llh@midacs.UUCP (Linn Hower) (09/11/85)
> Subject: great circle program (rather long) > > Linn: > > I'm going to trust you to keep my net path confidential. [edited] > > You shouldn't have any trouble figuring this out or compiling it > assuming you are running Unix. I'm running under 4.2. I wrote all of this > and consider it in the public domain, so spread it around. There must be > better ways to implement this, but at least the algorythm you want is in here. Thanks to all who responed to my request for help with great circle navigating, especially the un-named pilot who sent me his nav program. It was a good start for me. The referenced _nav_ program took a command line such as: nav -from ida -to kden -via bpi ckw and looked into a clear text data base for location/altitude/etc for airports at Idaho Falls (IDA) and Denver (KDEN) and enroute vors (Big Piney (BPI) and Cherokee (CKW)) and ploted true and magnetic courses and distances for that route of flight. This was fine except that the ploting was great circle, i.e. not a constant heading (in general) from point to point, so to actually fly these routes would be quite difficult. This is where I started hacking (sorry un-named, but I just can't leave well enough alone). I hacked the nav programs to compute rhumbline (constant heading) from point to point. I used the algorithms in _HP-25 Applications Programs_ as suggested by several netters. To this I added a new switch and used the program like this: nav -from ida -to kden -rvia bpi ckw With the rvia switch the great circle course from ida to kden is calculated first. Rnav waypoints, defined by radial/distance on the rvia vor's, are selected that lie on this great circle course. Then the normal rhumbline flight planning, from point to [way]point is done. "Works for me." I will make either/both versions available to anyone who wants them. If there is enough interest, I will post to the net. Be forewarned... I'm not claiming these are error free or a nice interface. My appologies to un-named for hacking up his interface. Examples follow. One final thing... Can anyone point me to a machine readable database that contains VOR ident and name, lat-lon, and altitude? Also a similar airport/intersection database? Thanks... _---------------------------------------------------------------------------------_ nav -from ida -to kden Fanning (Idaho Falls, ID) IDA altitude: 4741 feet IDA to KDEN Magnetic: 108 Distance: 392.7 NM (true course 125, Total distance 392.7) Stapleton Int'l (Denver, CO) KDEN altitude: 5333 feet nav -from ida -to kden -via bpi ckw Fanning (Idaho Falls, ID) IDA altitude: 4741 feet vor BPI freq: 116.5 IDA to BPI Magnetic: 106 Distance: 102.5 NM (true course 123, Total distance 102.5) vor CKW freq: 112.2 BPI to CKW Magnetic: 099 Distance: 119.6 NM (true course 115, Total distance 222.0) CKW to KDEN Magnetic: 120 Distance: 173.5 NM (true course 133, Total distance 395.6) Stapleton Int'l (Denver, CO) KDEN altitude: 5333 feet nav -from ida -to kden -rvia bpi ckw Fanning (Idaho Falls, ID) IDA altitude: 4741 feet rvor WP1 freq: 116.5 wp BPI R-164.0 / 0.1 IDA to WP1 Magnetic: 106 Distance: 102.5 NM (true course 123, Total distance 102.5) rvor WP2 freq: 112.2 wp CKW R-167.0 / 25.1 WP1 to WP2 Magnetic: 109 Distance: 132.3 NM (true course 125, Total distance 234.8) WP2 to KDEN Magnetic: 113 Distance: 157.8 NM (true course 126, Total distance 392.6) Stapleton Int'l (Denver, CO) KDEN altitude: 5333 feet -- Linn Hower Phone: 208-526-9353 ...!ucbvax!ucdavis!midacs!isew02!linn