General Category > Unofficial F/A-18 Acceleration Pack board
The Pitching Deck Saga
SpazSinbad:
It's what I do! They're everywhere - including in my sig below. :o ::) ;D
ESzczesniak:
--- Quote from: neutrino on December 11, 2009, 11:39:09 pm ---Hi, micro, thanks for the update! I can say from my experience with the carrier-ILS-capable HUD, that the ball is set at exactly 4.00 degrees, for both the default and the Nimitz carrier. I don't know if that helps. It's pretty high...
--- End quote ---
I had issues with this all the way back in FS9. I was having troubles landing, needing 1000-1100 fpm descents to stay on slope sometimes. In my investigation, I found the ILS was set to 4.00 degress, not the 3.xx that a land based is. At first I thought this was really stupid. However, I was neglecting the 35 kts of wind over the deck (whether it's from the carrier moving or a static carrier with wind down the deck).
If you think about what 4.00 degrees means in terms of tangent that angle represents some vertical height in proportion to some horizontal distance. The problem is the frensel system is static...it assumes the carrier is stationary.
But it's not. Let's assume we start at 600' MSL and trace to touchdown. Then a 4 degree glide slope means we are 8,580' from touchdown (tan(4degrees)=600/base).
The problem is that at a speed of approximately 130 kts (making an averageish calculation here). This comes out to somewhere on the order of 35 seconds to touchdown (time=distance/velocity calculation).
Well, in that 35 seconds, a carrier moving at 30 kts (again, rounding) will have moved moved about 0.3 NM or another 1,800 ft (distance=velocity*time).
However, our starting height is still the same. So now the two legs of are triangle have changed from 600' MSL and 8580' to touchdown to 600' MSL and 8580+1800' to touchdown (10380'). So if we recalculate the new angle, 3.25 degrees (arctan(600/10380)--in orther words the dynamic glideslope is your basic 3 degree glideslope. The 4 degree static glideslope is necessary to accound for this.
Note, I'm doing this math using the google calculator from a hotel room, you'll likely get different...and more accurate...results if you repeat them with a real scienctific calculator.
SpazSinbad:
ES...., probably you cannot see the GIF graphic (or the PDF zipped) from your hotel room connection. Anyway the table in the graphic says this:
WOD 35 knots - Basic (glideslope) Angle 4 degrees = Effective Glideslope 3.2 degrees
WOD 30 knots - Basic 3.5 degrees = 2.8 degrees
*Based on a 130 Knot approach speed
Thinking about variables in a carrier landing can be fun! The damn thing is moving away and to the right all the time (unless it is stopped).
micro:
--- Quote from: neutrino on December 11, 2009, 11:39:09 pm ---I can say from my experience with the carrier-ILS-capable HUD, that the ball is set at exactly 4.00 degrees
--- End quote ---
While I do believe you, I'm a little confused by this. I made an ILS for the multi-player carrier mission when it came out and set the glideslope on it to 3.0 degrees. When I fly that ILS the ball is centered all the way down. Any ideas as to what is going on there? Also, does anyone know where the FLOLS effect/gauge/light (or whatever it is) is actually located in the FSX folders?
SpazSinbad:
microbrewst, what are the conditions in the situation you describe otherwise. Perhaps my previous post explains - but not knowing flight conditions (WOD etc) it is just a guessing game?
Not being an FSX or flightsim tinkerer under the hood I can surmise that the ILS is set to 4 degrees but having your glideslope set to 3 degrees (in the wind conditions described "WOD 35 effective angle 3.2 degrees" things work out? Or am I on the wrong track?
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