I used to fly at Great Leighs in Essex.
One of the members, Malcolm Rose, had a diesel powered "classic" . This thing just kept flying and flying on a thimble full. He got it up so high, he laid down on his back to look at it....then fell asleep.
The plane was found at Black Notley railway station, about 6 or 8 miles away, where it had landed perfectly on the platform. He had put his telephone number in the model and some kind soul rang him!

At the same site, I was flying a Precedent Hi-Boy Turbo, an "advanced trainer", in a strong wind. It had Micron 7 kit built radio gear. I took off and as the model was turning cross-wind, the radio stopped responding. So it was at full chat, with a little left aileron applied. The model turned downwind and disappeared over our heads doing about 120 mph. After it cleared the boundary hedge, there was this little fountain of wood and covering that shot up above the hedge line. We had to dig the engine out with a spade. It turned out to be a cracked wire in the 1st IF coil. I flew the replacement model for about 20 years before I sold it at a club auction. (bored!)