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237 Beacon of Hope


About Enthalpy

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  1. Airbus' Press officer said few years ago that an "electric" A320 would have very limited transport capacity and range "because batteries are too heavy". So here are figures about a Boeing 737-800 NG with hydrogen and fuel cells. The B737-800 can take 26.0m3 = 21.1t kerosene. wikipedia 42% efficient engines transform that to 0.39TJ at the shafts. 60% efficient fuel cells and 95% electronics and motors make this energy from 5.7t liquid hydrogen in 5.7t tanks as described on Apr 14, 2013 here What's the peak power of one CFM56-7B26 kerosene engine? wikipedia Its D=1.54m fan pulls up to 118kN while the Trent 800's D=2.8m fan pulls up to 415kN. The Trent 800 can produce 36MW at the shaft, which scales to 9.9MW for the CFM56-7B26. Fuel cells for the Toyota Mirai weigh 0.5kg/kW wikipedia so 2*9.9MW need 9.9t fuel cells. The hydrogen, its tanks and the fuel cells sum 21.3t, as much as the kerosene. Motors replace the 2*2.4t engines, this should save mass, with a gear definitely. 80m3 hydrogen fit uneasily in the present design. I dislike the old proposals of a long tank above the passengers. Six long tanks could hang under the wing together with six motors and fans. Ellipsoids would be D=1.3m L=15.2m plus some insulation and shock-proof fairings. The long-range B777 Dreamliner would draw the same conclusion: hydrogen + tanks + fuel cells 20t lighter than kerosene, but the volume fits uneasily. So while the short-range Dornier 328 can just upgrade its nacelles to hydrogen September 16, 2018 here medium and long-range airliners need stronger adaptations, or better a new design. Drawings may come, later hence maybe. Marc Schaefer, aka Enthalpy
  2. Some polymer fibres have steel's strength and stiffness thanks to stretching and keep a plastic's density. Stretched polymers could hence excel as fast-spinning parts, especially as impellers of gas compressors and vacuum pumps, as turbines too where the temperature fits. These parts are uneasily made of fibres in a matrix. Intricate shapes hamper automatic production, thin sections held at thicker ones aren't quite natural to fibres. It's done at individual fan blades of turbofans, not at cheap small integral compressor impellers. I suggested to deform polymer raw material. Here strength is needed in the radial direction, by squeezing a disk, and in the azimuthal too, by a torsion. Then the part could be machined by usual methods, accurate and automated - if everything works as hoped. Or just inject the part. For instance LCP is known to harden much from small shear at injection. That would be perfect to harden the blades or thin disk of an impeller: Inject the polymer at the centre so shear is strong at the thin blades and disk periphery. Heat the resin and mould a bit less, compensate with more injection pressure. The blades and disk periphery of impellers and turbine rotors hold at a massive ring or disk section near the axis, where the material needs azimuthal strength too. This would be achieved by a rotating part of the mould, or maybe a separate construction used as the unmoulded part is still warm. Azimuthal shear could occur in the polymer between concentric tools, an outer one (optionally a mould part) that holds the impeller at its blades and a rotating inner one where the shaft will be. Other arrangement are possible, this one limits the deformations of the impeller. PA too hardens by deformation. Simple injection and rotation could make very strong and cheap impellers. ========== When extruding tubes, the kernel could rotate to give azimuthal shear. This can combine with the axial shear given by the extrusion. Marc Schaefer, aka Enthalpy
  3. A potential target for quick electric motors are vacuum cleaner. In the ones I know, a series-connected motor provides the 50m/s to the centrifugal compressor. Well proven, but the commutator and brushes wear out and cost something to produce. It adds also noise to the compressor's one. A brushless or a squirrel-cage motor would improve the reliability and noise, with proper design for the brushless. The drive electronics costs little (processor fans have some) and saves the commutator. The present series-connected motor may rotate at 20-30m/s as the compressor is wider than the rotor. A squirrel-cage or brushless motor rotates easily at 100-150m/s, which saves motor mass. Does my graphite fibre winding around the rotor bring more? Not sure. Quietness speaks against supersonic rotors. The engine's shape, short and wider than the compressor, would also be less convenient. But to improve the pressure, yes. ========== Quick electric motors would improve turbomolecular pumps for deep vacuum. They must rotate as fast as possible as compared with the molecules' speed, which is about Mach 1, or quite a lot for the residual hydrogen. An impeller of good aluminium can move its tips at >400m/s, expensive steel faster. Fast brushless or squirrel cage motors achieve ~200m/s at the gap. My graphite fibre winding doubles that, for a much shorter motor easily built. ========== Hydraulic pumps must achieve 210, 350, rarely 700 or 1500 bar. They are piston pumps typically. For 350 bar, a single staged centrifugal pump needs 350m/s tip speed, reasonable for good steel. 700 bar needs excellent steel, 1500 bar two stages. The centrifugal pump would be much smaller and silent than the piston pump, potentially more reliable and cheaper too. It needs a quick motor. Here too, a 400m/s rotor outperforms a 200m/s one. ========== High-pressure water jets clean façades, hard grounds and more. 500 bar or more result usually from a piston pump. A smaller, more silent and potentially cheaper centrifugal pump would achieve 500 bar from 370m/s impeller tip speed, reasonable for good steel, and 1000 bar from 526m/s, still accessible. Again, it needs a quick motor, and a 400m/s rotor outperforms a 200m/s one. ========== High-pressure water jets cut metal sheets. 2000+bar result usually from a piston pump. A smaller, more silent and potentially cheaper centrifugal pump would achieve 1000 bar from 526m/s impeller tip speed, accessible to excellent steel. The higher pressure would need few stages. A 400m/s rotor outperforms a 200m/s one at the quick motor. ========== Every German hobbyist has a "Minischleifer", a hand-held 130W+ 30,000rpm electric motor that spins grinding, polishing, milling, drilling bits. No idea how common these tools are elsewhere. I've seen only motors with a commutator and brushes. They are noisy, sensitive to the abundant dust, clumsy, and they get hot. A fast squirrel cage would improve that, a brushless motor of silent design even more. The casing would enclose completely the stator and have surrounding blown fins as usual for squirrel cages, gaining much reliability at once. The more efficient motor would run cooler. Without commutator, the motor could run on a safe voltage like three-phase 48V instead of 240V. The present alternative is 12Vdc, where the commutator limits to meagre 20W. Present rotors move at 50m/s, an awful lot for a commutator, easy for a squirrel cage. Shall this increase? The diameter can't. Maybe some tools accept more speed, nothing obvious for polishing or grinding wheels. Tools with a smaller diameter may be interesting. But a shorter, lighter and cooler motor would be welcome. Marc Schaefer, aka Enthalpy
  4. One more musician playing the cornetto nicely: Gustavo Gargiulo - gustavogargiulo.com/press - His Youtube channel
  5. Patricola moved their instrument's webpage to Oboe musette They keep now the E-flat transposition for themselves, but it can't change so easily. The linked video is now private. Here are more: H1XlT9tU7nQ at t=53 - 4ZAiqt_TZ38 - fzta9zlUe-M It seems difficult to play.
  6. More nice music on Wagnertuben, with interesting comments in English SlU7PMlSOkU - BNcajRV4sfc
  7. Compare again the piston piccolo with the baroque trumpet on Nathaniel Mayfield's website, both on Reiche's Fanfare natemayfield.com
  8. More records on the baroque trumpet, here by Nathaniel Mayfield mTBicT1v3vQ at t=7 - LOVGt__MTKc at t=13 - LeO2EvyFWr4 - His channel
  9. Here's a glimpse at the keys of the contrabass clarinet with bassoon shape. Nothing accurate nor complete. It's merely the sense that this folding eases the keyworks. Agreed, many designs seem easy until one puts true figures and dimensions. No rear view, despite the left thumb needs some parts for the written D/G for the register key(s) distinct from the tone hole. The right thumb is easy. Nothing about the 4L+4R low keys. At least, room is plentiful. The 500mm 1R trill keys would better be pivoting: robust, accurate. The two 1L high keys open long holes at the body's centre as this may improve the sound, but a better design should restore their shape that tells "I'm a clarinet". The 3L trill, the 4L written G#/C# and the 3R trill seem simple but the sketch has no room to show them. The D/G hole at 1L and LTh could be at the rear, the C/F hole at 1L too. Same complexity, so room can decide. Some couplings at the key's rest corks are not visible. At some concentric keys, leapfrogs are not shown. Folding eases 1R 2R 3R despite I doubled two covers: 1R open + 2R closed and 3R open + 4R closed. Marc Schaefer, aka Enthalpy
  10. Thanks Sensei! That was very informative. I checked how many subscribers a few musicians have... Rusanda Panfili (40 000) plays music easy to hear, she makes very much fuss around it, her videos contain much more than music, and she has put many videos on Youtube over a long time. Plus, the first word used with her name in Google search is "married". Her small band, plus the team (video, production...) might live partly from Youtube. Sarah Willis (33 000) makes videos about music. Informative, varied, entertaining. She too has a small team around her. She has 355 videos viewed 0.5k to 500k times, so even this doesn't make a full-time revenue for two people. To achieve such figures, she is known from the TV. What about putting just plain classical music on Youtube, and hoping that music lovers will listen to it? Here are some excellent musicians, picked randomly from my bookmarks, and their number of followers: Sophie Dervaux (38), Francesca Dego (2 000), Irène Duval (268), Viktoria Mullova (476), Clara Andrada (30), Basson français (58), Anne-Sophie Bertrand (196). That is, only Francesca Dego may qualify to earn money from Youtube, and with cumulated 250 000+ views, she might have earned some 300 bucks over several years. I didn't even check the men. So to earn money from Youtube, forget classical music. Put instead some pop music, or a dozen of videos about cats. Or a compilation of hurricane videos stolen somewhere.
  11. Hi Ahmet, just some thoughts... Very (extremely) few people achieve to live from music. Even less as a composer. You better make software: easier, well paid, many jobs. Violin professors have hundreds of students in their career, one is more talented and trains seriously, and becomes her or himself a professor. Sometimes, this exceptional student is even more exceptional and earns his living by playing music rather than teaching it. These are the orchestra musicians. Soloists are even much rarer, composers too. How many composers does a concert need? Presently, Covid-19 is an absolute disaster for all performing arts. No concerts, or concerts without public, meaning less incomes for the orchestra. Most musicians are not on the permanent payroll, so they get no engagement at all. Playing on the street is presently no-no in many countries. Youtube brings zilch to standard musicians. Romania is a fantastic place to hear music. But to play it? People from Romania and Moldova go to Germany and Austria to live from music. What kind of music? A few people manage to live from folkloric / cigani / klezmer / etc music. That could work better than classical music. It's often not a first choice. Illenyi Katica, Rusanda Panfili... are all excellent classical musicians who jumped into folkloric music to make a living. Or do you mean songs for the TV?
  12. The company Vibrato markets plastic saxophones, with walls of moderately thin polycarbonate, and even pads of elastomer. Here it there IruxMK3p_jY Plastic vs metal vTZzFIt2raw at t=58 Plastic G5ev6izRxpM Both The difference is huge. Thin polycarbonate makes a muffled tone and sounds just like plastic. Exactly like a plastic trumpet does, or the clarinet of thin injected plastic I tried years ago. The records can't tell how much the covers and pads contribute. At the oboe with thick walls and normal covers and pads, polycarbonate didn't behave that poorly as compared with Dalbergia. Some physicists still claim the material has no influence, essentially because they can't explain it, and because an influential ancestor botched that. Flawed reasoning. Marc Schaefer, aka Enthalpy
  13. Hi everyone! A Bb contrabass clarinet to written C has the range of a contrabassoon and the length of a bassoon. Some have a bass clarinet shape, very tall and with very long keys. Others have the compact "paperclip" shape, but they are of metal, which most clarinettists disdain. So here's a contrabass clarinet with bassoon shape. The aspect is unusual and the U-turn is a bit sharp to ease manufacturing. The other features are advantages: Play sitting (rather on the side like a saxophone) or standing. Weight similar to a bassoon. Bassoon makers can produce this contrabass clarinet: passive U-turn, bocal with register key. The double bore body is naturally stiffer, it's shorter, and of good material. The main part is as long as a baritone saxophone. Transmit one movement to the bocal, two to the bell. Most keys are short with few overlaps, and plenty of width hosts them. The ergonomic hand positions happen to shorten most keys. All synchronized covers sit on the same joint. The notes indicate the sounding height when a hole is open, in octaviated bass clef, noblesse oblige. Following Obukhov, an X notehead means this single note is a semitone higher. The soprano and bass stylized keys shall help the imagination. I suppose an Oehler system is feasible too. The covers' positions along the air column are approximative, and they can move to the side or rear. Double holes are not displayed. ========== The hands are at the same height as on a bassoon here. This simplifies the keys. Other contrabass clarinets with the right hand higher are easier to play between the legs when sitting. Most shafts for the downing bore could sit at the right side, passing below the right hand as on a soprano, with front and side holes. At the rising bore, the covers common to 4L and 4R could sit at the front and side, their shafts sit at the left side and pass below the left hand. I've read 30.5mm bore for a contrabass, so fingers access easily the centreline or the remote bore. With the left thumb's hole at the rear, the left fore fingers have 100mm free between the covers. 1L moves three covers immediately upstream, 1L 2L 3L 4L move some six immediately downstream. Together with 4R, 4L moves also five covers at the rising bore, nicely spread above and below the left hand. The split holes and keys as register hole and tone hole are as usual on low clarinets, though more register holes would be easy and useful. Putting at the side 4L's hole that sounds F#/B, the right for fingers have 140mm free between the covers. The holes that sound F/Bb to D/G site across the U-turn, just below their 1R 2R 3R. They could have two pairs of concentric shafts at the right side, one outer pair for the shorter 1R and the F/Bb key, one inner pair for the longer 2R and 3R, and the four covers near the body's centreline. At the 600mm long trill keys, pivoting keys like at a saxophone could be stronger and more accurate. The 4R key to open the sounding C#/F# is local, while the five other 4R keys probably transmit the movement to the 4L equivalents. RTh moves two long keys, supposedly pivoting at the rear, that reach the bell where the movements are synchronized. These two holes can face the easiest direction. If carrying a tone hole, the U-turn could be wider. It's already better than at most bassoons. The holes for 1R and 2R are farther apart on a soprano so open 1R intonates well with 2R closed, but bass clarinets tend to make streaming noise on that note, so it would be better to double the 1R hole with a second hole and cover near the 2R hole. Maybe a common cover can close two holes, as the right thumb does at the German bassoon. ========== The dual bore permits somewhat long tone holes near the centreline. Perhaps they improve a low instrument. Their inclination lets reach closer to the U-turn and rejects the condensation water if any. To make clarinettists comfortable, I'd have the bores side-by-side rather than superimposed. The wide cylindrical bore and the long ascending metal bocal should alleviate condensation elsewhere, giving freedom to place the tone holes. A waterkey is needed. The stiff and heavy in-line bell should improve the low notes, like a wooden bell at a bass clarinet. Stowasser's holes let the lowest note and its neighbours sound like the others, while the flare lets distinguish this clarinet from a bassoon. The bocal might hold in the body like at a saxophone, if it's more convenient or improves the altissimo. Some body materials enable it, or a metal part shall protrude from the body. I suppose the long shafts can be electroformed for width and stiffness, the bocal and U-turn for easier manufacturing scienceforums - scienceforums - scienceforums and following French bassoons still use precious wood that clarinettists praise. German system bassoons use lined maple, more easily available for big parts, but not renowned among clarinettists. Big parts are easier with maple. Parts already dried are a worry with any wood. Liquid Crystal Polymer could be excellent, more so with fibre load or if stretched scienceforums - scienceforums while stretching could make PP and polyketone good scienceforums - scienceforums Marc Schaefer, aka Enthalpy
  14. If stretched or rolled polyketone becomes stiff and keeps damping, it can make a superior material for wind instruments. Marc Schaefer, aka Enthalpy
  15. Stretching might stiffen and strengthen polyketone too. Initial E=1.3GPa and sigma~58MPa aren't brilliant, but polyketone is potentially very cheap, it has a good operating temperature range, low water absorption and high vibration damping. Maybe stretching brings a nice combination of properties. Polymers used as super-fibres should also improve as bulk materials. PA and PET, PEEK too. Machining would become easier too, useful for PA. Marc Schaefer, aka Enthalpy
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