It appears that a real life version of this F-19 concept was built and flown - the F19 Spectre, if I read this correctly!)
During one of the storylines which attempted to re-establish Dan in a more sensible timeframe, there was a sequence where Dan and Digby are at a future airfield and Dan had just tried out a new hypersonic aircraft that vaguely resembled the stealth fighter above.
Digby asks Dan "how did you find your first flight in a 'mud-mover?'". Theres no explanation of what he meant and the comment seems to be a reference to pilot jargon. Does anyone know what 'mud-mover' refers to ? Is it flying NOE or 'nap of the earth' under the radar or is it something else ?