Car Uses Innovative Timing and Lift

Has anybody ever designed a valve lift mechanism based either on hydraulic actuation or maybe electric solenoids, with lift and duration being regulated by engine demand? Wouldn't this allow optimal tuning for performance and mileage?

Honda VTEC, Toyota VVTL-i both has adjustable lift.

There are development with solenoid type valve control for individual valves. Much of the problem is how fast the solenoid can react. Also how to control and verify when and how much the valve opened. Like injectors, the solenoid will "float" at high freq.

Pineapple

And thanks to the low maintenance of this sub-sonic relic, we scrapped out the SR71 blackbird which could only cruise at mach 2.3 at over 100,000 as an unneeded Skunkworks toy. Todays fighters easily achieve 60,000 ft, none yet approach 100,000. The same for AA missiles. And the factor of 3 to 4 for the time required for an overflight makes our only remaining spyplane a target for anyone with a pea-shooter nowadays.

The U2 borrowed the disposable wing tip wheels of the B52 for take-off with a full load of fuel, whereas the SR71 could only lift off a runway with a 1/4 load, requiring in-flight refueling for just about any mission.

We apparently don't have any SR71 still flight-worthy due to a determination that we don't need it, but we still fly the U2. The top speed and altitude of the (defunct) SR71 is still classified, for what?

RichH

Huh?