Limitless LibertyMkiii's crazy belt drive car project

[LibertyMKiii]

Reviewing the ROSSA videos from this past event it is very evident to me even with dual motor setups how hard it is to push into the 190's with a 1/7 scale car. This has really pushed me to focus on this 200+ project car, which has a significant advantage in aerodynamics!

Today I finished up the upper chassis hole template and working towards getting this rig road-worthy. I want to do this ASAP so that I can utilize the newly paved highway not open to the public while I still can. Initial testing will be on 2s and 3s

I really wish from the beginning I had made clear plastic templates like this. The visibility really helps get things where they need to be and simplifies the setup time.

 

[limitless202+]

Reviewing the ROSSA videos from this past event it is very evident to me even with dual motor setups how hard it is to push into the 190's with a 1/7 scale car. This has really pushed me to focus on this 200+ project car, which has a significant advantage in aerodynamics!

Today I finished up the upper chassis hole template and working towards getting this rig road-worthy. I want to do this ASAP so that I can utilize the newly paved highway not open to the public while I still can. Initial testing will be on 2s and 3s

I really wish from the beginning I had made clear plastic templates like this. The visibility really helps get things where they need to be and simplifies the setup time.

View attachment 240134

Alright @LibertyMKiii its quite apparent this thing will be rolling this speedrunning season, so i gotta ask, what speeds do you think it’ll do this season?
Also does anyone know who was the fastest (and also slowest) at rossa this year?

 

[LibertyMKiii]

Alright @LibertyMKiii its quite apparent this thing will be rolling this speedrunning season, so i gotta ask, what speeds do you think it’ll do this season?
Also does anyone know who was the fastest (and also slowest) at rossa this year?

I don't think they posted the ROSSA results yet.

Not looking for anything crazy this year. 60-80 mph range first. Depending how that goes ill step it up to 100-120 and so on.
I don't expect to take this car beyond 150 mph this year.

Then next summer I'll push it to the limits unless it needs a re-design.

 

[Notorious J]

Alright @LibertyMKiii its quite apparent this thing will be rolling this speedrunning season, so i gotta ask, what speeds do you think it’ll do this season?
Also does anyone know who was the fastest (and also slowest) at rossa this year?

I think I saw some preliminary results on Facebook, and Raz Shifrin might have had the fastest pass of the weekend. He says in his video, that there was no way a top speed record would be broken there, as the surface of the runway was too coarse and the temperatures were extremely hot. He also had a really bad crash when one of his foams exploded near the end of a run. Here's videos from him and Kevin Talbot, as they spent the weekend together at Rossa.

 

[LibertyMKiii]

I think I saw some preliminary results on Facebook, and Raz Shifrin might have had the fastest pass of the weekend. He says in his video, that there was no way a top speed record would be broken there, as the surface of the runway was too coarse and the temperatures were extremely hot. He also had a really bad crash when one of his foams exploded near the end of a run. Here's videos from him and Kevin Talbot, as they spent the weekend together at Rossa.

The following is going to sound a bit harsh but I am drawing a clear line between saving face in the public eye and real mechanical science on speed runs.

Those are the videos I was referencing about how things went at ROSSA this summer. Also how the 501 Arkansas guys are having constant breakages with their dual motor builds and Peter Dirks too. The mechanical parts are pushed to their limits with this much power trying to shove this large object through 190+ mph air resistance.

For what it is worth Raz's airport runway back home is downhill. Raz's runs over 190 mph are not as valid as what he did there at ROSSA in my opinion. His real abilities appear to be there in the 180s.

The surface texture could be a limiting factor if it destroys the foams each run. But having "too much grip" is the worst excuse I have ever heard. No one wants wheel spin on their land speed cars. Temperatures are not a factor like he was claiming. I have run countless times at 100 F. (37.7 C ) and set a 3s world record (for 1/7 scale) on hot days like that where the road was 125-135 F. and ambient temps range between 95 - 102 F. It was pulling over 650amps and generating plenty of heat.

I am not buying that excuse at all personally. There are still some speed secrets that James McCoy knows that no one else does. Kudos to him for what he has been able to do on a country road

I spoke to James briefly about the ROSSA event and he had predicted how well Raz and Kev were going to do at the event within 3mph. He knows there are some things that Raz does not understand yet and until he figures those things out he will be stuck in that 180-198 mph range. He also agreed the heat was not the limiting factor.

 

[Tex Koder]

...
I really wish from the beginning I had made clear plastic templates like this. The visibility really helps get things where they need to be and simplifies the setup time.

View attachment 240134

So would you make the Actual Speed Chassis out of this Lexan sheet?
Cause all you really need is to stiffen it up with some carbon fiber rods and some custom brackets to mount them on...

 

[LibertyMKiii]

So would you make the Actual Speed Chassis out of this Lexan sheet?
Cause all you really need is to stiffen it up with some carbon fiber rods and some custom brackets to mount them on...

No just the template to get all my holes where I want them before transferring onto an expensive carbon or FR4 sheet.

I am really liking working with FR4 glass fiber sheet lately. It seems to be very close in strength with carbon fiber and usually pretty low cost. Also has the benefit of not being a conductive material or blocking RF signals.

​

 

[Tex Koder]

No just the template to get all my holes where I want them before transferring onto an expensive carbon or FR4 sheet.

I am really liking working with FR4 glass fiber sheet lately. It seems to be very close in strength with carbon fiber and usually pretty low cost. Also has the benefit of not being a conductive material or blocking RF signals.

​

Okay.
Gotcha.

Well, in case you need some carbon fiber rods ,I have a few 8mm x 775mm-ish on hand.

 

[Notorious J]

The following is going to sound a bit harsh but I am drawing a clear line between saving face in the public eye and real mechanical science on speed runs.

Those are the videos I was referencing about how things went at ROSSA this summer. Also how the 501 Arkansas guys are having constant breakages with their dual motor builds and Peter Dirks too. The mechanical parts are pushed to their limits with this much power trying to shove this large object through 190+ mph air resistance.

For what it is worth Raz's airport runway back home is downhill. Raz's runs over 190 mph are not as valid as what he did there at ROSSA in my opinion. His real abilities appear to be there in the 180s.

The surface texture could be a limiting factor if it destroys the foams each run. But having "too much grip" is the worst excuse I have ever heard. No one wants wheel spin on their land speed cars. Temperatures are not a factor like he was claiming. I have run countless times at 100 F. (37.7 C ) and set a 3s world record (for 1/7 scale) on hot days like that where the road was 125-135 F. and ambient temps range between 95 - 102 F.

I am not buying that excuse at all personally. There are still some speed secrets that James McCoy knows that no one else does. Kudos to him for what he has been able to do on a country road

I spoke to James briefly about it and he had predicted how well Raz and Kev were going to do at the event within 3mph. He knows there are some things that Raz does not understand yet and until he figures those things out he will be stuck in that 180-198 mph range.

That's why we listen to you here. Sometimes, the need to be famous and sell products clouds the truth, or possibly creates a dissolutioned state of mind. I'll follow the science any day.

 

[LibertyMKiii]

Okay.
Gotcha.

Well, in case you need some carbon fiber rods ,I have a few 8mm x 775mm-ish on hand.

Thanks for the offer!

That's why we listen to you here. Sometimes, the need to be famous and sell products clouds the truth, or possibly creates a dissolutioned state of mind. I'll follow the science any day.

I'd love to hear @vwturbowolf 's input on the heat topic given he has a dual motor 1/7 car running in that same ballpark of speed.
Maybe there is something I don't know, but we know the LiPos love to be warm/hot.
Motors like to be cool and the ESC likes to be cool but won't get hot till the end or after the run.

 

[limitless202+]

The following is going to sound a bit harsh but I am drawing a clear line between saving face in the public eye and real mechanical science on speed runs.

Those are the videos I was referencing about how things went at ROSSA this summer. Also how the 501 Arkansas guys are having constant breakages with their dual motor builds and Peter Dirks too. The mechanical parts are pushed to their limits with this much power trying to shove this large object through 190+ mph air resistance.

For what it is worth Raz's airport runway back home is downhill. Raz's runs over 190 mph are not as valid as what he did there at ROSSA in my opinion. His real abilities appear to be there in the 180s.

The surface texture could be a limiting factor if it destroys the foams each run. But having "too much grip" is the worst excuse I have ever heard. No one wants wheel spin on their land speed cars. Temperatures are not a factor like he was claiming. I have run countless times at 100 F. (37.7 C ) and set a 3s world record (for 1/7 scale) on hot days like that where the road was 125-135 F. and ambient temps range between 95 - 102 F. It was pulling over 650amps and generating plenty of heat.

I am not buying that excuse at all personally. There are still some speed secrets that James McCoy knows that no one else does. Kudos to him for what he has been able to do on a country road

I spoke to James briefly about the ROSSA event and he had predicted how well Raz and Kev were going to do at the event within 3mph. He knows there are some things that Raz does not understand yet and until he figures those things out he will be stuck in that 180-198 mph range. He also agreed the heat was not the limiting factor.

Once again, liberty brings out the facts. to much GRIP?!? Makes no sense, and in the last paragraph of all that, he shows James McCoy is still the speedrun king. 204 IN 2200!!!

 

[Diem Turner]

The following is going to sound a bit harsh but I am drawing a clear line between saving face in the public eye and real mechanical science on speed runs.

Those are the videos I was referencing about how things went at ROSSA this summer. Also how the 501 Arkansas guys are having constant breakages with their dual motor builds and Peter Dirks too. The mechanical parts are pushed to their limits with this much power trying to shove this large object through 190+ mph air resistance.

For what it is worth Raz's airport runway back home is downhill. Raz's runs over 190 mph are not as valid as what he did there at ROSSA in my opinion. His real abilities appear to be there in the 180s.

The surface texture could be a limiting factor if it destroys the foams each run. But having "too much grip" is the worst excuse I have ever heard. No one wants wheel spin on their land speed cars. Temperatures are not a factor like he was claiming. I have run countless times at 100 F. (37.7 C ) and set a 3s world record (for 1/7 scale) on hot days like that where the road was 125-135 F. and ambient temps range between 95 - 102 F. It was pulling over 650amps and generating plenty of heat.

I am not buying that excuse at all personally. There are still some speed secrets that James McCoy knows that no one else does. Kudos to him for what he has been able to do on a country road

I spoke to James briefly about the ROSSA event and he had predicted how well Raz and Kev were going to do at the event within 3mph. He knows there are some things that Raz does not understand yet and until he figures those things out he will be stuck in that 180-198 mph range. He also agreed the heat was not the limiting factor.

I agree with your assessment here. I will, however, offer up one factor that Raz mentioned in passing that you left out (not intentionally I don't think; may have just passed it over as he did just mention it briefly but I do think it's the most relevant, as the other two, I would agree, aren't really factors beyond perhaps 1-2mph).

The elevation. Or rather, the lack thereof. I don't know what elevation Raz's airfield is at, but from the videos it did look like the airfield where ROSSA is hosted is very close to sea level, which might not make a huge difference in normal situations, but when you begin to approach 200mph, it's more like "driving a car through a cheese cake" to, once again, quote Jeremy Clarkson. To that end, I do think that driving at higher elevations would provide a significant advantage in speed running as the motors, obviously, don't require oxygen to function.

Anyone got a runway in Denver? If so, get crackin'!!

 

[Velodromed]

When I looked at the close-up of the runway during the video I automatically thought ‘heavy’, even explained to my wife what that means, and that’s what I thought he was trying to imply by using the word ‘grippy’.

The reason I thought ‘heavy’ is, from experience, cycling on a road surface like that takes more effort than a smooth tarmac...it’s ‘heavy’ to pedal. So it made sense to me. I have no clue what the other factors mean but that’s what I thought about the runway surface by itself

 

[Diem Turner]

When I looked at the close-up of the runway during the video I automatically thought ‘heavy’, even explained to my wife what that means, and that’s what I thought he was trying to imply by using the word ‘grippy’.

The reason I thought ‘heavy’ is that, from experience, cycling on a road surface like that takes more effort than a smooth tarmac...it’s ‘heavy’ to pedal. So it made sense to me. I have no clue what the other factors mean but that’s what I thought about the runway surface by itself

Definitely know what you mean. I'm no cyclist like you, but I do ride bike semi regularly. The difference between "grippy" or "heavy" surfaces is immediately noticeable compared to silky smooth asphalt. To me it feels similar to trying to ride on flat tires.

 

[Velodromed]

Definitely know what you mean. I'm no cyclist like you, but I do ride bike semi regularly. The difference between "grippy" or "heavy" surfaces is immediately noticeable compared to silky smooth asphalt. To me it feels similar to trying to ride on flat tires.

Then you know exactly what I mean, sucks a bit of energy out of you. I no longer cycle so it’s hard to consider myself a cyclist… but I remember lol.

 

[Diem Turner]

Then you know exactly what I mean, sucks a bit of energy out of you. I no longer cycle so it’s hard to consider myself a cyclist… but I remember lol.

Yeah, it does. I'll still consider Michael Phelps a swimmer after his swimming career is over and, at least from what I've gathered here and there, it sounds like you were pretty serious into cycling at some point. And your name is Velodromed so...to me, you're still a cyclist

 

[LibertyMKiii]

I agree with your assessment here. I will, however, offer up one factor that Raz mentioned in passing that you left out (not intentionally I don't think; may have just passed it over as he did just mention it briefly but I do think it's the most relevant, as the other two, I would agree, aren't really factors beyond perhaps 1-2mph).

The elevation. Or rather, the lack thereof. I don't know what elevation Raz's airfield is at, but from the videos it did look like the airfield where ROSSA is hosted is very close to sea level, which might not make a huge difference in normal situations, but when you begin to approach 200mph, it's more like "driving a car through a cheese cake" to, once again, quote Jeremy Clarkson. To that end, I do think that driving at higher elevations would provide a significant advantage in speed running as the motors, obviously, don't require oxygen to function.

Anyone got a runway in Denver? If so, get crackin'!!

Yep I agree with that.
Sea level air pressure and humidity both do play a part.

Totally agree with the road surface requiring more energy.

How much each of these plays a part is hard to say. Probably a few mph 3-6 would be my guess total.

Another thing is that porsche 917 body has excessive downforce and just won't go as fast as the fc100 body.

 

[The Bean]

Definitely know what you mean. I'm no cyclist like you, but I do ride bike semi regularly. The difference between "grippy" or "heavy" surfaces is immediately noticeable compared to silky smooth asphalt. To me it feels similar to trying to ride on flat tires.

And then there is the worst of both worlds, "kinderkopjes" . It gives a "faux flat tire" and no grip

 

[jondilly1974]

I agree with your assessment here. I will, however, offer up one factor that Raz mentioned in passing that you left out (not intentionally I don't think; may have just passed it over as he did just mention it briefly but I do think it's the most relevant, as the other two, I would agree, aren't really factors beyond perhaps 1-2mph).

The elevation. Or rather, the lack thereof. I don't know what elevation Raz's airfield is at, but from the videos it did look like the airfield where ROSSA is hosted is very close to sea level, which might not make a huge difference in normal situations, but when you begin to approach 200mph, it's more like "driving a car through a cheese cake" to, once again, quote Jeremy Clarkson. To that end, I do think that driving at higher elevations would provide a significant advantage in speed running as the motors, obviously, don't require oxygen to function.

Anyone got a runway in Denver? If so, get crackin'!!

Why Denver? It’s not really that high of elevation. Try Colorado Springs at probably 2000ft higher elevation and the Air Force Academy runways

Hell let’s do a Pikes Peak descent speed run

Thanks for the offer!


I'd love to hear @vwturbowolf 's input on the heat topic given he has a dual motor 1/7 car running in that same ballpark of speed.
Maybe there is something I don't know, but we know the LiPos love to be warm/hot.
Motors like to be cool and the ESC likes to be cool but won't get hot till the end or after the run.

Mostly get hot when braking

 

[Robbbbbb66]

Why Denver? It’s not really that high of elevation. Try Colorado Springs at probably 2000ft higher elevation and the Air Force Academy runways

Denver is high in a different way.....