CBU 105, what does "wind corrected" mean?

[Megagoth1702]

Hey folks!

 

It is said that the 103 and 105 are "wind corrected". What exactly does this mean? Does the bomb get wind data from the plane for the certain point and then stores it into it's computer, aligning it's control surfaces accordingly?

Is it correcting itself automatically or is it just "corrected at launch" and then acts a dumb bomb?

 

Can you compare the accuracy to JDAM accuracy?

 

I am asking this because I am interested in detail and also because the accuracy I got from perfect CCRP drops at 15k was not satisfying, the bombs were sometimes overshooting the target, sometimes short. Maybe I am doing something wrong (hof was at 1800).

 

For now I drop 97s and 105s in CCIP, kinda gives me better accuracy, haha. :)

[159th_Viper]

What exactly does this mean?

 

It means that the tail-kit of the cluster is replaced with a WCMD guidance kit:

 

 

Guidance kit incorporates an inertial navigation system (INS), and has flip-out control fins to steer the bomb on target. Immediately prior to release the launch aircraft's GPS updates the INS of the guidance kit - BOOM!

Edited November 17, 2011 by 159th_Viper

[Megagoth1702]

Thanks for the quick reply.

 

Sorry, my english is not at the top ... Inertial translated to german means "not doing anything actively". So ... Mhh... Is the tail kit ACTIVELY guiding the bomb to the target depending on the bomb's position & wind in the area? Are the fins moving all the time to correct? Or is it just setting it's fins at launch and THEN this setup kinda guides the bomb on target?

 

Sorry if this seems redundant to some but I really don't completely understand this system... :-/

Edited November 17, 2011 by Megagoth1702

[159th_Viper]

Correct - fins are moving all the time. The guidance control fins corrects for launch errors and winds aloft, and computes the optimum flight path to target. Guides it all the way to the target.

 

Keep in mind too that the kit has an acceptable 90ft CEP (circular error probability).

Edited November 17, 2011 by 159th_Viper

[Megagoth1702]

Ah, thank you so much for your explanations.

 

So the bomb will "impact" in a 90ft radius around my SPI?

[159th_Viper]

...So the bomb will "impact" in a 90ft radius around my SPI?

 

Yes - that's when the dispenser skin of the cluster will sever, releasing the skeets/sub-munitions of the 105/103. Impact area can obviously be larger due to the inherent effects of the cluster-bombs and your HOF/RPM settings.

[159th_Viper]

 

Can you compare the accuracy to JDAM accuracy?

 

 

As an aside, a JDAM tail-kit has an approximate 25ft CEP so it's much more accurate, thanks to the INS and GPS system of the JDAM.

[Frostiken]

Immediately prior to release the launch aircraft's GPS updates the INS of the guidance kit - BOOM!

 

Is it? There's no 'hold the pickle button' on WCMDs like there is on JDAMs, which is done specifically because while you hold it you're feeding data to the guidance kit... it would make sense that it does update the INS from the aircraft since I can't imagine it's accurate for very long, but when does it do this? Periodically during flight?

[159th_Viper]

Is it?

 

The WCMD tail-kit contains a guidance unit and micro data processor and makes use of a rear plate umbilical that receives prelaunch target, launch parameter and environmental conditions data from the launch aircraft - as such it stands to reason that said info is passed at deployment, no?

 

Might just be a helluva lot faster than the JDAM due to lack of GPS.

[sobek]

Sorry, my english is not at the top ... Inertial translated to german means "not doing anything actively".

 

Es geht hier aber um inertial guidance, also Trägheitsnavigation. D.h. es wird die Trägheit eines Systems von Kreiseln sowie von Beschleunigungssensoren ausgenutzt, um den genauen Flugpfad nach dem Abwurf zu bestimmen und entsprechend zu korrigieren.

[Megagoth1702]

Ah! Thanks/Danke!

[Olgerd]

There's no 'hold the pickle button' on WCMDs like there is on JDAMs

 

Hm, sounds like a bug to me. I will check documents.

[BlueRidgeDx]

Yep, WCMDs need the same amount of time to pickle as a JDAM, and for the same reasons.