IIRC it was in the mid 70's that I learned that my friend, Col, Carl Crane in Texas had patented a system called Tell Me. It annunciated the distance run during landing or takeoff. I immediately realised that the receiver he was hoping to market was already installed on most aircraft in the form of the Marker and that fan shaped transmissions could be installed on the edge of the runway. Remember, DME was fairly new, and distance on the runway was not generally available. There had been a few accidents in that era associated with landing well off the numbers.
Working out the acceleration was my next leap. It made sense . . . back then. I smelled an investment.
I came back to the UK with an agreement that if he had North America, I could have the rest of the world. I was already in touch with our government's 'development scheme' (or some such) who were soon in possession of my drawings. They paid half of the research and development to successful applicants.
It was only a short time later that I got a letter saying they were already funding a similar system, and mine would be in conflict. I called the folk doing the testing and a nice guy told me their hopes and woes. It seems a BAC 1-11 was charging up and down a runway with doppler looking at the runway surface. A secondary dial on the ASI showed the accelerative progress. It worked . . . sometimes, the doppler unlocking with tedious regularity. Given how quickly DME became available on the runway, I guess it's a good thing neither of us poured too much into our respective dreams.
It had been a subject close to my heart. Despite having passed my performance A in 25 minutes, I was very aware that so much of it was utter bo-lox. Quite meaningless in many situations. For me, the most memorable was Split, with my boss doing the takeoff with a well loaded BAC 1-11. I still remember the thundering of the undercarriage on the uneven concrete slabs. It was soaking up energy. The simpleton on my left said nothing, then or later, despite me having called V1 as we passed over the rocky coastline.
I put a lot of effort into getting the subject discussed and talked it over with a couple of big name electronics manufacturers. There was a lot of interest, but even more inertia. No, the pun has not gone unnoticed.
I expect my phone could do a fair job of it these days.