Tiger time again

[crazydima]

Tovarischi,

Well, as many of you already know there was an incident with the SPR Tiger tank at the Indy Air Show last weekend.

The other forums have chosen not to discuss this matter for a whole set of strange reasons. None of which make sense but that is nothing new. However, due to the severity of the injuries and the fact it was in the public spotlight warrants some discussion as to what exactly happened.

If nothing else to help avoid possible future mishaps involving the same method of firing.

Please remember that this is the same tank which blew off its muzzle break and sent it down range at the Harvard, IL re-enactment last year.

Well It appears that a 1 lb. black powder blank charge detonated before they could get the breech closed. However, details are sketchy on just how it happened. At this point some of the details indicate that the powder charge was in some sort of casing with a section of cannon fuse supposedly cut to give 25 seconds before detonation.

Prior to getting kicked off the other forum I had asked exactly how the blank charges were being fired from the tiger. To date nobody has posted that information. Instead there seems to be a willingness to ignore the matter by the mods of the other forums. So much for safety concerns.

If it is a matter where they are placing a 1 lb. charge into the breech and then lighting a 25 second cannon fuse and then closing the breech to wait for detonation then there may be a problem in my humble opinion.

Civil War artillery(1860's) don't use fuses due to the safety issue of not having control over the exact moment of discharge. They use friction primers and cap locks. They are using blank charges varying from a few ounces to well over a pound depending on the size of the cannon.

So for 25 second you have no control over the charge and thus if needed to abort the firing you cannot. To me this seems to be a very poor method for firing such a large powder charge.

IMHO this incident deserves some attention and analysis from a safety point of view.

Sincerely,

Dima
(the alpha and the omega)

[adam]

I'm a lurker on here, who happens to also be a certified display pyrotechnician. We discussed this the other night at the pyro shop while testing some cannon fuse. I typed something up and posted it on one of the yahoogroups, if you're interested I could post it here. It's just my humble observations as someone who deals with this stuff quite regularly.

Discussing stuff like this is important. We regularly discuss mishaps (serious and not) at the shop. It helps makes everyone conscience of the dangers of working with this stuff.

Adam

[Konstantin]

Hey Sasha. You should see what I got today. ;D

[adam]

The biggest step these guys can take to fix this problem would be to go to an electric ignition system. I would say that somewhere around 70-80% of the fireworks shows we shoot are shot electronically, and I think that pretty much goes for the industry as a whole. I'm pretty sure that the ignitors themselves cost less than a buck a peice, and they can be fired off of something as simple as a 9 volt battery. The safest option would be to fire them off of a blaster, which you have to arm before you fire. Those are kind of expensive, but worth it.

As for what happened in Indy, there are a couple of possible explanations. One thing I wanted to mention, though, is something we learned in the shop the other night. One of the guys came into the shop with a peice of cannon fuse. He showed it to all of us and asked what was different about it. I finally picked up on the fact that it wasn't lacquered. No big deal, right? Well, lacquered cannon fuse burns much slower than fuse with lacquer on it because the lacquer cuts off some of the oxygen and slows burn time. Lacquered cannon fuse burns at a little of three seconds per inch; the un-lacquered stuff burnt at about two seconds per inch. We also tested a section of fast-burning fuse, which burnt at about one second per inch. So that's about a second's worth of difference between each of these fuses, all of which are available (why, I don't know) green-colored. So it is within the realm of possibility that someone could pick up one thinking it was the other. So, if that's what happened to these guys (can't say for sure), then the 25 second fuse they cut was actually a 10 second fuse.

That's my two cents on the matter.

[crazydima]

Tovarischi,

After reading Mike Lipe's posts on how they were firing the main gun it is a wonder that they did not blow themselves up prior to now. Plus there is little control over the round once the fuse is lit. It just doesn't look like much thought was put into safely putting this tank into the field.

Over the last two years I have used approximately 100' of cannon fuse for various pyro at WWII events. Usually in lengths of 3.25" for various simulators. So that means I have fired a few simulators to base my observations upon.

I have never had an incident where the fuse has burned faster than it was rated. I have used 3 different makes of fuse including the lacquered and non lacquered typed.

What I have seen is where the casing(lacquer) of the fuse would burn along the length of the fuse without the fuse itself burning. So if you have not properly fitted your fuse to your powder charge then this type of burning can and will lead to a uncontrolled detonation of the charge.

Thank God nobody was killed or hurt worse than they were.

Between this incident and the muzzle break incident I have decided to stay far away from this piece of equipment.

Sincerely,

Dima
(the alpha and the omega)

[crazydima]

Tovarischi,

Well I had a chat with one of my fellow engineers at my office and his words have made me even more concerned about "Montecore" aka the mock Tiger tank.

I asked him about the pros and cons of a cast aluminum muzzle break fastened to a steel gun tube.

Initially when the tank was obtained from the movie folks nobody bothered to give the gun tube a real good looking over. Thus the cast aluminum muzzle break which was shimmed on to the steel gun tube went unnoticed. Thus at the Harvard, IL re-enactment last year the muzzle break flew off and traveled 50-60 feet down range.

I was told that the muzzle break was re-mounted on the gun tube by bolting it to the steel gun tube. So now you have a cast aluminum muzzle break on a steel gun tube. Now such things as galvanic corrosion has to be considered as well as the stress being placed on the aluminum muzzle break from 1 lb. black powder charges.

This still appears to be a recipe for disaster and I will be staying away from this one when it is firing.

Sincerely,

Dima
(believer in self preservation)

[Konstantin]

crazysasha said:

Konstantin,
Don't tell you had UPS deliever a T34 to your front door. LOL
Sasha

Hehehe. Don't I wish. Naw, but I did get a 1987 dated soviet generals shirt. This postwar stuff rocks.

My fiance did by me a tank. A KV-1 to be exact. Granted it's a little on the smallish side. Use your imagination and try not to step on it. I'd cry.

-dave

I am hoping for a T-72 for a wedding gift. ;D