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I've noticed there is no repository for ballistic science documents the way there is for the Mechanized or the infantry forums (for example) so I decided to fix this. 


My first offering is dtic stuff from the past on some weird and novel ways to extend the L/D ratios of spin stabilized projectiles.   I originally learned about this from someone I was having a discussion with years back and hunting lead me to one of those discussions about bringing back the battleships on navweaps discussion boards where one of the posters (Zenmastur) laid out his master plan for Battleship resurrection.  Which included the aforementioned 'higher than 6:1 L/D ratio spin stabilized projectiles'.    It took awhile to hunt down but I eventually found some of the original documents that focused on novel projectile shapes (for a large improvement) and non-conical boat tails (for a much smaller improvement)   


Obviously this went nowhere insofar as I am aware, and I suspect they had drawbacks nobody addressed (like most do) but it's an interesting thing to look at anyhow.   Much of this is the work of one Anders S. Platou, who seems to be as prolific as the RAVEN guy. 





A series of projectile boattails have shown improved aerodynamic performance over the standard conical boatail. These boattails have equal or lower drag and an improved gyroscopic stability. Their Magnus and damping characteristics appear to be satisfactory so that the projectile should be dynamically stable. Also, these boattails increase the projectile wheel base considerably, thereby decreasing the balloting in the gun tube. The improved aerodynamic performance could lead to longer ranges, longer projectiles or lower spin rates for future projectiles.





A series of projectile boattails have shown improved aerodynamic performance over the standard conical boattail. These boattails have equal or lower drag and an improved gyroscopic stability. Their Magnus and damping characteristics appear to be satisfactory so that the projectile should be dynamically stable. Also, these boattails increase the projectile wheel base considerably, thereby decreasing the balloting in the gun tube. The improved aerodynamic performance could lead to longer ranges, larger payloads, or lower spin rates for future projectiles.

Improving the Flight Performance of Projectiles 



The BRL has been conducting experiments on spin stabilized projectiles using a new boattail shape called the Non-Conical Boattail. This boattail improves the aeroballistic characteristics of the projectile so that longer ranges are attained and heavier payloads can be flown to the target with good accuracy. Many of these experiments have been carried out on 155mm diameter full bore projectiles, but the aerodynamic characteristics can be applied to this configuration in any diameter including subcalibered projectiles.



The new boattail also provides a better configuration than a conical boattail for imparting spin as well as forward velocity to the projectile through a saboting system. In this report, the aerodynamic and aeroballistic characteristics of the new projectile as obtained from aeroballistic ranges, wind tunnels, and full range flights are summarized and compared to a similar conical boattail projectile.





Muzzle-blast loadings on spin-stabilized projectiles are analyzed and used to compute resultant trajectory deviations. Both conical and nonconical boattail rounds are treated. Approximations are made that permit the expression for the force on the projectile to be integrated; the resulting equation is used to develop a universal momentum transfer function that can be directly related to projectile jump. Although nonconical boattail configurations are more sensitive to muzzle blast than conical designs, the computed trajectory deviation in either case is small compared to the total measured dispersion of typical systems





Models, 7 calibers long, with a variety of conical, ogival (convex) and concave boattails were free-flight tested at M = 1.70, for drag and other aerodynamic characteristics. The total drag decreases monotonically for boattails longer than 0.5 calibers. For shorter boattails, the drag is higher than that of the square based body. For boattail lengths between 0.5 and 1.5 calibers, conical boattails have lower drag than either the ogival or concave configurations. The base pressure decreases with boattail length but increases with the boattail angle at the base. Among other aerodynamic characteristics, the boattailing appears to cause the most significant change in the Magnus torque coefficient. For certain boattails, this change may be sufficiently large to make the configuration dynamically unstable.









As part of the BRL program to develop the non-conical boattail projectile, twenty 155mm projectiles were fired from an M185 gun tube on 18 and 21 October 1977 at the Sandia Corporation, Tonopah Test Range, Nevada. This is the second phase of a planned three phase test program at Tonopah on the nonconical boattail projectiles. The report describes the experimental plans and presents the data records and some of the results obtained during the projectile flights.





As part of the BRL program to develop the non-conical boattail projectile, twenty 155mm projectiles were fired from an M185 gun tube on 14 and 16 March 1978 at the Sandia Corporation, Tonopah Test Range, Nevada. This is the third phase of the non-conical boattail program . This report describes the experimental plans and presents the data records and some of the results obtained during the projectile flights.





During the development and exploitation of the BRL NonConical Boattail Projectile, it became evident that a new projectile shape which combines a triangular nose with a triangular boattail would have low drag and a long wheel base for low balloting in the gun barrel. No aerodynamic data were available on the configuration (nicknamed the corkscrew) at the beginning of this program, so it was deemed advisable to conduct wind tunnel and range tests to determine its drag and stability characteristics.






~ Preliminary wind tunnel and aeroballistic range tests on a new and novel exterior projectile shape have shown that this S-caliber to 8-caliber long shape has extremely good aerodynamic characteristics. It not only has very low drag, but also low pitching and Magnus moments which in turn yield good gyroscopic and good dynamic stability. Extrapolation of the data to longer lengths indicates that 10-caliber to 12-caliber long projectiles having this shape can be flown with satisfactory stability.


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Today's weapons employ compact fragments as well as long rods and shaped)charge jets. From the viewpoint of an armor designer, it is desirable to have a method of dealing with all three types of penetrator both in theory and in practice, This report presents an equation of motion which in its most general form describes penetration by a forming, stretching, eroding jet. In various specialized forms, it describes penetration by pre-formed rods and compact projectiles. One specialized form reduces to the classical jet penetration formula according to which penetration in a semi-infinite target is proportional to the square root of the ratio of the jet and target densities. A correction for target hardness is automatically included. The solutions of the various forms of the equation of motion are given explicitly in closed form and are profusely illustrated by numerical examples and comparisons with experimental data.



In this report we restrict ourselves to one dimension and to finite or semi-infinite targets made of one material. The chapter on jets is also limited to descriptions of a standard 81mm, 420"copper cone device. These restrictions will be removed in future reports.)






This paper reviews available analytical methods for the study of kinetic energy (inert) projectile-armor interactions at ordnance velocities (0.5-2 kms ). Particular emphasis is placed on three-dimensional numerical simulation of perforation and results of two-dimensional plane strain and threedimensional finite element computations are compared with experimental results for impact situations leading to perforation and to ricochet. Problem areas and requirements for improved materials characterization are discussed.





A review is presented of the state of the art in the analysis of materials and structures subjected to intense impulsive loading. Emphasis is placed on the penetration and perforation of solids and current development its in three-dimensional finite element and finite difference simulation of impact phenomena. The need for adequate characterization of material response and failure at high strain rates is emphasized and current capabilities highlighted. An assessment is made of anticipated developments and advances in high speed computers, high strain rate materials characterization, and in numerical simulation techniques which will contribute to improved design and reduced vulnerability of materials and structures to impact loading.


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On 4/13/2018 at 2:43 AM, Collimatrix said:

Finally got around to looking at this. It's a blow forward.

I forget what other GL design of that era was messing with that system of operation, but I know there was one.

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On 6/10/2018 at 5:46 PM, Meplat said:

Finally got around to looking at this. It's a blow forward.

I forget what other GL design of that era was messing with that system of operation, but I know there was one.


Meplat, the one Chinn was working on was blow forward. This one is a long recoil constant react/FOOB (firing out of battery) gun designed by Russell S. Robinson, it even lists him as the design engineer in this proposal.


A whole bunch of Colt's proposals in this era came from them buying his company. (Robinson Improved Conventional Armaments / RICA) The SAR archives seem to have a pretty substantial chunk of them too including the CR-26 26mm gun/cannon, the lightning system, both his .50/.30 and 9x19 or .45 ACP SSB designs (but not his .30/.15 stuff), and I'm pretty sure that the GPAM had heavy involvement by Robinson and are all in the SAR archives.


GPAM gun


CR-26 feed system patent illustration


CR-26 gun picture



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Some random recoil impulse figures.  This stuff is interesting/important if you want to deal with guns from the back end rather than the front end, I find. 


Fire out of Battery Test results - a discussion of soft recoil/Fire Out of Battery recoil mitigation technologies (In the quest to put bigger guns on lighter frames)   It provides a number of Ogorkiewicz ratio figures for various armored vehicles (ratio of tank gun recoil impulse to its mass.  Rule of thumb  is 900 ns/ton as I recall)  

Ogorkiewicz Ratio [1], Round Impulse/Vehicle Mass, is often used when analyzing recoil effects on fighting vehicles, a ratio of 900 N*sec/M. ton is recommended as an upper design limit. The following table, (tablekl) is a comparison of Ogorkiewicz Ratio for a number of armored vehicles designed in the later half of the twentieth century compared to the FSC vehicle design concept.


Here is the list of 105mm 120mm and the Sheridan's 152mm gun:




Designer's Dilemma - recoil, what to do with it?  Covers towed/field artillery rater than sPG:


155mm towed gun figures:




Also a bit on FCS and tank guns, it includes a few interesting tidbits like recoil force and energy comparisons between 120mm and 140mm guns:




A future MBT concept can be expected to have the following features:


(1) Crew Extensive automation of basic functions—driving, navigation, reconnaissance, and operation—will enable the MBT to be operated by a two-man crew in a more compact fighting compartment (Hilmes, 1999).


(2) Weight The combat weight should not exceed MLC (Military Load Class) 60, or about 55 tons. The possible reduction of crew from four to two and the realization of a compact fighting compartment—with a net volume of about 3 m3 versus 10–12 m3 for current MBTs—will have a positive effect on weight reduction. And a similar effect will be realized by volume reductions in engine technology. For example, the Euro power pack is about 35 percent smaller than the Leopard 2 engine, but delivers the same power; however, the new armament system will increase weight. Increasing gun caliber to 140 mm—these rounds are about twice as heavy as 120-mm rounds—will increase overall ammunition weight even with a one-third reduction in the ammunition reserve. Weight gain will result from a bigger overall installation to accommodate higher recoil energy (from 155 to 270 kJ) and braking force (from 600 to 1,200 kN). The autoloader will weigh at least 600 kg. The greatest increase in weight is expected from demands for increased protection:


Future requirements are expected to specify protection levels for the fighting compartment area of [about] 1000 mm rolled homogeneous armor (RHA)-equivalent against 125 mm kinetic energy (KE) threats, and 1200 mm RHA-equivalent against shaped charge threats. If the KE threat is to be met with the use of purely passive protection elements, it would be necessary to think in terms of an area density of over 4 tons/m2 . It remains doubtful as to whether the KE threat can be effectively mastered in the medium-term (up to the year 2015) through the use of stand-off active protection systems. Protection against the shaped charge threat is less of a weight-related question. Here the use of reactive armor provides an obvious solution, through which a reduction of the penetration performance from 400-600 mm can be expected (e.g. Russian MBTs). Alternatively it is also possible to maximize the depth of protection through the use of passive armor technology, as adopted for instance in the turret area of the Leopard 2A5. Without significant developments to the basic protection concepts and protection technologies, combat weights in the region of 70 tons have to be expected for the next generation of MBTs. There could thus be no question of remaining within MLC 60 limits. (Hilmes, 1999, p. 74)


It's about 15 years old by now, but its still interesting. 

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On 10/12/2018 at 12:23 AM, N-L-M said:


Back in 2009, I stumbled across a site hosting the annual command histories for the Commander in Chief Pacific (CINCPAC) from 1960 through the mid-'80s. I found an interesting tidbit in the 1974 history regarding an examination of establishing South Vietnamese production of the Lazy Dog munition for the VNAF.



“Commander in Chief Pacific Command History 1974 - Volume I, pp 248-249”

LAZY DOG Weapon System as an Aircraft Area Munition

Scientific Analysis Group Report No. 1-74 on the LAZY DOG system was requested by the Defense Attache in Saigon as part of his effort to cut down on the cost of the continuing war in Vietnam. He was specifically looking for items that RVN industry could produce at lower cost than comparable U.S. items. Air delivered munitions, all produced in the United States, were one of the single items of greatest expense. LAZY DOG was believed to be a highly effective but unsophisticated anti-personnel weapon. It had been purged from both USAF and Navy systems, but there remained many “assets,” missiles, dispensers, drawings, studies, etc., located in the Air Force and Navy R&D community that were considered useful. Further assessment was to be made to determine the feasibility of developing a LAZY DOG manufacturing capability in the RVN, and a capability for the VNAF to deliver it. 1

1. J35 HistSum Aug 74; Scientific Analysis Group Report No. 1-74 , 25 April 74, Subj: A Review of the LAZY DOG Weapon System as an Aircraft Area Munition.


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16 hours ago, Vicious_CB said:


Comparing Advertised Ballistic Coefficients with Independent Measurements




If anyone needs a reference for "real" BCs. 


>Nosler’s advertised ballistic coefficients showing the largest overestimates.<


Nosler's BCs are in fact so outrageous that I can tell by looking at them that they are wrong.


I've been calling them out for deceptive figures for years.

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