It would be interesting to take an optical mouse assembly and focus it at infinity at the ground in an airplane. They don't account for rotation, but it would give you a fairly accurate idea of how fast you were moving both forward and sideways. Banking would show as a sideways movement with a corresponding return. Requires daylight flight, during which you probably don't need it, but still... I've heard people have hacked these into car speedometers. -Adam John Ferrell wrote: >You would be surprised how well you can read a compass in a light single >engine airplane on an overwater flight out of radio range. I suppose GPS >changes that now days, but not enough to rid the cockpit of the compass! > >BTW, unless things have changed, in the US every aircraft needs to have a >compass correction card but there is no rule that requires that it be filled >out! In all fairness, compass navigation to any real accuracy requires you >to know a lot more about the wind than you usually do. > >John Ferrell >http://DixieNC.US > >----- Original Message ----- >From: "Howard Winter" >To: >Sent: Thursday, June 10, 2004 5:10 PM >Subject: Re: [EE:] Mounting a compass sensor in a car > > > > >>On Mon, 19 Apr 2004 23:58:03 -0500, PicDude wrote: >> >> >> >>>> In use, it was a different story. Every time you remove or install >>>> >>>> >a > > >>>>piece of equipment in your vehicle, you have to check it doesn't >>>> >>>> >interfere > > >>>>with the compass, and re-calibrate if it does. >>>> >>>> >>>Sort like like how aircraft compasses get re-calibrated every time any >>>equipment is changed. They just add a little card with correction >>> >>> >factors > > >>>(degrees) for major points. >>> >>> >>Actually, "doing a compass swing" is quite an involved process - I've >> >> >helped do one. Some airfields have a > > >>"compass base" - a concrete circle that's well clear of any interfering >> >> >metal on which you place the aircraft, > > >>and you have to manually rotate the aircraft (I'm talking light aircraft! >> >> >:-) and repeatedly re-adjust the > > >>compass compensators to minimise the errors overall. This is with the >> >> >electrics and the engine all running. > > >>When you have it minimised, you then read the error at the 8 main compass >> >> >points, and write it on the > > >>correction card. What always amazes me is that when you're flying you >> >> >can't read the darned thing more > > >>accurately than about 5 degrees, but the correction card is filled-in down >> >> >to single degrees! :-) > > >>Cheers, >> >>Howard Winter >>St.Albans, England. >> >>-- >>http://www.piclist.com hint: PICList Posts must start with ONE topic: >>[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads >> >> > >-- >http://www.piclist.com hint: PICList Posts must start with ONE topic: >[PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > > -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics