).
Want to note that RDF Media puts on a great lunch feast and after all is done for the build day - a fabulous late night dinner party - in this instance, a Mexican food theme complete with Margaritas! Watching the show unfold on TV, it is probably hard to believe that there are 60 people working all day long (plus the teams, experts and judge). It is a busy place behind the scenes. I enjoyed talking with many of the workers - kind of mini-interviews to find out what their job was on the set.
J: You're not the first person to comment on the food. I think RDF needs to put out some sort of cookbook! You said earlier that you enjoyed being the judge...would you have liked to try being an expert?
D: I had tons of fun as a judge. I was ready to initially be an "expert" and would have loved every minute of that, but in a different sort of way. It would obviously be mentally rewarding to have made a machine in that ridiculous 10 hours of time that both worked and WON.
J: Maybe they'll have you back. In your opinion as judge, and expert in your own right, where did the Custom Cruisers car fail?
D: A combination of inadequate structural strength and stiffness for Brewsir’s “car” along with the entire drive system concept.
You couldn't tell from the video, but Brewsir’s structural frame was scraping along on the asphalt during most of the race. I.E.: It was acting as a “brake” on an underpowered machine. It did not sag to the ground in tests back on the floor of the junkyard build area. I suspect Brewsir was extra careful when getting on his vehicle back in the shop, but may have gotten excited and added a dynamic acceleration component to his static weight load when boarding during the excitement of the race. Probably yielded the dinky steel tube structure.
The Cruiser’s expert, Jim Papadopoulos is a Ph.D. in Mechanical Engineering who was way too rushed. It would have been wise to stop and take 5 minutes to do a quick stress and deflection analysis for the little 1” by 1” square tubular structure (probably 1018 junk steel with a mere 24,000 PSI yield strength). As soon as he saw the calculation results from applying a 300-pound Brewsir static payload, he would have realized it would need more strength. In this case, the simplest and quickest way would have been to stitch weld doublers using the same tubes (they had plenty of them).
The reason is that when you double the height of a beam it gets 8 times stiffer. The stitch welds would have easily carried the shear loads across the central axes that arise from all the bending of the tube when the Brewsir payload was applied. The actual stresses would be reduced by a factor of 4, not 8, because the distance from the central axis of the beam to the outermost steel being stresses is doubled. Anyway there would have plenty of room to package the new 1” wide by 2” tall rectangular tubes using the same clever packaging principles Dr. Jim originally conceived.
My gut feel on the inadequacies of their drive system was also proven correct. However, it took me a few days after the show to come up with a physical analogy that would make instant intuitive sense. Basically, you could think of it as taking a 7,000 pound Ford Expedition and trying to accelerate it by welding a 100 Horsepower motorcycle (fork and front wheel removed) to the back bumper. Worse, they were trying to do that with the motorcycle starting in high gear.
Traction is the product of what is called “Normal Force” and the “Coefficient of Friction” between the tire and the road surface. The word “Normal” in physics refers to a vector direction – not the opposite of weird. It is basically the amount of vehicle weight acting directly on the traction drive wheel. You have to note that static (no-slipping) coefficient of friction is higher than dynamic (slipping) coefficient of friction. This is the reason why it is easier to keep a heavy object sliding along a floor than to get it moving in the first place and also the reason for ABS braking system on cars. Soon as tires start slipping, their traction force goes way down. If you looked carefully during the show you would have noticed the melted black streak that the tires left on the asphalt.
In the case of the Ford Expedition, you probably have close to 3,500 pounds of “normal force” (weight) acting on the rear tires. If the coefficient of friction of rubber on asphalt is .7 then the vehicle in everyday driving could provide a maximum of (3,500 lb) times (.7) = 2,450 pounds of pulling traction before breaking loose. If enough engine power was available it could accelerate at (2450 lbs thrust)/(7000 lbs weight) = .35g. Our hypothetical weld-on motorcycle drive system on the other hand might have a mere 300 pounds of “normal force” pushing down on its rear drive tire. Thus the maximum traction force you could obtain to get the 7,000 pound vehicle moving would only be (300 lbs) times (.7) = 210 pounds. This means the big SUV’s acceleration capability (using the motorcycle drive only) would have been reduced to less than one tenth of the regular rear axle drive system. (210 lbs thrust)/(7000 lbs weight) = .03 g – a real dog! Zero to 25 mph would take 38 seconds (if it didn't start slipping first and losing traction, which it would do, if started in high gear).
In the case of the Cruiser's machine, the gross weight was in the 900 to 1,000 lbs range. I imagine the traction available from their floating single stage gear reduction chain saw was maybe 30 pounds max. If Jim would have further analyzed his engine horsepower and RPM, he could have worked backward to establish the torque available and then the max traction force through his tire rubbing single stage gear system. Alternatively, they could have “felt” the level of traction, while slipping or not, using their arms as a scale by pushing down on the running power unit when it was not attached to any other structure (fully supported by his arms only).
In summary, the high RPM chain saw engines needed a couple more stages of gear reduction and the design should have had all of Brewsir’s weight as the “Normal Force” (or better yet, 50% of all the vehicle weight – hard to do when each part of the train was on its own set of supporting wheels). The way it was set up, the best Brewsir could do was push down with his arms to increase the Normal Force. The second drive engine in the back had all the same problems and gave even less forward propulsion.
With an idea of the level of actual propulsion force before slipping, Jim could also have done a quick calculation to estimate what grade could be climbed. In the case of our motorcycle powered SUV that would turn out to be a max of 3% (only if started out carefully in a low gear and not allowed to start slipping).
J: My head is spinning...is that good? I'm almost afraid to ask...what about the Wenches machine?
D: The drive system that expert Hanz Scholz, Bike Friday Designer and Co-founder, came up with for the Wenches with Wrenches suitcase vehicle made a lot more sense than the Cruisers. It had a fore and aft axle with a frame holding the two together. Two axles with wheels, instead of eight like the Cruisers, meant that roughly 50% of all the weight would be acting on the drive wheel, so the traction developed – as a percentage of the mass that had to be propelled could be considerably more that the Cruisers. The small rubber drum directly driving against the rear tire has been used for decades in powered bicycle propulsion.
Also DC electric motors get their maximum torque at zero RPM (like getting a built in gear reduction for free), whereas internal combustion machine have very little torque at low idle RPMs. The chain saw engines that expert Jim used probably didn't get up to a decent torque output until 5,000 RPM or more.
The Wenches machine should have smoothly accelerated, but it didn't. Even the CO2 rocket boost didn't help (probably only gave an extra 20 pounds of additional thrust).
We know that their steering mechanism broke which halted all progress. That is merely the fate of the junkyards. Also their battery went dead. It may have been near dead when they found it. However, without an ammeter and voltmeter they had no way of knowing if the condition of that battery was healthy or not. Even worse, they were running it essentially in a continuous stall mode, which would be draining huge amps. You do that and a lead acid battery's rated amp-hour capacity can go down by a factor of 20. I should have gone over right after the race to see how hot the motor and battery felt, but didn't because I was having too much fun with the champagne!
The Wenches vehicle with payload probably came in a bit over 600 pounds. If they had it to do over again, they wouldn't have used a front wheel set from a child's toy. Obviously, both teams would do things differently if given the same challenge again. This is what engineers do – learn from mistakes and improve things the next time. There is no way to make a “perfect” vehicle. Everything can be improved - forever. If perfect was possible we would all be driving the ”perfect “ automobile – the 1942 Oldsmobile – hah!
In summary, the challenge arose from an evil demented mind (I am picking on segment producer Tristan Chytroschek here). I was right when Tyler Harcott asked me which team I would bet my life savings on and asked could I bet on that neither team would finish!
J: Those are two fascinating explanations. I'm glad I took physics in high school and university. One last thing Doug. I want to build my own robosaurus, or Truckosaurus for you Simpsons fans. What am I going to need?
D: First of all you need money contacts who can see and understand the vision. Robosaurus was obviously going to be a rather expensive entertainment toy! These investors probably need to be businessmen in the entertainment field, so they can instantly plan how they can make an eventual serious profit on all the capital that would be consumed to bring such a project to fruition.
Next you need a fabrication team that can think, be delegated to continuously and contribute to solving each and every days problems. You do not want inadequate people that you have to micromanage and be out in the shop prodding them to work all the time. It has to be a self-motivated team.
In a complicated project like this it is very important to trust and use the experience base of the people who are spending 40 hours a week, every year of their life building things in the shop. They can save you tons of time and money. It makes my life as the designer/engineer/structural analyst a whole lot easier and the shop people positively beam when the hot shot with the Master's degree from Stanford (me) switches to their ideas. Did that a 1,000 times.
MMM! Now that I think about it, building Robo was like a long term Junkyard Wars project. Our junkyard, in this case, was the entire USA. Although we had money and could buy all kinds of pieces and components, we still had to do a lot of scrounging for lower cost items and continually redesigned for simplicity to keep costs down.
J: Doug, thanks for your time.