Su25 ADI Problem

[GhostDog]

When flying the Su-25 in FC2, patched, I experience an issue with the heading bug and waypoint needle on the ADI. I start-up, taxi and takeoff normally, and after I'm airborne, I select "route" mode. The HSI course and waypoint arrows show that I am on the correct course, and the ADI altitude indicator works properly, but the ADI heading bug and waypoint needle don't indicate that I'm on the correct course. The attached screenshot illustrates the issue. Note the HSI needles and the waypoint selection on the short-range navigation panel.

[hassata]

allowing enough time for INS to align maybe?

[GhostDog]

allowing enough time for INS to align maybe?

 

I take at least 7 min from startup to takeoff. Should I wait for the INS to align before I start to taxi?

[hassata]

I would think you'd be ok with 7 mins. Maybe try waiting to taxi until someone with better knowledge chimes in.

 

Edit: Just throwing stupid suggestions out there, but does the HSI show you on the correct course, or 180 degrees off? Also, the ADI waypoint needle isn't so much that as it is a 'route' indication-so maybe go 30 or so degrees to the right, wait for the needle to start moving in to center then turn left to intercept, stopping at the correct heading to waypoint, but now on the correct line or 'route' there as planned.

Edited September 10, 2010 by hassata

[Kuky]

You need to give about 2min with avionics on and engines running before taxing. The missalignment comes as you taxi and turn, the harder/tighter the turn, the more the missalignment, if you taxi very slow and turn slowly it won't be that bad, but west is give 2-3min warmup before taxing out.

[GhostDog]

I'm certain I'm on the right course, so maybe it's the INS. I'll wait a few minutes before taxiing and see if that resolves it.

[mvsgas]

Could it be drift cause by wind? I have never taken the time to test it in FC2, but that is a known thing for navigation.

 

http://www.flightsimaviation.com/aviation_theory_23_VOR_Navigation_part_3.html

http://www.navfltsm.addr.com/ndb-nav-adf-2.htm

http://www.faa.gov/library/manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2015.pdf

Edited September 10, 2010 by mvsgas

[hassata]

Could it be drift cause by wind? I have never taken the time to test it in FC2, but that is a known thing for navigation.

 

http://www.flightsimaviation.com/aviation_theory_23_VOR_Navigation_part_3.html

 

Cool site.

[GhostDog]

I'm still getting weirdness. The strange thing is, about 30-40 km into my route, the ADI comes to life and aligns with my heading and course, then about 10 km later it dies again. I've attached a track so you can see for yourself.

iaf_nav.trk

[hassata]

Is this happening in all missions? Even quick missions?

[GhostDog]

Is this happening in all missions? Even quick missions?

 

I haven't flown any other missions. I'm working on getting up to speed with the Su-25.

[mvsgas]

Looking at part of you track , it look to me you just had to correct a little bit to the left. I see what your saying but, if I understand correctly and based on my experience with the SU-25, the ADI is a bit more precise than the HSI. What I mean is HSI will get you to the correct city while ADI will get you to the correct neighborhood ( I hope the analogy makes since)

 

So if your willing, try correct (a few degrees left or right, according to the yellow line on the ADI) See if that help.

 

Also, do not chase the needles, that may get you in Pilot Induce Oscillation (PIO) The Needle may jump around from time to time anyway, specially when you get closer. I stop looking at them when I get within 10 kilometers.

 

Hope this help in some way, if any.

 

One question, if you do not mind; why did you waited so long to raise your landing gear?

[hassata]

One thing I would suggest, jump on one of the online servers. You can fly someone's wing and they can cross check the nav indications and provide some tips. Almost all of the servers have someone helpful on at any given time. Fire up teamspeak and give it a go.

 

I would tend to agree with mvsgas. The ADI nav indication is sort of like ILS where you ahev to be very precise in following the planned route to get the needles to line up.

[GhostDog]

Looking at part of you track , it look to me you just had to correct a little bit to the left. I see what your saying but, if I understand correctly and based on my experience with the SU-25, the ADI is a bit more precise than the HSI. What I mean is HSI will get you to the correct city while ADI will get you to the correct neighborhood ( I hope the analogy makes since)

 

So if your willing, try correct (a few degrees left or right, according to the yellow line on the ADI) See if that help.

 

Also, do not chase the needles, that may get you in Pilot Induce Oscillation (PIO) The Needle may jump around from time to time anyway, specially when you get closer. I stop looking at them when I get within 10 kilometers.

 

Hope this help in some way, if any.

 

One question, if you do not mind; why did you waited so long to raise your landing gear?

 

I'm still a bit noobish, and I'm learning how to use my new pedals and HOTAS as well, so that's what's behind some of my less than proficient manuevers. But as far as being slightly off course, the ADI wouldn't be that far out of whack if I only needed to correct by a few degrees. And that wouldn't explain why it doesn't respond no matter what direction I fly (I've tried that), nor the intermittent behavior.

[hassata]

It would. Its not a matter of a few degrees. If you've been flying a few degrees off course for a while, it could take several minutes of flying a 30 degree angle ofset to re-intercept the correct course. Try this: turn ninety degrees in the direction of the needle, keep flying for at least 5 mins, see if it moves towards the center. You need to get on a precise line to the waypoint, 1 out of 360, so its pretty narrow window. Try an ILS landing as well.

[GhostDog]

Even if I were drastically off the course line, and you can see that I intercept the course line shortly after takeoff, as long as I was on the proper heading, the heading bug on the ADI would reflect that, and you can see that it never moves. My aircraft handling is a bit clumsy, but I know how to bushwhack, and I know what's in the range of possible deviation within a given time at a given windspeed (in this instance I think it's around 5 m/s). Something else is going on.

[GhostDog]

I let the INS align for a few minutes after selecting route mode. That did the trick.

[hassata]

Nice-glad it's all sorted.

[mvsgas]

Like I thought and like it is explained in all the links I posted, it is just typical navigational drift.

I set up a simple flight from Krasnodar East ( Pashlovskly) to Milenova with one way point over Mykop. I used bad weather ( cross wind, turbulence and low visibility) I also used a heavy and asymmetric load out ( Three external wing tanks, 2 R-60 and one jamming pod) to force me to trim heavily. Eastbound leg was flown at 5000m MSL and on the return flight I got bored so I descended to low altitude flying anywhere from 1000 meter to 300 m ( indicated by radar altimeter). I was able to have all navigational indicator centered and I was not paying attention to the sim, I just trimmed and eat a snack, drink coffee and walk around my living room bored. It took me about 1:30 minutes and I used my track IR so camera is constantly moving as I sat down and check on the sim or as I moved around.

 

If you guys want to see , here it is. Be mind full that is extremely boring...

lol is to large, Douh!

http://www.megaupload.com/?d=E99GO88K

 

PS

Eagle Dynamics, great job. Trim and navigation is amazing. I can't wait for more from you guys. Thank You

Edited September 11, 2010 by mvsgas

[GhostDog]

Thanks for the help guys.

[mvsgas]

Hope I was able to help