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FSX Foster RNAV XML gauge project.

Messages
62
Country
us-arizona
Progress finally on the Foster RNAV

After a lot of painful experimentation and work arounds of XML I think I have the RNAV math worked out and have it coupled to the HSI. I've tried several different waypoints and calculated the numbers using a terminal area chart for Phoenix and the numbers agree and the HSI points to the waypoint and the distance to go seems correct. The Century AP using the heading bug seems to have a problem but once established on course works OK. So what remains now is the buttons and switches for power and the display. I will have to figure out how to do a LED display that will show the VOR/DME data as well as the waypoint data.

I have included the math code below: The VOR_OFFSET value was inserted after the A:NAV1 OBS variable in the HSI (HSI from FSX Beech Baron gauge CAB) code with the exception of the OBS know INC/DEC element.

If anyone sees a problem with my code please speak up. I will appreciate any comments on the code and implementation method.

David

Code:
<!--convert VOR radial to 0-359 degrees-->
<!--calc angle between nav radial and wp radial -->
	(A:NAV1 RADIAL,degrees) dnor (L:WP1_BEARING,degrees) - s0 abs dgrd (&gt;L:VOR_WP_ANGLE,radians)
	
<!-- calc distance from WP to plane  = sqrt of (a^2 + b^2 - 2*a*b*cosC) 
a = wp dist from vor L:WP1_DISTANCE
b = dme dist VOR to plane  A:NAV1 DME
C = angle between nav radial and wp radial L:NAV1_WP -->
<!-- postfix  a^2 b^2 2 a b C cos * * * - + sqrt  -->
 
	(L:WP1_DISTANCE,nmiles) sqr
	(A:NAV1 DME,nmiles) sqr 
	2 (L:WP1_DISTANCE,nmiles)
	(A:NAV1 DME,nmiles)
	(L:VOR_WP_ANGLE,radians) cos * * * - + sqrt
	(&gt;L:DIST_PLANE_TO_WP,nmiles)

<!--calc VOR radial from WP in degrees
a = wp dist from vor  L:WP1_DISTANCE
b = dme dist VOR to plane A:NAV1 DME
c =dist from plane to WP  DIST_PLANE_TO_WP -->
<!--postfix  BAC = b^2 c^2 a^2 - + 2 b c * * / acos  -->

	(A:NAV1 DME,nmiles) sqr
	(L:DIST_PLANE_TO_WP,nmiles) sqr
	(L:WP1_DISTANCE,nmiles) sqr - + 2 
	(A:NAV1 DME,nmiles)
	(L:DIST_PLANE_TO_WP,nmiles) * * / acos rddg
	(&gt;L:VOR_OFFSET,degrees)
 	
	<!-- Calculate course to fly 
	if WP radial > VOR radial subtract VOR_OFFSET from NAV1 OBS
	If WP radial < than VOR radial add VOR_OFFSET from NAV1 OBS-->
	 l0 0 &lt; 
	 if{ (L:VOR_OFFSET,degrees) /-/ } 
	 els{ (L:VOR_OFFSET,degrees) (&gt;L:VOR_OFFSET,degrees)}
 
Last edited:
G

gr8guitar

Guest
Hello, did you get the RVAV to work? A long time ago, at: http://simviation.com/fsgauges4.htm there was Narco.gau that, if purchased, had RNAV. The maker was supposedly: David Newby Associates. I Googled this, and it's basically the same location (http://www.dnauk.co.uk) but no way that I know how to contact this person ('sending us an email' at the website doesn't function)...
 
Messages
2
Country
unitedstates
I realize this thread is long dead....but I've picked up the ball. I'm working on making a KNS80 gauge.
I have the dials and display finished and tried to above equations.

At first glance the distance equation is correct....shows the correct distance between the plane and phantom waypoint--
BUT as you get close...the distance will be wrong. If you look at the equation--it will NEVER goto a distance near zero.

I'm using the earlier approach of converting the polar's into Cartesian and going from there.

Since the real box would NOT have lat, long...I base my model using the angle and distances only...
making the real VORTEC at 0,0

It appears to work---I just need to run a lot of tests, in different quadrants to see if I accounted for everything.

:pat
 
G

gr8guitar

Guest
Hello. glad to hear you are working on the RNAV. You wrote:

Since the real box would NOT have lat, long...I base my model using the angle and distances only...
making the real VORTEC at 0,0

I must admit I'm confused because since the flight sim doesn't have an actual VOR transmitter, how can you bypass the lat , long requirements and conversions?
 
Messages
7
Country
us-pennsylvania
Message to Dave? I used your basic "core" XML file and developed a King "single waypoint" RNAV known from the 1970's as a KN 74, heard of it? At the present time, I am driving a special RMI indicator that shows the VORTAC I'm dialed in on (old ADF needle) and the waypoint "bearing" pointer (old VOR needle) and today I tried it on MS-FSX with almost an 88% satisfactory RNAV addition to my Piper Cherokee. Question is, can I ask you Dave, can I share my success with download sites like FlightSim.Com if I can finish the King KN 74 Project? In the day of GPS waypoints, I find it fun to "drop" a VHF-based waypoint anywhere I like, within range of the VORTAC and fly to it. Yes, I made my own Narco DME-190 to display either VORTAC or RNAV distances, etc. It's not done yet, but it's a nice addition to the King Silver Crown radios I posted already on FlightSim.Com download site. Comments? Ron
 
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