CBU-105 weapon of choice for tank groups

[Yurgon]

On 8/26/2021 at 6:35 AM, Captain Orso said:

I'm not actually sure tha CCIP takes wind into account.

 

It does.

 

You can easily test it: Go into a CCIP delivery with the pipper visible in the HUD, hit Active Pause, and then enter into the CDU whatever absurdly strong wind values come to your mind. The pipper will then adjust itself to account for the wind between your aircraft and the ground.

[Captain Orso]

10 hours ago, jaylw314 said:

 

That's garrulous and uncalled for.

 

The calculated wind is on the LASTE wind page in the upper right (also in the STRINFO page).  If you enter data in the LASTE wind page, it overrides the calculated value.  I don't know whether the value in DCS is actually calculated from position and air data or just copied from the mission settings, though there is not a practical difference in DCS

 

 

 

The LASTE page shows the waypoint information. The STRINFO shows the steerpoint information. The wind info on those pages are entered and not calculated.

 

If your target is not near a waypoint, you will have no wind information. If your target is in a valley and far enough from a waypoint that the waypoint is not within the valley, nothing in your closest waypoint wind information will be of any use other than coincidentally.

 

Now imagine there are gusts in addition.

 

The WCMD only makes sense if it is compensating not only the fall direction in wind, but also the drift of the BLU-108s while on their parachutes. The effect of wind on the canister is low, because of the weight of the canister (inertia) and its form. A 15,000 foot fall takes 30 seconds. Once the canister deploys (default = 2200 feet above target altitude) the BLU-108s are on parachutes. The BLU-108s are far lighter than the entire canister, plus they are hanging on parachute. The entire concept of a parachute is to increase as greatly as possible the force necessary to move an object through the atmosphere. conversely, wind (movement of the atmosphere over the earth) is equally great. After deployment the first BLU-108 fires at about 17 seconds and the last at about 27 seconds. During this time while hanging on their parachutes, the BLU-108s are blown off target a great distance. With 25 kts wind speed on the ground at the point of deployment, the BLUs drift so far that not a single skeet touches on of the target vehicles in the convoy (see video).

 

If the WCMD does not compensate for the BLU-108's drift while on parachute, it is useless.

 

DCS CBU-105 from 16k+

[Captain Orso]

9 hours ago, Yurgon said:

 

It does.

 

You can easily test it: Go into a CCIP delivery with the pipper visible in the HUD, hit Active Pause, and then enter into the CDU whatever absurdly strong wind values come to your mind. The pipper will then adjust itself to account for the wind between your aircraft and the ground.

Thanks for the reply.

 

At any rate, all the information the IFFCC and EGI contain were deemed to be insufficient to make a useful calculation for deploying the CBU-97 without adding a unit to dynamically calculate and control the fall of the weapon, and this compensation is only useful if it also considers the deployment of the BLUs, otherwise the expensive development and deployment of the WCMD would be pointless. See my immediately previous post (video).

[Frederf]

6 hours ago, Captain Orso said:

The LASTE page shows the waypoint information. The STRINFO shows the steerpoint information. The wind info on those pages are entered and not calculated.

 

If your target is not near a waypoint, you will have no wind information. If your target is in a valley and far enough from a waypoint that the waypoint is not within the valley, nothing in your closest waypoint wind information will be of any use other than coincidentally.

All of the statements in red are factually incorrect.

 

LASTE WIND page is global information and not associated with any waypoint. Distance to waypoint is irrelevant. The "WND" info on line 8 of the WAYPT and STRINFO pages is continuously calculated at the airplane's current position (not the target). That too is not a property of the waypoint and it is not entered by the pilot. The wind assumed at target position is not shown to the pilot on any CDU screen. Can the automatic calculation be inaccurate? Sure. That's why the system allows the pilot to override the automatic calculation with manual wind and temperature information. If the pilot doesn't do this then the automatic wind/temp calculation is used.

 

6 hours ago, Captain Orso said:

The WCMD only makes sense if it is compensating not only the fall direction in wind, but also the drift of the BLU-108s while on their parachutes.

WCMD does have dispense point wind compensation.

 

I admit I cannot find direct source that unguided delivery has compound ballistics too but in any case it's not present in DCS. You can see by inventorying two CBU-87s one at 300' HOF and one at 3000' HOF and switching between them when in freeze-pause with a crosswind. The aimpoint would change as the ballistics of the two are different if that factor was being taken into account by DCS.

 

Your argument that WCMD wouldn't have been invented if unguided CBU aiming already accounted for these factors is not a logical one. WCMD has value even if unguided delivery has aiming features which accounted for wind.

 

 

[AvroLanc]

Jesus guys, why are you all making this harder than it needs to be?

 

In any aircraft the CCIP/CCRP solution is calculated with the actual current wind being experienced by the host aircraft.
Some aircraft, like A10C have the ability to enter predicated winds at various altitudes I.e on the LASTE page. This is still only a prediction and the REAL winds will very likely vary at different heights during the entire time of fall. 
 

The INS guidance in a WCMD (or GPS in JDAM, or laser guidance in a LGB for that matter) is a closed loop system. The guidance will react and compensate for the various changing factors a falling object will experience.  There’s a reason PGMs we’re invented.  Remember that WCMDs can be dropped from a B-52 at 35000ft. CCRP wouldn’t be good enough for that expect in a completely perfect world. 
 

DCS doesn’t apply correction to the bomblets upon dispense. It clearly should and this is wrong at the moment. This value of the post-dispense wind can either be from mission planning, from the CCRP system at time of drop, or manually pilot entered.