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Need help with bombing in radar release mode


corvinus

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I've been trying to use the M71 low drag bomb in radar release (RR) mode. Despite following the procedure described in the manual (RC1), the bombs fall almost 1 km long.

 

 

I do the following:

- Radar off

- Weapon selector to RR

- Set the QFE of the target area

- Master mode to ANF

- Trigger UNSAFE

- Fly straight and level towards target at commanded safety altitude

- When the target is under the crosshair in the radar PPI I pull and hold the trigger.

 

 

The bombs release, but way too late. It is almost as if the bombs are dropped when exactly about the target (which is a television tower in this case).

 

 

What am I doing wrong? Track file is attached.

AJS-37 radar release.trk

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I'm no expert, but I believe you are too early with trigger UNSAFE. You should, for what I know, first align the reticle steady on the target and then go UNSAFE.

Helicopters and Viggen

DCS 1.5.7 and OpenBeta

Win7 Pro 64bit

i7-3820 3.60GHz

P9X79 Pro

32GB

GTX 670 2GB

VG278H + a Dell

PFT Lynx

TrackIR 5

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I have watched the track. I don't get the problem. It seems you hit and destroyed the target so what was the issue?

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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I'm no expert, but I believe you are too early with trigger UNSAFE. You should, for what I know, first align the reticle steady on the target and then go UNSAFE.

 

 

For other bombing modes this is true, but for the RR mode the manual states:

- Mode ANF. Commanded altitude = Safety altitude

- Trigger UNSAFE.

- Trigger pulled and held when the target radar return passes the firing range line at 3 km.

I.e., the trigger is pulled when the reticle is above the target. Mind you, the reticle is fixed (i.e. you cannot move it, it is always at 3 km distance).

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I have watched the track. I don't get the problem. It seems you hit and destroyed the target so what was the issue?

 

Hmmm, that is interesting. I'm running Open Beta, what version are you running?

 

 

Concerning my problem. If I watch the track from the TV towers perspective, this is what I get:

attachment.php?attachmentid=191683&stc=1&d=1533728614

 

The bombs fall far from the tower ...

screenshot.thumb.png.a7bdce82910709ca7e664a1a98a0a92c.png

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Hmmm, that is interesting. I'm running Open Beta, what version are you running?

 

 

Concerning my problem. If I watch the track from the TV towers perspective, this is what I get:

attachment.php?attachmentid=191683&stc=1&d=1533728614

 

The bombs fall far from the tower ...

 

 

I guess its just some replay glitch. If you watch it from free cam you can see the tower is hit and destroyed and its reported to be destroyed even on the mission result screen. I am running the latest beta also.

 

edit: I don't get it It seems that picture was taken in free cam mode also. I have watched the track 3 times and it was hit always I also played the track and I could destroy the tower for the first try with RR release just as in the replay.


Edited by Sharkh

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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The target is really still there. The screenshot is created using F12 (which placed the camera at the TV tower site, I then zoomed out to create the screenshot). In the screenshot you cat see that the bombs fall in the water, I also see that after using F6.

 

 

 

If I use NAV release (put the waypoint on the target and fly towards the waypoint with weapon selector at RR and master mode NAV), I do hit the target. So the INS is still correct. However if I use master mode ANF then it doesn't work.

 

 

I noticed that when the distance to the waypoint is 3 km the reticle is not over the waypoint! It seems that the reticle is not placed corectly. See screenshot below.

 

attachment.php?attachmentid=191685&stc=1&d=1533736022

1352752151_DesktopScreenshot2018_08_08-14_26_40_47.png.6f9a56bb836ccb7304616383e3531434.png

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The target is really still there. The screenshot is created using F12 (which placed the camera at the TV tower site, I then zoomed out to create the screenshot). In the screenshot you cat see that the bombs fall in the water, I also see that after using F6.

 

 

 

If I use NAV release (put the waypoint on the target and fly towards the waypoint with weapon selector at RR and master mode NAV), I do hit the target. So the INS is still correct. However if I use master mode ANF then it doesn't work.

 

 

I noticed that when the distance to the waypoint is 3 km the reticle is not over the waypoint! It seems that the reticle is not placed corectly. See screenshot below.

 

attachment.php?attachmentid=191685&stc=1&d=1533736022

 

So on the mission result screen you don't see that the tower was destroyed?

 

As I translate the instruction about this bombing you have to press the bomb release button as soon as the cross enter the circled area of the waypoint on the radar screen it does not have to be in the center so that picture looks alright.

 

 

But again... :D I have watched your track and I am pretty sure that everything went alright there and you got a perfect hit . The replay feature of DCS is not a reliable source to analyze what has happened. It just record the inputs the player does and than its like the AI fly and mimic these inputs so a few small error can lead to a very different result in the end.

 

I really have no idea how it is not working for you I played your mission and for me everything worked fine and I have done everything according to the procedures in the manual .

 

If it still does not work for you than try to press the release sooner because that could be the only problem that you thought you have to release when the cross in the center of the circle so you were a bit late with that.

 

edit: Btw try to use chuck's viggen guide for training the procedures if you haven't used it yet. There is a sticky htread about that guide with the PDF link.


Edited by Sharkh

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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...

...

Since you get very different results with the same track, just to maybe help with the bug hunt, what FPS do you guys get during the mission? I have a feeling FPS might affect stuff in very strange ways sometimes.

Helicopters and Viggen

DCS 1.5.7 and OpenBeta

Win7 Pro 64bit

i7-3820 3.60GHz

P9X79 Pro

32GB

GTX 670 2GB

VG278H + a Dell

PFT Lynx

TrackIR 5

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So on the mission result screen you don't see that the tower was destroyed?

 

As I translate the instruction about this bombing you have to press the bomb release button as soon as the cross enter the circled area of the waypoint on the radar screen it does not have to be in the center so that picture looks alright.

 

This is what the manual says:

"Trigger pulled and held when the target radar return passes the firing range line at 3 km."

There is no reference to a waypoint, which is not needed in this mode. I only used a waypoint to be able to compare the range at which the 3 km line on the radar screen is over the target. I think this should be at 3 km if the waypoint is directly over the target, but it seems not to be the case.

 

Anyway, I will make a new track because this track is apperently only complicating things.

 

I checked Chucks guide (thanks for the tip). The text is not very clear to me:

"When radar return or target point circle passes the firing range line, drop bombs by pressing and holding continuouslythe Weapon Release button until the FALLD LAST (STORES RELEASED) light illuminates."

But IF you use a waypoint (=target circle?) then the target radar echo should be in the center of the circle. I think Chuck refers to the reticle when he talks about target point circle. Nevertheless I will try this and see what happens.

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Ok, here is a new track. Different target now, just a few static structures. Same result though, bombs fall long of the target (I confirmed that the target is not destroyed by checking the target afterwards). To me it seems that the 3 km line on the PPI is not placed correctly. I think I am pressing trigger at the correct moment, am I not?

 

 

Any help and pointers are much appreciated!

AJS-37 radar release 2.trk

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So on the mission result screen you don't see that the tower was destroyed?

 

 

Exactly!

 

 

If it still does not work for you than try to press the release sooner because that could be the only problem that you thought you have to release when the cross in the center of the circle so you were a bit late with that.

 

 

If I release when the tip of the reticle (and thus not the center) is over the target, then the bombs fall way short ...

 

 

When do you pull the trigger (so where is the radar reticle in relation to the target)? Mind you forget about the waypoint circle, that is just to help me measure the proper distance to target.

 

 

Also, how do you explain that (when using the helper waypoint), the distance indicator shows 3 km before the reticle center is over the waypoint center? It would help if you can post a screenshot showing the PPI and the distance indicator at the moment you pull the trigger. Then we can confirm if I just release at the wrong time, or we are actually not running the same version a bug was introduced.

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So here I am again with some more info. This time I used the B-scope in the 15 km setting. I flew towards the waypoint which is centered exactly over the target, which is on the small island located in the delta of the river.

 

 

The distance to the waypoint is 0 km, so I'm exactly over the target. However the B-scope shows the island at a distance of about 10 km!

 

 

attachment.php?attachmentid=191741&stc=1&d=1533822060

742308893_DesktopScreenshot2018_08.09-15_35_10.15(2).png.546912eaf89ed4a4458415a0844c9df3.png

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I have watched your 2nd track and played it also and yes in this the bombs hit the ground too late I have played it many times by myself also and it was always a miss.

 

 

Maybe its just that the radar don't detect the target radar return in time. This release method can't be accurate consistently according to the manual so maybe in this case it does not work because the conditions are not perfect.

 

 

I will try it a few more times and I report back if I found out something :D

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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I will try it a few more times and I report back if I found out something :D

 

 

Thanks for looking into it, much appreciated!

 

 

 

Btw, the radar does not actively "detect" the target, i.e. it does not lock on to anything like the F-18C A/A radar. For the Viggen it is up to the pilot to interpret the radar echos.

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Thanks for looking into it, much appreciated!

 

 

 

Btw, the radar does not actively "detect" the target, i.e. it does not lock on to anything like the F-18C A/A radar. For the Viggen it is up to the pilot to interpret the radar echos.

 

 

I found some possible mistake in your procedure. In this 2nd track.

 

You didn't set the QFE to 1012.6 (its at 1013 its a small difference but who knows) , your altitude was a bit off . It seems the bomb was released too late but I am not sure why it seems you pressed release too late.

 

I have tried the mission many times where I done perfect shots a few times after a bit of training.

:D

 

 

 

Here is what I have done differently.

 

I have set the qfe than switched to barometric altitude instead of radar alt what you used. I also turn slav si to fran(off) I am not sure if it is affect this bombing but still I use this mode on low alt always. Than I set the suggested altitude by the hud after I selected master mode anf with RR mode selected ont he weapon selector. I have entered the 253 code also (disable radar ranging It probably doesn't affect this mode but who knows ehh) . I set unsafe about 8 km than I pressed release at 3 km from the target waypoint.

 

 

edit: I think your speed was also a bit slow. My bomb was alwas short below 0.8 mach.

 

 

Here is the track.

RRtest4.trk


Edited by Sharkh

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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So radar bombing in the Viggen is a bit of black art.

 

A couple things that can be issues:

 

1) The radar refresh/raster sweep rate leads to having to guess when the target is "exactly" under the radar bombing cross. The higher or faster you're moving the more this will effect your final bomb strike location.

 

2) Radar resolution, it's not super high like you might find in say the F-15E or the F-18, you are trying to put the terrain feature or the target blob under the center of the radar bombing cross. Radar bombing is only as accurate as the radar can generate a location or offset.

 

3) Wind this may or may not be an issue in your mission, but it certainly is one real world.

 

So I found through trial and error, you are having to basically guess when to release due to the sweep rate; the higher and faster, the bigger the chance of error. I've gotten to where I can hit most terrain features with a stick of bombs, or a building complex. I can USUALLY managed to get a hit on a stationary ship, but that's in good weather.

 

In the Viggen as well as a lot of it's contemporary AC, true radar bombing was the last ditch way to get the bombs off the AC if the weather was bad. Using the radar to locate a recognizable terrain feature, calculate your offset, run in, time to release, etc, was your backseater/side-seaters job. In a single man AC you'd need to be Sierra Hotel to pull that off in real time I'd imagine. Radar offset bombing could be pretty dang accurate if well planned and the profile flown correctly. In the Viggen the equivalent is Nav bombing and using obvious terrain features for checkpoints to keep everything from drifting.

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So radar bombing in the Viggen is a bit of black art.

 

A couple things that can be issues:

 

1) The radar refresh/raster sweep rate leads to having to guess when the target is "exactly" under the radar bombing cross. The higher or faster you're moving the more this will effect your final bomb strike location.

 

2) Radar resolution, it's not super high like you might find in say the F-15E or the F-18, you are trying to put the terrain feature or the target blob under the center of the radar bombing cross. Radar bombing is only as accurate as the radar can generate a location or offset.

 

3) Wind this may or may not be an issue in your mission, but it certainly is one real world.

 

So I found through trial and error, you are having to basically guess when to release due to the sweep rate; the higher and faster, the bigger the chance of error. I've gotten to where I can hit most terrain features with a stick of bombs, or a building complex. I can USUALLY managed to get a hit on a stationary ship, but that's in good weather.

 

In the Viggen as well as a lot of it's contemporary AC, true radar bombing was the last ditch way to get the bombs off the AC if the weather was bad. Using the radar to locate a recognizable terrain feature, calculate your offset, run in, time to release, etc, was your backseater/side-seaters job. In a single man AC you'd need to be Sierra Hotel to pull that off in real time I'd imagine. Radar offset bombing could be pretty dang accurate if well planned and the profile flown correctly. In the Viggen the equivalent is Nav bombing and using obvious terrain features for checkpoints to keep everything from drifting.

 

Maybe I am wrong but as I understand this bombing method the bomb release is done semiauto so when you press release the bomb is not released "instantly" like normal because the radar wait for a different return other than flat than its release the bomb as soon as it get a radar return of something else. Thats why its called radar release I guess and thats why it is suggested to be used only at a coastal location where the surface is flat possibly so its easier to the radar to "detect" a possible bigger "unnatural" object.

 

 

So if the conditions are ok for this release , flat surface, proper mission planning with a radar fix on the last waypoint(ingress speed set) before the target waypoint than a single building or bigger object can be hit consistently I think . I think its not about guessing its about practice and accurate navigation than you will deal an accurate shoot with the proper speed on the suggested altitude.

 

As far as I understand you have to be at 400 meter altitude(radar altitude at target waypoint so QFE has to be set and use QFE to set your alt) in this mode always because this is the hud is set every time in this mode with RR release and master mode ANF so you only have to guess the speed what is not really a guess after you practiced this. (wind can affect it obviously in reality)

 

 

Yes its not very reliable and accurate method but I think its far from back magic and the best shoot you can have in low visibility conditions.

 

 

I wonder if I am wrong or not about that the "radar"/computer decide when to release the bombs(in RR mode) because thats how it feels exactly but it seems you think that this is manual release? I haven't find anything about this in the "book" or on the internet but I think the release done automatically by the computer/radar after a few sec the release button have been pressed.

 

Anyway it seems it works for me every time I press release at 3km with a speed 0.80+mach at 400m from the ground.


Edited by Sharkh

FW 190 A-8, FW 190 D-9 Dora, MiG-15bis , Mig-21bis, AJS-37 Viggen , M-2000C, F-15C, F/A-18C, F-14, Supercarrier, NTTR, Normandy+WW2 assets, Combined Arms, Persian Gulf

AMD Ryzen 2600x , ASUS Rog Strix B450-F, Corsair H100i, Corsair Vengeance 32GB 3000MHz DDR4, MSI RTX 2070 8G, ASUS Xonar DSX, Samsung EVO 970 SSD , PSU - Corsair RM750, Headtracking - EDtracker Pro Wired, 58" Screen, TM Warthog, Windows 10 64bit Home

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I have set the qfe than switched to barometric altitude instead of radar alt what you used. I also turn slav si to fran(off) I am not sure if it is affect this bombing but still I use this mode on low alt always. Than I set the suggested altitude by the hud after I selected master mode anf with RR mode selected ont he weapon selector. I have entered the 253 code also (disable radar ranging It probably doesn't affect this mode but who knows ehh) . I set unsafe about 8 km than I pressed release at 3 km from the target waypoint.

 

 

edit: I think your speed was also a bit slow. My bomb was alwas short below 0.8 mach.

 

 

Here is the track.

 

 

Thanks for the track! I've watched it and you will be glad to know that on my system the bombs also fall on target. It is however impossible to see when you pulled the trigger. I've duck into the cockpit in order to see the trigger, but I think the button is not animated. So the big question is: Did you pull the trigger when the waypoint distance indicator (the gauge on the top right of the front panel) indicated 3 km, or when the reticle in the PPI was at the western edge of the island?

 

 

If I use your track and take control after you did all your settings and altitude corrections, the bombs still fall too far if I base my triggering purely on the radar echos. Mind you, the target area crosses the 3 km line on the PPI, I'm almost directly above the target.

 

 

 

Regarding your other remarks, they are correct I think, but in this case it doesn't matter much (the target area being almost at sea level). Also the commanded height is a safety height, the computer uses actual height for bomb release computations afaik.

 

 

So to summarize:

* If I base triggering on the PPI => bombs fall long.

* If I base triggerin on the waypoint distance indicator => bombs fall on target.

 

 

For me that leads to the conclusion that the 3 km indicator on the PPI is not placed correctly.

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Thanks for your reply, excellent suggestions!

 

 

So radar bombing in the Viggen is a bit of black art.

 

A couple things that can be issues:

 

1) The radar refresh/raster sweep rate leads to having to guess when the target is "exactly" under the radar bombing cross. The higher or faster you're moving the more this will effect your final bomb strike location.

This is a good point, I'm flying about 280 m/s, and the update time is a bit less than a second. So if your radar image is 1.0 s old you are 280 m too late. The error I'm getting is in the order of 800 m, which cannot fully be explained by latency issues like this.

 

 

2) Radar resolution, it's not super high like you might find in say the F-15E or the F-18, you are trying to put the terrain feature or the target blob under the center of the radar bombing cross. Radar bombing is only as accurate as the radar can generate a location or offset.

In the 15 km setting the pulse length is 0.5 microseconds. If the radar does not use pulse compression that would set the range resolution to about 75 m. If the radar does use pulse compression (I'm not sure if that was common in that era) then the radar resolution would be even better. So one can safely say that the range resolution is better than 75 m.

 

Now if you add the two errors the maximum error is about 350 m, which is significant if you want to hit a ship.

 

 

 

3) Wind this may or may not be an issue in your mission, but it certainly is one real world.

 

So I found through trial and error, you are having to basically guess when to release due to the sweep rate; the higher and faster, the bigger the chance of error. I've gotten to where I can hit most terrain features with a stick of bombs, or a building complex. I can USUALLY managed to get a hit on a stationary ship, but that's in good weather.

 

 

Did you also try this with the latest openbeta update? I'm asking because if I use the B-scope, the 3 km line in the B-scope seems way off. Therefore I am also a bit suspicious of the placement of the 3 km in the PPI. I think it was correct before the update, but I'm not sure.

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Anyway it seems it works for me every time I press release at 3km with a speed 0.80+mach at 400m from the ground.

 

 

Sorry to get back at this point, but it is not clear if you use the PPI or the distance indicator gauge (top-right front panel) to determine if you are at 3 km distance.

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The way I interpreted the RL manual is that the 3km cross is used to mark the target for bombing and then you follow the directions on the HUD as you would with a normal NAV-bombing. This is how it is implemented in DCS. No automatic measurements or something as implied above, it’s just up to the pilot to figure out if the cross is on the target and the computer more or less just handles the count-down to release. Real-life Viggen pilots mentioned that you could see individual buildings in the size-range of the Globen in Stockholm and ships contrasted to the sea but not much else hence I don’t think this mode was very useful.

 

Please note that the next release of Viggen (likely OpenBeta on Wednesday) will include improvements to the accuracy of the bombing. Most important change I think is that I implemented a “catching-up”

logic in the release interval where if the computer detects it is releasing long it will release more bombs at once so at least the final bombs will have correct ground interval (so 8 bombs before the target and 8 bombs after even if the first bombs start releasing long). It will not be able to compensate perfectly depending on how quickly the pilot changes attitude etc but tries to do its best to predict fast changes in altitude etc.

DCS AJS37 HACKERMAN

 

There will always be bugs. If everything is a priority nothing is.

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The way I interpreted the RL manual is that the 3km cross is used to mark the target for bombing and then you follow the directions on the HUD as you would with a normal NAV-bombing. This is how it is implemented in DCS. No automatic measurements or something as implied above, it’s just up to the pilot to figure out if the cross is on the target and the computer more or less just handles the count-down to release.

 

 

This is how I understood it from the manual. Imho the 3 km cross does not correspond to 3 km, I checked this by placing a waypoint. The distance indicator gauge indicates 3 km before the 3 km distance line in the PPI is over the waypoint.

 

 

 

What do you make of the screenshot below? The plane is at 3 km distance from the waypoint, but the PPI 3 km distance line is not at the waypoint. Doesn't that mean that the PPI distance line is not placed correctly? Note that this is after a few minutes of flying, so I don't think INS drift is an issue here.

 

 

 

attachment.php?attachmentid=191685&stc=1&d=1533736022

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