Well, as a final article (I'm going back to school next week and won't have any more time) I thought I'd write an article of something that I always wanted to try.
Hydraulic launch assist is a form of KERS. Except instead of using a flywheel or batteries/electric motors. You use hydraulics and nitrogen cylinders.
The concept works like this.
1. When you step on the brakes, a hydraulic pump engages.
2. The hydraulic fluid that the pump moves compresses a nitrogen spring (a nitrogen spring is basically a cylinder with one side filled with nitrogen, when it is compressed it stores energy by compressing the nitrogen)
3. When you step on the gas, the hydraulic pump is allowed to operate in reverse driving the wheels as nitrogen spring decompresses.
According to Ford's studies this mechanical method of recovering braking energy is about 60% efficient (in their test rig, who knows how efficient it could get after years of research). This compares to conventional electric hybrids which are maxing out at about 30% efficiency. Efficiency being measured where if you are going 100mph, hit the brakes and hit the gas you'd be able to get back up to 60mph with this system, or 30mph with the conventional hybrid system.
I guess now you are probably wondering why they don't use this system of cheap pumps and hydraulic lines instead of expensive batteries and motors. Well, it's because hydraulic launch assist is power dense where electric hybrids are energy dense.
Lets explain that concept. In a power dense system you are able to extract large amounts of energy at a very fast rate. In an energy dense system you are able to store large amounts of energy.
The thing that killed this concept was the fact that it would only last for part of your re acceleration before it would run out of energy and have no more effect on fuel economy. Electric hybrids on the other hand can only put out a very little amount of energy at a time and have a very large amount stored up, so it lets the engine work a less for a lot longer, especially under soft accelerations where you only need 30hp.
But when it comes down to it, I'm not interested in cars that maximize fuel economy by doing soft accelerations. I want a hydraulic launch assist car where I can dial in the rate at which it releases the energy (i.e. 500 extra hp for 3s or 50 extra hp for 30s). Even if I have to store the energy from several brakes before I get my fun run, it would still be funner then fuel mising. :D
Anyway, I have had my fun. Hope you all learned something from these articles.