The best way to test a longbows performance and efficiency is to measure its arrow speed. This is done with a device called a chronograph or chronometer and works by measuring the time taken for an arrow to pass over its two sensors , giving a result for its speed in feet per second, (fps).
Measuring the arrows speed with the chronograph gives an absolute speed for the bow being tested but as all longbows are different and have different draw weights there is also a method for establishing a estimated arrow speed for any bow that can then be compared with its actual arrow speed to give a value for efficiency.
This is done by adding 100 to the bows draw weight and using this number as the expected arrow speed for that bow, for example a bow pulling 38lb would be expected to have an arrow speed of 138 fps. These estimates are also based on the assumption that the bow being tested is pulled to its normal draw length and that the arrow used for testing is an average weight target arrow.
When testing with the chronograph the same 38lb bow might record an actual speed of 140 fps. This bow could be said to have an efficiency of +2 in speed above weight.
Obtaining a value for efficiency, expressed as speed above weight, basically allows a method of comparison for different types of bows. Getting a negative result for speed above weight could indicate a poor design, construction or wood choice but does not necessarily mean it is a 'bad' bow. Getting a positive result indicates a well constructed and designed bow made from the best quality and most suitable woods.
Below is a table of results for speed testing of Green Man Longbows. Click on the bow type for photos of that bow.
Bow Type
Ref No.
Wood
Between Nocks
Draw Length
Draw Weight
Speed ( FPS )
Speed Above Weight
018 Pacific Yew
72"
28"
38lb
172
34
English Longbow 040 Pacific Yew
72"
28"
47lb
177
30
013 Sinew backing, Pacific yew
66"
28"
45lb
173
28
028
Hickory, Purpleheart, Rosewood
71"
28"
33lb
156
23
Laminated Longbow 039 Hickory, Purpleheart, Lemonwood
74"
28"
50lb
171
21
022
Hickory, Lemonwood, Bloodwood
76"
28"
52lb
173
21
Laminated Longbow 037 Hickory, Yew (Take Down)
73"
28"
45lb
165
20
006 Pacific Yew
75"
28"
55lb
175
20
English Longbow 036 Pacific Yew
75"
28"
44lb
163
19
Laminated longbow 033 Hickory, Purpleheart, Lemonwood
76"
31"
64lb
183
19
043
Pacific Yew
72"
28"
47lb 165
18
English Longbow 017 Pacific Yew
79"
32"
47lb
165
18
Laminated Longbow 041
Ash, Lemonwood, Bloodwood
75"
28"
40lb
158
18
Laminated Longbow 015 Hickory, Purpleheart, Lemonwood
72"
28"
45lb
163
18
Laminated Longbow 029 Hickory, Purpleheart, Osage
74"
29"
52lb
170
18
020 Lemonwood (single piece)
74"
28"
39lb
157
18
English Longbow
000 Pacific Yew
68"
25"
43lb
160
17
Laminated Longbow 032 Hickory, Purpleheart, Lemonwood
72"
28"
44lb
161
17
Laminated Longbow 031 Bamboo, Yew
73"
28"
45lb
162
17
023 Hickory, Purpleheart, Rosewood
75"
28"
32lb
149
17
016 Lemonwood (single piece)
75"
28"
41lb
158
17
044
Pacific Yew
74"
28"
39lb 155
16
027 Pacific Yew
68"
27"
44lb
160
16
014 Hickory, Purpleheart, Lemonwood
74"
28"
36lb
151
15
English Longbow 046 Pacific Yew
74"
28"
46lb
157
11
029 Hickory, Purpleheart, Lemonwood
72"
28"
25lb
136
11
030 Bamboo, Hickory,
75"
28"
29lb
137
8
New results for new bows will be added when made and tested.
