There's been a number of rocket-powered cars, and while they're all pretty fun, they're basically only good for one thing: going fast, in a straight line.
There are certainly good and terrible reasons to do that, but real car people know that turning is fun, too. A lot of fun. So why don't we apply the raw power of rocketry to handling as well as to speed?
I had a crazy idea about how this could be done, so I contacted Jalopnik's on-call physicist, Dr. Stephen Granade, and resident racer Alex Lloyd. Here's what we came up with.
This was the question I emailed Stephen:
"What would happen if you installed a spacecraft-like RCS (reaction control system) on a car? Let's say you had quads of, say, Soyuz-type RCS thrusters at the corners of a car— how much do you think you could change the car's dynamics? Could you turn tighter, or with more stability, or thrust your way out of a spin, cancel under/oversteer, etc? Would RCS thrusters be strong enough to overcome friction, acceleration, etc? How strong would they need to be? Would this make the baddest-ass racecar ever?"
And here's Stephen's well-considered answer. I made some diagrams to go along with it, so you can start modifying your own cars as soon as possible:
You could definitely have some fun with a couple of RCS thrusters. The Soyuz RCSes weren't actually that strong, so let's use the Shuttle's instead. The Shuttle's RCSes came in two flavors: primary and vernier. The primary ones, which are Aerojet R-40As, are the ones we'll want, since they produce 870 lbs. of thrust. (This is also good since I happen to know of a bunch of Shuttles that won't be needing their RCS systems anymore. Check your local salvage yards! — JT)
It's not clear how well the primary thrusters will work in atmosphere. They were designed to work in vacuum, and that 870 lbs. of thrust I just talked about is called "vacuum thrust". You design rockets differently if they're going to work in atmosphere than in space. Rocket nozzles flare open so that the jet of fire coming out of them can expand as it exits, and for a rocket in the atmosphere you want the pressure of the burning fuel as it exits the nozzle to be the same as the ambient pressure. If the fuel's pressure is too low compared to that of the air around the rocket, something called "flow separation" happens. The jet's supposed to hug the walls of the nozzle, but if the air has way more pressure than the jet then the jet gets choked down and becomes unstable, really reducing your efficiency and giving you thrusts in unpredictable directions. In extreme cases you damage your nozzle.
I don't have enough information about the RCS thrusters to know if that's the case or not. But let's assume that we're fine to use them in atmosphere, and if we're not, we'll Mythbusters those suckers until they do work.
So. Let's strap a couple of RCS primary thrusters on either side of the back end of the car. Maybe we do an extreme mod so you don't have any trunk space and maybe no back seat any more, but you've got freakin' rockets on your car. Can you use them to corner better?
If you had two thrusters pointing to the side, you'd produce 1,500 to 1,700 lbs. of sideways thrust. You'd be shoving the rear end of your car sideways. That should be enough to overcome the tires' friction and break them free of the road. (more detail available if needed) If the thrusters are mounted in the back, you'll most likely break the back tires free and pivot around the front tires. Congratulations, you can over- or understeer at will!
You could use those thrusters to correct over/understeers and keep you pointed the way you need to go. It'd be a rocket-powered electronic stability control system! But that's lame. It'd be cooler if the thrusters would let us oversteer and corner much more tightly than normal. The problem with oversteering is that you tend to overcorrect and pretty soon you're fishtailing all around. But with the thrusters and some smart programming, you could have a computer system that counter-corrects the driver's overcorrection. That way you could go into a deliberate oversteer and corner much more sharply than before.
This would come at a cost, of course. The RCS uses monomethylhydrazine as its fuel, which is toxic and carcinogenic at low concentrations. You really, really don't want that stuff around. Its oxidizer is nitrogen tetroxide, which is also toxic and corrosive and its fumes are super irritating. You can breathe it in and days later you end up with bronchitis or emphysema. The tanks to hold all of this stuff at the right pressure (especially since nitrogen tetroxide has a boiling point of about 22 degrees C here on Earth) will add weight and bulk to the car. Luckily the thrusters themselves are only a bit over 20 lbs. each.
It's also going to be expensive to run. Each thruster burns through a gallon of monomethylhydrazine and a gallon of nitrogen tetroxide every 6.5 seconds. Back in 2001 a gallon of both would run you about $600, and that can't have gotten any cheaper in the last decade. Best case, you're looking at $100 a second to run your jets.
But hey: ROCKET CAR.
I know me making some diagrams and quoting a physicist is usually enough to get a jury to agree with me, but you, dear Jalops, are different. So, I took this idea to Jalopnik's own semi-domesticated racing driver, Alex Lloyd, and got his input. Here's what he said:
Firstly, congratulations on the craziest motherfucking post of all time... I'd love to be able to go into a turn harder and faster than is technically possible, and rely on badass rockets to defeat the laws of physics. I can imagine going into turn 2 at Laguna Seca and driving it in 15mph (or more) faster than is possible and the back immediately coming around and, presumably, sending me backwards into the wall. But as with stability control (just in a far more potent way) the rockets kick in before the car has chance and saves the day. But then to get the car around the bends the rockets re-fire in the other direction pivoting it around on a dime, all the while being controlled by the adjacent rocket keeping the back under control, too. Mind-blowing.
I could imagine it feeling like a roller coaster, almost driving itself. Of course the car would need heavy redesigning to manage the additional rear weight and some crazy-ass computers that can control the rockets and have them working in such a precise manner. But (with my miniscule brain) it seems like — if you ignore the obvious difficulties in making it a reality — that at least it may be possible.
Would I drive it? Fuck yeah. If you give it a spin first.
Alex apparently was thinking about this all night, scribbling on chalkboards and playing with his Hot Wheels, because he later sent me this message:
I was also thinking about rockets on both the front and rear. What would be awesome is when going into a long left hander, for example, having the front right rocket engaged fully along with the right rear rocket. If both of those were utilized to the exact level to balance the car, but also to effectively allow you to go around the bend at a completely nuts speed by forcing the car to stay on course.
That way you don't need to rely on either left rear or right rocket alternating power supply but they could work simultaneously via the front and rear to provide the maximum corner speed given the force provided by the rockets. Of course, adding 2 additional rockets to the front as well as the 2 we already have at the rear adds a bunch of weight we probably can't afford but seeing as we can't afford to do this in reality anyway, I figured why not.
So, there you go! It can be done! Who's going to be first to make the best-handling car ever? Just make sure to let everyone know you're using the Jalopnik-Torchinsky-Granade-Lloyd method, because that means quality.