Hi John, I can't help you with the replacement instrument, but I can give you my impression of the zero error.
As I understand it, zero errors appearing over time in mechanical varios is due to minute changes in the mass of the paint on the needle over long periods of time. The needle basically gets lighter as remaining volatile elements of the paint gradually escape. I agree with Independent Instruments that a hairspring would not normally be used to correct this zero offset error, what would be required is adjustment to the counterbalance on the other side of the needle. Otherwise you would have the needle affected by acceleration (e.g. it would read too high or too low when circling). Before you throw out the vario, try checking the installed system for leaks, as it is possible that the vario wasn't sealed or the baffles were damaged during the repair; and it is also possible that the old tubing used to connect it to the static source may have hardened over time and will not seal now. If I were you, I would cut an inch off the static tube and try that. Disclaimer: I'm an aerospace engineer, not an instrument technician. John Wharington On Mon, 2006-04-24 at 13:24 +1000, John Giddy wrote: > I should add that the panel is cut for an 80 mm diameter instrument. > No flask is needed, as a serviceable one is already mounted in the glider. > John G. > -- > John Giddy > 5/287 Barkers Rd > Kew, Victoria, 3101 > AUSTRALIA > tel/fax: +61 (0)3 9818 4524 > > John Giddy wrote: > > Further to my last post on this topic, it now seems that the vario I had > > "repaired" at Independent Instruments is stuffed (technical term). The > > original problem was just a zero error, which I was loth to fix myself, > > as it was not easy to remove the glass to get at the movement. The error > > seemed to be a balance one, rather than a spring setting. > > When I got the vario back from Independent Instruments, it was reading > > zero OK, but was entirely dependent on gravity for the restoration > > force. When I took it back to them, they maintained that there was no > > hairspring in such instruments, and that gravity was always used as the > > restoring force. I had my doubts, but, not having any qualifications in > > the instrumentation area, I felt I couldn't argue. Now that the > > instrument is mounted in the glider and a test flight done, we have > > determined that the vario doesn't work. > > I know I should take it back and complain, but I would rather just get a > > replacement and forget the whole mess. > > > > Does anyone have a secondhand working Winter Variometer for sale please? > > > > I don't want to fit a modern electronic vario, as the glider is a > > Bergfalke II-55, which would have been fitted originally with a > > mechanical vario. > > > > Regards, John G. > > > > John Giddy > > 5/287 Barkers Rd > > Kew, Victoria, 3101 > > AUSTRALIA > > tel/fax: +61 (0)3 9818 4524 > > > > John Giddy wrote: > >> Thanks for that Ian. > >> I don't know, but I suspect that Independent Instruments may be under > >> new management, as I didn't see the old gentleman and lady there on > >> any of my four visits over the last couple of weeks. > >> They always gave great service, but I am not sure the current lot have > >> the same dedication to quality. > >> Cheers, John G. > >> > >> > >> Patching wrote: > >>> Good question John, > >>> We had the same experience. I was going to send my ASIs' to Adelaide > >>> but it is actually cheaper to buy a new one from Wade Air in NSW. I'm > >>> not sure about the other instruments. > >>> The big question is just how old are the instruments? > >>> I am slowly replacing mine with new ones. > >>> Cheers > >>> Ian P. > >>> Kookaburra Precision Soaring Team > >>> ----- Original Message ----- From: "John Giddy" <[EMAIL PROTECTED]> > >>> To: "Discussion of issues relating to Soaring in Australia." > >>> <aus-soaring@lists.internode.on.net> > >>> Sent: Friday, April 07, 2006 5:59 PM > >>> Subject: [Aus-soaring] Instrument repair > >>> > >>> > >>>> Hi All in Victoria, > >>>> Where do people go for repair/calibration of instruments such as > >>>> ASIs, Varios, Altimeters etc. ? > >>>> I have been using Independent Instruments at Moorabbin, but my last > >>>> experience has not been entirely happy, and I would like another > >>>> possibility... > >>>> Cheers, John G. > >>>> -- > >>>> John Giddy > >>>> 5/287 Barkers Rd > >>>> Kew, Victoria, 3101 > >>>> AUSTRALIA > >>>> tel/fax: +61 (0)3 9818 4524 > > _______________________________________________ > > Aus-soaring mailing list > > Aus-soaring@lists.internode.on.net > > To check or change subscription details, visit: > > http://lists.internode.on.net/mailman/listinfo/aus-soaring > > > _______________________________________________ > Aus-soaring mailing list > Aus-soaring@lists.internode.on.net > To check or change subscription details, visit: > http://lists.internode.on.net/mailman/listinfo/aus-soaring _______________________________________________ Aus-soaring mailing list Aus-soaring@lists.internode.on.net To check or change subscription details, visit: http://lists.internode.on.net/mailman/listinfo/aus-soaring
