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249 Beacon of Hope


About Enthalpy

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  1. The extra touchpiece for the flute's F# I proposed here on May 19, 2018 is called a Rockstro or Brossa F-sharp key and existed a century ago PH1e0oEiR3I - dwsolo.com The Brossa key is located above the "D cover" as I proposed among several options, while the Rockstro key is between the E and D covers and the pre-existing trill touchpieces move one position higher. The Rockstro arrangement gives more room, the Bossa keeps flautists' habits. As the pre-existing trill touchpieces serve for high Bb, B and higher notes, with awkward slurs, comparisons between both should be patient.
  2. The pillars are screwed in a hole in the wooden body presently, so their orientation is unpredictable. The balls are then bored in the good direction, with manual skill as usual, and can get flat faces, a thread, a recess. If present, the conical screw tip accepts some misalignment. Some designs let align the pillar after it's screwed in the body, at least in patents. My proposal instead: Without a conical screw tip, the ball could belong to a subpart distinct from the pole and be assembled with proper orientation by brazing. An auxiliary metal sheet can protect the wood from t
  3. For really big forces, I'd go back to screws and electric motors. They are not as flexible as hydraulics, but they're more compact. Ball screws would save torque if they're compact enough, which I doubt, so the screw would rather glide against the nut. I got very small friction coefficient from a layer of nickel with embedded Ptfe (or a layer at each mating face, this won't gall) plus MoS2 grease. You may find this very hypothetical synthesis of cubane fun: chemicalforums I ignore if it needs light, for ethylene 2+2 cycloaddition it's 172nm. For fast production, a quick cycle of the d
  4. Found with gratitude a glossary shwoodwind.co.uk so in my previous posts: Shaft -> Barrel Cover -> sometimes Cup Lever -> sometimes Touchpiece Post -> Pillar Boule -> Pillar's ball, sometimes Pillar
  5. I already used hand pumps, from the catalogue, that create 150MPa (1500bar). Long lever, small piston, big pressure - with stiff parts and good seals. So I don't feel the necessity of sea pressure to achieve 110MPa. A lab and a pump feel more comfortable to me. Diamond anvils are often moved by screws. They achieve pressure far bigger than the Ocean does. The Ocean floor (most is at -3 000 m, while -11 000 m is rare) may have other advantages, like fewer cosmic rays. I'm not quite sure why some countries are interested now (or were few years ago): methane is one incentive, metal
  6. I'd like to recommend SI units. Not just for my personal interest (never lived in the US) but also for yours. SI units do bring simplicity and are the units of engineering and science. I even switched from mm2 and MPa, which used for mechanical engineering, to m2 and Pa when I began computing resonant frequencies, for mechanical engineering too. So 1000 psi are about 69bar=6.9MPa. That's not much. Hydraulic parts are commonly designed for 21MPa, 35MPa, less commonly 70MPa and 150MPa. You get all seals, dynamic too, and pumps etc up to 350bar anywhere. For 1500bar, you still get static se
  7. Long keys can get play on woodwinds. On a bassoon, a bass clarinet, on contrabasses... they can exceed 1/3m or 1/2m, but 0.2mm play, perhaps 0.1mm, hamper the operation of the pads at the covers. Compressed shafts don't work properly neither. Both do happen when a wooden body gets less or more damp, perhaps warm too. One good solution splits the function in several assemblies, where the shaft that carries the cover is short. But this isn't always possible or desired. At least one patent integrates some spring that pushes the shaft at the end opposite to the cover. The musician
  8. During interventions on a wind instrument, screwdrivers may slip away from the screw and scratch the instrument. Normally it doesn't happen to trained specialists, but operations are slower. The usual answer, for instance at computers, are cruciform screw drives wikipedia and many more, like the inner Torx. Maybe instruments could adopt such screw drives to gain some safety and time? I understand many screws are taylor-made, and the slot head is then easiest, but just a cross head isn't so difficult. Or could the screws be processed from industrial ones? Keep the head and adjust
  9. Hi IDNeon, thanks for your interest! My description doesn't specify a propellant amount, so the tank size adapts to the target design. For a given tank shape, the thickness increases proportionally to the diameter and to the ratio of accepted stress vs internal pressure. This implies that the ratio between tank mass and propellant mass depends on the accepted stress, the pressure and also the shape. Previously, I optimized more seriously all pressures for pressure-fed oxygen and a dense fuel. With maraging steel tanks (lighter than titanium alloy, easier to construct, cheaper) the be
  10. I've put heatshrink sleeve on a second bassoon bocal, similarly to Jul 18, 2020 08:13 PM here. 3 thinner plies instead of 2, and this time I needed sandpaper. 240 grit gives a reasonable pace at start. I didn't dare the vice, but sanding in the axial direction and the bocal on a table sufficed. The inner sleeve layer is shortest and the outer longest, so the ends show smooth transitions, better to sand and to introduce in the bassoon body. I had to glue the inner layer on the bocal with cyanoacrylate, otherwise the sleeves rotate around the bocal. I did it after shrinking partially t
  11. The rocket accelerates. The observer wouldn't be linked to an inertial frame then (aka free-falling). This can become quite more complicated.
  12. These cornetto A3 fingerings change the trills only, with two covers opened by the medium phalanges of 2L and 3L. They don't open an additional G# hole, suppressing all adjustments. The musician trills G-A by alternating the medium phalanges of 1L and 2L, quite reasonable, and Ab-Bb by synchronizing the medium phalanges of 2L and 3L. That way, the trill keys can hypothetically double to stabilize high notes as on the flute. Jumps between the levers get also faster. The proposed minimum keyworks shall be little visible to help accept the modernized cornetto. Most covers are at the si
  13. A single impactor needs guidance, possibly after the initial acceleration if the target has some agility and detects the missile start. A salvo of mirved missiles by a single truck could release dumb impactors against some targets and guide only the initial acceleration. A salvo of 8 000 impactors against an aeronaval group can use impactors of plain solid metal, which can't be fooled and offer some resilience. It has been demonstrated against ballistic nuclear missiles, yes. One advantage of kinetic impactors is that they are dense and fast, hence difficult to destroy and deflect.
  14. As a student or young engineer, I used to answer "impossible", for instance about Reagan's directed energy weapons. Meanwhile these weapons exist, and as my beard is white now, I say instead "I don't see how" or "Seems difficult to me". An aircraft carrier or a battleship aren't quite agile. The 700km range (just a natural figure from a single stage with safe smokeless powder) is covered in 4min. This gives a battleship time to change its course (an aircraft carrier has other constraints), not to flee far away. It has time to steer 90° away, and at 20m/s, be 5km away from the targeted l
  15. Hi everyone, thanks for your interest! As Exchemist says, speeds are relative to an observer. Apparently, you took implicitly an observer at the rocket's start point, and then the rocket moves faster than the exhaust gas, somewhere at the second stage. The best chemical engine spews gas at 4560m/s while satellites move with 7800m/s on low Earth orbit. If an observer moves at the rocket's speed at some time, for instance if he's in a space station joined by a rocket, then the same rocket is slow and the gas is fast. The events, for instance the rocket's acceleration, don't cha
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