A very light composing empennage allows to balance the model without adding any ballast to the nose.
一个非常轻的构成尾部让不需要把任何的压舱石加入鼻轨就平衡模型。
2
On this day I also tested the ballast tank and did a very brief full submergence dive, in the limited light I could not see below the surface and lost sight of the sub right away.
The traditional ballast starting, added high-pressure filament material suddenly without preheating, will take serious sputter and loss, and make the light turn black and scrap ahead of time.