Building Chinese Fire Arrows — The First Rockets in Human History

Select straight bamboo shafts approximately 80-100 cm long and 8-10 mm in diameter. Song dynasty military arrows were longer and heavier than hunting arrows because they needed structural strength to carry the weight of the gunpowder tube without flexing in flight. Each shaft must be perfectly straight — roll it on a flat surface and discard any that wobble.

Scrape the bamboo smooth and remove any side nodes that would interfere with the propellant tube binding. The rear end of the shaft should be notched for a bowstring, and the front end sharpened to a point or fitted with a metal arrowhead. The propellant tube will be mounted behind the arrowhead, along the forward third of the shaft.

Later Song dynasty fire arrows used paper tubes rather than bamboo for the propellant casing — paper offered more consistent wall thickness and burn characteristics. Cut mulberry bark paper into rectangles approximately 20 cm wide and 15 cm long. Roll each rectangle tightly around a wooden dowel (8-10 mm diameter) to form a tube, applying rice paste between layers to bond them.

Build up 5-7 layers of paper for sufficient structural strength. The tube must be tight enough to contain the burning powder without bursting prematurely, but thin enough that the combustion gases can eventually rupture the sealed front end. Remove the dowel carefully and allow the tubes to dry completely — at least 24 hours. Seal the exterior with a thin coat of tung oil to waterproof the paper.

Fire arrow propellant requires a slightly different composition than firecracker powder. The goal is sustained thrust, not instantaneous explosion — the powder must burn steadily for 2-3 seconds rather than detonating all at once. The Wujing Zongyao specifies a ratio with slightly less saltpeter than explosive-grade powder: approximately 70% saltpeter, 16% charcoal, and 14% sulfur.

The lower saltpeter content slows the burn rate. Additionally, the charcoal should be coarser than firecracker-grade — small granules rather than fine dust — which further controls the combustion speed. Grind each ingredient separately, then combine and mix gently. Prepare approximately 15-20 grams of propellant per arrow.

Seal one end of each paper tube with a clay plug pressed firmly in place — this is the front end (the nozzle end remains open at the rear). Stand the tube upright with the sealed end down and pour the propellant in slowly, tamping it down with a wooden dowel after each addition. Pack the powder firmly and evenly — air gaps cause uneven burning and potential tube failure.

Fill the tube to within 2 cm of the open rear end. The open rear end is the nozzle — the combustion gases will escape through this opening, creating the thrust that propels the arrow. Do not seal the rear end. The front clay plug acts as a blast cap — when internal pressure builds sufficiently, it ruptures and adds a final burst of flame at impact.

Insert a saltpeter-soaked hemp cord fuse into the open rear end of each tube, pushing it approximately 2 cm into the packed propellant. The fuse must make firm contact with the powder charge. Leave 5-8 cm of fuse extending from the rear — this is lit just before the arrow is shot from the bow.

The timing is critical in combat use: the archer lights the fuse, nocks the arrow, draws, and releases before the fuse burns down to the propellant. Song dynasty military manuals describe coordinated volleys where entire ranks of archers lit and fired simultaneously, creating a wall of rocket-propelled arrows.

Position the propellant tube along the forward third of the arrow shaft, with the open nozzle end pointing rearward (toward the feathered end). The thrust direction must align with the arrow's axis of flight — any misalignment will cause the arrow to spiral or veer off course.

Bind the tube to the shaft using thin hemp cord soaked in animal glue, wrapping tightly in a spiral pattern for at least 8 cm at the front and rear of the tube. The binding must be secure enough to withstand the vibration of the bowstring release and the acceleration of the rocket thrust without shifting. Allow the glue to dry completely before use.

Attach three feather vanes to the rear of the arrow shaft, spaced 120 degrees apart. Song dynasty military arrows used goose or crane feathers split and trimmed to approximately 12 cm long. The fletching is critical for a fire arrow — without it, the off-axis thrust from any imperfection in the propellant tube would send the arrow tumbling immediately.

Bind each feather to the shaft with fine silk thread and seal with lacquer. The fletching must be positioned behind the propellant tube's nozzle opening so the exhaust gases do not burn the feathers before the arrow reaches its target. Leave at least 3 cm between the nozzle end and the nearest feather.

Set up a target — a dirt bank or hay bale — at a distance of 30-50 meters in an open field clear of dry vegetation and structures. Fire arrows have unpredictable flight paths until the maker develops consistent tube-packing technique, so a wide safety margin is essential. Clear all people and animals from a 50-meter radius downrange.

Light the fuse, nock the arrow, and draw the bow. Release the arrow before the fuse burns to within 1 cm of the tube — approximately 5-8 seconds after lighting. The arrow will fly normally from the bow, then accelerate dramatically as the rocket propellant ignites mid-flight, trailing fire and smoke. A well-made fire arrow can extend the range of a standard bow by 50-100% and arrives at the target trailing flame.