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Amazing trajectory calculations QTU INFO UPDATE

Re: Amazing trajectory calculations

The XC feeds fine from the issued 700 mag box with 105 Berger VLD's at 2.795". 3,080 fps w/38.5 H4350 and the F210M's. The "L" cartridge is slightly shorter and would be a non issue in a DBM. The smaller Flash hole/primer pocket would allow for a slight accuracy edge and higher pressure. I doubt you'd be giving up much if anything by going to this cartridge, accuracy trumps velocity all day long, the higher BC bullets being mag feed is just icing on the cake.
grin.gif
 
Re: Amazing trajectory calculations

building and shooting are 2 different things dumbass!

Just in case you didnt know.
Do you think the guys that put the race car together can drive as good as the race car driver?

You must be pissed to have dug all those cheap plaques out and take apicture. Do you think just because of those you can shoot better than someone else? I dont think your mommy and daddy showed you enough attention when you were a little kid did they?
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thecloudofdeath</div><div class="ubbcode-body">building and shooting are 2 different things dumbass!

Just in case you didnt know.
Do you think the guys that put the race car together can drive as good as the race car driver?

You must be pissed to have dug all those cheap plaques out and take apicture. Do you think just because of those you can shoot better than someone else? I dont think your mommy and daddy showed you enough attention when you were a little kid did they? </div></div>
Your right, building and shooting rifles is two different things but, I can do both. The plaques mean dick to me, they're just wood and plastic but, I did whip someone else’s ass to get them
wink.gif
We're having a match this weekend, please come to it so you can show all of us how good you are. I'll pay your fee and "if" you win, I'll pay your gas back home and tell everyone how great you are, I'll even post pictures of your victory on the WWW. Speaking of pictures, weren’t you going to post some??

Now, I can be civil if you can, let’s try.
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: wnroscoe</div><div class="ubbcode-body"> accuracy trumps velocity all day long, the higher BC bullets being mag feed is just icing on the cake.
grin.gif
</div></div>

Agreed, the 6mmRem is a absolute winner in all regards, except mag confines.
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JessieJames</div><div class="ubbcode-body">Whats with all the fighting? </div></div>

That’s just love, can’t you feel it.
 
Re: Amazing trajectory calculations

2008 meters is a far piece. Are you making cold bore hits at that range?
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: thecloudofdeath</div><div class="ubbcode-body">Holy shit is that all? You are a joke dude,
Give me a minute to dump out the emptys I have shot this week and take a pic if you think 120 rounds is a lot for 5 months. I shoot more than that in a week. You need to check the advertisement for this site,
It says for the serious tactical marksmen, not the weekend warrior. </div></div>

scary_bb.jpg
 
Re: Amazing trajectory calculations

<span style="font-weight: bold">OFF TOPIC GUYS, STOP ARGUING HERE OR GO AWAY</span> thank you.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brown Dog</div><div class="ubbcode-body">
JL,

Got to start my answer with a question: What vertical dispersion did the dopplered shots show?

Because of all the interacting and unpredictable variables between shots (minor MV changes, slightly different bullet weights, slightly different bullet shapes, a 0.1 knot tailwind change etc) or between strings of shots (the slightly warmer barrel, the different bore surface /fouling compared to the last string, a 4mB pressure change etc) to claim to define a particular ammunition's drop to an exact value at 1.5km is....err, optimistic.

Each round in a string will land differently to the last. Thinking only in vertical terms; the rounds will have a normal (Gaussian)distribution. Some will land high, some will land low; 68% will land within one standard deviation of the mean POI....and it’s likely that that mean POI will be different from string to string and, especially, occasion to occasion.
smile.gif

</div></div>

BrownDog, thanks for your reply
Unfortunately I dont have doppler test details available.
Personally never even seen or tested radar system.
Alltough I know peoples who have done this for living. With 338LM too. Will ask for sure next time when I see those quys.

Still, I´d assume that when shooting test with radar, they are looking for average too. MV changes in test can be calculated to match trajectory in desired slightly lower or higher "correct" MV.

All other variables, such as slight bullet weight changes basically doesent matter after all since tester is looking for average..say at xx or xxx shot strings anyway.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brown Dog</div><div class="ubbcode-body">
I would say that any prediction that is within one standard deviation of the mean is ‘within tolerance’ ..or ‘close enough for government work’….because you’ve predicted data that will put your shot within the zone in which 68% of all shots will hit.

..and I rather suspect that this 7.5cm ‘error’ will be well inside one SD for rifle fire at 1.5km!

...and thus, in real world terms, I suspect 7.5cm at 1.5km cannot be sensibly described as an 'error'.
smile.gif

</div></div>

Yes, you´re right and I agree- 0.05mrad@1500 is minimal POI shift. SD can cause same or larger spread- among many other (shorter range) insignificant things too.


<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Brown Dog</div><div class="ubbcode-body">
(PS ...I spent some time at Rovajärvi several years back; great fun, although it was some time before I could look at vodka again!)
</div></div>

Rovajärvi....hmmm...artillery shooting area there, right?
wink.gif
 
Re: Amazing trajectory calculations

Didn't read through all the fighting topics. Here are some points I think need to elaborate.

- "radar measurement data" - you bump 100 rounds to the sky, measure for every shot the MV and the path with radar. Then correct the MV deviation in each shot and its effect to path. Then calculate the mean path. Next you define and fine tune Cd(v) = drag function to match exactly the "radar mean path". Now you have a bullet specific drag function defined. This entered to QTU was used to calculate paths.

- 0.05mrad error. BrownDog got it a bit wrong. Read my post again. What I said is that "Pejsa path prediction method" is possible to finetune to match against radar test results within 0.05mrad accuracy. Thus if we think the radar test results are the most accurate real life data available for reference, then Pejsa method is quite accurate with correct BC and DC values.

In general I'd say based on the weekend results, I'd guestimate the avg prediction accuracy of QTU taking into account all deviations etc is about 0.1mrad to 1000m, 0.2mrad to 1500m and 0.5mrad to 2000m.

- Coriolis. Coriolis affects trajectories. If it had not been accounted, the first shot deviations would have been bigger.

- Spin drift surely affects. If I recall right, for 2000m I used spindrift correction L1,6mrad.

- Cold Bore shot. On Sunday I made a cold bore hit to 1395m aftern normal light cleaning and bore only dried out from oil. It is possible if one knows the rifle well, how it behaves after cleaning and whether there is deviation with cold bore against avg POI and shooter knows how the MV changes as powder MV changes. Rest is math.
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MSA</div><div class="ubbcode-body">
- 0.05mrad error. BrownDog got it a bit wrong. Read my post again. What I said is that "Pejsa path prediction method" is possible to finetune to match against radar test results within 0.05mrad accuracy. Thus if we think the radar test results are the most accurate real life data available for reference, then Pejsa method is quite accurate with correct BC and DC values. </div></div>

Well, I'm a little loath to answer given the pissing contest that interupted our 'conversation'! -against that background, my answer may appear a little pedantic -that is not my intent!
smile.gif


With regard to Pejsa, you said: <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MSA</div><div class="ubbcode-body">It will get you out to 1500m within about 0.05mil error. ....Only QTU estimates better than this. </div></div>

I think my comments stand - I'm making no bigger point than, if you think you can identify a 0.05mil elevation 'error' at 1500m -and then unequivocally state that the delta between predicted and observed is due to the prediction method alone -thus disregarding the rest of the 'error budget' - then you are kidding yourself
smile.gif


You state: <div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: MSA</div><div class="ubbcode-body">
[the] Pejsa method is quite accurate with correct BC and DC values.</div></div>

Prediction within 7.5cm at 1500m only <span style="font-weight: bold">quite</span> accurate???!!

With realistic tolerances I think that's as good as it gets!



...what was the vertical dispersion for your 100 shots?

smile.gif


 
Re: Amazing trajectory calculations

JL, with due respect, color me skeptic...

Good job on the program and the fine shooting, but like BD said: "if you think you can identify a 0.05mil elevation 'error' at 1500m -and then unequivocally state that the delta between predicted and observed is due to the prediction method alone -thus disregarding the rest of the 'error budget' - then you are kidding yourself"
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: TiroFijo</div><div class="ubbcode-body">JL, with due respect, color me skeptic...

Good job on the program and the fine shooting, but like BD said: "if you think you can identify a 0.05mil elevation 'error' at 1500m -and then unequivocally state that the delta between predicted and observed is due to the prediction method alone -thus disregarding the rest of the 'error budget' - then you are kidding yourself" </div></div>

I think the only thing to do here is to stand it up to peer review. I'm sure someone else will get around to running this same test eventually, if we're lucky maybe we can get a couple sets of results to compare.

Thanks for sharing your knowledge on this guys, definitely learned alot from this thread despite the jabberjawing.
 
Re: Amazing trajectory calculations

Just one more clarification to this thread and especially about radar data reference.

- I did not shoot, nor measure, nor calculate the radar test shots.
- They were shot and measured at Artillery Proving Grounds with their radar.
- I'm not radar expert but I've been told they are able to measure the bullet path & location in millimeters rather than centimeters.
- Of course the bullet paths measured have some stdev and distribution. To my understanding MV deviations are corrected shot by shot in the data.
- Based on this measured data one is able to form and AVERAGE trajectory and speed of the bullet. Naturally deviations in bullet shape, head/tail wind, gun etc, cause error. Based on this measured average trajectory one is able to calculate drag function of a bullet = Cd(v).
- With this Cd(v) file, which consists of about 30 coefficient of drag entrys at various speeds, inserted to Quick Target Unlimited I predicted the trajectories.

About the accuracy: QTU + Cd(v) method was able to yield up to 1400m at various environmentia conditions and for various shooters and guns correction values to make first shot hits at 45x90cm targets. The same software was able to get me to 2000m (1.25miles) mark with about 0.5mrad accuracy.

The 0.05mil accuracy. All what I claim is that Pejsa method is able to predict the same average flight path that has been formed based on test firings within 0.05mrad deviation up to 1500m. I'm not saying that with this prediction method one would hit on field within 0.05mrad deviation from point of aim.

My point on this whole thing is to give you ER shooter guys a heads up! To my understanding QTU + Cd(v) information is a prediction method that we have dreaming of in terms of accuracy.

If I was you guys in US I'd be calling to Sierra and Berger to press them to publish this Cd(v) information for your favorite bullets.

Hope this clarified some of the stuff. And hell, in the end of the day I'm still a Finn and dont give rat's ass what antagonists think as long we keep hitting the Ivan where we want.

MSa
 
Re: Amazing trajectory calculations

It might be a language barrier error but I think you guys are slightly besides the point. As far as I can see, the point is:

"With correct BC & K, Pejsa calculations can be tuned to predict a path that at any point deviates no more than 0,05mrad from doppler radar path" .

Like MSA mentioned, the radar path is our currently known "best guess" so gettin Pejsa to accurately match that is just awesome. And not just for one bullet in one set of conditions, we're accumulating data that suggests a correct BC & K combination ( per bullet ) will yield correct results in varying temperature, station pressure and v0 variations.

I don't think anyone is suggesting we are measuring a sub- 0,05mrad deviation when comparing shot groups to doppler data -- like you guys said, it's very hard to measure such small differences.
 
Re: Amazing trajectory calculations

JRu, MSA,

Understood. It appears we may be violently agreeing!

Thanks for the clarifications!

 
Re: Amazing trajectory calculations

JRu, MSA, it makes sense, thanks a lot for the clarification.

Getting a "normal" program to match doppler data like that is awesome.

It is an approach more or less like the Sierra Infinity, that has several BC's for velocity brackets, but much more accurate because you have 30 real Cd(v) from doppler radar. The Cd(v) is all what matters.

The Sierra guys shoot the bullets in 300 m ranges at reduced velocities to get their BCs; only in some cases they have access to military doppler test data, and they only use 3-5 velocity brackets to simplify things for the user.

How do you guys enter the values for Coriolis, spin drift, etc.? Just have a table for these values, or is it calculated in some way?

I'm also interested if you can predict/calculate the vertical veriations of POI due to a side wind (or get from tables based on doppler data).

Thanks for an excellent report!
smile.gif
 
Re: Amazing trajectory calculations

Actually, you don't need doppler radar data - you just need accurate elevation data for multiple ranges under the same set of conditions, which is all that the doppler gives you.

And you can tune any ballistic program to match your shooting results, although it's easier with one which has provisions for multiple B.C.s in velocity ranges.

I've done that with HorusVision Atrag, Exbal, and Field Firing Solutions. All seem to do a pretty good job of modeling drag as a function of air density, so once you're good with one set of conditions, you should have some confidence in the results under other conditions.

It just takes some work for each load you want to do it with. Having only one load to cope with simplifies the problem.
laugh.gif


It may be useful to remember, when doing so, that in the real world, the results you want most accurate are at longer ranges, since near-range targets are usually relatively larger.
 
Re: Amazing trajectory calculations

Lindy, the radar data is just soo confidence inspiring... real world, flawless data, hopefully in a similar barrel. Getting good, solid, not wind influenced elevation data is tricky at long ranges.

And I agree with you, just playing with any normal program can get a pretty good fit up to at least 1000 m, making it match at the longest range and accepting (or knowing) the small errors at shorter ranges compared with real world data.

Still, this many-Cd's approach is excellent, IMO far better than using the best fit drag curve and hopping for the best. The only problem for general use would be to get those 30some pesky Cd...
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Quote:</div><div class="ubbcode-body">...hopefully in a similar barrel.</div></div>

Aye, there's the rub - and not <span style="font-style: italic">just</span> the barrel, either. There are lots of other variables. The notion that the only way to have good data is with a doppler radar is simply silly. I'd rather have data obtained for <span style="font-weight: bold">my</span> rifle with <span style="font-weight: bold">my</span> load than wish for data obtained with a radar.

I believe the bullet. And I believe <span style="font-weight: bold">my</span> bullet.

 
Re: Amazing trajectory calculations

Hi,

CORIOLIS:
=========
Coriolis is calculated in QTU automatically. Basically a few 0.1mrad clicks elev or windage dependin on the direction you are shooting and location on earth.


SPIN:
=======
For spindrift in my custom Excel pejsa model (which I use up to 1500m) use following guestimateformula for SpinDrift.

SpinDrift[cm]=constant * TOF^2.

For 338LM 1/12 250gr bullet constant 15 has given quite accurate estimates. Constant is typically within the range of 12-20 depending on rifling, twist, bullet length etc.

The point in this whole report was that I was personally amazed the accuracy QTU can do with CD(v) data. We've been discussing only 338LM here BUT I did also the following bullets and found out that they we're well in align too
- .30 150gr Scenar up to 1100m 865m/s
- 6,5mm 7g Scenar uo to 1400m 1085m/s
- 6,5mm 9g Scenar up to 1400m 940m/s
- .338 250gr LockBase up to 1400m 910m/a

It just can't be a coincidence that all these bullets having cd(v) data at my disposal behaved exactly how QTU suggested.

Using BCs or even multiple BC in trajectory predictions is like climbing to tree with your arse first. The method is ancient and yet still fundamentally just a quick and dirty patch for predictions for bullets having other shape than the reference bullets shape. Using coefficient of air drag function which is specified for the projectile is the correct method of prediction. QTU does it the right way.
 
Re: Amazing trajectory calculations

MSA: I saw that you used 33.3 Mrad elevation for the 2000 meter shot. That is about 120 MOA (if I haven't miscalculated). I have tried the S&B 5-25x56 once (outstandig scope!), and I do think that it "only" had about 100 MOA of elev. adjustment, or about 28 Mrad. Did you use the reticle to hold over, or does the S&B 5-25x56 have more elevation adjustment than I thought?

Nice shooting by the way, keep it up!
Greetings from a neighbour
 
Re: Amazing trajectory calculations

Lindy, I believe my bullet too... but sometimes reading accurately the environmental conditions is very tricky, and this makes our real world data "lie": if you are shooting at long distance on a particular range it is very difficult to see vertical up/down drafts, even more if you are getting your data over a canyon, etc.

A state of the art 6DOF program coupled with radar data, wind meters downrange, etc. will factor in all these factors, plus calculate the influence in vertical POI of side winds, etc.

Ideally, you should get your "baseline" come ups in a windless day and over a flat range. And then re-test several times in other conditions, see if there are variations with a side wind, etc. This is the best way, but it is a lot of work/time involved.
 
Re: Amazing trajectory calculations

Only reason I started this thread was access to new (to me) trajectory calculation method.

For years, I (or we) have desperately calculated trajectorys with 15-25% reduced BC by G1, G5 or G7 DF, and still get only rough elevation values- still accurate enough to hit big LR or ER targets.

Problem at "home-testing" LR elevations really is change in weather conditions.
Previous week or even month tests are not valid or at least not 100% comparable anymore- more or less waste of money and time.
As said, f.e. sidewind direction change causes deviation in elevation (Magnus)- and most of us can never be sure about shooted data compared to one shooted at previous time- and thats only one of many inconstant variable.
So in fact, its only estimation of exact drop.

Now, as some of us have access to radar-based data, trajectory prediction really starts to be good enough for LR first round hit sniping too- as long as range estimation goes smoothly.
And why shouldnt it, now program uses that specific bullet path as base for calculation.
I would even dare to claim that in practice QTU program can give same or even more accurate trajectory data than actually shooted ones -just because LR and ER shooting at same weather and conditions is so difficult.
And even if one manages to shoot all ranges from at same time 100 to 1600, wind and weather at each bullet path may vary.


bye bye PCB, will miss you...(not!!)
grin.gif
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: SAKO-75</div><div class="ubbcode-body">MSA: I saw that you used 33.3 Mrad elevation for the 2000 meter shot. That is about 120 MOA (if I haven't miscalculated). I have tried the S&B 5-25x56 once (outstandig scope!), and I do think that it "only" had about 100 MOA of elev. adjustment, or about 28 Mrad. Did you use the reticle to hold over, or does the S&B 5-25x56 have more elevation adjustment than I thought?

Nice shooting by the way, keep it up!
Greetings from a neighbour </div></div>

Neighbour from Norway,

I had 20,3 mrad in turret and took 13mrads from the P4 reticle. Had to power the scope down to 12-14x to see enough reticle.
 
Re: Amazing trajectory calculations

JL thankyou for sharing with the group, I apologize for the completly out of place comments made to this exciting thread.

What was the weather like that day?

Are your barrels Hammer Forged and do you check for any harmonic deviation in the barrel?

Do you like the MRAD over MOA in general for ELR?

How do we come over and shoot with you PM me.
 
Re: Amazing trajectory calculations


How big was the target? 45cm x 90cm or 17.7" wide, 35" high.

35" high straight on, but at what angle is the projectile coming down at and approaching the target thereby reducing that to what size surface exposure? just a thought.
you are so far beyond me I'm amazed.
 
Re: Amazing trajectory calculations

I am sure this has been talked about already but, what do you guys think about the bors system? I dont know alot about it, I hear it does all the work for you. Is this something worth buying?
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: ND Norm</div><div class="ubbcode-body">
How big was the target? 45cm x 90cm or 17.7" wide, 35" high.

35" high straight on, but at what angle is the projectile coming down at and approaching the target thereby reducing that to what size surface exposure? just a thought.
you are so far beyond me I'm amazed. </div></div>

Bullet was shot about 2.0deg elevation angle to horizontal.
At 1200m the path tangent angle is zero.
Bullet hits target 2008m with about -4.4degree angle
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: 7mmRM</div><div class="ubbcode-body">Hes almost MoD material. </div></div>


Minute of Dumbass?
 
Re: Amazing trajectory calculations

Incredible shooting
cool.gif
MSA
Nice pissing contest too
cry.gif
. If I didn't know better I'd think you 2 were husband and wife!!
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: Jo</div><div class="ubbcode-body">Welcome to the hide thecloudofdeath,

If you could you please stop posting for a moment and take a few hours to read through post's made on this forum.
What ever you think you know about LR shooting there are people here who have so much more experience and could quite possible be the very sources to the facts that you refer too.
So be humble, read and learn, and you will have a great experience here on the hide.

So please help us get this tread back on track and stop ruining my "neighbors" post.

...

JL & MSA

I'm very impressed of both your calculations and shooting! Great post! Loistava MSA!

Jo

</div></div>

+1000000000
 
Re: Amazing trajectory calculations

JL, you were fast.

Thought that this would interest our fellows overseas too.

I'll make a new topic for this, since this REALLY was "a small step for Lapua, but a big step" for LR shooting.

MSa
 
Re: Amazing trajectory calculations

<div class="ubbcode-block"><div class="ubbcode-header">Originally Posted By: JL</div><div class="ubbcode-body">Finally, Lapua published their Cd:s. 28 bullets available for QTU....

Enjoy! No more estimated G1 calculations
smile.gif


http://www.lapua.com/uploads/media/LapuaBulletsCD-Data.zip

Info:
http://www.lapua.com/uploads/media/LapuaBulletsDragCoefficient.pdf

</div></div>
It s been a long time.
Link is not working anymore.
By chance, do you have another source or link or can you send it by mail?
Thanks
 
Re: Amazing trajectory calculations

Very interesting and entertaining thread.
 
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