Le sap (93)
Translation French to english by reverso.net
Dart Groupings cal 04 PREMIUM Series
The grouping test described below was carried out on a sample of 8 darts from a pack of 25 PREMIUM series darts (a special production for the « Comptoir des Associations in France ) delivered at the end of 2020.
Regarding the quality of the cones and their external appearance (see my fssa report with pictures of 16 October 2020 ).
PROCEDURE for my 10m distance target grouping tests performed on 05May2021 by zero wind (mandatory condition for valid and reproducible tests ).
Performance of target groups 10m distance
Preliminary checks on 8 darts.
The good concentricity of the 8 cones mounted on the steel drums is visually checked by rotating the darts held between the fingers.
The 8 darts are weighed together to more accurately measure their average mass( 1g20).
Each dart is introduced from the cone side into one end of the selected tube to check for proper slide without detectable friction , and that the dart slides by its own weight into the pipe held vertically.
The tube used for the shots is placed horizontally and supported in two points , the first at the blowing mouth and the second at about 50 cm from the first to reproduce as closely as possible the natural conditions ( the most used in France ) 2-hand holding pipe.
It is checked beforehand that the tube is perfectly straight. An effective test is to roll the tube on a smooth and flat floor in order to detect a possible prohibitive blunder.
The blowing machine is adjusted to reproduce as closely as possible my «teee» type breath ( or any other type of breath if necessary ).
To adjust the blowing machine, the pressure of my breath has been previously recorded with the pipe and darts objects of the following grouping test.
The blowing pressure of the machine is continuously visualized and adjusted by a specific DIY electronics maintaining the pressure automatically to within plus or minus 1mbar on a value close to 120 mbar set. The dynamic blowing pressure, when variable during the progression of the dart in the tube , is compared and adjusted at the start of the fire tests to the shape and intensity of the desired human breath by means of sensors , electronic controller and adhoc acquisition equipment.
It is in fact essential to adjust to the same form and intensity of blowing pressure in order to obtain reproducible internal ballistics conditions to make performance comparisons of groupings of arrows.
The trajectories of the arrows and their target groupings are largely dependent on the ejection speed itself, which is highly dependent on the blowing pressure.
Under the conditions of the tests, the dart ejection speed obtained is 40 m/s. ( with a variation less than 0.5 m/s )
Each dart is placed in the tube by means of an adhesive device preventing any movement of the tube between each shot during manipulations.
To avoid Robins degrading the cones, each arrow fired is moved from the target at each shot.
( the recovery time of the arrows is used to automatically raise and stabilize the blowing pressure of the machine ).
Below is a photograph of the impacts of the 16 arrows shot one by one.
The target used is a sheet of BRISTOL paper with a 5 mm grid step, very convenient for measuring distances.
The 8 lance-type steel drums used are supplied with the PREMIUM cones in the same pouch.
Observations on the photo of the target group at 10m
The 16 impacts are located in the 22.5mm circle, drawn virtually in blue.
A concrete visual reference of the area occupied by the target grouping is given by the red circle , drawn virtually , of 60mm diameter delimiting the zone 7 of the IFA target .
Personally I think that the grouping obtained under the conditions of tests carried out described in the photograph is VERY SATISFACTORY and gives confidence , because the grouping occupies a very much smaller area than the central zone ( zone 7 ) of the IFA target.
The bundling test described above was performed on an 8 dart sample from a 25 dart PREMIUM series pouch (a special fabrication for the « comptoir des associations in France » received at the end of 2020.
The groupings recorded are those obtained under the test conditions described. It is indeed necessary to start on well-defined technical conditions to compare between them the materials of fire.
It is also necessary to be aware that any change of material, length of tube , size and mass of barrel AND the possible alteration of cones to use, etc... , will change more or less significantly the surface of the grouping.
Any good shooter must be careful and check the state of his arrows and do not hesitate to change his thrusters cones in case of doubt before AND during competitions .
The variabilities of material characteristics affect the groupings, but the fields of investigation of their degree of influence on the groupings is immense and highly mobilizing in terms of the time to be devoted to them.
Report rev.0 written by PIME alias on fssa.fr on 08May2021 .
(*) Message edité le Lun 10 Mai 2021 - 23:12:00