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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