A 1HP motor is rather large to control efficiently with a triac,
If this is a typical Radial fan, the smaller the out-going aperture, the lower the current.
Nothing connected to inlet/outlet = maximum current.
Max.

 

For shutter control maybe only 90 deg. rotation is needed so a gear reduced DC motor might do.

 

Closest I can come up with is from Granger, Controllable air damper, 14" dia. $ 150.

 

Thank you all for your thoughts and advice - it was very helpful! I didn’t have time to do a lot of r&d so I went with the suggested method of adding ducting on the discharge side to let out some of the airflow. I made a ‘Y’ joint 18” past the fan, with one arm going to my inflatable and another equal size arm discharging air flow. The first time i turned the thing on it calibrated itself for me by ripping a much bigger discharge hole in the middle of that joint! Haha. I turned it off and reinforced the edges of the ducting with duct tape.
I experimented with making smaller exhaust ports on the inflatable itself on the front side - each one was like 2” in diameter. I made like 9 rows of them, with like 8 ports on each row. That was too much exhaust, and the inflatable lost too much pressure and didn’t inflate. So then I went through the rows and closed them off a row at a time and testing for inflation. Eventually I closed basically all of them to get the thing to inflate fully in a way that I liked. Part of my thinking with these little exhaust ports was making fun ‘windsock’ type features that would flicker and dance as air flew through them, but I was okay giving up on that. Once the structure was sound, I painted Both sides of the inflatable and layered some liquid latex on the front side. When the latex dried i ripped little holes in it for gory texture and then painted more over that.
When I got it in the studio, we lit it nicely from the front and back, and i covered it in some goo made w water, xanthan gum, food coloring, and corn starch. Our actors got in front of it and then we staged one Grip crew members on either side of the inflatable. The inflatable was mounted on a frame, and the uprights of the frame were 1/2” steel conduit and the horizontal pieces of the frame were 1/2” pvc pipe. The two Grips blended the frame around the actors like a taco. The idea was that the character me had been enveloped in a cocoon made by a giant worm, and the scene was them trapped inside of the cocoon.

here’s some video and pix:

 

Thank you all for your thoughts and advice - it was very helpful! I didn’t have time to do a lot of r&d so I went with the suggested method of adding ducting on the discharge side to let out some of the airflow. I made a ‘Y’ joint 18” past the fan, with one arm going to my inflatable and another equal size arm discharging air flow. The first time i turned the thing on it calibrated itself for me by ripping a much bigger discharge hole in the middle of that joint! Haha. I turned it off and reinforced the edges of the ducting with duct tape.
I experimented with making smaller exhaust ports on the inflatable itself on the front side - each one was like 2” in diameter. I made like 9 rows of them, with like 8 ports on each row. That was too much exhaust, and the inflatable lost too much pressure and didn’t inflate. So then I went through the rows and closed them off a row at a time and testing for inflation. Eventually I closed basically all of them to get the thing to inflate fully in a way that I liked. Part of my thinking with these little exhaust ports was making fun ‘windsock’ type features that would flicker and dance as air flew through them, but I was okay giving up on that. Once the structure was sound, I painted Both sides of the inflatable and layered some liquid latex on the front side. When the latex dried i ripped little holes in it for gory texture and then painted more over that.
When I got it in the studio, we lit it nicely from the front and back, and i covered it in some goo made w water, xanthan gum, food coloring, and corn starch. Our actors got in front of it and then we staged one Grip crew members on either side of the inflatable. The inflatable was mounted on a frame, and the uprights of the frame were 1/2” steel conduit and the horizontal pieces of the frame were 1/2” pvc pipe. The two Grips blended the frame around the actors like a taco. The idea was that the character me had been enveloped in a cocoon made by a giant worm, and the scene was them trapped inside of the cocoon.

here’s some video and pix:

*bended, not blended. maybe I will get some footage from the camera and upload to show what I mean. With flexible pvc on the horizontal frame pieces, we could bend this backdrop around the actors standing in front of it, to wrap them up like in a taco or burrito.

 

Oh Wow!! Quite something indeed. and it may be that the same arragement can work for some other inflatable projects. It will be interesting to see the movie when it is completed.