HP-67/97 Ballistic Program

[plore90]

Hi everyone, here I am again with a ballistics program for the HP-67 (and HP-97). The program was inspired by Chris Menes' DROP1 HP-48GX program. I had to "struggle" a bit to develop it on the HP-67 due to the scarcity of both DATA and Program registers available. The program is based on the retardation law of a bullet fired through the air which under standard atmosphere conditions R = 1 is subjected to a deceleration by friction with the air which is called DRAG. This delay R is proportional to the velocity squared and to other parameters. I do not want to explain the concepts of ballistics here but only the parameters on which the program is based. The delay table based on speed bands is the classic Mayevski one, but due to the limited number of registers of the HP-67, the lower band from 0 to 670 fps is missing. The program foresees the manual insertion of the following initial data.
Height in "of sight from rifle bore eg -1.5" in R1
Distance in yards at which the shotgun was zeroed eg. 100 Yard in R2
Initial speed in fps of the projectile (muzzle velocity in fps) eg 2800fps in R3
Maximum distance in yards at which to calculate the DROP of the projectile eg 200 yards in R4
Ballistic coefficient BC of the bullet eg. 0.470 in R7.
The program requires two registered cards which will be merged after the first phase plus a Data card which contains the values ​​of the Mayevski table. The steps to follow are as follows:
Read the DATA card first
Then read the Ballistic12 card
Enter manually the previously mentioned values ​​in the respective registers R1 R2 R3 R4 R7 and press A
The program will perform some calculations of the delay from 0 to ZR to prepare for the actual calculation from 0 to X final. When the initial Drop appears on the display eg. -1,5 "press GTO .099 g (blue) MERGE key. Insert the second Baiilistics 22 card and press the A key again. The program will calculate both the speed and the DROP of the bullet and the display will show every 25 yards the distance covered and the relative DROP. After a few minutes it will show the final distance, the final speed and the final drop. The test carried out with the example data gives an exact speed and drop value very close to the speed and drops calculated with the ballistics table of Col. INGALLS.
Unfortunately the program takes up all the storage space of the HP-67 (with the MERGE 224 steps are used). And there is no space left for a data reset utility for a new calculation. The HP-67 must be turned off and on again, and both the data and the program must be re-entered.