[Private_collector]

Hi Alex! Thanks for the photo. I don't actually know what the correct item looks like, but someone more knowledgeable than I can tell us. That one looks like it requires a degree in mathematics to operate, too. Fascinating things. When I used to fly (aircraft), I had an analog flight 'computer' which was used to calculate fuel burn time and make correction for wind, amongst other things, but luckily it was not always needed. I didn't like the damn thing. Not so hard as it looks, once you got used to it. It came with a wide Velcro strap, and would be held to your leg, to stop it moving around. See photo below.