Limitless LibertyMkiii's crazy belt drive car project

[LibertyMKiii]

Have been out of it for a bit, work has been savage then had my hols. Really enjoyed the update @LibertyMKiii keep em coming

Thanks, man! This project continues to be a challenge.
It needs some significant time invested still. I am finally coming to terms with the fact that it is likely that it won't hit the roads until next summer, but I want to see this thing go!

Everything with these shaft and pulley setups has to be very precise or the belts want to run off. This will also lead to bearing wear and other issues. It needs to be right and will just take more time

I do have belt tensioners with guides but want to be cautious with the belts. The long front belt costs over $100 and takes 4-6 months on order.

 

[chekos1]

I took some screen shots from the video of the guy running his jet powered car at the ROSSA 2022 August event. He showed briefly a car much like this one I am making. Key difference I see is that his is only RWD and based on 1/10 scale tires.

Overall I like what he has done but the 2wd is going to hurt him without access to a runway all the time.

I heard he did something like 150 on 3s which is impressive

View attachment 239308

View attachment 239309
View attachment 239310

Hello Liberty. That’s my car! I was actually following your thread here while I was building it.

Yes you are right, belt driven RWD with 1/10 scale tyres (at the front at least!). I am not planning to run on public roads, this is a build specifically for ROSSA or Darley.

Initially I spent so much time trying to find the best layout and I was confident that 4wd with a belt drivetrain was the best solution. But I didn’t want to just copy you. So I decided to go for RWD and I spent quite some time designing the aero and optimizing the weight distribution. Obviously I knew that RWD was a bit of a risk, but I thought its advantages might be worth it. And after ROSSA I am thinking it might be just as good, or even better than 4wd.

ROSSA was incredible, I can’t really describe it. I was afraid in the beginning that my design would have a huge issue that I didn’t think about that would make the car undrivable. In the end I left my first event with 150.84 mph on 3s. Mind you, that’s with no experience in speed running at all. That’s how easy it is to go fast with a custom car.

I have to say that the people there is what really makes the event so great. Everybody is so helpful and couldn’t have done it without their help.

Now I know that the car has a solid base and the setup is good and my confidence with it is improving. I am really looking forward to the next ROSSA event, there is so much more speed in it, even on 3s.

That said I did find some issues with my car and I had a few crashes, but fortunately nothing serious. I am planning a redesign of the rear shaft and wheel assembly as a backup in case my current design starts encountering issues at higher speeds. Then maybe build a second car as a spare.

Really looking forward to seeing your car run. All the time you put into it and then seeing it go fast for the first time, it’s priceless. If you need any help or want to discuss anything just let me know.

 

[Grimbles]

@chekos1 I have been watching your YouTube channel. Crisp.

 

[LibertyMKiii]

Hello Liberty. That’s my car! I was actually following your thread here while I was building it.

Yes you are right, belt driven RWD with 1/10 scale tyres (at the front at least!). I am not planning to run on public roads, this is a build specifically for ROSSA or Darley.

Initially I spent so much time trying to find the best layout and I was confident that 4wd with a belt drivetrain was the best solution. But I didn’t want to just copy you. So I decided to go for RWD and I spent quite some time designing the aero and optimizing the weight distribution. Obviously I knew that RWD was a bit of a risk, but I thought its advantages might be worth it. And after ROSSA I am thinking it might be just as good, or even better than 4wd.

ROSSA was incredible, I can’t really describe it. I was afraid in the beginning that my design would have a huge issue that I didn’t think about that would make the car undrivable. In the end I left my first event with 150.84 mph on 3s. Mind you, that’s with no experience in speed running at all. That’s how easy it is to go fast with a custom car.

I have to say that the people there is what really makes the event so great. Everybody is so helpful and couldn’t have done it without their help.

Now I know that the car has a solid base and the setup is good and my confidence with it is improving. I am really looking forward to the next ROSSA event, there is so much more speed in it, even on 3s.

That said I did find some issues with my car and I had a few crashes, but fortunately nothing serious. I am planning a redesign of the rear shaft and wheel assembly as a backup in case my current design starts encountering issues at higher speeds. Then maybe build a second car as a spare.

Really looking forward to seeing your car run. All the time you put into it and then seeing it go fast for the first time, it’s priceless. If you need any help or want to discuss anything just let me know.

Great to have you here! What is your YT channel BTW so I can follow your progress?

I have been very nervous to run this car yet. Some of the parts need to be re-created by CNC as the accuracy seems to be off by a hair with my manually drilled chassis.

Maybe I will give 2wd a shot as the front drive is what has been giving me the most issues lately.

A small/narrow custom car like you and I have created is the way to the big numbers. The large cars just have to push too much air out of the way although I really do enjoy driving my VTE2.

 

[Grimbles]

Great to have you here! What is your YT channel BTW so I can follow your progress?

I have been very nervous to run this car yet. Some of the parts need to be re-created by CNC as the accuracy seems to be off by a hair with my manually drilled chassis.

Maybe I will give 2wd a shot as the front drive is what has been giving me the most issues lately.

A small/narrow custom car like you and I have created is the way to the big numbers. The large cars just have to push too much air out of the way although I really do enjoy driving my VTE2.

It's ProjectAir. @chekos1 where is home for you?

 

[TN-RC]

It's ProjectAir. @chekos1 where is home for you?

Who is ProjectAir @Grimbles or @chekos1?

 

[Diem Turner]

Who is ProjectAir @Grimbles or @chekos1?

He's the bloke from the UK who strapped an RC jet engine to the top of a Limitless. Does a lot of really intriguing and unique projects in all things RC. Well worth a sub

 

[TN-RC]

He's the bloke from the UK who strapped an RC jet engine to the top of a Limitless. Does a lot of really intriguing and unique projects in all things RC. Well worth a sub

I know who he is I think Grimbles was making a joke and I did not pick it up. Lib asked what chekos1 YT was.

 

[chekos1]

Just to clear some of the confusion, that's not my channel. I met the guy who owns it, his car was really cool. Sorry to disappoint you haha

I was not planning to document my build, but might start a thread here or a youtube channel if there is some interest for it.

 

[LibertyMKiii]

I had seen in the videos maybe it was Talbot's that the owner of that car @chekos1 is not the same guy as project Air

Just to clear some of the confusion, that's not my channel. I met the guy who owns it, his car was really cool. Sorry to disappoint you haha

I was not planning to document my build, but might start a thread here or a youtube channel if there is some interest for it.

Absolutely!
We would love to see it.

Espeically any detail around the design choices, engineering, how it was made, lessons learned etc....

 

[Diem Turner]

lol...I think we all just successfully did this...

I know who he is I think Grimbles was making a joke and I did not pick it up. Lib asked what chekos1 YT was.

lol...neither did I

 

[chekos1]

I had seen in the videos maybe it was Talbot's that the owner of that car @chekos1 is not the same guy as project Air


Absolutely!
We would love to see it.

Espeically any detail around the design choices, engineering, how it was made, lessons learned etc....

I will start a thread then after I finish modifying the rear. In the meantime if you have any questions feel free to PM me.

 

[LibertyMKiii]

I will start a thread then after I finish modifying the rear. In the meantime if you have any questions feel free to PM me.

Your car/project just might motivate me to get focus on finishing this one...
I was already dreaming of another 2 projects I want to start LOL

 

[Grimbles]

lol...I think we all just successfully did this...
View attachment 243865

lol...neither did I

Lol... mostly me. Sorry everyone!

 

[Diem Turner]

Lol... mostly me. Sorry everyone!

All good mate, it keeps us on our toes!!

 

[LibertyMKiii]

I'll have a big focus to get this car on the road in the spring/summer of 2023.
Recently I had big concerns about adding additional downforce, but of course, didn't want to introduce big drag additions also.

After watching the following video I have decided (talked about this earlier in the thread) that I will move forward with making this a sucker car with an EDF mounted on the rear. This will allow me to utilize the existing ultra-low drag body and add a significant amount of downforce.

The biggest challenge next may be making the seal(s) under the car and exactly where to open airways through the chassis. It will already draw air from the wheel openings.

 

[Diem Turner]

Fan cars are a trip. I first found out about their existence when the Red Bull X2010 prototype was added to Gran Turismo 5. Of all the insane cars that found their way into GT over the years, this was on an entirely new level of insanity. The speeds at which you could blast around turns was absurd.

About a year ago a guy on Youtube had a go at making an RC fan car that went through a few different iterations. Dunno if you've seen his videos before. The challenge definitely lies in the construction of the skirts that make the low pressure area under the car possible. If you haven't seen these, there might be some good information in there for you in terms of what did and didn't work.

 

[LibertyMKiii]

Fan cars are a trip. I first found out about their existence when the Red Bull X2010 prototype was added to Gran Turismo 5. Of all the insane cars that found their way into GT over the years, this was on an entirely new level of insanity. The speeds at which you could blast around turns was absurd.

About a year ago a guy on Youtube had a go at making an RC fan car that went through a few different iterations. Dunno if you've seen his videos before. The challenge definitely lies in the construction of the skirts that make the low pressure area under the car possible. If you haven't seen these, there might be some good information in there for you in terms of what did and didn't work.

Absolutely all projects seem to start with searching what other people have done. Oddly enough the big parking lot where he tests this vehicle is about 10 mins away from me. I believe he lives in the McKinney TX area. One of my biggest takeaways from his and project air's testing was the screen material is needed to keep road debris out of the fan. Also that you need a large surface area of this screen because it can get blocked up and stop the airflow.

Every RC Car application of fans has been to attempt what F1 teams did for improving cornering speeds. I have yet to see one specific for speed uses.
I don't think I'll need a perfect seal to the ground and go that extreme. I had done some reading years ago about cars that hand venting and reduced the pressure under the "bonnet". Doing this created a pressure difference and that was calculated across the surface area of the car's body. This was said to increase the downforce significantly. I believe I can suck the air out from the body and will generate some good downforce. Pulling also from under the car should further improve the downforce. Certainly cannot hurt!

My biggest concerns with seals is excessive drag or sudden changes in pressure/seal and the car's balance gets upset causing a crash.
So for now keeping things simple is the plan. Lots of low-speed testing and work my way up to higher speeds. This is critical since the car is new and untested anyway.

My initial thought is to look at a 4s 70mm EDF but wondering if I should go with more airflow? Hanging a ton of weight off the rear is my main concern with larger EDF units.

 

[Diem Turner]

Absolutely all projects seem to start with searching what other people have done. Oddly enough the big parking lot where he tests this vehicle is about 10 mins away from me. I believe he lives in the McKinney TX area. One of my biggest takeaways from his and project air's testing was the screen material is needed to keep road debris out of the fan. Also that you need a large surface area of this screen because it can get blocked up and stop the airflow.

Every RC Car application of fans has been to attempt what F1 teams did for improving cornering speeds. I have yet to see one specific for speed uses.
I don't think I'll need a perfect seal to the ground and go that extreme. I had done some reading years ago about cars that hand venting and reduced the pressure under the "bonnet". Doing this created a pressure difference and that was calculated across the surface area of the car's body. This was said to increase the downforce significantly. I believe I can suck the air out from the body and will generate some good downforce. Pulling also from under the car should further improve the downforce. Certainly cannot hurt!

My biggest concerns with seals is excessive drag or sudden changes in pressure/seal and the car's balance gets upset causing a crash.
So for now keeping things simple is the plan. Lots of low-speed testing and work my way up to higher speeds. This is critical since the car is new and untested anyway.

My initial thought is to look at a 4s 70mm EDF but wondering if I should go with more airflow? Hanging a ton of weight off the rear is my main concern with larger EDF units.

Yeah, that's a good point. For a pure straight line speed build such as this, it won't be necessary to achieve maximum suck. Simply creating a chamber of lower pressure under the car will improve your adhesion to the road. I might even go so far as to stipulate that too much suck might even have an adverse effect on top speed. You could, theoretically suck yourself close enough to the road that the skirts make contact thereby creating drag.

Interesting question regarding how many and what size EDF to use. In my mind I imagine those EDFs moving metric forktons of air and my gut instinct says that a 70mm should be adequate. But that's really just pure conjecture on my part. But I can't imagine that being too difficult for you to work out

 

[LibertyMKiii]

Yeah, that's a good point. For a pure straight line speed build such as this, it won't be necessary to achieve maximum suck. Simply creating a chamber of lower pressure under the car will improve your adhesion to the road. I might even go so far as to stipulate that too much suck might even have an adverse effect on top speed. You could, theoretically suck yourself close enough to the road that the skirts make contact thereby creating drag.

Interesting question regarding how many and what size EDF to use. In my mind I imagine those EDFs moving metric forktons of air and my gut instinct says that a 70mm should be adequate. But that's really just pure conjecture on my part. But I can't imagine that being too difficult for you to work out

At the moment I am thinking there is room for a 90mm and I can always run it at lower speeds, but a maxed-out 70mm would require a different purchase and re-design. The weight difference from 70mm to 90mm is pretty minimal. The only thing that would weigh more is a 6s pack but I plan to switch it on with channel 3 or 4 on the radio and back off so it only has to run around 8-10 seconds. This will allow me to run a smaller lipo for it.