Sunday, January 31, 2016

The Aluminum Xray...and a note on the Serpent wing

After some races with the Xray X1 on the new CRC black carpet, I was interested in possibilities of stiffening the car overall.  The X1 has shown it capabilities on various surfaces from asphalt to carpet. This versatility is great since the car will be competitive almost anywhere, but sometimes there are areas where specialized parts help.

Jan Rathiesky showed up at the first ETS race of the season -  on carpet- with the aluminum chassis on his Xray. (photo - RedRC)
This is probably a hint.

Anyway, what stood out to me after a couple of these events on the high traction CRC black carpet was that the new CRC F1 with the transverse battery looked awesome...and it was also very flat on the track.  It rarely seemed to pick up a tire or traction roll.  CRC's website does make mention of the high stiffness weave of their chassis.  The car also has a solid lower arm, which I assume is stiffer than the Xray lower arm.

In any event, I wondered if trying to remove some of the flex in the Xray car could help in high traction.  

I was able to get an Xray aluminum chassis as well as front lower arms by Xtreme Racing.  They sell a lower arm with additional bracing for some more stiffness.  I added both these parts to my car, keeping the setup close to see what, if any, difference could be found.  Note that the aluminum chassis is 2mm vs. 2.5, so the links and the "football" pivot need a 0.5mm shim to maintain the proper orientation to the stock pod plate.

At the track, I prepared the tires as I did with the original equipment.  Putting the car on the track, I noticed the car did not have quite as much mid corner steering as it had before, but it was very flat as it went around the track.  This was good as there was recently a well attended series race at the track on the same layout and traction remained very good, though not as high as the CRC black carpet.  I also felt like the car was smoother and more predictable all the way around the track.  I could drive in a more on power style as well, which I prefer.  Adding 0.5mm to the rear of the upper arm for a total of 2.5mm of dynamic caster spacing added the mid corner steering I wanted.  It seemed like the car held better corner speed, as I could roll down in throttle and the car didn't seem to bog or "stop" in the corner as it did occasionally before.

Overall, the car gained a more composed feel on carpet.  As good as the Xray car is, there have been times where getting the amount of steering into the car to be competitive could make it a little unpredictable.  During on of the races, a marshall commented on how good the car looked, and how easy to drive it looked as well.  It was really good for how little I had to change in setup.  In a couple weeks I'll be attending another race on the new CRC carpet so a real shake down will occur then.  I'm sure I'll have some more thoughts about the new chassis.

Serpent wing update:
I mounted the wing to the graphite tongue I made with aluminum screws.  PLEASE USE ALUMINUM SCREWS HERE!  I had a harsh crash in practice at full speed, and one screw sheared off.  Nothing else was damaged.  The aluminum screws are like a fuse that will pop off in a very bad accident and save the wing and/or the graphite parts on your car!  I also wound up using 5mm spacers to keep the wing off the track....

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