Main Curtain Speed

[Footer]

How fast should a main curtain move? Just got a spec to go automated on our main rag. 180fpm hoist. That feels way too slow to me. We trim at 22' but can go out to 24' if need be. That is 7 seconds top to bottom, 9 seconds if you account for acceleration and deceleration. Looking at Clancy's site, you don't get any faster until you go line shaft and even then your still looking at 240fpm. A good flyman can get our rag in/out in 3-4 seconds. Am I crazy here or do they not make a motor fast enough for this purpose?

 

[porkchop]

If I remember, in the book written by a few of the big guys from Stage Tech they said they start a spec at full travel in 8 seconds, but I'll double check when I get to work. Our main travels ~60' in up to 240fpm, although I believe our normal move speed is more like 120-180fpm.
We have winches that go up to 30 fps (1,800 fpm) so I'm sure than there are winches that go as fast as you'd like. My question is how important is that extra 6 seconds to you if the movement is safer and more consistent? I can certainly see how that could be a huge difference, but I'm also fairly sure that a decent director could easily work with the additional move time.

 

[de27192]

I once worked with a winch that could run at 100 m/s. So there is no act of physics that means a winch can't go fast!

On the JRC I can't find any speed specs for their drum winch or pilewind. (The 2 most popular types for theatre flys). They should be able to provide whatever speed you ask for, or better yet a varispeed winch that will allow you to set the speed yourself.

 

[BillConnerFASTC]

The general rule for a straight lift main is 400 fpm. I heard it from people at Albrecht that they tested Kennedy Center opera house for manual speed an three stage hands could reach 400 fpm so the built a machine to do that. In fact, the spec for the machines at a current project - 36 of 39 at least - is just that 400 fpm. (And 2000 pounds for 32 of them.) No, these are not catalog winches, but not unusual for Tait nor hard for Clancy and others.

 

[kicknargel]

Artistically it'd be a shame to be limited to one speed of operation. Maybe it saves a bunch of money on operators and is a trade-off that's worth it. But think of the old gag of someone trying to make a dramatic exit through a door with a slow auto-closer. Kinda ruins the moment.

 

[BillConnerFASTC]

Well, imeant max, which controls design.

 

[Footer]

The general rule for a straight lift main is 400 fpm. I heard it from people at Albrecht that they tested Kennedy Center opera house for manual speed an three stage hands could reach 400 fpm so the built a machine to do that. In fact, the spec for the machines at a current project - 36 of 39 at least - is just that 400 fpm. (And 2000 pounds for 32 of them.) No, these are not catalog winches, but not unusual for Tait nor hard for Clancy and others.

Thanks Bill, I kind of figured as much. No clue why our Clancy guy had the engineer on this project spec a 180. One more thing to add to the list on this little project... right up there with they are re-roping the room but only replacing sporadic loft blocks.

 

[carsonld]

Our school is installed with 34 JR Clancy automated battens and we usually have to choreograph around the scenery as it goes up and down because it so slow, even with it as fast as it can go. It take about 9 seconds for our scrim to go up, which we use a lot for our pre show curtain. It's kinda a hassle but it makes things more challenging. No one else really notices how slow it goes though since we try and manipulate the lighting and blocking with it.

 

[BillConnerFASTC]

They can make faster (and higher capacity) motorized line sets but Vortec sort of set the standard when they introduced the first (arguably) "packaged hoist" for stage lineset use. Had they introduced a 360 or 400 fpm - which is not uncommon for some hoists - it would have been more than twice as expensive, and IMHO they were trying to get to a three to one cost over manual counterweight for marketing purposes. Let's face it - offering a school district a manual counterweight rigged stage for say around $300,000 or all motorized for $1,000,000 (imagine Austin Powers saying that) - was hard enough. Saying $2,000,000 was suicide.

180 fpm - typical max for basic 1000 pound variable powerlift/vortec/prodigy - is a little slow especially after factoring in accel and deaccell. Lots of room for discussion though.