Tesla Roadster - Technical discussion - How did they do the demo?

[JBee]

It's been a while since I've posted online on Tesla forums, but hey there's finally some new Tesla tech to talk about!

The intention of this thread is not to talk about if it's real, rather to talk about how they did the Tesla Roadster demo, and how the systems work/could work.

There are two additional and separate systems that make the demo work on top of the EV drivetrain.

1) is the suctions fans that suck it to the road at twice the force of how much it weighs (2g). The
2) is the cold gas (just compressed air) thrusters that gives it attitude (body orientation) control and the ability to change direction, and takeoff, land and hover.

These components can be made out in the x-ray video:



They said it has 80kN of thrust (max) but that would only last about 1.7sec at full power, but it only needs 17kN to lift the car and hover, so you get about 10seconds of hover time using the 600L of compressed air tanks onboard.

The way they did the show was likely like this:
1) the first bit driving up the ramp was just with the suction fan so it stuck to the ramp, even upside down or at 90degrees. (There's no cold thrusters on that can be seen)

2) the second part was they drove up the ramp with a bit of speed (momentum) using the suction fans and launched off the end of the ramp, essentially in free fall. This is where the second system, the cold thrusters kicked in and spun it around (attitude control), and slowed down the car for a safe landing. Probably only needed half of the tanks for that, simply because they got to the height using the ramp and suction fans, and not using the cold thrusters.



3) the kickflip jump was similar, in that the car sped up on the ground first creating the forward momentum to carry the car over the other teslas. The thrusters just "kicked" the car in the air, like a normal car ramp jump would, then midway the thrusters spun it around, and then recovered the orientation to land on the ground safely. Like with a normal ramp jump (or rally car jump), the car itself actually does the flying after the ramp, it's just that the thrusters replaced the ramp, so you can do it anywhere without a ramp.



4) Technically, I think the last one was pushing the thrusters further than the other two, as it jumped the highest there, which means more energy to get up and down than the ramp trick, where it only had to slow coming down.

Some rough numbers:

1. - 10's of meters in vertical jump are possible with the air onboard
2. - a hop at 100kmh can be 200-300m long -faster will go further, but car has attitude thrusters so could control how it's car body flies through the air. This will be the canyon jump demo.
3. - one compressed air recharge will take about 50kWh (so a quarter of the battery - so you could do 10sec of hover 3x times) and depending on the compressor size could take anywhere between 30min with a 150kW compressor (probably one of the drive motors clutched to a scroll compressor) to 2hrs to recharge at 50kW on a dedicated in vehicle compressor system.
4. - that sounds long to recharge the air tanks, but in real life the thrusters will only need to use sub-second bursts to keep the vehicle on the road, meaning that it's possible the recharging time should be fast enough to sustain any track race with full power, if you start with full air tanks as well (there's essentially 50kWh of energy stored in the tanks that can come from the Supercharger plug before you start the race).
5. I'm guessing the hover thrusters might not make production, or will be locked out for road use, whereas the attitude thrusters can be used onroad/track without to much issue.
6. - That brings me to another side effect of compressing air, that is heat generated and how they get that out of the car. It's possible the suction fans might also help with cooling for air compressor system heat rejection, which should help to lower part count. But in saying that 150kW of heat is doable with a car radiator with enough airflow.
7. I'd also like to mention that the demo feature set seen today is unlikely to be the delivered vehicle feature set. (Sorry for being a downer so early on) But the primary function of the thrusters will likely be limited to 0-230mph acceleration, possibly deceleration braking (didn't see any front thruster nozzles tho), and active cornering compensation. That will also contribute to making the 600l compressed air last long enough to make extreme lap times, even longer Nürburgring ones, possible. (Seems the Roadster order page would agree with this)

Overall absolutely insane that they put it together like this, but technology wise quite possible as we now can see with our own eyes.

 

[Administrator]

Some incredible footage from the development of the new Roadster.

 

[JBee]

Hagerty and Top Gear have some more technical detail videos:





Some extra points:

1. 200l air tank on Thruster model, 600l on Rocket one seater - so flight is obviously limited to that model. Thrusters are left/right side to modulate for yaw control (otherwise you'd launch off the road). Air recharge times are measured in hours but they are working on 30min version in line with my assumptions above.
2. Suction fans use 80kW for 2g of downforce, but adaptive aero can also produce 2g downforce at speed. It also reconfigures to be more slippery for better cruise milage and uses suction for added thrust when configured in pass through at high speed
3. Vehicle weighs 1700kg and is RWD only, so pack is probably only around 100kWh, if that seeing it only has 300mile range. But battery and cooling is optimised for high performance so little to no sag down into single digit SOC. This will be critical for track performance and will give it 10min recharge times
4. Removable roof panels in the doors means it is a Roadster not a Coupe
5. Rocket version Design is meant to achieve 0.55sec 0-60 with rollout.

 

[gtgarner]

My question is:

What did tesla put in the thruster tanks to show air moving through air?

What was that? Nitrogen? any guesses?

I'm only asking because I want to use that when I demo my "thrust" roadster.

 

[mongo]

My question is:

What did tesla put in the thruster tanks to show air moving through air?

What was that? Nitrogen? any guesses?

I'm only asking because I want to use that when I demo my "thrust" roadster.

They didn't add anything other than nitrogen. Going from high pressure to ambient cooled the gas off enough to condense the moisture in the ambient air.

 

[mongo]

Hagerty and Top Gear have some more technical detail videos:





Some extra points:

1. 200l air tank on Thruster model, 600l on Rocket one seater - so flight is obviously limited to that model. Thrusters are left/right side to modulate for yaw control (otherwise you'd launch off the road). Air recharge times are measured in hours but they are working on 30min version in line with my assumptions above.
2. Suction fans use 80kW for 2g of downforce, but adaptive aero can also produce 2g downforce at speed. It also reconfigures to be more slippery for better cruise milage and uses suction for added thrust when configured in pass through at high speed
3. Vehicle weighs 1700kg and is RWD only, so pack is probably only around 100kWh, if that seeing it only has 300mile range. But battery and cooling is optimised for high performance so little to no sag down into single digit SOC. This will be critical for track performance and will give it 10min recharge times
4. Removable roof panels in the doors means it is a Roadster not a Coupe
5. Rocket version Design is meant to achieve 0.55sec 0-60 with rollout.

Also MotorTrend