Fascinating thread. Couple of things to throw in the research...
First, it isn't the height the car gains that counts, it's the energy that you are trying to dissipate. Despite the height, the videos I've recently seen of Off-Road cars seems to show that, despite the height, the landing is quite soft, as you guys try to catch the downslopes of jumps and land the car like an aircraft. In those situations the spring/damper isn't doing a great deal of work.
Second, the main reason that this has never happened before is because whilst we can scale the size of the cars, we can't scale the Laws of Physics. All the ideas from full-size shocks rely on oils working in large spaces with large strokes, whereas we work in small spaces with short strokes. The basic characteristics of the oil remain, so, for example, the reaction time is slower relative to the movements of the suspension for our cars than a road car.
I tried the idea MRD wrote about with small flaps on piston holes back in the day. It did alter the compression/rebound ratio, but despite all sorts of testing, we never could get it to react fast enough, and eventually we abandoned it. I remain sure that the first person/company to crack a variable rate damper will sell their product like hot cakes, as it will improve handling and roadholding.
However, there will be no silver bullet, nor product monopoly - if there were only one killer way of doing it, there would only be one damper for all road cars, race cars and bikes. Since changing damper suppliers is a regular feature of race teams and road car manufacturers, it's clear that there is a lot remaining to be developed in damper world. There is constant change in the damper market, so once this is started, it will be the same in off-road RC. You might want a better damper, but be careful what you wish for!!
