Interesting and I agree about luck. Sorry, but I didn't see you
published. I wasn't willing to wait for 10 minutes for such a gigantic
PDF to load.
Chuck Norcutt
On 3/12/2012 9:11 PM, Mark Marr-Lyon wrote:
> I still vote for lots of luck :)
>
> I'm guessing that 100 years ago, the electrical signal was something
> like the old-timey box and plunger in order to reliably get enough
> current to heat up the wire enough to start the primer. This could be
> fairly hard to sync to but even if they did, there's still quite a
> large variation in how long it takes the gunpowder to get going. It's
> hard to find very much data about this, since the military generally
> doesn't care as long as the gun works reliably, but in the bigger guns
> it can easily be tens of milliseconds, which for this gun would be
> tens of feet in the location of the projectile. It's much better to
> sync to a signal that tells you when the projectile has left the
> barrel, which may or may not have been possible 100 years ago. Similar
> problems would be found in trying to light a (very!) large pan of
> flash powder.
>
> There's lots of people who have posted pictures of Fort De Soto, but I
> couldn't find the picture in question. Here's a web page about the
> Corregidor installation of the same mortars (warning: lots of
> pictures, but I found them interesting even if I didn't read the whole
> page)
>
> http://corregidor.proboards.com/index.cgi?board=threads&action=print&thread=1012
>
> About 1/3 down the page is a WWII photo of a similar mortar firing
> with the projectile peeking out of the smoke cloud, so it is quite
> possible to get lucky and catch one. I especially like the photo of
> the round still loaded in one of the guns, though I would be worried
> about how the aging of ammonium picrate affected its sensitivity if I
> were taking the photo.
>
> Anyway, sorry to blather, but I did spend a fair bit of time learning
> interior ballistics and trying to find out what causes the powder
> ignition delay variation. In our case, the flash is a large proton
> accelerator and the mortar is a 40mm research gun. See (again, fairly
> large):
>
> http://www.lanl.gov/science/1663/issues/january2012.pdf
>
> for more info starting on page 18. The images on the bottom of pages
> 20 and 21 are mine (Woohoo! I've been published!) Since my management
> and I had a significant difference of opinion on the matter a while
> back, I no longer am trying to find the cause but at least I haven't
> been proven wrong in the past couple of years and it is still not
> working. Not that I'm bitter or anything :)
>
> Mark
>
> On Mon, Mar 12, 2012 at 12:24 PM, John Ockman<jrockman07@xxxxxxxxx> wrote:
>> Very slow film, electrical sync. and lots of flash powder is my guess.
>>
>>
>> On Sat, Mar 10, 2012 at 4:52 PM, Chuck Norcutt<
>> chucknorcutt@xxxxxxxxxxxxxxxx> wrote:
>>
>>> To my mild surprise the guns were fired electrically. Perhaps it was
>>> possible to synch the camera with the firing signal.
>>>
>>> Chuck Norcutt
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