Making an MIL-MI 26 in Inventor

For the Make it Resilient Contest, I have replicated the design of an MIL-MI 26 helicopter In Inventor and have made plans to 3D print it. The MIL-MI 26 is used in order to help communities that live in mountainous regions gain access to supplies. The MIL-MI 26 is able to carry up to 20 tons and is optimal for transporting supplies, equipment, or even troops to remote locations.

https://www.aircharter.com.hk/aircraft-guide/cargo/milhelicopters-cis/mil-mi-26

https://vertipedia.vtol.org/aircraft/getAircraft/aircraftID/332

https://en.wikipedia.org/wiki/Mil_Mi-26

These are some references I used when designing the MIL MI 26 in Inventor. The scale I used was 1 inch in Inventor was equal to 1 meter in real life.

I made 3.1 inch by 3.2 inch rectangle, with 3.2 inches representing the height of the helicopter and 3.1 inches representing the width of the helicopter. Then I extruded the rectangle 12.1 inches.

Then I created part of an ellipses that was 3.2 inches tall, 8 inches long, and had an arch that was 12.726 inches long. I extruded this sketch 3.1inches.This figure was filleted by .1in.

The body of the helicopter was filleted by .1 inches.

I sketched a trapezoid figure on the top of the body of the helicopter to mimic the shape of an MIL-MI 26 helicopter. This was done by making the XZ plane visible, and then going to "Plane" and the dimensions of the trapezoid were 6.004in for the bottom, the left side was 2.150in tall, then 4.251 across, the right side was 1in tall and the connecting side was 1.753in long.

Then, I created a circular sketch on the front of the trapezoidal figure. The diameters of the circles were 1.550in. After finishing the sketch the circles were extruded 3in.

After extruding the circles, I started a new sketch on the surface the surface of the cylinders, making two circles each with a diameter of 1.331in. These circles were extruded 1in. Each of these cylinders were filleted by .65in.

Then I sketched a 8.096in by 3.1in rectangle on the remaining space behind the trapezoid. The rectangle was extruded 1in and filleted on each side by 1 in.

In order to mimic the curved base of the tail, I drew a 18in line and added a 81.818 arc, and then mirrored the arc. The sketch was extruded by 1in and filleted by 1in on both sides.

Then, I made another cylinder on top of the helicopter. Another work plane was made to start the sketch by offsetting a plane from the XY plane. The sketch had a circle that was 1.5in in diameter, and was extruded 1.1in one way and 3.15in in the other direction. Then I sketched two more circles on the side of the cylinder. The outer circle had a diameter of 1.326in and the inner circle had a diameter of 1.095in. The ring of space between these two circles was extruded .2in inward. The cylinder cutout left was filleted by .54in.

In order to make the base for the helicopter rotors, a plane was created by being offset from the XZ plane. A circle was sketched that had a diameter of .773in and extruded 1.5in.

Another plane was offset from the XZ plane and one rotor was sketched. The length of the rotors are 15.619in and a line of .575in was drawn. These lines were mirrored and at the bottom, by the base of the rotor, a .387in arc was sketched. This rotor was extruded .25in. Then, using the "circular" command, 8 rotors were then copied around the center of the circle.

The front of the helicopter was designed by sketching the side profile of the plane, and then extruding the sketch, and filleting the extrusion. Starting 2in above the bottom of the helicopter, a 3.5in line was drawn to the left, serving as the base of the sketch for the front of the plane. After the profile was sketched, it was extruded 3.1in. Only certain edges, as shown in the third picture, were filleted by .9in, as this was too much for other edges. The remaining edges, shown in the fourth and fifth pictures, were filleted by .125in.

To make the wheels, a circle with radius .273in was drawn .866in from the center-front of the bottom. This circle was extruded .5in. A curved sketch was drawn on a plane going through the center of the extruded cylinder. The curved sketch was .193in tall with .5in long bottom and .227in long arc. It was extruded by .2in in each direction and all edges were filleted by .05in. From the middle of the side of the curved extrusion, a .480in line was drawn. Using this line as reference a .480in diameter circle was sketched. This circle was extruded .4in one way and .6in the other way to make the base of the wheel and make it symmetrical. Starting a new sketch on the side of the cylinder, a .722in diameter circle was sketched and extruded by .3in in each direction. Then, on top of the .722in diameter circle, another .48in diameter circle was drawn and extruded .2in into the wheel.

In order to make the other side of the wheel, another .722 diameter circle was made on the side of the circle, also extruded by .3in in each direction. Another .48in diameter circle was sketched on top of this cylinder and extruded .2in into the wheel. This process was repeated two more times in order to make all three wheels. The diameter of each of the base of each of the two wheels in the back begins 11.498in from the front edge of the bottom of the helicopter.

To make the tail of the helicopter, I created a sketch on a plane offset the YZ plane. Then I sketched a a figure with a side that was 6.5in long, with a 1.529in long line connecting it to a 5.667in line and .990in line. The base of the figure was 2.065in long. This sketch was extruded 2.2in and filleted by 1.1in.

A line was drawn on top of the tail of the helicopter, and a circle was sketched with a diameter of 1.529in. The circle was extruded 3in both ways, so 1.5in in each direction. The plane that the circle was sketched on was offset the YZ plane. Then, another sketch was drawn on a plane offset the XZ plane. starting from the center of the extruded circle, a 2in line was drawn. Then, a .339in line was drawn, and another line was drawn connecting the .339in line to the edge of the cylinder. A last line was drawn connecting this longer line back to the center of the cylinder. This shape was mirrored to the other side of the cylinder and both sketches were revolved around the 2in line.

The rotors on the side of the helicopter tail were created by sketching a 3.941in line. Then, a .222in line was drawn from the top, and connected the 3.941in line to a 3.579in line that went back to the base of the rotor. A .232in line was sketched from this line to the original line, and mirrored over the 3.941in line. This sketch was extruded by .3in in both directions, so 1.5in each way, and was sketched on a plane offset the YZ plane.

Then, I added another figure to the tail as per the design of the MIL-MI 26. It was sketched on a plane offset the XZ plane. On this plane, starting from the center of the tail, a 3.5in line was drawn. Then, a .650 line was drawn upwards. These two lines were mirrored and the arc connecting them was 23.494in long. This sketch was mirrored over the 3.5in line so that the figure was also inside the tail of the helicopter. The sketch was mirrored .3in both ways, so 1.5in in each direction.

Connecting pieces were added to the helicopter to make each part more secure and have the pieces "blend together." Starting with the two filleted spheres on top of the helicopter, a plane was offset the XY plane. On this plane, a 1in line was drawn from where the two cylinders met. Then, a 1.425in line was drawn to the left, and an arc was sketched that was 1.458in long. From the end of this arc to the beginning of the 1in line, a .775in arc was drawn. These lines and arcs were reflected over the 1in line. This sketch was extruded by 3in.

Then, going to the cylinder on top of the helicopter, another joining piece was created. This was still created on the plane offset the XY plane from before. From the endpoint of the diameter of the cylinder, a 1.1in line was drawn. A 1.531in arc was also drawn and a .750in arc was drawn connecting the previous arc and line drawn. This was mirrored over another line drawn. This sketch was extruded 4.25in.

On the bottom of the helicopter, a plane was offset the YZ plane. There were gaps from having previously filleted the body of the helicopter in places where the fillet had taken off/chipped away part of the body of the helicopter. In one spot toward the back of the helicopter, a 1.208in line was drawn and the arc drawn mimicked the path of the helicopter. The figure was extruded 1.5in in each direction and filleted by .1in. Towards the front of the helicopter on the bottom and on the same plane, a .466in line was drawn, followed by a 1.193in line. The arc connecting these lines was 9.030in long. This sketch was also intruded 1.5in in each direction and filleted by .1in.

In order to 3D print the helicopter in the best way, the pieces of the helicopter had to be separated so they could be printed as separate bodies. In copying the helicopter, the wheels were taken off and made a separate file, as were the rotors, and then every other part of the helicopter. The rotors were added to a thicker base/ring so that they would be more supported coming out of 3D printing. In order to attach the rotors to the helicopter, a cylindrical hole was made inside each ring so that they could be fastened to the body of the helicopter when completed. To accommodate this ring, on the main body of the helicopter, the tail has a revolved body on one side, and a cylinder sticking out on the other side.