From: Stephen Selby To: Subject: Fw: Using the Chu Ko Nu Date: Saturday, January 01, 2000 10:21 AM ----- Original Message ----- From: David R. Watson To: Stephen Selby Sent: 31 December, 1999 5:46 PM Subject: Using the Chu Ko Nu > Steven: Your account on the Chu Ko Nu looks pretty much on to me, > except that the iron lever that draws back the machine gives you about a 3 > or 4 to one mechanical advantage, so the actual draw on the prod can be as > much as 100 lb (at about 6-7 inches), with the draw on the lever still > being only about 25 lb. This still makes a pretty weak bow, with about as > much power as perhaps a 35 or 40 lb. handbow. (Compared to English > Longbows from ship Mary Rose, that are calculated as a minimum of 100 lb. > draw at about 22 inches, and the average bow from that find of 139 bows > coming out at about 125-130 lb. draw. (The heaviest max out at about 175 > lb. of draw. That oughta take a pretty beefy fellow to draw.....! ) > I have made several of the Chu Ko Nu repeaters, so I can speak of this > with some authority from experience. First, the maximum practical rate of > fire is about 1 shot a second. Attempting to go faster than that can lead > to misfires and scattering bolts all over creation. Sometimes the thing > misfires, and 3 or 4 of the top bolts in the magazine hop right out of the > magazine if it is not closed. With a little practice you can keep the 10 > or so bolts of a magazine pretty much in a 3 foot circle at 15-20 yards. > This is not a precision instrument. To some degree, you walk your shots > on, like a badly handled machine gun. The first shot may be low, but you > can raise your aim point with later shots. Since the bolts stack atop one > another, the last shot has slightly more power than the first. The > clearance of the moving parts necessary to make the machine run smoothly > and quickly increases the inaccuracy of the delivery. There just has to > be a little slack in the machinery. > The system does have a fair amount of internal friction, so it is not > very efficient. The use of Mulberry for the prod is certainly about right. > Mulberry is probably the best bow wood generally available in Asia, and it > compares pretty well with Osage Orange (Bois'd'Arc) and Yew. > The bolts for this machine are generally unfletched, or have at most a > very long, very low (1/8 inch or less in height) spiral fletching around > the shafts. It is possible to groove the back half of the shafts to > improve balance and flight, if you are using hardwood for bolts. Without > any grooving or fletching, the bolts do not fly quite so accurately, though > bamboo bolts with fairly heavy heads should fly reasonably well. If you > fletched the bolts, you would get better flight, but the fletchings tend to > tangle together in the magazine, and the machine almost certainly jams up > one or more times in a 10 bolt run. > The double magazine, that carries two bolts at a time would be less > accurate, as the two bolt grooves are slightly off center, but it would > spread more bolts around in the target area. > The machine is generally shot from the waist, with the butt against the > abdomen or hip. It is not generally accurate in any sense, though with > practice, you might shoot better than I expect. Presumably you could put > some sort of rudimentary sight atop the magazine, to make the first shot a > bit closer to your preferred point of impact. > The Chu Ko Nu is bulky and unwieldy, though not particularly heavy. It > may weigh 10 lb. with bolts in magazine. It should be quite effective in > the way of point defense, like defending a gate or doorway, and a few > people could certainly produce a cloud of arrows for a limited amount of > time. I think you could consider it a poisoned shotgun. The weight of > bolts adds up. When one is carrying a large number of bolts for such a > machine, the weight really begins to matter. If you shoot such a bow in a > field, the featherless bolts disappear under weeds, grass or vegetation > right away. I have painted bolts for Chu Ko Nu's that I built a bright > Chinese red, so I could find them a bit easier. It looks rather > appropriate that way. > Most illustrations show the magazine fitted with a top plate, that keeps > the bolts from hopping out in shooting (that can happen). Apparently most > surviving machines have the top cover removed from the magazine, as the > cover seriously impedes fast loading. You can dump bolts into the top > pretty quickly, but if they are poisoned, I think you would want to wear > gloves. That might slow the loading process. > I am particularly interested in the use of goose quill to reinforce the > serving around the center of the string. I have found it is necessary to > serve the center with some really hard, strong stuff, like a fairly thick > Nylon monofilament, such as is used for substantial fishing lines or nets. > The thin, flexible goose quill would probably work as well. > Even so, the string wear is pretty fast. Since the bow is not very > strong, it is not too difficult to replace bowstrings, but if someone is > writing a story featuring these weapons, they should include a bit of > string changing or worry. Breaking a string would give a good excuse for > bow failure at a critical time in a story. > The illustrations and plans featured in Ralph Payne-Galwey's "The > Crossbow" work pretty well, though the actuating lever should be iron, not > wood. A wood lever, as illustrated in P-G's plan, does not stand up to > fast shooting well. Also, I use a striker plate on the top of the stock, > where the bone or iron push-pin for the lock hits the wood. Otherwise, you > wear a hole in the stock at this point rather quickly, and the thing won't > shoot at all! > The machine is certainly a useful weapon for certain limited > applications. Photos I have seen from the "Boxer" uprising of 1900 show a > number of Chu Ko Nu's lying about the ground in the Taku forts, after they > were taken by European forces, in preparation to the march to Peking, and > the relief of the foreign legations. So it looks like they may still have > been in use as late as 1900. Or perhaps the Europeans found them in > storage, and placed them about the fort for the pictures, just for > interest, or as an insult to the Chinese military. > Feel free to forward these comments to your correspondent. > Happy New Year. DRW/NWA > >