Strategy for pop up ... general question

[TOViper]

Hello Viggen drivers!

 

I have a general question regarding precision bombing, maybe I have overseen something here. :huh:

 

The difficulties I have at the moment is related to the TERNAV status.

It doesn't relate to a known bug or error in the module, it is more how things work in this old but wonderful bird.

 

Some facts (as I understand them) by reading the manual and other information around here give me the following understanding:

The radio altimeter feeds TERNAV with altitude information. The TERNAV then compares this altitude information with the internal map stored in a memory.

I guess this is done by mathematical correlation, and maybe using the altimeter setting (QFE) too ... ???

Then the TERNAV calculates a drift, and sends it to the CPU of the navigation computer. The navigation computer takes this drift into consideration and shows the waypoint symbols in my HUD at the correct position in relation to the outside world. OK, nice so far.

 

If I do bombing rides, I do it the usual way of approaching my target.

Very fast (at least M0.85, but not using burner at a distance > 15km), very low (often beside trees, which is hard in areas with dense wood ... *g*), and silently (no radar).

Then comes the pop up manoeuvre for the aiming phase (e.g. ARAK or low drag bombs for DYK). And here comes the problem.

 

I pop up late (<10km of the target) by pulling up, rolling 180°, pulling down, rolling 180°, and then diving depending on the weapon used.

During the pop up manoeuvre the radio altimeter is obviously not able to send radio altitude data to TERNAV since it looks into the sky, and this means that the position error increases quickly (this happens at my machine, and mostly in areas with flat terrain).

Then, when the diving is done, the TERNAV system is not able to re-calculate the drift in a timely manner since the distance was low and speed is high, and thus the waypoint is shown at a wrong position.

This leads to inaccurate bombing, which is - at least my personal - experience.

 

I tried flying the pop up upright (no rolls), by pulling, then pushing (g-lock is disturbing this process massively, which IMHO is not realistic as stated in another thread), and then performing the dive smoothly. I got some position errors flying this way too (TERNAV decreased from 5 down to 2). Only if I perform the pop up very(VERY) smoothly, the TERNAV status stays at 5 (at least sometimes it does). During this earlier and smoother pop up I can feel the heat around the corner from SAMS, AAA or EWRs, since my aircraft is exposed to many threats for a comparatively long time, which I don't like so much. :D

 

What can I do there?

Would it be a strategy to somehow "freeze" the drift or the navigation data (before performing the pop up) by turning off the radio altimeter or TERNAV?

Does anybody have work-around strategies for this specific problem?

 

Any answer is highly welcome.

 

Thanks guys and keep this wonderful bird flying! :joystick:

 

TOViper

 

EDIT: sorry for this long post ... :music_whistling:

[Home Fries]

Inertial and Doppler drift are not as extreme or fast-acting as you seem to think. You’re probably talking about no more than 3km of drift per hour. It’s a lot for precision aiming, but not that bad for navigation.

 

TERNAV compares the difference between the RADALT and BARO alt and compares the elevation with the terrain map in its bank, as you expected. However, instead of compensating for drift, it actually corrects its position. Therefore, if TERNAV has updated your posit prior to pop-up, your accuracy is not degraded. This is also why pre-GPS strikes often incorporate an IP that is easily visible by radar or eyeball, so that you can do an accurate position update just prior to drop.

[QuiGon]

As Home Fries said, drift is accumulating very slowly. So the amount of drift that is accumulating during a pop-up maneuver is so small that it shouldn't even be noticable. But you said your waypoint is shown in a wrong position, because of the pop-up maneuver. Well, have you checked the position of the waypoint before the pop-up? Because I think the wrong waypoint position is because it started drifting much earlier and accumulated over time.

That is why you should have an IP waypoint just before the target waypoint, which you can use to update your nav system as Home Fries said:

This is also why pre-GPS strikes often incorporate an IP that is easily visible by radar or eyeball, so that you can do an accurate position update just prior to drop.

Remember, the TERNAV was implemented in the Viggen with the AJS-Upgrade in the 90s. Before that there was no TERNAV to correct drift so Pilots would not have been able to do precise bombings at all, if drift would accumulate as fast as you thought it would.

 

Besides that, drift ist irrelevant for targeting in your example anyways, as ARAKs and bombs in DYK mode don't care about the waypoint position and drift. That's only important for BK90 employment and bombs in NAV/TOSS mode.

[TOViper]

Thanks very much for your answers guys.

Picture is getting clearer now, at least I think so.

 

What I sometimes see is that the target indicator ring in the HUD "jumps" around the "real" position (e.g. the middle of a bridge where I put the waypoint in the mission editor) during dive. The deviation is then somewhat of 10 to 100 meters or so, depending on TERNAV status (I think). When the dive is very long lasting (e.g. from higher altitude and/or less speed), the circle moves stepwise to the correct position, where it should be.

 

I think I will have to dig deeper and in more detail on this, in order to improve my overall understanding and how I can handle this and that during weapon deployment. I will start by flying stupid waypoints and observe the influence of my flying style on TERNAV and accuracy before using any weapon :noexpression:.

 

Will be a hard job in the bird they said ... :music_whistling:

[QuiGon]

The target circle jumps? Interesting, I have never seen it doing that.

 

Anyways: I think you're relying and focusing too much on TERNAV. It's just an aid for general navigation, nothing else. You still should perform a manual nav fix on the IP prior to the target waypoint.

Edited February 11, 2018 by QuiGon

[TOViper]

The target circle jumps? Interesting, I have never seen it doing that. Anyways: I think you're relying and focusing too much on TERNAV. It's just an aid for general navigation, nothing else. You still should perform a manual nav fix on the IP prior to the target waypoint.

 

Thanks QuiGon for this answer!

I think I have to produce a video. This means I have to record every single flight the next days. But never mind, I think it is worth it. :joystick:

At least my computer is capable of doing this. Power is everything in this case :D

 

Read you soon and kind regards

TOViper

[TOViper]

The target circle jumps? Interesting, I have never seen it doing that.

 

Hello folks!

 

Coming back from my supercomputer, I have attached a video showing what's going on in my aircraft.

 

The very short mission is to:

.) Engage 3 tanks at the old airfield, elevation 10m, QFE 1012.

.) Weapon: ARAK in ANF mode and target motion disabled (TAKT 221).

.) Data cardrige loaded, waypoint 3 is the target point M3.

.) TERNAV active

 

Approaching the target you may see that the target circle is not shown at the place where it should be according to the mission editor and the already set QFE.

It should be a little more to the right since I placed the waypoint directly on the second tank. The QFE is set correctly to 1012, but the target circle is not shown directly on the tank (to match the target circle with the tank it would be necessary to change QFE about around 5-10 hPa, which is far away from the calculated value).

 

When approaching the target I tried focusing on the HUD.

From this video I think QFE has much more influence than drift. Or there is something wrong, I really don't know.

 

Now, let's see what you guys see. :smartass:

 

Kind regards,

TOViper

Edited February 11, 2018 by TOViper

[Rudel_chw]

The little circle is just a reference where the computer thinks is the waypoint, it serves just to show you the general target location.

 

you do the targetting using the small central dot, have to place that over the target, it seems to me that you are using the "fin" as a sight.

 

Also the rockets have a minimum distance to target, and you fired below that minimum ... thats why the two vertical lines show up on the last few seconds. The point to fire is when the two "wings" appear on the sides of the sighting dot

 

On the first pass 5.25 the distance line shows up on the bottom of the display, thats your cue to be ready to fire, it appears two seconds before the firing point. At 5.27 the two wings appear, thats when you should fire, but the aiming dot was nowhere near the target.

 

At 5.34 the small vertical bars appear, telling you that you are now too near to fire.

 

The second pass is a bit better, but again you miss the firing cue (the two small "wings" around the aiming dot) and so the rockets fall long.

 

For this kind of target I prefer the high drag bombs, you can launch them at 100-150 meters exposing your craft much less ... the most common error with this kind of bombing is going too slow, as the firing cues will be so low on the hud that you will not see them, use a speed of M0.85

Edited February 12, 2018 by Rudel_chw

[Zabuzard]

Are you operating the trigger safety correct? You must line up on the target first, place the dot exactly over it. Only after that you should open the trigger safety.

 

At the moment where you open the trigger safety, the computer takes your movement and assumes your are following a moving target (like a vehicle). It therefore corrects the aiming sight leading the target.

That is, at the moment where you open trigger safety, if targeting a static target, you must not move the dot around.

In the video I can definitely see the assumed target position circle move while you approach. This, for me, is a sign that you had the trigger safety opened and the computer corrects since it assumes that you are following a moving target.

 

Target motion can be disabled by entering 221 (see the manual for details).

 

Also note that the computer makes an automatic navigation fix based on the impact of your weapons. So if you miss, you mess up your flight plan.

Edited February 12, 2018 by Zabuza

[Rudel_chw]

Actually, I found that if you fire the rockets just when the -.- cue appears, they will fall short ... so in reality I aim a bit long to compensate, like I do on this short sample:

 

tD3ntpnQbkc

 

This was a practice for a firing competition on our Virtual Squadron, the idea was that the rockets had to hit within the target ring but with no impacts outside the border square.

 

Since the Viggens rocket tend to spread quite a bit, for this flight I used just the two central rockets pods (ie no pods on wings), and a diving approach, to impact on a more reduced area.

 

If you hear carefully, you can hear the "click" when I operate the trigger safety cover, at that moment the computer removes the waypoint ring from the display, leaving just the aiming dot.

 

As Zabusa says, its a good idea to disable the Target Motion Detection, but the code for doing so is actually 221 ... I'm not 100% sure but I believe that RagnarDa mentioned that since a recent patch the default for TMD is OFF, so no need to worry about it.

 

Best regards.

[QuiGon]

Hello folks!

 

Coming back from my supercomputer, I have attached a video showing what's going on in my aircraft.

 

The very short mission is to:

.) Engage 3 tanks at the old airfield, elevation 10m, QFE 1012.

.) Weapon: ARAK in ANF mode and target motion disabled (TAKT 221).

.) Data cardrige loaded, waypoint 3 is the target point M3.

.) TERNAV active

 

Approaching the target you may see that the target circle is not shown at the place where it should be according to the mission editor and the already set QFE.

It should be a little more to the right since I placed the waypoint directly on the second tank. The QFE is set correctly to 1012, but the target circle is not shown directly on the tank (to match the target circle with the tank it would be necessary to change QFE about around 5-10 hPa, which is far away from the calculated value).

 

When approaching the target I tried focusing on the HUD.

From this video I think QFE has much more influence than drift. Or there is something wrong, I really don't know.

 

Now, let's see what you guys see.

 

Kind regards,

TOViper

 

Now I see what you mean. Well, this is just the general inaccuracy of the Viggens nav system. The waypoint circle is just a general reference of the target area and is not something that should be used for aiming as Rudel_chw pointed out quite rightly:

The little circle is just a reference where the computer thinks is the waypoint, it serves just to show you the general target location.

 

 

 

Are you operating the trigger safety correct? You must line up on the target first, place the dot exactly over it. Only after that you should open the trigger safety.

 

At the moment where you open the trigger safety, the computer takes your movement and assumes your are following a moving target (like a vehicle). It therefore corrects the aiming sight leading the target.

That is, at the moment where you open trigger safety, if targeting a static target, you must not move the dot around.

In the video I can definitely see the assumed target position circle move while you approach. This, for me, is a sign that you had the trigger safety opened and the computer corrects since it assumes that you are following a moving target.

 

Target motion can be disabled by entering 221 (see the manual for details).

 

Also note that the computer makes an automatic navigation fix based on the impact of your weapons. So if you miss, you mess up your flight plan.

He did disable target motion as you can see in the beginning of the video ;)

 

 

Actually, I found that if you fire the rockets just when the -.- cue appears, they will fall short ... so in reality I aim a bit long to compensate, like I do on this short sample:

 

*video*

 

This was a practice for a firing competition on our Virtual Squadron, the idea was that the rockets had to hit within the target ring but with no impacts outside the border square.

 

Since the Viggens rocket tend to spread quite a bit, for this flight I used just the two central rockets pods (ie no pods on wings), and a diving approach, to impact on a more reduced area.

 

If you hear carefully, you can hear the "click" when I operate the trigger safety cover, at that moment the computer removes the waypoint ring from the display, leaving just the aiming dot.

 

As Zabusa says, its a good idea to disable the Target Motion Detection, but the code for doing so is actually 221 ... I'm not 100% sure but I believe that RagnarDa mentioned that since a recent patch the default for TMD is OFF, so no need to worry about it.

 

Best regards.

Rockets seems to work fine for me:

 

Edited February 12, 2018 by QuiGon

[Rudel_chw]

.... Rockets seems to work fine for me

 

 

I'm glad, perhaps Heatblur corrected the slight sight error that you can see on my video, recorded on November on versión 2.2 ... I place the sight dot just beyond the target, yet my rockets all impact on the target :)

 

 

... anyway, the procedure is the same and hope that the OP can see that the TERNAV is more important for navigation than for actual shooting.

 

 

Best regards

Edited February 12, 2018 by Rudel_chw

[QuiGon]

... anyway, the procedure is the same and hope that the OP can see that the TERNAV is more important for navigation than for actual shooting.

 

Exactly :thumbup:

[TOViper]

Thanks guys for digging so deep. :thumbup:

 

One of the things I am doing wrong here is that I often open the trigger safety too early, and also did not pay enough attention to the small dot and the wings.

While you were watching the videos, I was doing a few rides more, and things are getting better and better.

As soon as I come back to my supercomputer, I will do some more flights, taking into account the tips you have given.

 

THANKS. Now the module get's hotter and hotter, day by day.

Isn't this great!?!?!?

 

Kind regards,

TOViper

[Rudel_chw]

THANKS. Now the module get's hotter and hotter, day by day.

Isn't this great!?!?!?

 

 

Glad we could help .. but you will find that day by day it will also become more interesting as you start to learn the more complex weapons, like the Rb-15 air-ship missile, that has three modes of operation ... or the Bk90 stand-off cluster bomb ... the Viggen has quite a lot of depth, much more than it seems at first sight :)

 

 

Lets hope Heatblur keeps ironing the bugs that it still has.

 

 

Cheers!

[TOViper]

Glad we could help .. but you will find that day by day it will also become more interesting as you start to learn the more complex weapons, like the Rb-15 air-ship missile, that has three modes of operation ... or the Bk90 stand-off cluster bomb ... the Viggen has quite a lot of depth, much more than it seems at first sight :)

Lets hope Heatblur keeps ironing the bugs that it still has.

Cheers!

 

I never had any doubt that the module has more in it that had been initially visible at first sight. But after looking into the BETA manual I was again surprised.

 

I fly the Viggen since it exists in DCS, but never spent much time in one piece, only an hour now and then. The day will come where I have eyes looking like squares :D . I am looking forward the day will come.

 

I always found it the most exciting module in DCS, I loved the Viggen since my early childhood. Now digging deep really shows me what's in the box ... and what I can see is an absolute amazing and outstanding piece of enthusiasm, realism and highest level of sophistication.

 

So far I was able to "ride the bike", but spending time with that machine makes a weapon out of us two ... :pilotfly:

ACG, I am on my way ... :megalol:

Yeah, yeah, the MiG-21s will laugh their pants off ...

 

And ...

Lets hope Heatblur keeps ironing the bugs that it still has. Cheers!

YEAH!! Edited February 12, 2018 by TOViper

[QuiGon]

In that case I can really recommend the Red Flag campaign for the Viggen! It is truly a great piece of work and makes good use of the Viggens capabilities!

[TOViper]

In that case I can really recommend the Red Flag campaign for the Viggen! It is truly a great piece of work and makes good use of the Viggens capabilities!

 

I already bought this campaign, but I was only able to play the first and second "mission", which were a big disappointment ... but this is another story :noexpression:

 

Anway, thanks for this tip ... looking forward to play them once they are bug fixed completely sometimes when I have time for that. :smilewink:

[QuiGon]

I already bought this campaign, but I was only able to play the first and second "mission", which were a big disappointment ... but this is another story :noexpression:

 

Anway, thanks for this tip ... looking forward to play them once they are bug fixed completely sometimes when I have time for that. :smilewink:

 

I would like to here that story, as I just played these missions last week in 2.5 and they were absolutely flawless and stunning :thumbup:

[TOViper]

I would like to here that story, as I just played these missions last week in 2.5 and they were absolutely flawless and stunning :thumbup:

 

OFFTOPIC:

First mission was accomplished when I was few miles away from airport and in flight.

During second mission I lost my wingman since he decided to crash into a hill. Never understood why waypoint constraints can overrule basic flying and basic survival strategies of AI aircraft ... :noexpression:

Don't get me wrong, but I don't understand the first two missions as real missions, and thus I paid money for mission 3 to something I guess ..., which I will hopefully give a try within the next weeks.

OFFTOPIC_OFF

[QuiGon]

OT indeed. PM sent.

[TOViper]

OT indeed. PM sent.

 

Got your comments, many thanks! :joystick: