<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=Content-Type content="text/html; = charset=us-ascii"> <META content="MSHTML 6.00.2800.1126" name=GENERATOR></HEAD> <BODY bgColor=#ffffff> <DIV>Richard</DIV> <DIV> </DIV> <DIV>I guess that it is air compression that throw the bullet out of the gun, I = understand deceleration occur as soon an object is not propelled.</DIV> <DIV> </DIV> <DIV>Tubular shanks loaded with compressed air for piano hammers = (patent pending)</DIV> <DIV> </DIV> <DIV>Greetings</DIV> <DIV> </DIV> Isaac OLEG Entretien et réparation de pianos. PianoTech 17 rue de Choisy 94400 VITRY sur SEINE FRANCE tel : 033 01 47 18 06 98 fax : 033 01 47 18 06 = 90 cell: 06 60 42 58 77 <BLOCKQUOTE dir=ltr style="PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px = solid; MARGIN-RIGHT: 0px"> <DIV class=OutlookMessageHeader dir=ltr align=left>-----Message d'origine----- De : pianotech-bounces@ptg.org [mailto:pianotech-bounces@ptg.org]De la = part de Richard Brekne Envoyé : dimanche 27 avril = 2003 12:26 À : Kevin E. Ramsey; = Pianotech Objet : Re: hammer velocity </DIV>  "Kevin E. Ramsey" wrote: <BLOCKQUOTE TYPE="CITE">Richard BrekneI believe = there is a letoff position (just under 1mm) that is so close that the hammer = does not have a chance to start de-acceleration. I havent gotten into all = this side of things very much yet, so I am not sure of myself here, but isnt = there some sort of "left over" force that keeps an object in acceleration = for some small period of time even tho the origional applied force is removed = ?  Like a bullet coming out of a rifle ?? Doesnt that meet its maximum acceleration some few milliseconds after the explosion of the shell ? RicB     No, Richard, no "left over" force is = there to continue accelerating an object after it's direct influence is = removed. If you really want to know what happens inside a rifle, feel free to = write me privately. No, the bullet doesn't continue accelerating after = leaving the barrel.  The only thing that I think could possibly continue accelerating a hammer after the jack has tripped would perhaps be = the flex of the shank becoming straight again, but at 1 mm, I'm not sure that = it could be measured without high-speed cameras to capture the action.    In reality, the pianist has the skill to adapt to the instrument, and = still make music.  All we can do is to provide them with the best = regulated and voiced instrument we can, and they can take it from there, if = they are truely "musicians".Kevin.</BLOCKQUOTE> Well like I say guys... I havent brushed up my inertia physics = in a long time :) Another fellow (who knows I like Star Trek series) wrote = privatly to me as asked me if I'd ever seen the episode where the Enterprise = does a saucer seperation... and he aske me "now is the saucer accelerating = away from the ship, or is the ship just slowing down faster"... I kinda got the = point :) Still, there does seem to be some pent up force in the entire = system that is throwing the hammer upwards. Key and shank flex are two that get = mentioned a bit in this connection. Seems to me that all this is the direct = result of the amount of force put on the keyfront. Just where and how this pent = up energy gets released I am unsure of. Within the space of 1mm  of = key travel perhaps ? btw... the rifle thing... I dont think I mentioned anything about = after leaving the barrel... did I ? I think I said quite clearly after the = initial explosion. Cheers -- Richard Brekne RPT, N.P.T.F. UiB, Bergen, Norway = <A href="mailto:rbrekne@broadpark.no">mailto:rbrekne@broadpark.no</A> = <A = href="http://home.broadpark.no/~rbrekne/ricmain.html">http://home.broad= park.no/~rbrekne/ricmain.html</A>   </BLOCKQUOTE></BODY></HTML>