LOL Screwballs – interesting question - with some merit (and controversy) too! My 0.5 penny’s worth! Not quite sure (as a simple bloke) where your “..around the earth” dit comes from – but, as a some-time simple glidist, I often have to work a similar question out for real - when looking for a rescue-thermal to save my bacon. My question in a dying thermal is “How long have I got before I have to commit to a ‘Downwind to a field landing’ decision?”
The simple answer I apply is ((Current height agl (estimated from topography) – 800ft agl)/ROD (ft/min)) = time left before I have to give it up and head for the sheep/cow/barley field! I know (roughly) how many RPM I am doing so I could work out how many orbits I could make. So, in theory, you could multiply TAS (GS should even out as constantly flying “into” and “out of” wind) by the time to “downwind decision point” or “crash site” to give a distance travelled to either event!
But, practically, I just work on a closest cut-off altitude to a downwind leg. When I reach that – "Hello sheep/cows/barley"!!!!! As for distance travelled? Mmmm, don’t care really as a pilot – but, using a formula for a conical spiral (or my calculation above), I guess you could work it out if aiming at a particular sheep within said field! However, in practical terms – neither I nor the sheep would be worried – provided (from both sides) I missed the sheep on flare/roll-out!!!!
Hope this is of mild curious interest! If not – my apologies! Ho hum!!!
H 'n' H
Last edited by Hot 'n' High; 15th January 2009 at 19:34.