Project Streamliner: Version 3 Initial Test - Pt10

[@Firashelou]

You are a true engineer ! I am a mechanical engineer and I cannot do what you do this professional way ! Amazing work again !

[@supadeluxe]

Wow. Huge improvements over last version. Looks much more stable. I like where this is going.

[@EngineeringAfterHours]

Excellent content. Your math really helps show why speedrun tires are on the larger diameter side and like you said...lightweight. The larger diameter really helps keep the RPM down cutting centripetal force. You also did a great job communicating the importance of traction. The best "skill" you can have as a speedrunner is access to a long smooth running surface. I'm in the middle of a video that details just how much downforce and drag influence your acceleration curve.

[@IndeterminateDesign]

Thanks. It really is a difficult set of trade offs for these cars. If I go to larger diameter tires I need more frontal area, and more power and weight. I’m also fighting the visibility issue. It’s hard to manage you wheel spin when you’re standing 300-400 feet away from the car when it takes off. A more sophisticated traction control would help a lot.

[@EngineeringAfterHours]

@@IndeterminateDesign yeah I've been trying to think of a way to make a higher end traction control. Right now I'm settling for a throttle delay and exponential curve, but that requires pretty solid understanding of the drag and lift values. I suppose if you don't mind slower acceleration than optimum you can just set a linear throttle curve with a throttle delay as long as -lift/drag is greater than 1.

[@Casey_Schmidt]

I wish I would have seen this sooner! It didn't even show up in my sub feed until about 12 hours after it released. For the weight issue, you could used a heavier/stronger body for testing purposes so you can get more runs in before it breaks and then print a dedicated 'race' body that is lighter and weaker when you actually try and go for your record runs. I can't wait to see more progress!

[@IndeterminateDesign]

That definitely makes the most sense. I'll run a PLA heavy body until I can stop crashing. :-)

[@bytesandbikes]

Thanks again for sharing, it's fascinating. Looks a vast improvement. Maybe allowing it to wheelie at low speeds would help with traction?

[@IndeterminateDesign]

I’m not sure I could get it to wheelie without getting more weight on the rear though. It does squat pretty hard when taking off. Maybe I need go throw down some tire prep and see what it can do.

[@Liberty.Francis]

Number one issue we have in this hobby is places to run them. At some point I recommend a castle mmx8s esc. Much higher amperage rated and data logging is a massive help. Rear only brakes are tuff to slow the car down without a really long road.

[@IndeterminateDesign]

I agree. With only 1 wheel doing all the work, the car really needs a significant amount of downforce to brake in a reasonable distance, or a big parachute. I may switch to AWD before this is over.

[@kiiiisu]

interesting stuff

[@joell439]

👍👍

[@fdoelmand]

DId you consider using glass/carbon composites for the chassis design to lose some weight?

[@IndeterminateDesign]

Yes, that would be the ultimate way to go and I could cut the weight in half. I was initially aiming for the 3d printed RC car world record at 180mph (but that car actually is just a 3d printed body shell on a carbon chassis). I may try 3d printing molds, but traveling the country full time in an RV right now makes composite fab difficult. I also think if I printed the body very thin polycarbonate that I could bond carbon fiber directly to it.

[@PowerScissor]

The best part is no part at all...

[@xxxratixxx]

It's looking awesome