I'm trying to figure out how you get the RCS value for ships, aircraft, installations, ect ect. I know there's a formula out there to do it, but for life of me, I can't find it, and I've spent close to 2 hours trying to find it. Any help would be greatly appreciated.

Howdy,

If you are looking for a formula to come up with a m^2 RCS number estimate, perhaps someone else here has some references. If you are looking for a tool for Harpoon Classic, then see the spreadsheet at http://harpgamer.com/harpforum/index.php?a...amp;showfile=28

 

My preferred way to work in the spreadsheet is to enter a starting guess HC RCS value in cell B22, and the radar range of the detecting platform (E-3 Sentry ~360nm is the default entry). Look at the resulting value in cell G22, that is the most optimistic range the radar could detect the ship (that calculation ignores weather degredation and line of sight limitations, among other small modifiers). Once you reach a detection 'solution' you approve of, use that HC RCS number in the PE (Platform Editor).

 

An alternative is to enter a m^2 RCS number into cell A18 which will guess at an HC RCS number but I don't think you'll find that to be as rewarding or as valuable as the method of the previous paragraph here.

 

Finally there is the comparative approach, using the drop-down for RCS in the PE, find a similar platform and use the same value.

 

Throw a couple of Prowlers into the mix with active jamming and really have an adventure

The formula for determining the RCS of a target is:

 

σ = Geometric cross section x Reflectivity x Directivity

 

Where

geometric cross section is the size of the target as viewed from the aspect of the radar;

reflectivity is the ratio of the power leaving the target versus the radar power which illuminates the target (the rest of the power is absorbed by the target); and

directivity is the ratio of the power scattered back in the direction of the radar versus the amount of power that would have been reflected to the radar if the total reflected power were scattered in all directions

 

There is also an effective “gain” in the radar-signal transmission path that is a function of the RCS. The equation for this “gain” is the following:

 

G = -39 + 20 log(F) + 10 log(σ)

 

Where

G = the ratio of the signal leaving the target to the signal arriving at the target (with isotropic antennas) (in dB)

F = the transmitted frequency (in MHz)

σ = the RCS of the target (in sq.m)

 

Now, if you can take that kind of "serious math" and translate it effectively into HCE database values, I'd love to hear about it.

Hehe...Well...that was more math than I needed today, but I thank you both. I'll give TonyE's idea a shot...if I don't like, I'll just guess. I *was* going to ask how you determine the BaseSourceLevel, but I'm scared I'll have to go buy a graphics calculator.

Hehe, Brad caught me by surprise there too, I like it! With BSL we started with the BSL numbers hard coded into the game as the reference, where those initial BSL numbers came from/how they were derived, I don't think we know (they originated before HC97). So guess and check is the official answer on the BSL numbers which usually leads directly into looking at the existing platforms and picking a number you think right for your own platform.

 

More variables go into the sonar calculations than the radar and nobody has produced a thorough sonar spreadsheet for HC. Part of the sonar model will need adjustment after HCE release so perhaps we can go thru and make at least a chart of ideal detection ranges of certain sonars against certain submarines with specific BSL numbers.

 

Oh, and before I confuse this all too much, the equations you see in that RCS spreadsheet are exactly what the model is doing in the game, we made the spreadsheets first to test the idea, then plugged the equations into the game.