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If you are interested in this stuff there is a really good Sandy Munro interview with NowYouKnow here .

It is better than 1.8 to 60 according to the test driver. In an early model I experimented with Bernoulli for 0 to 30 because in that regime you are friction limited - at (some) higher speed you will be traction limited. If you still like the pure thrust story then a similar argument could be...

@AirKuhl Thanks for that. I am hoping that he will announce the car soon.

Read and make your own mind up. This supplements Elon's Tweets.

You are right - Elon might be using actual thrusters that can push and corner a two tonne car but I also think that you are right to guess that that solution might not be road legal. My bet is still for suction using an air curtain rather than small directed nozzles. In the last month or two I...

Ah - we might see a Roadster with the SpaceX option tonight so here are the results of the calculations using everyone's best guesses about the mechanics inserted into my model (These are for my Bernoulli theory). For the velocity of air in the curtain I am predicting 130 mph (though that will...

By the way - thank you to everyone who contributed to this forum. It has been great fun. I predict that Elon will reveal some of this stuff before the end of March because Tesla would like to have a better share price when some of their debts mature; if the share price is high then the debts...

Elon’s latest tweets seem to favour this version of the Roadster 2020 SpaceX options: (a) 2 thrusters on each side of the car (b) 2 front and back (c) 2 under the car (that gives us the ten promised thrusters) Given his latest comments it now seems to be that the thrusters on the front and...

@BioSehnsucht thank you for your comment – I loved the Draco rockets. They should have played some music. I am not so sure about any kind of temperature change to the COPV gasses unless it happens slowly. I find it hard to think of fast heating of the air as it is released – my Uncle worked on...

I like your comments - I would be interested in your opinion of this Speculative Aerodynamic Model of Thrusters

I think that they have a design studio that does special versions - normally for a special price but try to see if they would help here. They turned out a bunch of surf boards that fit into their other cars. Elon gets a kick out of helping people; if you look in the margins you can see him doing...

Pebble Risks and Thrust As promised (@Pmac727 and @Joerg ), I have looked at the possible exhaust velocities of the curtain and thrust versions of the SpaceX options package. My preferred thruster model is still the suction model (as you will know by now!) but I also cover the...

@Pmac727 Could I try and convince you otherwise using this video ? I see where you are coming from but the experiment in the second video does not have the downward flow that you saw in my original demo (It is hard to build a convincing demo with cardboard and a glue gun!). One of the demos...

I think that playground rides are limited to 2 or 2.5 g. I think that the SpaceX options put the car in that range for several seconds; I think that it is initially limited by grip and then later by maximum power) For example 2 g at 60 mph is ~ 1,000,000 Watts (assuming low losses) At zero mph...

@Joerg great video; I had not been able to get anything like it. I could be wrong about them reusing the exact design because they know a lot about this stuff - here is a video about the BFR that I liked . Interesting to see how he reuses the SpaceX tech.

I have been proposing a model where thrusters create suction (which is safe for 'strollers' because my gas velocities are quite low in comparison to 'thrusters as rockets') BUT you may instead prefer your thrusters to act as rockets that point up, or sideways, (by projecting momentum). You...

@Pmac727 Thanks for that. Previously I had been looking for terms like ‘Coefficient of Friction’ and I got links like this http://theengineersjunction.blogspot.com/2011/02/tyre-adhesion.html which only gave µ up to 0.8, 0.9 or perhaps 1.0 – and a lot of these sources are unhappy with µ > 1...

@Joerg Yes - I also think that the narrow nozzles are not the way that he went (we will find out at some point!). My reading of Elon's tweets is that his ten thrusters might be arranged to form one curtain around the car using three nozzles on each side with two front and back. (In my demo I...

@Brando Hi, apologies for taking some time getting back to you, these are my first few videos (my video editing is getting faster). I've made another video with some extra explanation: Hope this helps. @LargeHamCollider Hi - thanks for your comment. The reason I do not favour the idea...

@Brando - Another way of measuring suction could have been to insert a pressure-measuring tube from the top of my second draft car and glue its opening so that it opened into the space under the car (in the centre of the car). I could have measured the suction using water in a U bend. In the...

This links to a video showing my aerodynamic models of the Roadster 2020 with SpaceX options and how it might perform. It is of course speculative. At the end of the video I compare my model with Elon's cryptic tweets. I have 'test driven' the video against a range of people in an attempt to...

Exhausting the air outward in a ring creates suction behind the nozzle. The area behind the curtain nozzles is ~ 9 sq meters so the low pressure area behind the nozzle is a 9 m^2 suction patch under the car. An extra few percent pressure reduction under the car gets you a big additional grip...

Thank you for your comments. I believe that my calculations assume mu<=1; let me know which bits of the pdf were confusing and I could repost something that is clearer. I am very surprised that it is possible for mu to be higher than 1 in a practical situation. For the avoidance of doubt I am...

On the 9th June Elon Musk tweeted “SpaceX option package for new Tesla Roadster will include ~10 small rocket thrusters arranged seamlessly around car. These rocket engines dramatically improve acceleration, top speed, braking & cornering.”. On the 12th June I tried to clarify Elon’s mysterious...