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.
To get a good and consistent reading from the chronometer I have to use arrows that match the bow ,(this is mainly getting the spine rating right). I have a few different arrows I use. They have 5/16 or 11/32 inch shafts, 100 grain or 125 grain points, 3" or 4" parabolic fletchings. The overall weight of the various arrows is between 3/4 to 1 ounce.
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
Gallery Number Wood
Between Nocks
Draw Length
Draw Weight
Speed ( FPS )
Speed Above Weight
1
English Longbow 018 Pacific Yew
72"
28"
38lb
172
34
2
Mongol Bow * 063
Horn, Yew, Sinew
48"
28"
27lb
159
32
3 English Longbow 040 Pacific Yew
72"
28"
47lb
177
30
4 Composite Flat bow 013 Sinew backing, Pacific yew
66"
28"
45lb
173
28
5 Laminated Longbow 028
Hickory, Purpleheart, Rosewood
71"
28"
33lb
156
23
6 Laminated Longbow 039 Hickory, Purpleheart, Lemonwood
74"
28"
50lb
171
21
7 Laminated Longbow 022
Hickory, Lemonwood, Bloodwood
76"
28"
52lb
173
21
8 055
Buffalo horn, Bamboo, Sinew
51"
28"
40lb
160
20
9 Laminated Longbow 037 Hickory, Yew (Take Down)
73"
28"
45lb
165
20
10 English Longbow 006 Pacific Yew
75"
28"
55lb
175
20
11 059
Pacific Yew
74"
28"
54lb
173
19
12 English Longbow 036 Pacific Yew
75"
28"
44lb
163
19
13 Laminated longbow 033 Hickory, Purpleheart, Lemonwood
76"
31"
64lb
183
19
14 043
Pacific Yew
72"
28"
47lb 165
18
15 English Longbow 017 Pacific Yew
79"
32"
47lb
165
18
16 Laminated Longbow 093 Hickory, Lemonwood, Snakewood
74"
28"
37lb 155
18
17 Laminated Longbow 041
Ash, Lemonwood, Bloodwood
75"
28"
40lb
158
18
18 Laminated Longbow 015 Hickory, Purpleheart, Lemonwood
72"
28"
45lb
163
18
19 Laminated Longbow 029 Hickory, Purpleheart, Osage
74"
29"
52lb
170
18
20 Lemonwood Longbow 020 Lemonwood (single piece)
74"
28"
39lb
157
18
21 English Longbow 000 Pacific Yew
68"
25"
43lb
160
17
22 Laminated Longbow 032 Hickory, Purpleheart, Lemonwood
72"
28"
44lb
161
17
23 Laminated Longbow 031 Bamboo, Yew
73"
28"
45lb
162
17
24 Laminated Longbow 023 Hickory, Purpleheart, Rosewood
75"
28"
32lb
149
17
25 Lemonwood Longbow 016 Lemonwood (single piece)
75"
28"
41lb
158
17
26 044
Pacific Yew
74"
28"
39lb 155
16
27 English Longbow 027 Pacific Yew
68"
27"
44lb
160
16
28 Laminated Longbow 014 Hickory, Purpleheart, Lemonwood
74"
28"
36lb
151
15
29 English Longbow 101 Bamboo, Purpleheart, Lemonwood
74"
27"
51lb 165
14
30 English Longbow 046 Pacific Yew
74"
28"
46lb
157
11
31 Laminated Longbow 029 Hickory, Purpleheart, Lemonwood
72"
28"
25lb
136
11
32 Laminated Longbow 092 Hickory,lemonwood, yew
74"
28"
55lb 166
11
33 English longbow 108 Pacific Yew
74"
27"
40lb 151
11
34 English Longbow 097 Pacific Yew
74"
27"
50lb 161
11
35 Laminated Longbow 030 Bamboo, Hickory,
75"
28"
29lb
137
8
36 English Longbow 090 Pacific Yew
74"
28"
52lb 159
7
37 English Longbow 102 Pacific Yew 'Silver Dragon'
72"
26"
40lb 141
1
New results for new bows will be added when made and tested.
N.B No 02 . * Using lightweight arrows, 1/4" shaft.
