I then opened the assembly to the point just short of the hinge being fully extended, and scribed another line at the actuator rod pivot point. The spot that the two arcs intersect is the pivot hole location for the actuator rod. The last two photos show the completed mock-up of the hinge/rib/actuator assembly in both open and closed positions. All of the area between the frame rails is reserved for the radiator and mounting brackets. Next job is to finalize the shape and location of all of the ribs that will support and stiffen the tilt shell.
The first two photos show the hinge/rib assembly in the half-open and full-open positions. The full open position was a little too far, so I decided on something less than full hinge travel. The total travel distance of the actuator, along with the mounting position of the actuator on the frame will also dictate how far the tilt will open.
After a lot of trial and error, I located a spot on the top of the frame rail that would be the attachment point for the actuator motor. The 10" stroke actuator turned out to be the correct length. These actuators work by being either fully open or fully closed, and the mounting points have to take that into consideration. Now that I found the mounting point on the frame, I needed to locate the pivot point on the rib. Last photo shows the actuator/hinge/rib in the fully closed position. I took a pencil, put it through the rod pivot hole and scribed an arc on the rib. I'll continue this on the next entry.
After trying a few different rib shapes, I settled in this layout. I omitted the front angle piece that was on the hinge in favor of bolting the hinge arms directly onto the rib. The width of the hinge/rib is set by the width of the grille, which has tabs that will bolt to the inside face of each rib. This means that the hinges will not directly attach to the frame, but to a separate bracket. Horizontal and vertical adjustment of the hinge will be done at the bracket that attaches the hinge to the frame. After spacing the hinge/rib assembly the correct distance away from the frame, I clamped the assembly to the side of the frame and got ready to locate the linear actuator.
Now that I know the hinges will work, I'm moving on to the linear actuator mock-up. After looking at and comparing a lot of actuators from different vendors, I decided to use the Dakota Digital units. I got the dimensions of the units I was interested in and made up a "working" model. This is a 12" stroke model here, but I ended up using the 10" stroke unit instead.
Probably the biggest problem with having a one piece fiberglass front end is that it is very flimsy and needs a lot of structural support to keep it from flexing and twisting when it is opened and closed. Add to that the forces put upon it by linear actuators, and some serious reinforcement is necessary.
My first thought was to make a frame out of square steel tubing, which would not only stiffen up the fiberglass shell, but also mount all of the hardware including hinges, actuators and grille. Steel angle clips could be bonded and 'glassed in place onto the interior skin of the tilt shell. The steel frame would then bolt to these clips. Although this would probably be the most practical way of doing it, I didn't like the way it would look. I wanted something a little more "finished".
So, I decided to use ribs instead. These would be made out of ¼" thick aluminum and attach to the shell with bonded and glassed-in clips, also made out of aluminum. This would stiffen up the shell, similar to the ribs in an aircraft fuselage or wing, and also add some "looks" to the finished tilt.
The last photo shows the beginning stages of using the rib idea. I modified my temporary wood brackets that I used for the hinge mock-up by through bolting it to the tilt shell. A plywood rib was attached to the side of the bracket. This rib will be large enough to accept the hinge, the linear actuator rod, and will also mount the grille.
This is the rest of the opening action. These hinges will work out well. Smooth opening and closing, and the tilt shell actually moves forward as it opens, giving more room to work around the motor. The last photo shows the hinges fully extended, and I'll probably limit the travel to something less than that. It was a lot of work just for the mock-up, but I'm satisfied with the results.