General Category > Unofficial F/A-18 Acceleration Pack board
Determining Carrier Heading
SpazSinbad:
sun444, it has been awhile but thinking about all these issues can numb one's brain.... ;D Yes there are theoretical issues but practical rules. It is best to be practical as SLUDGE is suggesting. On carriers there are instruments (often including an actual wind flag or two visible forward from the bridge) to help find the wind to have it going down the angled deck. The LSO will keep an eye on this also with his instruments at his station, wind swirling around the island in certain situations may affect the WOD. There are +/- factors.
Perhaps FSX does not always simulate the real world so well either but I have not tried to investigate that thought. Perhaps lots of experimentation will find an ideal WOD setup formula. Keep in mind that the carrier is moving (relative to the approaching aircraft) away & to the right, so the aircraft has to constantly 'wing waggle' to the right to correct lineup. Perhaps further experimentation could allow for this in the wind setup but by now my brain hurts and I'll stop. ;D BTW 'drifting' by starting either right or left of the angle deck centreline to allow either ship movement or wind direction or both to move the aircraft to centreline at touchdown is a recipe for a crash and never allowed anyway by the LSO. Why the crash? The aircraft centreline is not parallel with the angle deck centreline and at right angles to the arrestor gear (if the aircraft is allowed to drift as may be the case ashore). Drift and not lined up will cause an arrest crash/tipover (depending).
Keep in mind that the way to do the carrier approach is purely visual looking at the mirror and angle of attack and line up down the angle deck. Within reason (with the WOD more or less down the angle deck) then nothing else matters. Follow all the visual cues staying 'on glideslope, on lineup at Optimum AoA' and you will have a good landing experience. It is essential to start well and to remain on the three parameters to the best of your ability constantly.
SpazSinbad:
I'll start another thread about WOD.
http://dictionary.babylon.com/wod/
"VFA-13 Aviation Glossary
Wind Over Deck. The relative wind caused by an aircraft carrier's motion. Usually the carrier is turned so the actual wind is aligned down the axial [here I think this definition found online is in error - it should say 'angle' instead of 'axial' but perhaps times have changed] carrier deck during recovery."
The wind likely does not blow steadily in force or direction so in any event some averaging out is necessary by carrier to get an average WOD (with other factors). The carrier may deviate from a defined BRC by one or two degrees if conditions require it but probably if WOD is within limits set (from practical experience on that particular carrier) then the carrier remains on a steady course while the sea wind fluctuates slightly so then will the WOD. On old slow carriers finding wind was important while 'searching for wind' by looking for 'wind lanes' on a calm ocean could consume everyone onboard. This will never be a problem on a CVN though. It makes WAVES! ;D
_____________________
EDIT Did some LSO NATOPS researching to discover this:
http://www.robertheffley.com/docs/CV_environ/00-80T-104--LSO%20NATOPS.pdf
(LSO needs) Accurately calibrated relative wind indicator (RHW). 1997 LSO NATOPS
EXCESSIVE WIND-OVER-DECK OPERATIONS (RHW=Relative Head Wind or WOD)
Turbulence and ramp burble increase significantly with RHW values in excess of optimum, resulting in an increased frequency of high landing gear loading. Winds starboard of the angle also adversely affect recovery conditions. The burble, aft of the ramp, becomes stronger and moves closer to the ship as the magnitude of recovery crosswind is increased. The airflow disturbance requires corrective pilot technique if the recovery crosswind exceeds 7 knots for all carriers. Even with corrective pilot technique sinking speeds 3 to 6 feet per second in excess of those experienced during normal (no recovery crosswind) operations can be expected. For these reasons, recovery headwind should be maintained as closely as possible to the optimum velocity and the centerline of the landing area. Shipboard aircraft recovery operations with recovery crosswinds in excess of those specified should be avoided.
________________________
http://www.vaw120.navy.mil/NATOPS/UE_Instructions/LSO%20NATOPS.pdf
2007 LSO NATOPS (RHW = Recovery Head Wind)
Wind Over Deck (WOD) Requirements
RHW should be maintained as close as possible to the optimum velocity and the centerline of the landing area.
CAUTION
The LSO shall immediately inform the air officer of any adverse wind
conditions unsafe to aircraft recovery, and the air officer shall inform the
LSO of downwind recovery situations. EMCON conditions permitting,
pilots shall be advised of adverse wind conditions or downwind recoveries.
______________
EXCESSIVE WIND-OVER-DECK OPERATIONS
Turbulence and ramp burble increase significantly with RHW values in excess of optimum, resulting in an increased frequency of high landing gear loading. Excessive crosswinds adversely affect recovery operations. If the recovery crosswinds exceed 7 knots, rates of descent 3 to 6 feet per second in excess of those experienced during normal operations can be expected, even with corrective pilot technique.
Shipboard aircraft recovery operations with recovery crosswinds in excess of 7 knots require the approval of the CV/N commanding officer.
Sludge:
Sun...
I dont think Im in error on this one. Either by my practical FSX way (just using 10 deg instead of 9, as is the real offset of the angled deck), or by CV NATOPS, which is "the bible" used in US Naval Aviation.
http://a4skyhawk.org/specials/cv-natops-21oct99.pdf
I know its dated '99, but since modern carrier aviation has been around since the Vietnam era, I think its safe to say this is a valid document. On NATOPS pg. 5-19 (pdf pg. 87/126), fig. 5-6, the illustration shows a natural wind down the angled deck. It might be off a deg or two, who is to tell. Additionally, one of the board posters here, Average Joe (a prior real-world USMC WSO on delta Hornets), gave me some real world info. to work with when I was tweaking the Sludge, as to how the pattern is flown and what conditions exist.
Finally, I have flown this in FSX using this specific technique for carrier landings, setting up the FSX wind 10 deg left of BRC and it has worked like a champ. Most of the board posters that have flown with me on the weekend multiplayers we did this winter should be more than happy to tell you how my patterns were usually "on the numbers".
I dont think youre entirely wrong, as there is probly some vector addition involved, but from what Ive used in FSX and what CV NATOPS says, it is fairly negligible. Also, thanks Spaz for the LSO NATOPS pull. Good info there.
Good question, no doubt.
Later
Sludge
sun444:
I was just looking at it as a physicist, not as a pilot, and forces from different directions are added by adding the vectors. Of course Sludge you're right considering the real situation or let me say the situation in FSX. I hope you don't take it as me being a wise guy.
No it's just that I was siumlating autopilots for terminal guided weapons at Martin Lockheed and I had to take all kinds of effects into the account.
Now I'm going back and do some more recording tests, doesn't look bad so far.
CU
sun
Sludge:
Sun...
No big deal, it was a good question, and made me question where I came up with it. Just made me do some digging and re-verifying where I got my numbers and procedures.
I was wondering if you have used Orion's SFCarrier mission? That has some good views, the carrier moves and provides good Wind-over-Deck (35 kts), and if using two people, Im sure we could get the views and the action covered. Heck, I could even add some 30 sec Fraps clips, and then we could "crop out" the "FRAPS" title overhead? Youd also be able to get me in the "grunge Sludge" w/full effects (ie, smoke "puffs" when LSO calls for power) in the PLAT Cam. Ill email you my carrier landing video ideas template.
Later
Sludge
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