RAAF Hornet HUD

[SpazSinbad]

Hi Resolution photo of an RAAF Hornet HUD is here:

http://www.defence.gov.au/opEx/exercises/bersamapadu10/gallery/20101011/20101010raaf8165233_024.jpg

Only a thumbnail pic here:



Explanation from Legacy Hornet NATOPS here: EDIT: Meant to add this text from Legacy Hornet NATOPS yesterday - apologies. Text is repeated below now also....

F/A-18A/B/C/D NATOPS:
"Velocity vector. The velocity vector provides the pilot with an outside world reference with regard to actual aircraft flight path. The velocity vector represents the point towards which the aircraft is flying (aircraft flight path). The position of the velocity vector is limited to an 8° radius circle centered at the HUD optical center. If the velocity vector reaches this limit during high angle of attack flight or large yaw and/or drift angles, then it flashes rapidly to indicate that it does not accurately indicate flight path. With GPS or EGI installed, if the INS velocity data becomes unreliable, the mission computer utilizes the GPS information. If INS velocity data becomes unreliable the mission computer utilizes air data computer information and the last available wind data to compute the velocity vector and this degraded velocity vector is indicated by a slow flashing of the symbol. In the NAV master mode, the velocity vector may be caged to the vertical center line of the HUD by the cage/uncage switch on the throttle. When it is caged, a ghost velocity vector is displayed at the true velocity vector position if that position is more than 2° from the caged position. The flight path/pitch ladder and steering information are referenced to the caged position. The ghost velocity vector flashes when limited. With MC OFP 09C, 11C, 13C, and 15C, the flight path/pitch ladder is referenced to the waterline symbol when the velocity vector is caged.
WARNING
Sustained climbs and descents can result in uncued vertical velocity placement errors and subsequent HUD velocity placement errors. Error magnitudes increase at slower airspeeds and lower altitudes. Errors of up to three degrees have been observed in the landing configuration. Three minutes of level flight may be required to allow the INS to correct the vertical velocity function."

[neutrino]

Spaz, this is the best HUD picture I've ever seen. It contains so much information. Thanks for finding it 

[Sludge]

Spaz...

x 2 to what JR said.  Also, what does the PLUS symbol indicate just above and to the right of the Horizon Bar on the Pitch Ladder?

Its now very clear how a HUD draws its lettering.  Using vector graphics, it literally connects-the-dots between points to make up numbers/letters/HUD symbology.  The number 8 for example is 15 points connected by lines.

Again, thanks for the great pic, Spaz.

Later
Sludge

[Razgriz]

Its now very clear how a HUD draws its lettering.  Using vector graphics, it literally connects-the-dots between points to make up numbers/letters/HUD symbology.  The number 8 for example is 15 points connected by lines.

Engineer wizzo here (me) figured that one out.  That is also a reason why the VRS has lag issues.  It has to do numerous calculations to properly calculate the vectors on a 3d graph, and connect the lines, probably at 35FPS [35 times a second, can legally classify as cpu physical abuse].

[Sludge]

Raz...

Yes, you did.  Good job, future-WSO "wizzo".  And yes, its frame rate intensive, as we talked about what Scott figured out trying to make his original Hornet HUD vector drawn.  OUCH.

Later
Sludge

[SpazSinbad]

Sludge, looked for that 'plus' + sign explanation in both Hornet and Super Hornet NATOPS (both HUDs almost identical I think) without result. I can think of one explanation: that the + shows the boresight. With the boresight off to the right then for the sake of taking photo I suspect a bootfull of right rudder has been entered briefly. I'm only guessing on that score. Why that might be needed I don't know. Perhaps the aircraft is out of rudder trim by a large margin due to asymmetric store loading? Again I'm only guessing. Looking again at the overall picture it would seem that there is some 'out of trim' condition. Never seen a HUD of any kind, especially in flight to know anything about them. Extracted pages about the Legacy Hornet HUD from NATOPS are attached to this thread.

[SpazSinbad]

I had not posted text from Legacy Hornet NATOPS as intended yesterday, which will perhaps make clear why the 'ghost vector' is off to the left, with the boresight off to the right, with the flightpath vector in the middle. Meant to post this info with the first graphic above. I'm getting too old for this.  

F/A-18A/B/C/D NATOPS:
"Velocity vector. The velocity vector provides the pilot with an outside world reference with regard to actual aircraft flight path. The velocity vector represents the point towards which the aircraft is flying (aircraft flight path). The position of the velocity vector is limited to an 8° radius circle centered at the HUD optical center. If the velocity vector reaches this limit during high angle of attack flight or large yaw and/or drift angles, then it flashes rapidly to indicate that it does not accurately indicate flight path. With GPS or EGI installed, if the INS velocity data becomes unreliable, the mission computer utilizes the GPS information. If INS velocity data becomes unreliable the mission computer utilizes air data computer information and the last available wind data to compute the velocity vector and this degraded velocity vector is indicated by a slow flashing of the symbol. In the NAV master mode, the velocity vector may be caged to the vertical center line of the HUD by the cage/uncage switch on the throttle. When it is caged, a ghost velocity vector is displayed at the true velocity vector position if that position is more than 2° from the caged position. The flight path/pitch ladder and steering information are referenced to the caged position. The ghost velocity vector flashes when limited. With MC OFP 09C, 11C, 13C, and 15C, the flight path/pitch ladder is referenced to the waterline symbol when the velocity vector is caged.
WARNING
Sustained climbs and descents can result in uncued vertical velocity placement errors and subsequent HUD velocity placement errors. Error magnitudes increase at slower airspeeds and lower altitudes. Errors of up to three degrees have been observed in the landing configuration. Three minutes of level flight may be required to allow the INS to correct the vertical velocity function."