The Pitching Deck Saga

[micro]

Sorry for the delay fellas. Well, here is what I have so far on the pitching deck: long story short, the deck was made to pitch by slewing the pilot-able version of Javier’s carrier. I chose that as my “aircraft”, raised the altitude to about 30 feet, and then started pitching with my stick. I recorded it with FS-Recorder, and then played it back to land on.

Now, because it is technically an aircraft dressed up to look like a carrier, the meatball does not work. So what I’m trying to do is take track of the pitching carrier and insert it into a mission where the real carrier plays it back. That way everything will work, and you might even have a tanker on station to really get your blue water jollies.

If you open up the sim.cfg for the carrier, you’ll see a line at the bottom that says “static_pitch”. While tinkering with that I discovered that the FLOLS is actually stabilized (kind of). In the following pictures I set the pitch from +1.0 to -1.0 hoping that would get the deck to start pitching.






Unfortunately the deck stays at the pitch angle you set, but if you notice, the ball is not “physically” attached to the model. It kind of floats in its normal position giving the illusion of being stabilized. The problem, as you can see, is that as the bow of the ship goes down, the deck actually starts to obstruct the ball. Just like in real life, the solution to this would be to have a higher than normal glideslope (3.5 – 4.0 degrees). Maybe someone out there with a knowledge of the FLOLS in Flight Sim can tell us if that is possible, but I would have no idea how to pull that off.

As for making the carrier itself get a pitching motion: according to the guys at FSDeveloper it should be possible, but for the moment it has a lot of people scratching their heads (go to fsdeveloper.com forums and search ‘bobbing’). That’s why I’m trying the mission route. That is where I am at. I would gladly appreciate anyone and everyone to join in on this project. Maybe together we can knock this out.

[neutrino]

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, but because in the carrier missions the carrier is moving at 35 kts and there is 10 kts headwind, that 4.00 degrees is a good value. The route you're following seems correct, I'll scratch my head too, see if anything comes up  

[Razgriz]

I can look around and provide some insight, but I'm no expert with carriers.  I'd love to see pitching deck ASAP, so I'll look around.

[SpazSinbad]

USN LSO NATOPS might interest those looking at the pitching deck and associated issues. Graphic from one example (there are many online with different publish dates but the data is mostly the same): http://www.navyair.com/LSO_NATOPS_Manual.pdf (1Mb) EDIT Matter of fact same PDF (one of the smaller example PDFs) zipped should fit here BELOW.

[Razgriz]

USN LSO NATOPS might interest those looking at the pitching deck and associated issues. Graphic from one example (there are many online with different publish dates but the data is mostly the same): http://www.navyair.com/LSO_NATOPS_Manual.pdf (1Mb) EDIT Matter of fact same PDF (one of the smaller example PDFs) zipped should fit here BELOW.

You're really a PDF ninja.   

[SpazSinbad]

It's what I do! They're everywhere - including in my sig below. 

[ESzczesniak]

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...

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]

I can say from my experience with the carrier-ILS-capable HUD, that the ball is set at exactly 4.00 degrees

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?

[micro]

Yeah Spaz, I think you may be over-complicating the scenario. What I’m referring to is that that FLOLS seems to be at 3.0 degrees in the multiplayer carrier mission. The ILS I made and the ball on the ship, seem to give the same glideslope information all the way down (as they should). Since I set my ILS to 3.0 degrees, I thought that is what the ball was set to.

Whether it be the ILS (ICLS) or the ball, they will and should always give the same info regardless of the conditions as they should be parralel. The effective glideslope comes into play only as the ship moves forward through the water and shallows out the approach profile.





Just as the pilot is expected to correct for the line-up moving to the right, he/she is also expected to correct for the apparent glideslope change.

[SpazSinbad]

microbrewst, OK thanks for explaining. I'll shutup now. 

[micro]

I did not mean it that way at all bud. I hope you didn't take it that way. Like I said, I'd like everyone to chime in on this. By all means, lets do this together and figure this out!

[SpazSinbad]

microbrewst, I cannot help with the sim part because I have never nor will I be likely to use the multi player or other missions (except what is in standard FSX Accel missions). Even though you explained about part of the conditions you did not mention WOD (how much) or if the carrier moved. Perhaps this is obvious to the mission user but I'm not in that boat.

I'm not sure if the small LSO PDF manual goes to all the detail. One or similar goes to a lot of trouble to explain all the variables. I will check. Forgive me for another PDF....

http://server2.simulacion-esp.com/Janes%20FA18/Documentacion/?download=Landing_Signals_Officer.pdf (5.5Mb)

A heck of a lot more detail is in this PDF "LANDING SIGNAL OFFICER REFERENCE MANUAL" but if it is relevant I'm not sure. For the moment I'll leave my investigation at this reference because otherwise I have seen now too many LSO PDFs (that are more or less the same) with this last larger one being comprehensive.

[Razgriz]

Maybe some sort of model animation could make it pitch on the CoG.  I do believe the meatball is lined up with where the carrier pitches, so it has minimal movement.