Air-stripper spec's

Discussion in 'General Airgun Chat' started by Greenwing, Nov 12, 2009.

  1. Greenwing

    Greenwing New Member

    Joined:
    Apr 29, 2009
    Messages:
    35
    Location:
    Livingston, Scotland
    Club:
    Dunfermline
    Does anyone know anything about the science behind air-strippers?

    I have an idea for designing one but I'm wondering what kind of gap there should be between the end of the barrel and the tip of the cone. I realise that it needs to be adjustable as every rifle may be set up a little different but I'm looking for a ball-park figure to start from. Will it be around 10mm, 20mm, 30mm,.....?
    I'm also wondering about the boresize of the cone. Obviously the smaller the better but to avoid any clipping issues what kind of allowance is normally added to the 4.5mm pellet.

    (I know I could ask someone to make one for me but sometimes it can be a bit of fun to make your own stuff)

    Any help and advice would be gratefully received.

    Cheers :)
     
  2. Conor

    Conor Never been banned from sales Staff Member

    Joined:
    May 4, 2009
    Messages:
    3,061
    Location:
    Ardboe, Co.Tyrone.
    Club:
    Back Hill Ballistics; DFTC; Nelson FTC
    It's all trial and error for different barrels, pellets, velocity etc proably ball park 10mm from barrel 5mm cone.
     
  3. nyamazan

    nyamazan New Member

    Joined:
    Oct 30, 2009
    Messages:
    9
    Location:
    Weybridge
    How much difference do they make, are we talking mm's here?
     
  4. Conor

    Conor Never been banned from sales Staff Member

    Joined:
    May 4, 2009
    Messages:
    3,061
    Location:
    Ardboe, Co.Tyrone.
    Club:
    Back Hill Ballistics; DFTC; Nelson FTC
    1/2mm's at times!!!:eek:
     
  5. Flannelmeister

    Flannelmeister Member

    Joined:
    Aug 30, 2009
    Messages:
    43
    Location:
    Blaengarw, "The Valley That Time Forgot"
    I'm sure I have heard it said that a good starting point is about the length of the pellet you are using.
     
  6. Sam Vimes

    Sam Vimes New Member

    Joined:
    Jan 5, 2009
    Messages:
    186
    Location:
    Richmond or the Yorkshire Wolds
    Yep, that's generally where I'd start testing a stripper. I'd prefer a stripper to have enough adjustment to cover pellets such as Webley Mosquito Express and JSB Exacts then that bit more to cover a minimum of half a pellet length and at maximum of at least twice a pellet length.
     
  7. peakecentral

    peakecentral Scout & Proud

    Joined:
    Sep 24, 2009
    Messages:
    71
    Location:
    Twyning, Glos
    Club:
    Worcester Air Rifles
    If you have it, there was a good piece on air strippers in the Nov 2008 Airgun World magazine.

    Martin
     
  8. Greenwing

    Greenwing New Member

    Joined:
    Apr 29, 2009
    Messages:
    35
    Location:
    Livingston, Scotland
    Club:
    Dunfermline
    Cheers guys, that's very helpful.
    I know the difference to groupings can be minimal but I was reading a post somewhere that the length of the shroud on early Mk4s can cause a bit of "turbulance" as the expanding air is contained within the shroud for so long. I don't know if that's actually true or not but shortening the Mk4 shroud seems to be a popular modification, maybe it's purely for handling reasons.
    I know I could get my shroud shortened like a lot of others but I was wondering if I can build an air-stripper into the rifles existing shroud - just to be different :). I think it'd look pretty good being built in rather than an obvious bolt-on. If it doesn't work I can always just fit a short shroud and there'd be no harm done.

    Thanks again
     
  9. simmmo

    simmmo Active Member

    Joined:
    Apr 16, 2009
    Messages:
    449
    Location:
    Buxted County HFT Republic of Sussex
    UK Neil made this for me a while back, don't use it as was an experiment for my benchrest RT and it shoots best with no shroud or anything else.

    The shroud is fully free floating being slightly less diameter than the original and attaches to the barrel at the rear where the slightly thicker piece can be seen. Air cone section also thin enough to free float in Daystate figure of 8 the reason the rest is so thin is it originally was made with a balance weight for harmonics which I have removed as I realised my design was flawed.

    Looks great when fitted. Might put it on a HFT setup.

    Andy
     

    Attached Files:

  10. Greenwing

    Greenwing New Member

    Joined:
    Apr 29, 2009
    Messages:
    35
    Location:
    Livingston, Scotland
    Club:
    Dunfermline
    Thanks for that, I managed to get hold of an old copy
     
  11. rich

    rich Active Member

    Joined:
    Nov 8, 2008
    Messages:
    1,679
    Location:
    Shebbear, N Devon
    The job of a stripper is to separate the escaping air from the pellet. Imagine the conditions at the instant the back end of the pellet leaves the muzzle. This is when the air starts to try to rush past the pellet that has blocked its path all the way along the barrel. If there is a gap in front of the pellet before the head end enters the stripper cone, what is to stop the air rushing round the pellet and getting there first? When the head of the pellet enters the cone (which has a clearance bore but is still quite tight to the pellet diameter) the only convenient path for the air is to expand radially and flow around the outside of the cone and out through the vents or ports.

    So I think that the gap can easily be too large for efficiency, just as it can be too small.
     
  12. chrispro97

    chrispro97 New Member

    Joined:
    Jun 10, 2009
    Messages:
    1,062
    Location:
    atherstone
    Club:
    purley chase ftc
    wot gun you shooting matey top flight guns dont require them a break can stop the kick but the stripper can make no difference matey,try a ajustable one and keep adjusting doing groups at 55 yards on paper matey,ive been down this route matey with a steyr 110 and a break works better stops the kick so u can watch the pellet strike the the target:)
     

Share This Page

  1. This site uses cookies to help personalise content, tailor your experience and to keep you logged in if you register.
    By continuing to use this site, you are consenting to our use of cookies.
    Dismiss Notice