Search found 355 matches

by Bill Jurens
Mon Mar 28, 2005 5:47 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Yaw and drag.

Of course. and your point is...? Yaw can be either calculated (but only if one knows the values of enough of the initial variables required, which is rarely if ever the case for old bullets), observed on the range via yaw cards, spark images, or yaw sondes, or -- at least in principle -- derived by ...
by Bill Jurens
Mon Mar 28, 2005 5:36 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Formulas

Hi George: Your package contains probably a hundred formulas, and it would not be feasible for me to comment on them all. What particular ones were you interested in? Most (or all) of the formulas are fine. But when you work them out using real-life numbers you will indeed find that the drag effects...
by Bill Jurens
Sun Mar 27, 2005 1:28 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Computations

Well, please keep me posted on your results. It's easy to bury your head so far in theory that you forget that the theory -- at least theoretically -- should lead to practical solutions as well. I suspect that you have somewhat over-emphasised Dr. C's concern regarding yaw effects, or that he is spe...
by Bill Jurens
Thu Mar 24, 2005 5:06 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Projectile drag

Hello George: Certainly the shape of the ogive is of great importance in determining the drag. The difficulty lies in selecting an appropriate drag function that reflects the shape one is interested in. For simple bullets, e.g. tangent ogives, and simple secant ogives, this is fairly straightforward...
by Bill Jurens
Wed Mar 23, 2005 6:52 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Head height

The head height or the nose height (or head length or nose length) -- many near-synonymous terms are used -- is really only clearly defined in the case of a tangent or secant ogive with a perfectly pointed tip. As soon as one rounds off (or chops off) the nose, then the theoretical length no longer ...
by Bill Jurens
Wed Mar 23, 2005 6:42 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

15" Ogive

No, it's a 4CRH ogive in my book. I think you've made an incorrect assumption, namely that the center of the ogive for the bullet body is in the same place longitudinally as the center of the ogive for the windscreen. It isn't; if you move the center of your 4CRH ogive towards the stern about 4.08 i...
by Bill Jurens
Tue Mar 22, 2005 10:58 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

projectile shapes etc.

So far as line drawing were concerned, I was referring to the drawings that you posted earlier on this thread, and apparently the drawings you have just posted now, the difference being that posting 1 contained two drawings and posting 2 contains three. Those profiles, all nearly the same, are what ...
by Bill Jurens
Tue Mar 22, 2005 5:28 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Addition to previous.

I neglected to add the air density for this table, which was 534.22 grs per cubic foot.

Bill Jurens
by Bill Jurens
Tue Mar 22, 2005 2:20 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

15" Range Table

As it turns out, I have a copy of O.U. 6090 (D), the official range table for the 15" gun and the 1920 lb projectile here. The preamble states" "Calculated to small arc accuracy with O.B. Ballistic Tables with values of Co varying from Co=12.493 (ks = 0.682) at 5 degrees elevation to Co = 11.529 (ks...
by Bill Jurens
Mon Mar 21, 2005 3:20 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Range table

Thanks, Marty1. Your objective is perfectly clear now. Please give me a bit of time to go through my files -- and make a few inquiries -- to see what I can find regarding 15" range tables. I have four or five of these now in my files now, but most, as I recall, were 'corrected' to later dates, and s...
by Bill Jurens
Mon Mar 21, 2005 2:28 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

huh?

I hate to appear to be thick, but I still cannot for the life of me figure out exactly what you are trying to demonstrate by these calculations and graphs, so cannot really respond coherently. If you read back in the thread, you will see that I've really never been able to grasp what you are trying ...
by Bill Jurens
Sun Mar 20, 2005 10:39 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

"Problems" with USN 16" guns, etc.

I am, in conjunction with another author, currently preparing a detailed paper -- an extension of my previous paper on the "Evolution of Battleship Gunnery in the US Navy" -- which will provide comprehensive coverage of the WWII gunnery experiences of the 'fast battleships' and address most of these...
by Bill Jurens
Fri Mar 18, 2005 3:34 pm
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Ballistic coefficients etc. (to Marty1)

Hi Marty: All I can suggest is that you try to numerically integrate a few trajectories and see how they behave. Your observation is correct, of course, certainly in principle, but it appears that the practical effect of the weight change on projectiles this big is much smaller than one might at fir...
by Bill Jurens
Fri Mar 18, 2005 6:04 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Trajectories and velocity drop

I'm not sure exactly what reasons you are referring to, but if you don't believe me, try to run a few trajectories and you will see that if you use the same drag function (i.e. identical projectile geometries) and and compare relatively light high velocity projectiles against relatively heavy low ve...
by Bill Jurens
Fri Mar 18, 2005 2:26 am
Forum: Naval Weapons
Topic: 1921 firing trials against Baden
Replies: 145
Views: 91846

Velocity drop curves etc.

I ran a few trajectories which showed that the German KDos data vs the British data seemed to be behaving properly. I was going to write a memo explaining this observation, but I see others have 'beat me to it', and the apparent difficulty has been identified, understood, and corrected. The data is,...