FAQ
Questions
Answers
Q: Is EB suited for range
estimation of handgun projectiles?
A: Yes!. EB is able to calculate trajectories,
independent of the angle of departure (-90° to + 90°). Ranges can
be in the meter or even the kilometer range. A calculation can be embedded
into a real-world terrain.
Calculations of long range trajectories
should be based on the particular drag function of the bullet under consideration
rather than a ballistic coefficient.
As a further restriction, the "point mass
model" applied by EB assumes that bullets fly stable.
Q: Can EB calculate
trajectories of vertically fired bullets?
A: Yes! A bullet can be fired vertically
up (+90°) or even vertically down (-90°, from an airplane?). However
EB assumes stable bullet flight over the whole trajectory which means that
EB assumes that a bullet returns to the ground with its tip forward. This
of course (for firing vertically) is not true in reality, as these bullets
will land base first. Thus a "vertically-up" calculation is only reliable
for the ascending branch. For the downward branch of the trajectory a second
calculation should follow, assuming a base-first orientation of the bullet
(which requires a different drag coefficient than the nose forward orientation).
Q: Is EB suited for
"large" calibers?
A: Yes! EB has been tested for the "biggest"
bullets ever used in ballistics (d=0.8 m; m= 7.5 tons), giving ranges in
the 40 km range. Of course, EB considers the decrease of air density and
gravity with altitude.
Q: Can EB be run on
an XT (8086 processor)?
A: Yes, but it is not really recommended.
Calculation times, especially when calculating ballistic tables can be
extremely long (in the hour range?). At least a 80286 processor should
be available. For modern PENTIUM processors, calculation times of trajectories
are typically in the Millisecond range.
Q: How accurate is EB?
A: This is not an easy to answer question.
There are generally three types of errors:
-
Computational errors
-
Parameter errors
-
Model error
After a long period of testing and comparing
with the results of other exterior ballistic software it was shown that
EB does not contain computational errors. This means that all numeric
errors (programming errors which may cause false results) were removed.
This error type however is very easy to control.
When comparing a real trajectory and a
computed trajectory there might be discrepancies due to parameter errors.
This means that the conditions and parameters on which the calculation
is based may deviate from the real-world conditions and parameters. Generally
the bullet´s drag function cD(Ma) is a critical parameter, but all
other parameters (mass. diameter, muzzle velocity, departure angle,....)
may also have errors. Parameter errors can be reduced by proper measuring
technique.
A model error is the worst that
can happen. EB is based on physical models. Physical models are generally
simplifications of the real world. One restrictive assumption of all the
models applied by EB is bullet stability over the whole trajectory. However,
if a bullet is unstable, EB will produce false results, not because it
is a bad software, but because the model assumptions are not fulfilled.
It has been observed that bullets may
be stable close to the muzzle and become unstable as they travel on. In
this case, EB will give reliable results for the first and "stable" part
of the trajectory only.
Q: Is EB Y2000 compatible?
A: EB requires the date for two purposes:
-
the first part of the default-filename of
a calculation is made from the month and the day at which the calculation
was done. E.g. "22feb3.sfc" is the default - filename of the third (3)
calculation (single trajectory in forward mode = sfc) made on the 22nd
of February (whatever the year may be).
-
listings of a calculation (on paper, on screen,
into a file) include the date.
EB receives the date from the operating system.
As long as the operating system gives the right date, EB will have the
right date as well.
Q:EB refuses to start
on my computer. What can I do?