LibertyMKiii's dream speed build (shooting for 200+mph)

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LibertyMKiii

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What software did you use to calculate the aerodynamics???
That body was hand made and no real data visualizations were done. I just went with what I thought looked best.
My new designs that I will be 3D printing are analyzed with AutoCAD CFD wind tunnel.

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LibertyMKiii

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I guess if it all goes south at 200 MPH it will be stigmatized with autoBAD WTF mailbox post.
I didn't put much value on the results CFD, but did use it to compare different concepts and the aero drag. The downforce will be different since the CFD does not utilize a rolling road simulation.

First part of the print that will become the plug/mold creation completed today for the 4Tec 2.0
(sitting next to the 1/8 Typhon streamliner)

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LibertyMKiii

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New design to fit 1/8GT cars and 1/7 cars like the Limitless/Infraction. Mostly for the purpose of selling them, but ill be running one also.
3D printed this one to keep things symmetrical and precise
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After sanding it was primed and waxed several times. Ready to make a mold.
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Mold created and is green from the PVA mold release spray.
moldCapture.JPG


Finally laying up some carbon fiber for my first customer who ordered 2 bodies!

carbon in mold Capture.JPG
 

AClegg

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Looks awesome! I do a make a lot of molds for fiberglass. I use bondo for the final layer to be smoothed. It feels in all the imperfections, it's hard, sands very good, and paint/epoxy sticks to it really good.
 

LibertyMKiii

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Looks awesome! I do a make a lot of molds for fiberglass. I use bondo for the final layer to be smoothed. It feels in all the imperfections, it's hard, sands very good, and paint/epoxy sticks to it really good.
I have used bondo, but try Dolphin glaze it will change your life. Goes on much thinner and better at getting a perfect finish.

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AClegg

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I have used bondo, but try Dolphin glaze it will change your life. Goes on much thinner and better at getting a perfect finish.

View attachment 122702

I have heard of it. I will give it a try. I just never got around to using it because bondo is so readily available. Bondo also works good with you mix it with resin. I like to use that to get a thick self-leveling layer that is extremely smooth.
 

LibertyMKiii

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As usual I have neglected this thread.
I have completed about 3 of these 1/7 bodies. As you can imagine the front produces extreme downforce. Maybe too much?
Hard to say now that the XLX 2 ESC came out people are pulling wheelies at 130+mph.

Capture.JPG


I have been focusing more on 1/10 scale stuff lately for the 4tec 2.0
It is a tricky car to get driving straight but pays off if you can get it dialed in correctly. The aerodynamic foot print is significantly smaller.

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I ditched this pointed nose recently for a more tear drop aerodynamic design + added a tail section.
Lots of body work still left to do to have this one ready to make a mold.
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LibertyMKiii

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are you going to make rear wing be like a elevator?..
Are you talking about the 1/7 body with the orange rear wing? That one is an airfoil shape and has 3 positions for angle of attack.

On the 1/10 that I am working on now with the blunt nose, you will notice the rear of the car is angled. I plan to have a diffuser there and may do a ducted fan to suck the car to the ground. I'd prefer to avoid extra drag where I can. I will have a single tail as it helps keep the car going straight like a rudder.

tail Capture.JPG
 

LibertyMKiii

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Oh this extremely neglected thread.
I ended up stretching the 4-tec 2.0 chassis and then realized I don't want to pursue this car anymore as I know it will have an Achilles heel. I can't handle how weak the hubs, axles/CVDs are for for 8s use. (probably could have set some 2s and 3s records with this one though)

18in WheelBase Capture.JPG


I finally decided I need to do what has always been burning on the back of my mind. I need to make my own car and avoid all these weak points of production RC cars.
I have designed in CAD a chassis, full running gear etc, and body that will be for the sole purpose of breaking that 200+mph record.
The car as you could imagine is narrow and designed for optimal aerodynamics like a Bonneville salt flats car.

For now I have a prototype made from 3D printed parts. I am going to the CNC shop next week to have some parts made from Aluminum and I will then begin cutting some carbon fiber for the chassis and upper brace.

Pics of the prototype as it stands today next to the Arrma Limitless for size reference:

Center over front Capture.JPG


3 quarter Capture.JPG


The 3D printed 1/3 of the body is sitting in front of the car, but would of-course fit over the wheels/chassis. For the purpose of making the mold it is an solid object so I couldn't put it on the car....

Visual of the design from CAD.
bodyCapture.JPG


Lots of work to do still on this build, but as you can tell this is the no compromise build I have been working my way up to. I have dubbed this one the 200+ of bust build. It will be my last one as I want to get back into 1:1 cars.
 
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LibertyMKiii

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Chassis upper and lower have but cut out of carbon fiber plate. (my first time making my own carbon plate)
Also had my 3d printed parts cut out of aluminum at a local CNC shop.

3Capture.JPG


It has been very difficult to drill through the case hardened chrome plated axles, but got the rear done so far.

Rolling chassis Capture.JPG
 

Greywolf74

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Good luck my friend. I know from my time spent with a 100+MPH Rustler how much money and heartache you'll end up with invested in this. I've been a long time follower of Nic Case and I wish you the best of luck with your endeavor!
 

LibertyMKiii

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This is still the coolest scratch built ever!
Thanks man!
Good luck my friend. I know from my time spent with a 100+MPH Rustler how much money and heartache you'll end up with invested in this. I've been a long time follower of Nic Case and I wish you the best of luck with your endeavor!
I appreciate that!
There are tons of engineering challenges for RC cars to go these speeds, and that is what makes it fun/interesting. The 2wd Traxxas cars are especially difficult. Especially in the braking at high speeds. Physics just don't work well for braking only with the rear tires

I am excited to have finally taken this approach to make my own car without the compromises of production RC cars. This is certainly the correct approach and the un-avoidable path that this journey has led me to.
 

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Thanks man!
My visits on this forum are many months apart, but yes I am on RCTalk also.
Ya I too admit I'm not on here very often but not a lot of help I need from here also. And I've been told things like the BSR foams balloon to twice their size at over 40mph and all kinds of fun stuff🤦
 
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