Level bombing in the Viggen

[john4pap]

From the manual (p.298):

"Level bombing can be done in a slight climb or dive if necessary. Release altitudes is around 200 metres."

 

 

From this statement only it appears to me that what you call "safety height" should be automatically set in relation to your armament. Under what plausible situation would a Viggen be configured to NOT be able to employ a weapon (here, level release with low drag bomb) just because the intended release height (200m here) is outside the limits of the "safety height"? Is this serious?

 

 

 

If there is a reason for that, please do update the manual. RC2 was released in the meantime but there's nothing specific on safety height in it.

[LastRifleRound]

From the manual (p.298):

"Level bombing can be done in a slight climb or dive if necessary. Release altitudes is around 200 metres."

 

 

From this statement only it appears to me that what you call "safety height" should be automatically set in relation to your armament. Under what plausible situation would a Viggen be configured to NOT be able to employ a weapon (here, level release with low drag bomb) just because the intended release height (200m here) is outside the limits of the "safety height"? Is this serious?

 

 

 

If there is a reason for that, please do update the manual. RC2 was released in the meantime but there's nothing specific on safety height in it.

 

What do you mean? Safety height effects SO guidance, but does not inhibit release in PLAN.

[john4pap]

What do you mean? Safety height effects SO guidance, but does not inhibit release in PLAN.

 

 

Not per se, however it is inhibiting any satisfactory release if the targeting cues disappear under the HUD due to an incorrectly set safety height, isn't it?

[LastRifleRound]

Not per se, however it is inhibiting any satisfactory release if the targeting cues disappear under the HUD due to an incorrectly set safety height, isn't it?

 

I guess I don't understand the question. Could you re-phrase what you don't understand about the safety height?

[john4pap]

I guess I don't understand the question. Could you re-phrase what you don't understand about the safety height?

 

Certainly. I'm saying that once you equip with low drag bombs and the safety height is left to default in the mission editor, you cannot aim to release in level bombing since the targeting cues disappear under the HUD. Correct?

 

Now, if level bombing is supposed to be performed at "around 200m" (and supposing that this is accurate information), why should there be any option for different safety heights? The logical thing is that once a type of weapon is loaded, the aircraft should be automatically set up to be able to employ that weapon effectively. We’re supposed to be piloting the Viggen not performing the tasks of the ground crew, isn’t it? :)

[LastRifleRound]

Certainly. I'm saying that once you equip with low drag bombs and the safety height is left to default in the mission editor, you cannot aim to release in level bombing since the targeting cues disappear under the HUD. Correct?

 

Now, if level bombing is supposed to be performed at "around 200m" (and supposing that this is accurate information), why should there be any option for different safety heights? The logical thing is that once a type of weapon is loaded, the aircraft should be automatically set up to be able to employ that weapon effectively. We’re supposed to be piloting the Viggen not performing the tasks of the ground crew, isn’t it? :)

 

Ok I understand now.

 

The manual is somewhat inaccurate. The default safety height for LD bombs is 400m, not 200m. Your cueing is below the Hud because it is commanding a climb. The system is designed in such a way that when you go trigger unsafe to designate a spot, the reticle shifts to show the desired flight path. You must maneuver the aircraft to place the pipper back on the spot you designated. So, if the reticle is low, nose up to place it on target and you will climb such that at bomb release you will be at the safety height.

 

When you depress the trigger, the steering order performs this same function as the target. Keep the dot in the SO, and the correct attitude is achieved.

 

As to why there are different heights, I think more than frag pattern is considered, like threat levels, terrain, egress maneuver, etc. The Viggen is designed to have 99% of mission params done before takeoff.

 

Hope this helps.

[randomTOTEN]

To piggyback on LRR's excellent explanation:

 

 

In the Appendix of the manual, on pg. 378, there is an explanation of the "Safety Height" settings for the Mission Editor. It has some relevance to understanding Level Release,

 

 

These are setting that in real life is set in either the apparatus

bay or on the weapon itself by either the pilot or the crew chief, such as safety or seeker

settings...

 

 

Safety height:

Sets the safety altitude for weapons. This will affect values such as minimum firing distances

for rockets and commanded altitude for level bombing.

Can be set to either Low, Medium, or High.

Values for each height preset varies with the weapon system and mode used.

In general, a higher setting will be safer, but less accurate. Set to medium by default.

 

 

Describing the bombs themselves, pg. 221.

The bombs exist in low-drag and high-drag (with a drag

chute) versions. The bombs can be fitted with either an instantaneous fuse (ÖHKSAR) or an

airburst fuse (ZONAR).

I hadn't thought about it until just now, but I wonder if perhaps the Medium and High safety altitudes have any relation to the use of air bust fusing? Perhaps there's 2 HOF settings for the M/71?

 

 

I don't think we have the option for air burst fusing in DCS, but I hope this helps explain some of the peculiarities of the Viggen.

 

 

For practice, I suggest taking a rack of LD bombs over flat terrain or sea. Fly at safety height > ANF > Unsafe. Observe the movement of the symbology. Return to safe, change altitude, and then Unsafe and observe.

 

 

Do this multiple times while changing altitude or airspeed and notice how the symbology placement changes. It's a very interesting system and intuitive once you learn it (and it can calculate the release cues and impact point correctly lol).

[john4pap]

Ok I understand now.

 

The manual is somewhat inaccurate. The default safety height for LD bombs is 400m, not 200m. Your cueing is below the Hud because it is commanding a climb. The system is designed in such a way that when you go trigger unsafe to designate a spot, the reticle shifts to show the desired flight path. You must maneuver the aircraft to place the pipper back on the spot you designated. So, if the reticle is low, nose up to place it on target and you will climb such that at bomb release you will be at the safety height.

 

When you depress the trigger, the steering order performs this same function as the target. Keep the dot in the SO, and the correct attitude is achieved.

 

As to why there are different heights, I think more than frag pattern is considered, like threat levels, terrain, egress maneuver, etc. The Viggen is designed to have 99% of mission params done before takeoff.

 

Hope this helps.

 

Thanks for the clarification! I have read the manual on level bombing multiple times so I have already understood most of what you're describing. So, are you saying that the manual is inaccurate in saying that level bombing should be performed at 200m, and that 200m is rather the minimum altitude at which level bombing may be performed? If so, I can understand why we are given the choice of different safety altitudes.

 

Now I'm wondering: what is the max altitude at which one can perform level release? Also, is there any reason the manual instructs to maintain 0.8 to 0.9 mach during level bombing?

[LastRifleRound]

Thanks for the clarification! I have read the manual on level bombing multiple times so I have already understood most of what you're describing. So, are you saying that the manual is inaccurate in saying that level bombing should be performed at 200m, and that 200m is rather the minimum altitude at which level bombing may be performed? If so, I can understand why we are given the choice of different safety altitudes.

 

Now I'm wondering: what is the max altitude at which one can perform level release? Also, is there any reason the manual instructs to maintain 0.8 to 0.9 mach during level bombing?

 

Yes, you are correct that the manual is inaccurate when it says level bombing should be performed at 200m. It should be done at the safety height, which by default is 400m.

 

There is no max altitude, but you will find your cues glued to the top of the HUD and they won't be too useful.

 

The reason you are instructed to maintain mach .8-.9 is it increases the chances you can go trigger press (flashing "wings") with the target in view, which should translate to better accuracy due to aim refinement (but doesn't in DCS, because the initial designation point is used for impact, so it doesn't matter how much you refined the aim).

 

Now here's where I go in to speculation mode, but the actual Viggen manual (not the DCS one, the one for the real jet) suggests that the final target point that is used is the one under the pipper when you hold the trigger, not the point of trigger unsafe. Essentially, there are 2 designations, one at unsafe that guides you to the target at the right attitude, and a second when you hold the trigger, that the SO then indicates. This is probably why the real Viggen manual repeats that going trigger pull early will lead to a less accurate bombing solution.

 

In DCS, you could hold the trigger right away and just fly the SO and it's just as accurate, so aside from the general benefit of going faster, maintaining mach .8-.9 doesn't do anything as far as the bombing algorithm goes. You'll be just as accurate at mach .5 as you would be at mach .8.

Edited April 16, 2020 by LastRifleRound

[john4pap]

Yes, you are correct that the manual is inaccurate when it says level bombing should be performed at 200m. It should be done at the safety height, which by default is 400m.

 

There is no max altitude, but you will find your cues glued to the top of the HUD and they won't be too useful.

 

The reason you are instructed to maintain mach .8-.9 is it increases the chances you can go trigger press (flashing "wings") with the target in view, which should translate to better accuracy due to aim refinement (but doesn't in DCS, because the initial designation point is used for impact, so it doesn't matter how much you refined the aim).

 

Now here's where I go in to speculation mode, but the actual Viggen manual (not the DCS one, the one for the real jet) suggests that the final target point that is used is the one under the pipper when you hold the trigger, not the point of trigger unsafe. Essentially, there are 2 designations, one at unsafe that guides you to the target at the right attitude, and a second when you hold the trigger, that the SO then indicates. This is probably why the real Viggen manual repeats that going trigger pull early will lead to a less accurate bombing solution.

 

In DCS, you could hold the trigger right away and just fly the SO and it's just as accurate, so aside from the general benefit of going faster, maintaining mach .8-.9 doesn't do anything as far as the bombing algorithm goes. You'll be just as accurate at mach .5 as you would be at mach .8.

 

 

Many thanks for your answer! That's really helpful :thumbup:

 

 

 

On the speculation part... I'm not sure that I understand... are you saying that in the real Viggen, the pilot would possibly be getting more information than we do after trigger unsafe (altitude and steering cues perhaps)? But then he would have to aim again in order to hit the target?

[LastRifleRound]

Many thanks for your answer! That's really helpful :thumbup:

 

 

 

On the speculation part... I'm not sure that I understand... are you saying that in the real Viggen, the pilot would possibly be getting more information than we do after trigger unsafe (altitude and steering cues perhaps)? But then he would have to aim again in order to hit the target?

 

No I'm saying I think the designation position should be updated when trigger is held.

[john4pap]

No I'm saying I think the designation position should be updated when trigger is held.

Alright. Thanks again!

 

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