Ian, Yes it would sets the turrets for windage and drop compensation. The piezo elements should compensate the small drifts of the shooter himself at the moment the shot breaks - either by measuring accelerations of the rifle or by image recognition of the target.

However, I certainly do not have the time for such a project. Furthermore, I am in match shooting and regard this a bit over the top.

Rober

mman, I missed this.

any progress?

... the reason I heard from an offical trainer is that the wind does affect less.

this is in contrast to the theories I know?

movements: e.g. connect piezo actuators to the barrel

elevation & windage: one could connect a step motor to the turrets, program a cross on a telescopic tv screen ...

I have looked to port BfX to windows mobile and concluded that the Excel running on it was not able to run the BfX.xll.

How much work Quick Office is I do not know. In BfX the physics part is relatively small, the integration with Excel makes it special. This integration software has to be redone.

My pet project, for which I do not have time, would be the 6DOF. Another one would be controlling the crosshairs of a telescopic sight via a computer in the sight - even compensating for the small movements of the shooter

Quote from: mman on November 27, 2011, 09:23:01 AM
However I can't be absolutely sure that those effect you mentioned can always be ignored but it is very hard to know right input values for them even though I wanted to take them account.

This is closely related to one of the interesting things in life. If one looks at many finite element calculations, microscopic particle simulations, etc one has to notice that most of the effects cancel each other and where they do not, simple phenomena arise together with phenomenological laws. Laws that do not depend much on details of the underlying interactions.

I am leader of the www.urbanflood.eu consortium that creates an early warning system for dike failures. In the Netherlands we have about 2400km of realy crucial dikes and some 16000km dikes that are a bit less important. However as the composition of dikes are only partly known, if any, as the measurement of this composition is neither technical possible and feasible, we realy can not rely on fundamental theory to understand sensor readings. Instead, I stimulate  the uptake of data driven modelling techniques. As dikes are "exited" by passing ships, tides, cars, rains we model their response.

The more scientific side of me is drilling down on "emergence" and the control of complex systems. Appart from dikes, "swarms" of spacecraft, telecommunication networks, wafer steppers are application cases.

Quote from: mman on November 27, 2011, 10:06:40 AM
One thing I would like to add to the model is correlation with regulation length and cylinder pressure. The correlation is different for every gun but I think it could be solved from the measurements of muzzle velocity and cylinder pressure. I think the valve's equation of motion is something like this:

striker rod impact force(t) - firing valve spring force(t) -  cylinder pressure force(t) = firing valve acceleration(t) * firing valve mass

It is here that the Cardews did some work.

Quote from: mman on November 27, 2011, 09:23:01 AM
Yeah this is just for PCP guns. I once measured velocities (Air arms S410) from many different pellets with same regulation setting and cylinder pressure. Interestingly enough they all gave almost exactly the same muzzle energy. I used this information when testing the model. I'm just saying that this result shows that effect of pellet seating, hardness and shape are insignificant.

However, the Cardews showed that for spring air rifles, this is crucial for accuracy. From the book I learned that one should take hard pellets (H&N FTT) for (my .22 HW97K) spring rifle, and softer ones for pneumatic rifles.

Half a year ago we did a test with pneumatic rifles and tin (Sn) pellets. Here we noticed an enournous effect on velocity spread and accuracy of pellet seating and the way the pellet was pressed in.  Only those rifles that mechanically pressed the pellet in where accurate.

For me this is not so bad, my job has many cool aspects. I do the ballistics stuff mostly to kick off ...

Impressive. I once read the "Airgun from trigger to target" from Cardew & Cardew. I just flipped some pages again, serious stuff. Although mostly oriented on spring guns it still quite informative. For spring guns they have tables of in-barrel velocities. A spring gun is more complex as  a pneumatic one, as the book shows that all of them quite heavily rely on combustion of oil.... Furthermore the book reports on the effect of pellet seating, hardness and shape.

Bad. Work and shooting completely exhausted my free time.

You really put a lot of effort in this. Is there a way you can calibrate the chrony?

This topic has been moved to Ballistic coeficients.

http://www.bfxyz.nl/smf/index.php?topic=66.0

environment added in spreadsheet

These are things I like By the way you can now use a custom drag table (e.g. the jbm one).

I get a bit different results. I think there are two variables here: the average v0 and the average bc. I have, using solver, optimized them both to get a best fit with the data.


bc   0,108   ra4      
v0   324,6   m/s      
            
I have included the spreadsheet that does the job. The spreadsheet can be used to determine the accuracy of the fitted values - i did not do it.

mman, are you having ICAO conditions for the measurements or is the weather in Finland a bit colder?