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Delta III SD©

Important: This program can be purchased only on an SD or micro-SD card; it will run ONLY on PDAs that come equipped with an SD port.  It will not function in an adapter used for other ports.  The operating system on the PDA must be, at a minimum, WM 5.0 or above.  For best viewing, purchase a PDA with a rectangular screen 240 x 320 pixels in size.

An evaluation version is not available, but you may download the manual to review the software's features and tools.

Delta III SD Manual
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Purchase: Delta III SD $200			Upgrade: Delta III to Delta III SD upgrade $99.95   Purchase
Standard   Purchase Standard Micro   Purchase Micro Card Size Note:  1 Gb is the standard card size for this software.  SD cards that are 4 Gb and larger are "SDHC" (Secure Digital High Capacity) and may not be readable in older drives.  However, newer drives that can read SDHC cards are backward compatible and can read standard capacity 1 & 2 Gb cards.  Check with the manufacturer of your device before ordering SDHC cards.			Optional Card Size Upgrade: 4 Gb   -  Add $20      Purchase 8 Gb   -  Add $40      Purchase 16 Gb -  Add $60      Purchase 32 Gb -  Add $100    Purchase The 16 & 32 Gigabyte cards are "special order" and will delay shipment of card.

Kestrel® Bluetooth Interface
The Kestrel model 4000, 4200, 4300 and 4500 comes with Bluetooth communication capability that can deliver the pressure, temperature, humidity, wind speed, and, in the 4500 only, wind direction.  The program will allow the user to update these variables by either pressing the Enter button on the face of the PDA or set the program to continuously update these values at intervals from 2 to 60 seconds.

The POI Method of Obtaining Muzzle Velocity
As the manual points out, chronographs are not self-calibrating; it is not known whether the velocities they output are correct or not. While chronograph data errors, even if erroneous by 10% or even 15%, will not show up when shooting under 500 meters, at longer ranges the errors in muzzle velocity, even small errors, will produce inaccurate trajectory data.

Feedback from military personnel operating in Iraq indicated that a non-chronograph method of obtaining or verifying muzzle velocity was needed in order to test new lots of long range ammunition as well as scavenged ammunition. The POI method was derived wherein the user shoots at a target somewhere between 300 to 600 meters and notes whether the group is impacting above or below the point of aim. The program subtracts the scope error (the difference between the total value of the clicks and the computed elevation - the dialed elevation and the computed elevation will almost never be the same) and then computes what muzzle velocity is required to print the group where it actually is on the target.

It turns out that this method is an excellent way to check the accuracy of the chronograph because it is highly accurate and clearly can be a better data point than that obtained from the chronograph. Even if the chronograph is used initially to obtain a muzzle velocity, the POI method should be used to verify the data. Once a valid muzzle velocity has been obtained, it can be used to calibrate the chronograph by suggesting an error rate or percentage that can be used to correct chronograph output. And this allows the user to compute a better ballistic coefficient for use in the program.

Obtaining a Better Ballistic Coefficient
To compute a ballistic coefficient two velocities are needed: a muzzle velocity and a downrange velocity. The further downrange the better, but realistically since a chronograph will be used to obtain this velocity, the range has to be close enough so our chronograph is not hit by an errant bullet. Max range will therefore probably be between 300 and 500 meters. First the chronograph is used to obtain a muzzle velocity, then the chronograph is placed downrange to obtain a second muzzle velocity. The ballistic coefficient workspace is then used to compute a trial ballistic coefficient. If the muzzle velocities are erroneous, this calculated trial BC will also be erroneous. Example: If the velocities were high by 10%, the calculated BC will be larger by about 5%. A way to correct for the chronograph velocities is obviously needed.

By using the POI method of computing a muzzle velocity, two important data points are obtained: an accurate muzzle velocity and a means to compute the error of the chronograph by simply dividing the chronograph value by the POI method value. This error rate can then be used to correct the downrange chronograph velocity. Of course, this supposes that the chronograph has a consistent error rate. This cannot be determined for certain, but this is probably a decent assumption and better than taking the downrange result at face value.

Using the corrected velocities, a good ballistic coefficient can then be computed for that bullet and it will probably be different from the value given by the manufacturer. Using this newly derived ballistic coefficient and using the POI Method workspace, the muzzle velocity is then re-computed. If the muzzle velocity is altered appreciable, go back to the BC computation workspace, calculate a new error factor, derive a new downrange velocity and re-compute a new BC. This iteration process is repeated until both the computed muzzle velocity and BC don't change materially. At that point very accurate values for both muzzle velocity and ballistic coefficient have been computed and may be used with a high degree of confidence to produce excellent theoretical trajectories.

Deliverables
The Delta III SD can be delivered in the standard size SD card with not less than 1 Gigabyte of memory, as a mini-SD card, or as a micro-SD card with the same amount of memory and housed in an integral adapter for use in regular sized SD card slots.