Quest for g7 ballistics programs (can we please make a list)

Discussion in 'Rifles, Bullets, Barrels & Ballistics' started by Horsemen, Aug 20, 2009.

  1. Horsemen

    Horsemen Active Member

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    I'm still not sure which program to get. I know that it needs to have the OPTION for using the G7 drag function. Not all programs state weather they do. Can you help compile a list of ballistics programs, that use G7. And weather they are PC, PDA(Pocket PC), Windows based, or Apple based.

    Your help would be greatly appreciated by my self, and others, that are about to go down this road.

    Regards : Mike
     

  2. kcebcj

    kcebcj Well-Known Member

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  3. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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    Great Idea Mike.

    I'll add the one's I know of. As others post new ones below, I'll update this list so that they're all compiled in one place.

    JBM (free; online)
    RSI ($99.95; PC)
    Point Mass Ballistics ($39.95; PC) this is the one that comes with my book
    Al Bal (free; PC) Download-able from JBM site
    BulletFlight (~$12; iPhone app)
    Ballistic ($10; iPhone app)
    LoadBase 3 ($148.50; PC and PPC)

    I've been talking to Gerald Perry about adding G7 capability to Exbal. I don't know if he'll do it, he was talking about another program that he's working on that will have G7 though. I'm sure the more pressure he gets from customers the more likely he would be to consider adding G7 to Exbal.

    -Bryan
     
    Last edited: Sep 11, 2009
  4. LouBoyd

    LouBoyd Well-Known Member

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    It seems to me that writing new programs whch use G7 BCs is a step in the wrong direction. All of the data for complete drag vs velocity tables for or every bullet made would fit on one DVD and take only a small portion of the hard drive space on a modern laptop computer. Why not dump the use of BCs completely? Didn't the US Army (BRL) cease to use BCs in the 1980's?

    To me the term BC shouts "Before Computers" more than "Ballistic Coefficient". Certianly the use of ballistic coefficients were a valuable tool before about 1980 when computers became available which were powerful enough that routine calcuations using complete drag functions were practical. Today a $300 notebook PC has orders of magnitude higher perormance and storage space than anything available to military ballisticians in the 1970's.

    To allow a computer program based on drag functions to get started for bullets where that data doesn't exist the initiall database could be synthesized from existing BC data using whatever BC model is the better match for the bullet shape until measured or calculated drag functions become available. Calcuations done that way would be no worse than the exisiting programs which use G1 or G7 BCs and new entries as the data becomes available would be be better without the builit in errors.

    The old MgDrag program does a decent job of generating a drag vs velocity function, but then most of the results get trashed when a single value G1 or G7 BC is derived from those caluations. The same is true when single value G1 or G7 BCs are derived from multiple screen chonograph or miillimeter wave radar test firings.
     
    Last edited: Aug 21, 2009
  5. Mikecr

    Mikecr Well-Known Member

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    So Lou, how would any bullet maker define their bullet, if not with BC?

    Sounds like your suggesting that someday we should download drag curves for each bullet instead of accepting a single relative BC. But that data will never be available.
    So adjustments to drag curve will still require a single reference in one form or the other.

    Might as well be BC
    G1 BC
    G7 BC
    Or LouBoyd BC, if your's is right
     
  6. ss7mm

    ss7mm Writers Guild

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    Bryan:

    LoadBase doesn't give you the ability to directly use the G7 drag form. It does allow you via velocity/distance tests to input data that will try and match the G1 form more closely with the G7 form. It comes as close as anything out there but it does it by massaging the G1 form. It does however, convert whatever you have for G1 data into G7 but it's still a massaged G1 form albeit verrry close.

    In the end, when you look at the drag form used when ending up with your final Shoot data, you are using the massaged G1 form
     
  7. jmason

    jmason Well-Known Member

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    ss7mm is correct.

    If Bryan makes a mobile version it will likely be the first to use G7, I wouldn't count on GP to do either. He's got some catching up (or to do list items as he put it) with Exbal.
     
    Last edited: Aug 21, 2009
  8. bigbuck

    bigbuck Well-Known Member

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    This is going to sound like I'm intentionally throwing rocks at a hornets nest, (i'm not)with that being said. If you use nightforce or any of the other software programs on the market to hit targets at 800,1000,1200 or further what difference does it make? If I can range a target at 1200 yrds put all the data into nightforce pull the trigger and hit that target why would I need G7?

    BIGBUCK
     
  9. jmason

    jmason Well-Known Member

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    If you are truly doing that with the programs mentioned you are fudging something. Not trying to argue w/ you but I've used several programs enough to know that they aren't 100% w/o some fudging. There's a market (guys like me) for programs that use good data to come up w/ results. Again, not trying to be derogatory.:)
     
  10. Mikecr

    Mikecr Well-Known Member

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    If you can git-r-done with single shots at every abstract range out to 1200, you got no problems in my view. But it is still relative...
    For one, your capability must be taken to cold hard moa of accuracy(not grouping).
    Second, can you really maintain this accuracy at any range?(again, not group shooting)
    Most shooters can not.

    A ballistic challenge for us relates to use of a poor standard in drag curve(G1). It's poor because it doesn't match ANY of our bullets. This mismatch causes our true G1 BC to vary with velocity, just as it varies with air density.
    Normally, you enter a single G1 BC and your software must assume this is correct for your entered muzzle velocity.
    Is it? Possibly for you, never for me..
    Now as the fired bullet drops in velocity, it's real world G1BC departs from what you entered, and what your software assumes, because this is all based on the G1 drag curve,
    I believe Bryan(Berger) has made efforts to help us reduce the real world affects of the 'G1 problem' by averaging G1 BC over a likely velocity range. There is potential here to cut error in half.

    Another solution to the 'G1 problem' is to switch to a 'G7 problem'. This curve more closely matches that of long range bullets we use. It ain't perfect, never will be, but a step in the right direction. If your software could reference a truly matching curve for each iteration downrange, your BC would be right on the money and it would not change at all.

    With this, your accuracy might drop off with distance in a very predictable manner, instead of seemingly abstract.
    For instance, if you set a 1moa target at each 100yd increment out to 1200, and fire single shots to center of mark, you might expect that 1/4moa of accuracy at 100 would turn into 1/2moa at 500, and 3/4moa at 1000, etc. It gets tougher and tougher.
    But using G1 BC, you might find that 1/4moa at 100 turns into 2moa at 1000, or just opposite(depending on where you zero'd).
    I'm not talking about moa of grouping here. I'm talking moa of accuracy.

    This is where all the interest in use of G7 comes from.
     
    Last edited: Aug 21, 2009
  11. phorwath

    phorwath Well-Known Member

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    Yup. Some good rationale explained here.
     
  12. BryanLitz

    BryanLitz <b>Official LRH Sponsor</b>

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    Great discussion!

    First I'd like to thank those who've set me straight on the G7 capable software; turns out LoadBase doesn't accept G7 BC's as I thought it did. It's been removed from the list.

    I sure wish I was a smarter programmer and had the time, there's a real strong market for G7 capable PDA's. Right now, if you don't have an iPhone, it seems there aren't any options.

    Lou,

    You bring up a good point about computational resources, and the possibility of using unique drag curves for each bullet. Computers certainly aren't preventing us from doing that, but I think there are still other very practical and useful reasons to continue the use of BC's.

    First, BC contains more than just drag information. It includes sectional density, and is an important 'comparison' number to use.

    Second, there isn't enough experimental data to start using it exclusively. If you use
    McDrag or some other computer prediction program, you're looking at +/- 10% error and it's no better than an estimated G1 BC.

    My experimental data is collected using acoustic sensors, which means they only work (well) during the supersonic portion of the bullets flight. Using a BC referenced to a standard projectile, you can extrapolate the measured, high speed data down to transonic and subsonic speeds. You can also extrapolate to higher speeds than those tested because the standard curve is known. If you rely only on measured data, you can only predict trajectories over speed ranges that you've actually measured and that is a practical limitation.

    When radar data exists, it's usually quite good and can be used to calculate very accurate trajectories. However, it's unlikely that such data will exist in bulk any time soon for anyone other than Lapua.

    If you look at trajectories predicted with Lapua's direct drag data compared to a G7 BC that's based on the drag data, there is very little difference between the two trajectories at all ranges. There's certainly much less difference than a G1 vs G7 based trajectory.

    I like to think of the move to G7 BCs as an important and practical improvement in the potential accuracy of ballistic calculations. Is it the most precise way? No. But it's the point of diminishing returns between complexity and accuracy. In other words, going to G7 BC's removes 90% to 95% of the velocity dependence problems associated with G1's, and most hunters/shooters can adopt the G7 BC's with little pain and confusion (provided the mobile software becomes available). Getting that last 5% to 10% would require using many other standards (G2, G5, etc...) or raw drag data unique to each bullet. There's no reason for some curious individuals not to explore these more complex options for their own use, but I don't feel they're the right solution for general use. Of course, that is a matter of my opinion, and is arguable.

    I need to get on the ball and learn how to program PDA's already!

    -Bryan
     
  13. ss7mm

    ss7mm Writers Guild

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    Guys:

    I contacted Gus this morning and in a couple of emails he has supplied some very interesting news. He said it was o.k. to share the correspondence so here goes.

    I sent him an email and asked him about any future plans for LB to utilize the G7 drag form and I told him that most serious long range shooters considered it the way to go. Here is his reply.................

    ==========================================================

    Hi Dick,

    Let me start by saying that LB3D is almost ready to roll. Just need to
    finish some new features, since it's not a revamped LB2, it's a complete
    rework, making it a 100% .Net-based app (same as LB3M), which entitled a LOT
    of programming work, including some new features.

    I've been busy developing and delivering the new ballistics system to be
    fielded by the British Army Sniper Teams, and that took some time off LB3D.

    On the other hand, LB3M next update is almost ready too, which incorporates
    some changes to make it fully compatible (features and functions) with LB3D.

    A new and novel method to account for MV/Air Temp compensation has been
    developed (to fit the British requirement...lots of math there!) and will
    make its way into LB3D/M.

    Both, will do exactly what you've asked for. To give the user the option to
    choose between G1/G7, among other things.

    So, as you pointed out, no further need to use the Analyzer.

    In fact, I've been discussing that with Bryan some time ago (he already
    posted that LB is one of a few to handle G7), then I decided to make life
    easier for those believers in G7...

    Just let me point out, that LB3 ballistics engine does not rely on any "G"
    function at all, however to make things simpler it uses a known BC (G1 or G7
    now) as a "starting point".

    I prefer not to go into the debate of G1 vs G7. But just let me say that G7
    is neither new nor the Holy Grail. It's just a good form-factor to same
    bullets, while bad to others.

    Hope this make the wait worth!

    Gus

    ================================================================

    I then replied that I knew the G7 was not the end all of ballistic problems but I felt that it would be a more accurate place to start than with G1.

    Here is his reply...............

    ===============================================================

    [FONT=&quot]Dick,[/FONT]

    [FONT=&quot]Well, improving the software is always a high priority, especially to listen to user’s feedback, it’s important to make the end user into the development cycle. I think the user deserves the best I can possible deliver.[/FONT]

    [FONT=&quot]Please go ahead and share the news.[/FONT]

    [FONT=&quot]The issue I see with G7 is not only its scarcity but the fact that it’s not a good form-factor for almost any bullet shape. G1 on the other hand is a quite good compromise if handled adequately.[/FONT]

    [FONT=&quot]Of course and IMHO, G1/G7 is not the real answer to the problem of finding the best way to compute a bullet’s deceleration, that’s why a Coefficient of Drag is always the best possible mathematical description.[/FONT]

    [FONT=&quot]However one must account for practicality, meaning the availability of those values, usually obtained by Doppler radar readings, which is so far the most accurate instrument to measure velocity loss, among other parameters.[/FONT]

    [FONT=&quot]Would you like to participate in Beta testing of LB3M/D ?[/FONT]

    [FONT=&quot]As such, you’ll have the opportunity to test the software, suggest changes, etc[/FONT]

    [FONT=&quot]Thanks![/FONT]

    [FONT=&quot]Gus

    ==============================================

    I thanked him and told him I'd love to test it and also told him that I thought that Bryan would be an invaluable person to have evaluate the software.

    We'll see how thing go but it sounds like Gus is continuing to do what he always has and that is to improve LoadBase and try to give us the best software out there.
    [/FONT]
     
  14. phorwath

    phorwath Well-Known Member

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    Hot diggity! Thanks for sharing this information. I really look forward to receiving the LB3 Desktop and being able to input Bryan's G7 drag function BCs for my Berger VLDs. This should result in a sweet fit of predicted drops to actual field drops right from the get-go. Life is about to get better. :)