Search found 882 matches
- Fri Oct 13, 2006 2:43 am
- Forum: Naval Technology
- Topic: Iowa Class real performance
- Replies: 67
- Views: 34361
Faceplate penetration
Well, you sure know how to flatter a guy... I am working on a number of other things now, but your kind comment enticed me to do a quick 'back of the envelope' calculation using the USN's official ORD SK78841 as a guide. This suggests that penetration of an Iowa faceplate by a 15" bullet was im...
- Thu Oct 12, 2006 6:19 pm
- Forum: Naval History (1922-1945)
- Topic: South Dakota´s barbette impact
- Replies: 9
- Views: 3087
Barbette impact
The hit on South Dakota is unlikely to have been from an armor-piercing round. The steel doesn't lie; an impact from an a.p. round would have caused much more damage at the impact point, and the amount of damaged and removed decking is much too large to have been removed by the relatively small char...
- Thu Oct 12, 2006 4:34 pm
- Forum: Naval Technology
- Topic: Iowa Class real performance
- Replies: 67
- Views: 34361
Armor impacts
The hit on South Dakota is unlikely to have been from an armor-piercing round. The steel doesn't lie; an impact from an a.p. round would have caused much more damage at the impact point, and the amount of damaged and removed decking is much too large to have been removed by the relatively small char...
- Mon Feb 27, 2006 4:58 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Photogrammetry
You can disagree all you like, but I'll stand by my statements, with a few comments. I will reiterate that the analysis of these photographs in many cases amounts to a Rorsach test. With apologies to Simon and Garfunkel, "... A man sees what he wants to see and disregards the rest..." You ...
- Fri Feb 24, 2006 5:59 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Off-the-wall
The photogrammetric equations are rock-solid and will give correct answers to any degree of precision one wishes. Unfortunately, accurate photogrammetric analysis requires the precise measurement of very small distances -- sometimes to within a couple of thousandths of a millimeter in size -- and th...
- Tue Feb 21, 2006 2:36 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Photogrammetry
For what it is worth my photogrammetric analysis of this photo strongly suggests that it was indeed taken with a 50mm lens on a 35mm camera. The general field of view of what appears to be a nearly full-frame reproduction closely matches what might be expected using a 50mm lens on 35mm film, and oth...
- Sun Feb 12, 2006 12:39 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Speed changes during maneuvering
I am not certain how well the new -- or for that matter the old -- track charts account for the speed losses typically experienced during turns, which can be quite considerable. The exact amount of the speed loss during turns varies quite a bit with sea state, and even varies from ship to ship of th...
- Sat Feb 11, 2006 7:48 pm
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Photogrammetry, etc.
My analysis of NH69722 used a variety of methods. One of these involved comparing the relative size of Bismarck to that of various and sundry foreground objects after resecting for camera position. This resection checked for a field of view equvalent to a 50mm lens, which is one reason I believe the...
- Fri Feb 10, 2006 3:35 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Photography
It is worth noting that when examining prints of poor quality photography -- which this certainly is -- it is generally impossible or at least very difficult to determine whether a change in image size is due to a change of lens or a change in enlargement made in the darkroom. My guess is that the c...
- Fri Feb 03, 2006 3:49 pm
- Forum: Bismarck General Discussion
- Topic: Who really sank the Hood? Bismarck or Prinz Eugen?
- Replies: 45
- Views: 87331
Forward Magazine Explosion
The documentary suggesting the forward magazine explosion, which is not too bad otherwise, keeps coming up again and again. As a member of the Marine Forensics Committee of the Society of Naval Architects and Marine Engineers, and the author of "The Loss of HMS Hood -- A Re-examination" I ...
- Thu Jan 26, 2006 6:33 am
- Forum: Bismarck General Discussion
- Topic: Determining Distances from Photographs
- Replies: 57
- Views: 27567
Photographs
Your initial hypothesis regarding photogrammetric calculations is incorrect. In fact there is no justification whatsoever to support your statement that that there are no equations that can be used to compute distances in front of the horizon. The geometry about the horizon line is (nearly) symmetri...
- Thu Aug 25, 2005 4:24 pm
- Forum: Books and Reference
- Topic: For young Mr Jurens!!
- Replies: 4
- Views: 2606
Old Warship Internationals
I did indeed receive the lists I was looking for from a gentleman name Art Mears, in eastern Canada, an ex-SeaBee. I haven't heard from him in years, but still appreciate his efforts. It's hard now to recall how long ago this was, both in terms of time passed, and in terms of how things are done now...
- Sat Aug 20, 2005 11:12 pm
- Forum: Bismarck General Discussion
- Topic: Photo # NH 69722 distance evaluation
- Replies: 80
- Views: 40535
Photogrammetry
I must begin by thanking Jose for issuing me a new password which allowed me to enter the forum again. I have been having difficulty logging on over the past few days. I have been following the thread regarding the analysis of Denmark Strait photography for several days now. With respect, I'd sugges...
- Wed Jul 13, 2005 10:55 pm
- Forum: Naval Weapons
- Topic: Hoods rangefinder (instrument)
- Replies: 7
- Views: 4194
Clocks...
You are probably referring to what was typically known as a 'range clock'. These items, which varied somewhat in appearance from navy to navy and from time to time, had a large (usually) circular clock-like dial facing fore-and-aft, with hands that could be moved to indicate (via a variety of system...
- Sat Jun 25, 2005 11:43 pm
- Forum: Bismarck General Discussion
- Topic: DS reversed photo theory and battle maps comparison
- Replies: 63
- Views: 35352
No Vendetta
Hello, Bob: No vendetta, honest. I was responding to your often-repeated statements that your theory was supported by various individuals and institutions, and more precisely to your implication that these endorsements, apparently dating back to 1993 or so, are still relevant. One very recent exampl...