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Comment: Re:Brake override is built-in already ... (Score 1) 911

by digitac (#39674723) Attached to: Mandatory Brake-Override Proposed For All Cars
In ideal situations, yes. However I was able to demonstrate that in both of my well-maintained cars there was a reasonable series of actions that could be taken in which I couldn't stop the car.

Quick lesson: modern braking systems have a brake booster. This is a system that multiplies the force you apply to the brake pedal using vacuum generated by the engine. The vacuum comes from the air-intake manifold just past the throttle body, where at idle there's roughly a 22 inHg vacuum. Cars also have a vacuum reservoir so that the brake booster works even when the car isn't running.

So, maybe you already see the problem. The vacuum reservoir is a limited (non-infinite) size. When the gas pedal is all the way down, the throttle plate is wide open and there's virtually no vacuum in the intake manifold. The brake booster still works because of the reservoir. However if you pump the brakes a few times, for instance a tentative "why am I accelerating" tap on the brakes or if you are pumping the brakes in a (pointless) effort to keep them from locking up or overheating, you can quickly "drain" the reservoir.

I found on both my cars that the first 3 presses of the brake pedal had nearly full effect and would easily stop the car at full throttle. The fourth pump of the pedal was harder but it was still conceivable to stop the car. The fifth pump felt like there was a brick under the pedal and the car kept accelerating because I no longer had any assistance from the brake booster. I was quite literally trying to overcome the power of the engine with just some very inadequate hydraulic mechanical advantage.

Please do not try this at home.


Comment: Re:SPARC is dead (Score 1) 128

by digitac (#37546362) Attached to: Is the Sparc T4 Too Little Too Late?
I've never taken on the role of grammer nazi before, but the OP was correct.

and of course, Wikipedia:

In the spirit of fair play, I did due diligence of searching for opposing opinions that would support your view, but came up empty handed.


Comment: Re:Anything can carry nuclear warheads (Score 1) 194

by digitac (#37060486) Attached to: DARPA Loses Contact With Hypersonic Glider
The problem with ICBMs, as far as I'm aware, is that they are Ballistic. This thing can presumably maneuver in the atmosphere and therefore hit smaller or moving targets. I'm not sure what the current state of ICBMs are, but if all the aiming is done in the boost phase then you're probably aiming at something the size of a city, while this thing could hit a city block or maybe a house. Disclaimer: The above is all speculation on my part.

"Mach was the greatest intellectual fraud in the last ten years." "What about X?" "I said `intellectual'." ;login, 9/1990