Rocket Starts
When I was working on cruise missile engines, at least one of these small turbofans was started by a "pryotechnic ignitor". This was basically a small solid-fuel rocket engine aimed in at the first turbine; spun the poor thing up to 63,000 rpm in no time at all. Another little pyro device shot burning gases into the combustion chamber to light it off. Crude, but reasonably effective, as the pictures on CNN a year ago indicated.
Less crude is the ignition system on Honda's CBR900RR. Honda has put a lot of tick marks on the ignition pick-up, and provided a black box that's quick enough to determine engine speeds and crank position in just a fraction of one crank revolution. The result is light-off in the first two crank revolutions, according to Honda.
Why is this important, other than that the bike runs almost as soon as you push the starter button? Well, the CBR900RR makes do with an 8 amp-hour battery, smaller than used on any other Honda four-cylinder I know about -- my 1977 CB400F with less compression by 2 points and 500cc less displacement used, if memory serves, a 12 amp-hour battery. The 900's little battery works because it doesn't have to spin the engine much, and probably saves 2 to 3 pounds over a more conventionally sized battery.
This stuff is hardly revolutionary, as many new car engines start up on the first revolution -- the combination of effective, powerful engines and precise fuel injection systems. Not only does that save electrical power, it also reduces hydrocarbons during the start, as raw gasoline isn't being pumped through the engine. Having spent a fair amount of time setting timing with ignitions using points, I love this solid-state stuff. Yeah, you can't fix it if it breaks, but it rarely breaks, and the best of it offers advantages you just can't have any other way.