If you have used YM before, you probably see some dramatic differences from what you are used to when designing new antennas or checking the mechanical stability of existing designs. The most significant part of this is because previous versions of our Yagi Mechanical® software used element pieces defined by cross sectional material in order to calculate wind speed and ice loading survivability. While this provided useful results the process could be difficult depending on how your antenna was designed - usually for multiple wall designs - and what was determined by YM for the Element View and Bill of Materials was not always reliable in these cases.
With our new release of Yagi Mechanical® we have rebuilt all aspects of the program, including how we look at the tubing used to build your designs. The largest difference is that you no longer specify sections but rather sizes of tubing and where they physically reside in relation to the center of the element. This takes some adjustment if you are used to the old method, but the code behind the scenes produces mechanical data that is just as accurate while now allowing a more accurate report on the Bill of Materials and making our new 3D View possible.
When starting a new design from scratch, define your first piece of tubing in the Element Design tab. The left field in each row of the Physical Sections box is a menu where you can drop down and select the type and size of material that you want to use (use the search filter box to find items more quickly). The next column - Interval Start - allows you to set the location of the tube in relation to the boom and Interval End specifies the length of the tubing with relation to the start point. Begin with zero and work your way further out as you taper the element to reach your desired frequency. For each change you make, Yagi Mechanical® will automatically recalculate all of the properties of the design. When entering in your locations you can use whatever units are comfortable for you and YM will automatically convert it to inches. This automatic conversion exists in many fields in the new version to make for easy usage.
Adding another piece of tubing below what is already there can be done by clicking Add Tube 
, or add in a specific spot by selecting the tube where you want to add and then click Add Tube. To remove a piece of tubing select it and click Remove Tube 
to remove it from your antenna design. Just like when changing locations or lengths of tubing, YM will automatically recalculate everything when adding or removing tubing. In the Mechanical Stress box below you can see the cross-sectional pieces that are generated from your defined tubes and used to do the calculations.
While the start and end position field can be directly edited, there are some additional buttons to make it easier to tweak the length and location of your sections. The Lengthen Tube button 
will add an inch of length to the selected tube and move following sections the same distance. Use the Shorten Tube button 
to do the opposite and shorten a selected tube by one inch. If you want to keep the length of the tubing the same use the Shift Left 
and Shift Right 
buttons to move the currently selected tube by one inch in either direction. This does not affect the length or position of the other pieces of tubing in the design.
Our 3D View has replaced the old Element View to show a virtual view of your design. The view has been extended to include the whole design, including full elements, the boom, and center supports. Stress points and their values are labeled, with the ability to show the cross-sectional equivalents used to calculate the stress. Another useful addition is a circle representing the maximum turning radius, determined from the location of the element tips in relation to the boom’s mounting point. The built in controls allow viewing from any angle and zooming in as much as you need to see how the tubing fits together.