Very Tall Flats

[jeffspec]

hi.

my name is jeff. i direct plays in unusual places. i live in new york.

my current project is unusual for me because it demands a large set piece. to be exact, i have to create a life-like drive-in movie screen.

it wouldnt be such a huge deal if i could build it like a real screen. unfortunately i can not anchor into anything, which means i need to build a 40-foot wall with a lot of sandbags.

does anyone have any suggestions off the bat? the dimensions are 28 tall by 40 wide. i can make the supporting truss at the back at any angle. also, i can not guy line it from the top: the screen has to be freestanding.

could i get away with building dozens of flats and zipping them together, then propping them up with oversized jackstands? seems crazy to me.

any pointers greatly appreciated. i guess what i'm asking for more than anything is: can anyone point me to a guide for making a 30 x 40 foot wall?

thanks!

j

 

[MNBallet]

If you really have to build a wall that large that is free standing I would say build it out of steel.

My gut tells me to try a different route, more sugesstive. A backdrop of a drive in movie screen? A video projection of one? (that way you can get the movie on it too - a two for one deal!)


Ken Pogin
Production / Tour Manager
Minnesota Ballet

 

[jeffspec]

steel would certainly do it, but it just seems so ... monumental. we have a relatively short run.

as for backdrop, yes, we considered that, but the piece needs to be something that an audience could move around on all sides.

is there a proper ratio that would dictate the angle of my jacks (how much run i would need to the rise) in order for the flat wall to not topple? how about a rule regarding the amount of weight?

 

[scenerymaker]

Dumb question: Is it going to be used inside or outside? If inside, how many thousand pounds of ballast weights will your stage support? If outside, RUN away, of course.

 

[MercyTech]

Why make a wall? Why not make it out of a soft good?
For the "Shadow Dance" number in 42nd street we made a very large "Shadow Screen", which was made of a heavy opaque plastic/mylar sheet stretched over an aluminum pipe frame. It was about 20'x30', but it could have been made bigger.
It moved on t-frame wheeled struts. It was light, big and had to be moved easily, because we had to get actors behind it and light the unit from behind to cast shadows on the screen.
We already had the screen material, which I think may have been an old projection screen, but it was sitting in the rafters for years.

 

[ajb]

Will this be outside? That much surface area (1120 sq ft) means a potentially very large wind load.

If it's inside, then things are a bit easier. It's a fairly simple statics problem, but as stated every term is variable.

Here's a free body diagram showing the significant forces to consider:

A and B are forces acting on the screen, C is the weight of the screen, and D is the weight of the counterweight. d is the distance to the center of gravity of the counterweight.

The screen can pivot about point F, in which case you need to sum up the moments around that point: Aa+Dd-Bb [the signs depend on the direction of rotation. clockwise is positive, counterclockwise negative], or around Point R: Aa-Bb-CL-D(L-d). If you identify values for A, B, a, and b, and set the sums to 0, you can calculate the weight & distance needed to counterbalance the given forces. Of course if you will need to incorporate some safety factor so that the loads are more than just balanced.

 

[Fronz]

I would just use the cyc and a projector...

But you could make multiple flats, bolt them together, stand them up, and screw a (i can not think of the name of this for the life of me ) but its like a triangular support used to hold things up and you can put like 1-2 per flat and get a lot of sandbags and cover each flat with canvas! im not sure what you would do about the seems though... dutchman it? white gaffe if it fits properly... not sure if i helped any...

 

[jeffspec]

Great responses.

First, yes, it is indoors, which makes the whole project easier. But not easy.

The main thing is that we end up with an object. It needs to look more like a drive-in screen than a theatrical representation of a drive-in screen.

I could see how the aluminum pipe solution would work if we were just trying to get that surface, but again, i think we need the whole -- not just the flat surface. Here is a picture of what we're trying to do:



Should I start thinking of this as a construction project and start looking at - i dont know -- how to build a barn? Or is there a way to go big with flats that i've overlooked?

 

[MPowers]

As you've already seen, there are a multitude of solutions to the problem. The question is which one fits your budget, crew, etc. One possible solution is to rent truss, then stretch a Muslin cyc/drop/scrim/lino filled scrim over for the screen. Using standard 12" box truss your frame size would be 30' x 42' or 32' x 40'. some rental houses might have "special" lengths that would allow you to work toward your desired 28'x40'. The "Screen" might be available through a rental house, though getting the exact size might be an issue.

Indoors, depending on audience/talent/crew proximity, your base could be as short as 10' free standing, 5' front, 5' back. If you can put a solid anchor to the floor or a significant amount of weight, 6' to 8' to the rear might be sufficient. The company renting the truss will be happy to help you determine the best/proper way to rig the truss. I can't give you specific info without being on site and working with you to figure the answers. In your location, there are probably 100 companies ready and willing to help.

Just for the record though, over the years I have built and worked with 20' tall by 6' wide conventional (lumber flat to the face) soft cover flats, double height to make a 40' tall wall, think Grand Opera, old school, and framed drops 30' high x 50' wide, long before Hollywood style flats and steel tube framing were even thought of. It can be done.!

Michael Powers, Project Manager
ETCP Certified Rigger - Theatre
Central Lighting & Equipment Inc.
675 NE 45th Place, Des Moines, Iowa, 50313

 

[jeffspec]

Sorry Michael, I have to bite on this: 30 x 50 flats? 40 foot tall frames?

You're the first person who says this is even possible with Hollywood flats. So I have to ask? Did you stack two 20 foot flats on top of each other, then support everything with oversized jack stands?

Also: Thanks!

 

[MPowers]

Sorry Michael, I have to bite on this: 30 x 50 flats? 40 foot tall frames?
You're the first person who says this is even possible with Hollywood flats. So I have to ask? Did you stack two 20 foot flats on top of each other, then support everything with oversized jack stands?
Also: Thanks!

You need to read a bit more carefully. 30'x50' were framed drops, not flats, big difference. A framed drop is built in sections, then flown and attached. When the frame is complete, the muslin drop is attached, usually by folding around the edges and stapling (used to be carpet tacked, old school). Framed drops are usually used when there are large opening for arches, stairs and/or second story windows cut into the drop. The fabric is cut to about 3 or 4 inches from the framed opening and wrapped around and again fastened to the back. Functional doors and windows can be attached and flown with the drop. Rolling platforms and stairs behind the drop provide the talent access to the openings.

second, again, read more carefully, I said the 20' flats were conventional style, lumber flat to the face NOT Hollywood style. A single 20' flat could be braced with old fashioned stage braces that twisted into brace cleats on the back or standard framed stage jacks 14' to 16' tall. If the wall has jogs and right angles of sufficient size, it can be self supporting with bracing only needed at the free ends. When 2 20' flats are used to make a 40' high wall, they are flown and the flats are securely attached, one above the other. Hope this explains a bit and clears up the description.

Michael Powers, Project Manager
ETCP Certified Rigger - Theatre
Central Lighting & Equipment Inc.
675 NE 45th Place, Des Moines, Iowa, 50313

 

[jeffspec]

you're right: i wasnt reading closely. thanks for the clarifications.

 

[kicknargel]

As other have said, there are lots of ways to do this. A skilled carpenter could come up with something involving flats and jacks, or a custom structure of wood or steel. I think something this big falls into the category of (let's all say it together) if you have to ask, you should hire a professional. Even if you get basic strategies for building this here, there's so many factors of specific materials, dimensions, connection details, etc that you need someone with skill and experience. Not to mention, at that size and height, there are significant dangers just in setting it up (working at height, etc).

 

[jeffspec]

Just in case someone looks for information on building large flats in the future, I wanted to share a follow-up.

In short, we figured out a way to make a very large drive-in screen (32 x 40 feet) using modified stage flat techniques. (And, somewhat brattishly I have to point out that we did it cheaply, using used wood, and without calling in the professional carpenters suggested in this thread.)

Anyway, photos:

View attachment JEFF1-tower_082810.pdf