Weight Class Rant
Below I have grouped information by weight classes and type of information. The four groups I have used are based around what is commonly built around the world. Most Countries have a 0.15 kg, 1.36/1.5 kg, 13.6 kg, and 100 kg weight classes. I struggled with where to put US antweights, but I find them to be closer to the 0.15 kg segment in terms of construction than the 1.36 kg group. This break down is not perfect but it roughly breaks each group into an order of magnitude difference in weight 0.1, 1, 10, 100, and each grouping should share many parts and construction materials.
I have focused most of my attention on groups 1 and 3, but I have done some investigation into groups 2 and 4.
US Fairy/UK Ant, and US Ant
0.15 kg and 0.45 kg Weight Classes
0.3 lb and 1 lb Weight Classes
1.36-1.5 kg Weight Class
3-3.3 lb Weight Class
Hobby, Feather, and Light Weight
5.4 kg, 13.6 kg, 27-30 kg Weight Classes
12 lb, 30 lb, 60-66 lb Weight Classes
Middle and Heavy Weight
54 kg and 100-113 kg Weight Classes
120 lb and 220-250 lb Weight Classes
Intentionally left out are the 1 kg/2.2 lb, 6 lb, and 15 lb weight classes, as well as sportsman or plastic weight classes. The 1 kg/2.2 lb and 6 lb weight classes are very rare and both fall in the Beetleweight order of magnitude.
The 15 lb or BBIQ weight class overlaps heavily with the Hobbyweight class. Such that they are essentially the same. A robot will add or shed components to compete in both. In fact the call for the two weight classes to be merged in to a single 15 lb weight class has come up more than once. Interestingly this weight class debate occurs near the breaking point where the weight classes go from a factor of 3 between classes to a factor of 2.
3x (0.3/1/3) 2x(3/6/[12-15]/30/60/120/240) lbs
In order to maintain factors of 3 (or god forbid factors of 9) between weight classes: 0.3/1/3/9/27/~80/240
In order to maintain factors of 2: ~0.3/0.75/1.5/~3/7.5/15/30/60/120/240 We have to round some, but we actually maintain almost all the weight classes while splitting the 1 lb into 2 weight classes.
Which is why I prefer to pretend it is an order of magnitude arrangement or: 0.3/3/30/250 lb [0.15/1.5/13.5/110 kg]
I think many others simply organize it very practically, based on Arena Size: Insects/Hobby: 0.3/1/3/6/12 and Near Heavy: 15/30/60/120/240. With insects in 8x8 arenas (sometimes 4x4 for US fairy), feathers in 16x16 arenas, and heavys in 32x32-50x50 arenas
It is convenient that the most popular weight classes as the "largest" for their respective arena sizes. Which are also the 0.3 lb 4x4 arena, 3 lb 8x8 arena, 30 lb 16x16, arena, 220-250 lb 32x32 arena.
But if we pretend the 12 lb weight class is a compromise between 10 and 15, it become acceptably elegant again.
Tripling and rounding (0.3/1/3/10/30) and then doubling (15/30/60/120/240)
I believe the history comes from two directions. The insect classes and the heavy weight classes, hence the two different multipliers. The early insect classes were 1 and 3 lbs. The early large classes were 60,120, and 240. BBIQ was added as a college level at 15 lbs, and feathers eventually came along at 30 lbs. Some time before the 30 lb weight class the 12 lb Hobby weight robots came along.