Page 1 of 3 123 LastLast
Results 1 to 6 of 13

Thread: Optimum length longbow

  1. #1
    In the White Asafan's Avatar
    Join Date
    Feb 2008
    Location
    Velikie Luki, Ru
    Posts
    32
    Thanks
    1
    Thanked 0 Times in 0 Posts

    Optimum length longbow

    I have attentively read messages at a forum (and has received a lot of pleasure ), but have not found discussion of optimum length longbow. On the one hand there are restrictions on length ELB Rules (rather reasonable from the engineering and historical points of view). On the other hand the superfluous length of a bow at a small draw reduces speed of an arrow and increases hand concussion.
    I did many gaugings force/stretching of a bow, measured speed of an arrow etc.. Tomorrow I will illustrate the reasons.
    For now I ask to tell those who knows: what length ELB it is necessary to take to the girl with a draw 24 "and arrows 26"?
    Andrey

  2.  

  3. #2
    It's an X Del the Cat's Avatar
    Join Date
    Oct 2008
    Location
    Harlow Essex
    Posts
    3,964
    Blog Entries
    2
    Thanks
    23
    Thanked 374 Times in 312 Posts
    I'd go by the old fashioned measurement of 'as tall as the archer' !
    That will give plenty of draw length and be historically reasonable.
    Out of interest I have a lovely symetrical Maple stave with some natural recurve on each limb. So I'm making it into a longbow...it just happens to be 89" long.
    I expect the linb length/mass will make it slow, but conversely the length will mean it's draw weight increases slowly, so it can start at a higher initial poundage thus storing more energy.
    I shall make it the same poundage at 28" as my Yew bow, so it will be fun to compare the two.
    It will probably get shortened and re-tillered at some point.
    It will be an interesting experiment, it will also probably be capable of an extreme drawlength 32" or so.

    Del
    Health Warning:- These posts may contain traces of nut.

  4. #3
    In the White Asafan's Avatar
    Join Date
    Feb 2008
    Location
    Velikie Luki, Ru
    Posts
    32
    Thanks
    1
    Thanked 0 Times in 0 Posts
    Here by way of illustration a question I will result 2 drawings. The first - a F-D curve of a bow 76 "in the length. A bow 76 # on 32" draw.


    The second - curve speeds at different weight of an arrow and a different stretching. On a horizontal - weight in gran. Fat circles - values of speed at 10gran/pound.


    Certainly, gaugings are not absolutely exact. And certainly longer will live a long bow at a small draw. Where a golden mean?
    This bow has been made of a casual stick of a hazel grove specially for testing. A bowstring - 14 threads B-50.

  5. #4
    In the White Asafan's Avatar
    Join Date
    Feb 2008
    Location
    Velikie Luki, Ru
    Posts
    32
    Thanks
    1
    Thanked 0 Times in 0 Posts
    If this bow to mark 63#&28 "is will represent the facts. If to write 55#&26" - too it will be true. But the matter is that such use longbow will give a bad throw and will tear a hand. But it is possible to give a guarantee on selfbow 3-5 years without worrying about breakage. Problems of the marksman will be left in the basket!

  6. #5
    In the Black
    Join Date
    Feb 2006
    Location
    Kent England
    Posts
    83
    Thanks
    0
    Thanked 3 Times in 3 Posts
    Good to see someone going about things scientifically for a change.

    If you are of exactly average build your arm length will be a proportion of your height hence the rule of thumb that you should shoot a bow about your height. However like most rules of thumb this doesn't work for every one. I'm 5'11" (71") but my draw length is only 25". I just happen to have short arms. When i first started with ELB i was told 71-73" was what i should get. It took me about three years and 200 to work out this was incorrect for me.

    I now shoot bows of around 68-69" which are a lot quicker and because they aren't asked to bend that much i don't get much stacking or hand shock which is usually associated with shorter bows.

    If the person has a draw length of 24" i would suggest 66-67". GNAS and BLBS allow ELB as short as 60" for an archer using less than 27" arrows. This rule has been around for donkeys years so i think you could argue a shortish ELB was still a LB!

  7. #6
    In the Red
    Join Date
    Jan 2008
    Posts
    324
    Thanks
    0
    Thanked 11 Times in 11 Posts
    As far as arrow speed goes, I think there's a straightforward rule linking optimum nock to nock bow length and draw length. So a 50lb@28in flight bow must be made 66 ins long (more or less).

    Any shorter and the bad string geometry reduces energy storage and much longer and the bow becomes too massive. Maybe you know this stuff already.

    So, at 24ins drawlength, the bow should be the minimum 60ins for max speed, but then speed isn't the only thing and durability and comfort would be improved by adding on a few inches- maybe 66ins.

    I'm 5ft 10ins with a short 26in draw and like a 71in bow.

    David

Page 1 of 3 123 LastLast

Similar Threads

  1. Optimum Arrow Length?
    By aim-for-the-yellow-bit NULL in forum Recurve Bow
    Replies: 15
    Last Post: 05-04-09, 08:41 PM
  2. Arrows: Optimum Arrow Length??
    By Zippo in forum Recurve Bow
    Replies: 16
    Last Post: 28-11-08, 07:24 PM
  3. The optimum length of a stabilizer
    By hollowpoint in forum Methodology, Tuning, Coaching etc.
    Replies: 17
    Last Post: 13-09-07, 12:21 PM
  4. optimum bow length for 27inch draw 66 or 68 inch
    By sambow in forum Recurve Bow
    Replies: 12
    Last Post: 26-08-07, 06:57 PM
  5. cam 1/2 optimum draw length
    By oldy in forum Compound Bow
    Replies: 12
    Last Post: 10-01-07, 12:00 PM

Bookmarks

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •