I'm not a 6DOF expert, but Magnus moment and pitch damping coefficients tend to have a lot of uncertainty.
G1/G7 Discrepancy
- Thread starter mdmp5
- Start date
Hi,
This test article shows their margin of error in those is 15% but yet Doc says +/- 50% accuracy aka margin of error.
http://citeseerx.ist.psu.edu/viewdoc/download?doi=10.1.1.843.9226&rep=rep1&type=pdf
But also testing done for NDIA by Arrowtech shows:
Pitch Damping Moments can accurately be measured typically down to 15% margin of error from wind tunnel testing and down to 1% with spark range.
Magnus Moments can accurately by measured typically down to 10% margin of error from wind tunnel testing and down to 1% with spark range also.
Sincerely,
Theis
I can only speculate about AB having access to Govt' radars, not bad and quite expected given the contract. Just let me say that there is no such thing as "secret", all serious papers on ballistics are always published for peer review. So, I cannot take the "classified" word seriously but for marketing purposes. When I said the 2000y data is useless is because I got the feedback from a retired Army expert who checked out the radar trace you posted and his conclusion was that the gaps render that zone useless for serious Drag derivation. Anyway, I'll always welcome any better data or information you guys can share with us to make better LR predictions. Let me be a little bit skeptical about "ideas of ballistic solvers" because for as long as you stick with PM, everything that needs to be said about (3DOF, 4DOF, 6DOF) has already been said. However if you can do "banded Drag" maybe you can have something to write Mom about. Now, if you can provide better data we'll receive it with open arms.
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Look at the actual experimental data in that paper. It's pretty noisy. Other sources show similarly scattered results. Again, I'm no expert, but I'm told by folks who've worked extensively with this stuff that PRODAS numbers should only be used with caution, because some of them are pretty wrong. I do know that CFD is a GIGO kind of thing - it's not a one size fits all technology (and it's a lot of work). Take that as you will, I'm not trying to argue or denigrate the people working on this stuff. It's hard.
Hi,
I completely understand @damoncali, anyone can debate anything lol....But Spark Range is pretty hard to dispute although some try
Biggest issue with it is that it cost (typically) $2000-$2500 per shot. But it provides the information one is seeking.
Sincerely,
Theis
I completely understand @damoncali, anyone can debate anything lol....But Spark Range is pretty hard to dispute although some try
Biggest issue with it is that it cost (typically) $2000-$2500 per shot. But it provides the information one is seeking.
Sincerely,
Theis
So I guess that you really better have your shit together beforehand to design a minimal COF that will still provide meaningful results. Plus a really big budget or grant.Hi,
I completely understand @damoncali, anyone can debate anything lol....But Spark Range is pretty hard to dispute although some try
Biggest issue with it is that it cost (typically) $2000-$2500 per shot. But it provides the information one is seeking.
Sincerely,
Theis
Can I assume the wind tunnel is not 2000 yards or longer ?
Had a quick look at the link , and the projectile was 25mm , sabot discarded . Not sure of the implications
for a copper jacketed , lead cored bullet or a solid fired from a rifled barrel . How long is the wind tunnel
used in that test ? I’m thinking it might not be 2000 yards . Predicting , and measuring the extra 2 DOF
would appear to be tricky without this capability . 4 DOF and CDMs are working very well for me .
Heard the same thing many times before, after all, it's a model and as such relies on its data inputs and the underlying design
