Wikipedia:Reference desk/Archives/Science/2020 November 29

= November 29 =

Capturing scents
Being a fan of scented candles, I've often wondered if there is a way to "capture" more savory scents, and infuse them into an oil or cellulose to recreate as a custom scented candle? Examples would be: the smell of sauteing the holy trinity (onion, bell pepper & celery). Or freshly popped popcorn. Or the smell of new rain on hot asphalt. Any ideas? Ditch &#8733; 20:20, 29 November 2020 (UTC)
 * Bee or cheaper regular petroleum candles may get jury rigged good enough without solvents if you barely heat a candle to runny liquid while encased in clay or something with a top and bottom grip to keep the wick centered i.e. dig the bottom out with fingernail and try to pack the crater tight with clay to pinch the wick before finishing uncapped clay cocoon. Then grind fresh enough to still be very edible whatevers, replace some of the wax with them, mix thoroughly, put clay on remaining uncocooned surfaces, keep it at 120 F for maybe 2 hours then put in freezer that doesn't have anything temp sensitive in either chamber as food and refrigerated prescriptions can spoil from putting hot things in the freezer or fridge then take out when inside is warm but not soft and burn immediately on something that's okay to get savory food oil on. A cooler of icewater can work if the plastic doesn't get damaged. Heating plastic till it stinks causes cancer. Sagittarian Milky Way (talk) 01:40, 30 November 2020 (UTC)
 * Have you (SGM) actually tried this? The point (I think) was to preserve the scent for a longer period than a couple of hours. --Lambiam 12:57, 30 November 2020 (UTC)
 * Nope. Sagittarian Milky Way (talk) 16:45, 30 November 2020 (UTC)
 * I'm not sure why not? The method of producing liquid smoke is essentially as simple as "burn wood, cool smoke and catch it".  The water vapor and particulate smoke can me made to recondense rather easily; and Alton Brown covered it in one of his Good Eats episodes.  The question is always is it worth it.  After all, you need to be able to concentrate enough of the gaseous output of, say, fresh popped popcorn to concentrate said material and infuse it into a candle or atomizer or some such scent distribution system.  Whether that method is efficient enough to be more worth it than, say, obtaining the key scent components from petroleum distillates and some basic chemistry is a different question.  Could you do it is different from should you do it here.  -- Jayron 32 16:08, 30 November 2020 (UTC)

Stall speed of an aircraft
Aircraft have stall speed. For some WWII fighters it was 110 m/Hr. If the speed drops below that, the aircraft drops down like a piece of junk. I remember an episode in California when a small private plane flying over a residential area all a sudden stalled according to witnesses and went into the ground. Perhaps the pilot failed to maintain the proper speed. To avoid this sad outcome the pilots in WWII had to open up the throttle a bit more and increase the power of the engine(s) and thus the speed.

Well, how about the military gliders. On D-day in Normandy hundreds of gliders flew from England to France, packed with people in military gear, sometimes with the addition of jeeps and other machines and nobody dropped from the sky unless shot down? How come they maintained the proper speed? What is the secret? Thanks, - AboutFace 22 (talk) 21:56, 29 November 2020 (UTC)
 * Outside of finding an available updraft, gliders don't climb very much. Instead, they fly on a glide path which is intentionally losing altitude (even if not quickly). Increasing the engine power is not the only way to increase or maintain airspeed. Pointing your nose slightly down will also increase your airspeed. Gliders are intentionally designed with low stall speeds, which also aids in their performance. Basically, those battle gliders would have been released at a high enough altitude that their glide slope has more than enough distance to reach their target dropzone. That said, this certainly wasn't 100% successful, and not all gliders reached their intended targets. --OuroborosCobra (talk) 23:35, 29 November 2020 (UTC)
 * Aerodynamic stall is fundamentally about loss of lift, and is formally determined only by angle of attack. Now, in a fixed-wing aircraft, the craft has to be moving through the air to generate lift. However, the craft's stall speed will depend on things like weight, drag, and the characteristics of the airfoil. If the craft has flight control surfaces like flaps, these allow the pilot to change the stall speed, by modifying the airfoil. --47.152.93.24 (talk) 23:57, 29 November 2020 (UTC)


 * Also they were designed to stall at a very low speed; the British Airspeed Horsa stalled at only 48 mph. In a glider, if you begin to stall, you put the nose down to increase the speed. Also, military gliders were towed by obsolete bomber aircraft to within a few miles of the target, so the starting speed would have been well above stalling; they weren't designed to climb, just to descend at a controllable rate and make a reasonably safe landing, although this was often akin to a crash. Alansplodge (talk) 13:29, 30 November 2020 (UTC)

Thank you all for the information. AboutFace 22 (talk) 15:42, 30 November 2020 (UTC)