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Several RC magazines around the world have asked us to write a monthly column. With the kind permission we will re-publish the column at our web site too so all of the XRAY fans can read the latest news and behind the scenes information. Enjoy.

Archive:
Column #1 - Behind the Scene Stories

Column #2 - Worlds Flashback

Column #3 - T2'007 Debut


The real challenge for a model car designer is to decide when to improve and release development of the current model that happens to be very successful in the current market. The T2 platform has really superseded all of our expectations and I was extremely happy that this car was so successful both with performance on the track and mostly with the overall satisfaction of the consumer. As such, I could not afford to make any mistakes in development that would negatively influence either the performance or the overall satisfaction of the current car. When designing a touring car it is important to always keep in mind that the car will be run in a wide range of racing conditions… on carpet or asphalt… with either foam or rubber tires. All of these conditions are completely different and as such the car and setup needs to be adjusted to those particular conditions. The invention and release of Multi-Flex Technology™ provided an excellent setup tool that allowed the T2 to be adjusted for any of these conditions — this proved to be invaluable in 2005 and 2006. But as everything evolves I had a very clear idea how to further develop the T2 to push the limits beyond expectations.

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Since the release of the T2 in the winter of 2005 we have very carefully collected feedback from not only team drivers but also from regular drivers and customers worldwide. The goal for the new T2'007 was very clear - make the car faster and more consistent but easy to drive at the same time. One of the main issues I wanted to solve was to minimize tweak after a crash. Of course our team is attending all the world's highest competitive races and as such the drivers need the best no-compromise performance but I always keep in mind that regular drivers are running their cars at local tracks. Though I hate to say it, regular drivers (including myself) usually crash more frequently than the top drivers, so my goals were very clear, I wanted to make the car the nest for the average racer. I just needed to find the proper way how to achieve it, keeping both high competition and local racing requirements in mind… not an easy task. From the beginning I had a clear vision and idea — we need to build two different cars that would allow us to capture the outer spectrum of the highest competition in the two common conditions: using rubber and foam tires. For this reason we decided to design a US version for foam tires and an EU version for rubber tires.

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I started logically by eliminating the parts that did not require any changes. As the suspension plays a very significant role in performance my first attempt was to look at the suspension. However, long term results and reports confirmed that the suspension geometry and suspension parts of the T2 have worked everywhere and as such I could see the T2 suspensions mounted on several competition touring cars used by some of the factory team drivers as well. I knew that the suspension did not need any further development. However, having plenty of experience with different composite compounds from the T1 platform, I knew that the stiffness of the suspension is very important and thus we tested extra-stiff compounds for the foam-tire car which I was convinced would again be a step further in performance.

Other areas, which I was confident in, were the drivetrain parts. The only drivetrain part updated was the ball-differential. Because brushless motors are being used more frequently along with new more powerful batteries, the power and abuse transferred to the drivetrain parts has increased significantly. For this reason I decided to make the ball-diff from a new improved 7075 T6 material which increases the strength by 30% and should prevent the outdrives from opening or breaking in a bad crash. The other minor (but still very important) update were the drive shaft clips which have been updated in material and design to accommodate the higher forces put upon them.

As my time on the track is very limited, I always look for solutions that will make my work on the car faster and easier. One of the setup features I am working with very frequently are different Ackermann settings. However, I was getting very tired disassembling/reassembling the car to do this (not to mention the time-intensive geometry adjustment afterwards) so I thought about making a new servo saver that would allow me to make small Ackermann adjustments quickly and easily. After a few brainstorming sessions, I came up with a very easy yet clever solution: the Quick-Saver™. I’ll leave it to the drivers to rate this smart invention.

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After eliminating the areas that did not need significant updates, I could fully concentrate on the remaining parts. The first task was to minimize tweak. We had created several bulkhead designs and top deck designs (both with countersunk and standard holes) to analyze and test how and when tweak occurs. The best results we achieved were by making the top deck as long as possible with key mounting on the top of the bulkheads. Based on previous experience I knew that by elongating the top deck I would gain more traction and the car would be easier to drive.

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Testing of the countersunk holes on the top deck analysing if tweak occurs or not
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The next task was to even more improve stability and agility of the car, while keeping it easy to drive. The way to achieve this was to lower the top deck to control flex and dramatically decreased the CG which helped the car to be more stable and predictable. To gain more rear grip we separated the rear bulkheads into two pieces allowing more flex on the rear portion of the chassis, and since we have lowered the top deck we had to lower the motor mounting. After several weeks of being stuck in this one area, and with several motor mounting systems on the go, I realised that I simply had to forget about the traditional way of how motors are mounted and then it came to me… it was so simple that I could not believe why I did not think of it before: simply mount the motor in the horizontal plane and then there was no more space limits on the motor bulkhead. Sometimes the best solution to complicated matters is to use the simplest solution!

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First prototype of a lowered top deck, see the mounting at the level of the bulkheads
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Multi-Flex Technology™ has proved to be an extremely helpful setup feature during the season, but as with any other concept, evolution is only natural MFT™ undergo some changes to improve the feature of the car. Armed with several different top decks, we had the chance to experiment with the MFT™ points as well as with the width of the top decks to find the best compromise. In the end the results showed that for foam racing the extra wide top deck with alu mounts set as wide as possible will make the car super stable for the high grip conditions; while for rubber racing we needed the top deck to be more flexible… so I decided to go with two different top decks for the final kit. By redesigning the new top deck I needed to gain more rear traction and also more steering, especially for asphalt racing where the solid axle is being used; with the narrow top deck the car was already too stable and steering was decreasing. Based on this I decided to redesign the top deck so I could reinforce it more in the rear part and move the flex more towards the front of the car. This is the reason that the designs of the foam and rubber top decks are different; there are different performance requirements for each type of car.

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All the different prototype top decks which were tested to find the best and optimum flex
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With our strategy of developing two different cars, I could experiment more with chassis flex. This allowed us to tailor chassis stiffness from medium to extra stiff as appropriate. For the US version car (foam tires) we decided on an extra-thick chassis which was super solid and handled superbly with foam tires. For the EU version car we slightly redesigned the MFT™ slots to adjust flex to the 2-piece rear bulkheads as well as to accommodate the elongated top deck.

Loaded down with all of the new prototype parts, the team spent a long time at tracks around the world testing. Myself? I used the prototype to test all different combinations for several months, attending not only private testing and local races but also large international races including the Worlds and Euros. As usual it was difficult to keep away the prying eyes of the public and press, but I needed to test the car in high-competition racing conditions. Over long term testing, I have gone through several crash-tests finding that the tweak problem has been significantly reduced and the performance has increased. I was very confident that regular customers would love the new car.

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After many positive results we decided to start production despite facing a very big dilemma. The T2 was only released in December 2005 so if we came out with a new version of the car earlier many customers would not be happy to have a new version of car available so soon. Traditionally, we would bring out a new version in the middle of the season. However, I felt strongly that the improvement difference in both performance and reliability warranted the decision to release the car just for the season. The debut of the T2'007 at the International Indoor Championship was spectacular and I am convinced that customers will get the same enjoyment and satisfaction from the new T2'007 once they build it and race it.

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‘Til next time…

Dipl. Eng. Hudy Juraj
Chief Designer XRAY