What do you know today, that you did not yesterday?

172 watchers

Groundhog 22 Aug 12:14pm, 22 Aug 2024 6,390 posts	0 Groundhog When animals browse, holly trees make more spiny leaves, an example of epigenetic adaption to environmental pressure. This works for holly trees that aren't grazed but just brushed against as well - i.e. the bits that stab me when running down the ginnel near my house.
Eynsham Red 22 Aug 12:48pm, 22 Aug 2024 11,269 posts	0 Eynsham Red Cerrertonia wrote:It's the Great North Air Ambulance, Helimed-58. It doesn't normally appear to travel so quickly, but perhaps there was a medical reason. 270mph is very impressive though. Ah, ok that one is a Dauphin and its max speed is 190mph, but would normally cruise at 160, so yes there was a good bit of wind assistance there! #bitofahelicopternerd
Neal 22 Aug 3:11pm, 22 Aug 2024 289 posts	0 Neal Until 1840 "everyone knew" that Emperor Septimus Severus built that wall across the north of England. Then some bloke writing a History of Northumberland worked out that Hadrian was responsible, and added it to his book as a footnote. That footnote was 173 pages long. bsky.app
Cerrertonia 22 Aug 3:30pm, 22 Aug 2024 21,688 posts	0 Cerrertonia There are several 4th century Roman sources that say Septimus Severus built a wall in Northern Britain from sea to sea - it wasn't just Eutropius making stuff up. It's possible that he attempted to repair the Antonine Wall, when fighting in the central belt in AD 207.
MudMeanderer 22 Aug 3:39pm, 22 Aug 2024 2,634 posts	0 MudMeanderer If this is a Yorkshire Air Ambulance AH145 then they can cruise at 270 mph unaided. Ate you sure you've got your units right there? 270mph seems very fast for a conventional helicopter. One of my lecturers at uni had worked on the Lynx rotor when that had the record, and the suggestion was it wasn't really worthwhile trying to make them go much faster. Both the zero airspeed of the retreating blade but more so the near sonic velocity of the advancing blade made for a problem not generally worth solving at very high flight speed. Hybrid designs (with small fixed wings and jets/props) seemed more favourable if high speed was really needed in a helicopter.
Eynsham Red 22 Aug 4:01pm, 22 Aug 2024 11,270 posts	0 Eynsham Red My apologies from someone who thought he knew more than he does. Misread kmh for kts (as that’s what airspeed is normally measured in) and converted to mph! 🤦‍♂️ You’re absolutely right about the advancing and retreating blade issues even with lead/lag blade adjustment. Are you still involved in Aviation @MudMeanderer ?
MudMeanderer 22 Aug 4:08pm, 22 Aug 2024 2,635 posts	0 MudMeanderer I'm not. I was very interested in rotary wing dynamics in my student days (at Bristol we had lots of links to Westland/GKN), but found it tricky to get into. Still in engineering, but my aerospace knowledge is now more as an enthusiastic amateur with a bit of academic background in it.
Eynsham Red 22 Aug 4:34pm, 22 Aug 2024 11,271 posts	0 Eynsham Red I studied Aircraft Maintenance Engineering in Bristol at what was Brunel College (not to be confused with Brunel Uni). It’s long since amalgamated with City of Bristol College.
Ocelot Spleens 23 Aug 3:07pm, 23 Aug 2024 39,510 posts	0 Ocelot Spleens Incredible news about Penguin biscuits.
Groundhog 23 Aug 8:52pm, 23 Aug 2024 6,398 posts	0 Groundhog Sisterly Iceland (the country) has run out of cucumbers. BBC News - TikTok blamed for hit to Iceland cucumber supply bbc.com