How many grains does 30 Jin reflect and how many degrees of arrows are appropriate?

1 30 kg is suitable for using 2 10~300 grains of arrows with 700 turns.

2. Grains: historically used units of weight. Initially, in Britain, the weight of a barley was defined as 1 grain. 1 gram = 1/7000 lbs = 64.438+0 mg.

3. Deflection generally refers to load-bearing members (multi-fingered beams), which will bend when bearing loads, and bending to a certain extent will also be considered as damage. This degree of bending is called roundness. There are two main aspects of winding: on the one hand, the tension of itself; On the other hand, it is mainly the cracks on the lower side of the beam. Generally, the beam works with cracks, and the width of cracks is generally required to be 0.3mm, which will lead to excessive winding of the beam. Although the beam can continue to bear the load, it can be regarded as reaching the bearing limit.

4. recurve bow is a kind of bow that looks different from ordinary longbow from the side: the end of one bow arm of recurve bow without bowstring bends outward. One of the special definitions points out that the difference between recurve bow and other bows is that recurve bow's bowstring, that is, the winding person, is in contact with its bow arm. Compared with the straight-arm bow, recurve bow can store more energy, which makes the shot arrow have higher kinetic energy. So recurve bow can make it shorter than the ordinary bow, but it can keep its power. This advantage makes recurve bow suitable for places where long weapons can cause inconvenience, such as jungles, forests or horseback riding. Relatively speaking, the traditional straight long bow will have a "cascading" effect-that is, the more the bow is pulled open, the more the force required to pull the bow will increase obviously.