CMU School of Drama


Wednesday, September 23, 2020

Effects of Recoil Forces From Large Scale Pyrotechnics on Entertainment Structures

Protocol: IN THE SPRING OF 2018, I was working on a pyrotechnics design for a large stadium tour and the usual questions were being asked: Where will the pyrotechnics devices be located? How high will the product go? What are the safety distances required? These are all standard questions for every pyrotechnic design. This project however posed some additional questions since the pyrotechnics were to be mounted high in the structure on horizontal spans, such as: How much does the gear weigh? How much recoil is generated by the functioning devices? The first question was easy to answer, but the question about recoil forces was not as easy, and required some experimentation to understand.

7 comments:

Maureen Pace said...

This was absolutely fascinating to me; if I hadn’t applied/chose to enroll in theater school, I was planning to study physics, so it is super interesting to see the two intersect (physics affects everything, so no big surprise there though). They ran 63 tests with different trusses and pyrotechnics to calculate the forces at play, and this information (which is still in development- the conclusion addressed this) can be used to create safer and smarter rigging for pyrotechnics. In one of the linked videos, it was really interesting to see how much the trusses moved when the explosions happened. I’ve never used pyrotechnics before, so I’ve never spent time thinking about this issue. While some of the physics went over my head (two years is a long time), it made a lot of sense that they had to think about the resultant force of the explosion and the effects on the truss, as well as any lighting equipment.

Emma Patterson said...

This is really cool! Large scale pyrotechnics are not anything I have ever really gotten to be involved with, and I find the math behind them really interesting. I enjoyed how this article really walked through the full process that a pyrotechnics designer takes when calculating recoil forces from large scale pyrotechnics on entertainment structures. It makes sense that they did 63 tests to examine the different forces and gather data to determine the safest choices to deliver the designed effects. The key issue I am struggling with at the moment is I look at this article and think “cool”, and I want to write a really cool comment on it. However, there is not much to say about physics or math, when your brain can barely tolerate arithmetic, so I will spend the rest of this comment talking about how the pictures they used were very exciting, and I miss being able to see pyrotechnics in person at events.

DJ L. said...

I have always been interested in pyrotechnics and...well, fire. Some of my friends may even call my a pyromaniac. I was fortunate enough to shadow a couple people at a pyrotechnic company back at home. In doing this, I learned a lot about the operations of them including how they are set up, how they are triggered, and how they work. That being said, I didn't know or learn anything about how forces from the pyrotechnics effect the objects or structures they are attached to. It was super interesting to see how much force the pyrotechnics can kick back on the stage structures. This math and data can clearly be used to adjust how we rig pyrotechnics in order to create a safer environment for everyone in and around the show. I hope to get to spend more time working with pyrotechnics in the future, allowing me to apply some of this data.

Akshatha S said...

This article really showed me how much I love to be a technician. It seems as a technician you get to have different careers based off of the projects you are doing, somedays being an architect, some days being a physicist, and some days being an artist. I think the amount of physics and science that goes into design and creation surprises people, even people working in the industry, as a lot of it seems to come inherently to successful technicians. When a technician breaks down the physics and tests the science behind what they are doing and the decisions they make, I think the industry moves ten time forward. I never thought about calculating the kick back pyrotechnics have, rather it seems like something I had always kept in the back of my mind subconsciously. By testing the kick back and explaining the physics behind the pyrotechnics effect on the structure, there can be a deeper understanding on how the structure should be created and what is the right decisions to be made about materials. I think the ability for a technician to become a scientist for certain projects is one of the biggest reason I decided to go into this major. You not only experiment and figure out the science but also see all of it in action every time the show is put on.

Al Levine said...

I have always found pyro fascinating, but I have never wanted to follow through with that interest as much as I have after reading this article. There is something in the back of my head that gets so excited when I see pyro, or something goes BOOM (love fireworks!). As such, I found the article to be really informative and engaging- I had never considered much about designing pyro or the special considerations that come requisite with such an effect. While it makes sense to ask questions about where the devices go, how high the payloads will go, and what the minimum safe distance is, I find it surprising that nobody seems to have asked how sturdy the structure needs to be. I guess, to some extent, that there's a David vs. Kevin argument to be had there: We just need to beef up the structure so it won't eat itself vs. Let's do the math to figure out how strong it needs to be. A lot of the recommendations make sense intuitively, but it is nice to have the math to back it up, even if I might not do it out in the field.

Nicolaus Carlson said...

This is interesting. It is very short, but interesting. My main question is, why do the manufacturers not have the recoil data? And why haven’t they studied it extensively? I understand that their concern does not deal with structural strain and force generation. They are likely concerned with machine ability and reliability and chemical compositions with many regards to safety and stability of those chemical compositions. But I would still argue that you probably want to know force values and such for your product even if it is not for structural reasons. However, despite all this, the way these people wen about testing and finding these values is to be commended. I am sure there was a lot of work involved and that it is definitely a concerning thing you want to get right. I wish the article had some more depth as this provides a good overview but there is more information worth noting; I am sure.

Elliot Queale said...

This is a fantastic article and well designed experiment. It is presented with all the necessary information without getting too lost in the weeds, while giving resources for those who want to dig deeper into their process. Specifically, I like that most of the results include links to more data, instead of cluttering up the page. That's at least my thoughts on the article as it was written, but what about the data! What the result of this experiment point us to is that we can often assume that we can use pyro on our structures simply because we have beefed them up to the point where any anomalies are captured by our design factor. We just need to factor in the momentary force caused by the device as a point load in our system. Since, as the article notes, the load cells never read higher than this value, using that point load will lend a conservative design. The big note here from a structural design standpoint is that we are no longer dealing with static systems, which is what our math is founded upon. The less static our system, the less accurate those principals become. In this case, we are still safe, but that will not always be true! What this experiment does is give us a sense as to how the reality of these systems corresponds to our boiled down structural analysis. That is the most valuable part of this article.