A little more on the Alavekiu Bow Limbs

Here’s a little summary of my survey of the Alavekiu "1-mile" Foot Bow limbs. They are all very well made and each one a little unique from the rest. George was obviously looking for the magic combination of design elements and used a very exhaustive trial and error approach. Based on stories passed down to me, Harry Drake seemed to take on a similar trial and error approach. 

George’s 1-mile series were intended to be drawn 18”-20”. String lengths varied between 44” and 46”. The limb length ranged from 18.5” to 22” with the working portion of the limb taking up 11” to 13” of the total. There were two primary widths produced, 1-3/4” wide and 2” wide. The side profiles were produced on at least three forms. Type one is labeled “Turkish” which is a very wide open reflexed recurve. Type two has relatively shallow reflex and then sharply recurved at the end. Type three has a more open and less abrupt recurve shape with no reflex. 

 

There are draw weight numbers marked on some of the limb sets taken at 1” of draw and 2” of draw. The heaviest set lists a draw weight of 67 pounds at only two inches of draw. Such a bow should exceed 400lb drawn 18”, and I estimate 270-280 foot pounds of stored energy!

Construction is pretty conventional. All designs fall the static recurve category, where the outer third of the limb does not bend. The limb core is made from several hard maple laminations with additional tapered pieces at the fades and reverse tapered wedges to form the rigid recurved tips. A majority of the bending takes place over a six inch section of the limb. This creates a hinge-like tiller which has proven to be most effective at reducing efficiency losses from limb vibration and deflection with high arrow speeds. The Turks used it. Harry Drake used it. It is pretty much universal among successful flight bow designs. The limb is backed and faced with either clear or black uni-directional glass laminations and are around 0.05” thick. Plain E-glass is used on almost all of the limbs, but small portions were made with S-glass. In many cases, there is an additional thin layer of woven bi-directional glass cloth under most of the outer glass laminations which help prevent longitudinal splits. Many of the limbs which were shot heavily show small uni-directional splits in the outer lamination even with the use of the reinforcing underlayment.

The broken limbs I have most often failed by delaminating at the fades on the belly side or elsewhere between the maple laminations. I feel that the limb would be more robust if the curvature of the belly side fade was not so severe. Many limbs also show damage where the string cut through the nocks. I will use reinforced loops to prevent this. One set had severe compression failures in the glass at the fades. It formed a set of chrysalis that I normally only see in overstressed all-wood bows.

The limb tips are wider than I would consider with my designs. A limb set with 2” wide working limb section typically tapers down to .88” wide at the tips. I assume that this area is a common point of failure as the string pulls taught at the end of the shot and stops the limbs. I am not convinced that it has to be this way. A lighter and narrower limb tip should be quicker and transfer less force to the string, but I am a relative new comer and may change my mind after building a few more limb sets of my own. The tips are often reinforced with glass cloth and glass wedges to prevent splitting. George grooved the belly side of the limb where the string and string loop rests against the outer recurved portion of the limb when at brace.