Shell Calc - is it realistic

Discussion in 'Professional Fireworks' started by Jerry, Oct 8, 2018.

  1. Timer fuse time is not 4.5 sec ??????
    Is this a way too conservative program??????

    https://shellcalc.wordpress.com/

    Essential Input Parameters
    Type Shells/Bombettes select type from list
    Shell Diameter 3" (75mm) select calibre from list
    Firing angle 0 ° angle from vertical
    Tumbling/Mortar Drift Typical select option from list
    Wind Speed 30 km/h
    Relative Wind Direction 0 ° relative angle

    Calculated/Entered Output Values
    Max Height 137 m from ground level (z)
    Normal fallout range (approx) 162 m from origin (x/y)
    Long Burn range (approx) 299 m from origin (x/y)
    Approx Burst Diameter 75 m
    Ascent Time 4.5 s
    Burst Time 4.7 s

    Burst Distance (from firing point) 38 m
    Burst Height (from Ground Level) 136 m
    Max Downrange (Blind distance) 84 m from origin (x/y)
    Flight Time (if shell does not burst) 13.5 s
    Calculated Muzzle Velocity 105 m/s
    Calculated Shell Mass 187 g
     
  2. Jon

    Jon Pro Firer/Crew

    I think it's more designed for you to put your own figures into for your own stock.
     
  3. Pyro Productions

    Pyro Productions Pro Firer/Crew

    My experience is that whilst it might show you the worst case scenario it is pretty realistic.

    I was once filming a show and debris from a 30mm single shot fell near me at 190m (ish) from where it was fired. Put the figures into ShellCalc and yep, that was about right for the conditions on the night.
     
  4. AtomFireworks

    AtomFireworks Pro Firer/Crew

    We had an incident on a show where a member of the audience clamed a " rock" from the fireworks had hit her on the head.

    Even though she was the only one complaining out of the 700+ spectating we carried out an extensive debris map and checked what shell calc would predict, pretty much bang on. Armed with that and witnessed reports of kids throwing toffees around the audience we were confident it was not us.

    It is a great tool in my experience, although the variable that is the wind speed and direction can only be assumed at altitude, best to add more distance than be on the border.

    Jay
     
    Pyro Ed, scoops and Pyro Pete like this.
  5. It's very accurate if you give it the right data, I've seen an artificial pitch downwind where it's easy to see the debris, and it stops right where the shellcalc says it will