Constant force impact protection device

A protective impact device, comprising:

• (a) a first impact surface;
• (b) a second impact surface substantially parallel to the first impact surface;
• wherein the area of the first impact surface is smaller than the area of the second impact surface,
• wherein a perpendicular distance between the first and second impact surface defines a stroke distance;
• (c) a compressible vessel held in between the first and second impact surfaces, wherein a cross-sectional area defined by the compressible vessel increases in a continuous fashion over the stroke distance from the first impact surface towards the second impact surface and wherein the compressible vessel in between the first and second impact surfaces defines an inner wall shape with a positive second derivative slope defined over the stroke distance, defined over the entire inner wall and defined from the first impact surface towards the second impact surface, wherein the compressible vessel has reinforcement fibers to prevent the compressible vessel bulging;
• (d) a fluid contained within the compressible vessel;
• and
• (e) one or more orifices to allow the fluid to bleed out from the compressible vessel when an impact force causes compression of the protective impact device, wherein the compression is defined by the first impact surface moving towards the second impact surface along the stroke distance.