NavGun Development Thread

[Nobody]

New version, with new options and an adapted table. Therefore with new texts to proofread.

What would you call the angle between the shell and the target ship, if it's not hitting perpendicular?

[KWorld]

As I recall, when I've seen it elsewhere it's called angle of fall.

[Nobody]

No that's not what I mean (I already use angle of fall). What I mean is the angle when the ship I'm shooting at is not traveling parallel to me. For example if that ship is coming straight at me that angle would be 90° and I wouldn't be able to penetrate or even hit the belt armor.

[Carthaginian]

No that's not what I mean (I already use angle of fall). What I mean is the angle when the ship I'm shooting at is not traveling parallel to me. For example if that ship is coming straight at me that angle would be 90° and I wouldn't be able to penetrate or even hit the belt armor.

Is "Angle of Incidence" what you're 'shooting for' in this discussion about gunnery? ;)

[Nobody]

Is "Angle of Incidence" what you're 'shooting for' in this discussion about gunnery? ;)

Judging by the translation - no. I'm looking for a 'portion' or component of that angle. The angle of fall is one, I'm looking for the other one. Maybe I should call it "target angle"?

[Carthaginian]

Hmmm... that sounds like the best solution.
The only other term I can think of is simply "Relative Bearing."


Maybe this article will have it in there:
http://en.wikipedia.org/wiki/Mathematical_discussion_of_rangekeeping

[Delta Force]

Is "Angle of Incidence" what you're 'shooting for' in this discussion about gunnery? ;)

Judging by the translation - no. I'm looking for a 'portion' or component of that angle. The angle of fall is one, I'm looking for the other one. Maybe I should call it "target angle"?

I suppose you could call it the yaw angle (left/right), and you could call the fall angle the pitch angle (up/down). Although those are more aviation terms, but I really do think that yaw angle is probably the clearest way to describe left/right angles.

[KWorld]

Oh, OK, that's the angle of obliquity, if I remember correctly.

[Delta Force]

Finally had a chance to try the program out, it is quite interesting. Do you still need the batch file for angles over 60 degrees or is that already included with the most recent file?

[Nobody]

Finally had a chance to try the program out, it is quite interesting. Do you still need the batch file for angles over 60 degrees or is that already included with the most recent file?

The batch file should be included in the newer zip-files and you might still need it for higher angles, but the limit should be a bit higher now.

[Delta Force]

Could you take a look at this Nobody? I was simming that to get a baseline for a 7.5 inch gun and ended up with a range of 20,143 meters at 15 degrees and an armor penetration of 316 mm at 2,433 meters using the information given by Naval Weapons. I've double checked the inputs as well as the pressure and density and they are well within range of what I have found when simming 27 mm, 35 mm, and 50 mm weapons. Something really strange is going on with this gun.

[Nobody]

Could you take a look at this Nobody? I was simming that to get a baseline for a 7.5 inch gun and ended up with a range of 20,143 meters at 15 degrees and an armor penetration of 316 mm at 2,433 meters using the information given by Naval Weapons. I've double checked the inputs as well as the pressure and density and they are well within range of what I have found when simming 27 mm, 35 mm, and 50 mm weapons. Something really strange is going on with this gun.

Well the thing is there is nothing in the program yet that distinguishes a 1890 from a 1940 gun in aerodynamics yet. You can however change the armor & shell quality. Also note what is written under the penetration value at navweaps:

Data from "The Grand Fleet:  Warship Design and Development 1906-1922" for an angle of obliquity of 30 degrees and a striking velocity of 1,640 fps (500 mps).  Projectiles were salt-filled (blind).

So if you switch to quality value for uncapped vs FaceHard (>1.1, I choose 1.2), change the belt incline to 19° and look at e.g. at
                                190mm/L45 C/03
Angle   Range    Time    vHit    AoF    Belt  inclined  Deck  sloped
[°]     [m]         [ s ]    [m/s]      [°]    [mm]    [mm]    [mm]   [mm]
8.0    13690    21.51    506    11.2    138     117      21     59
you get 117 mm @ 506 m/s and 30.2°.

Close enough?



About the aerodynamics. I would like to use something called "McDrag", because that would be just plain cool, I think. The problem is that whenever I forward sensible data, the results are rubbish or plain wrong (e.g. negative drag). Only when I use very simple shell forms, like a round nose on a cylindrical body, the results are within a sensible range, but then the program itself complains that the parameters are out of range because "the nose is too short."
What am I doing wrong?
Anyone with firearms experience ever used a program like this and/or willing to check results for real bullets?

[Delta Force]

Could you take a look at this Nobody? I was simming that to get a baseline for a 7.5 inch gun and ended up with a range of 20,143 meters at 15 degrees and an armor penetration of 316 mm at 2,433 meters using the information given by Naval Weapons. I've double checked the inputs as well as the pressure and density and they are well within range of what I have found when simming 27 mm, 35 mm, and 50 mm weapons. Something really strange is going on with this gun.

Well the thing is there is nothing in the program yet that distinguishes a 1890 from a 1940 gun in aerodynamics yet. You can however change the armor & shell quality. Also note what is written under the penetration value at navweaps:

Data from "The Grand Fleet:  Warship Design and Development 1906-1922" for an angle of obliquity of 30 degrees and a striking velocity of 1,640 fps (500 mps).  Projectiles were salt-filled (blind).

So if you switch to quality value for uncapped vs FaceHard (>1.1, I choose 1.2), change the belt incline to 19° and look at e.g. at
                                190mm/L45 C/03
Angle   Range    Time    vHit    AoF    Belt  inclined  Deck  sloped
[°]     [m]         [ s ]    [m/s]      [°]    [mm]    [mm]    [mm]   [mm]
8.0    13690    21.51    506    11.2    138     117      21     59
you get 117 mm @ 506 m/s and 30.2°.

Close enough?

That works quite well. Once aerodynamics are taken into account to give more accurate figures for a given range (as opposed to velocity) you will have created the Springsharp of artillery.

[Delta Force]

Is sloped meant to represent armor like that found on protected cruisers?

[Nobody]

Is sloped meant to represent armor like that found on protected cruisers?

Yes, a turtle-deck configuration.