Tank Turret Shells

[Strip]

Diehard,
    I know the quoted portion says "rocket type-gas generator" but in the context of the chapter it is referring to any gas generating combustion, which a tracer is. I have very specific testing data but the legalities of releasing it are not something I want to test. Ceterus paribus, a tracer round leaves the barrel with more velocity than a non-tracer round. Range on the other hand is dependent on a multitude of parameters.

Lusche,
    Chemically similar to rocket fuel, tracer compounds, produce descent quantity of gas per volume during decomposition.

Strip

[Die Hard]

In some way, he actually is right. What Strip is talking about are not rocket-assisted projectiles but base bleed projectile. The reduce drag by producing a stream of gas. However, tha WW2 tank projectiles are just tracer, not base bleeders.

Well, base bleed is a 1970s technology mostly (if not solely) used for artillery rounds. Normal tracer rounds also have slightly reduced drag due to the same effect, but not enough to offset the loss of mass (weight).

[Keiler]

Strip,

alright, I feel that I have to stand corrected.
Its about 5 years ago that I tangled with the finesses of exterior tank ballistics that I completely forgot about the base-bleed effect.

I also have to admit that I am not into the matter anymore that I could argue with what Die Hard said in the previous post.

What is the consesus now? Is there any "rule of thumb" you could give on how much this effect is actually a ballistic benefit for the projectile?

If I dont reply soon that means I am out of town, I am really interested on this subject.

Regards!
Matt

[USCH]

I would just like to thank you all for being so nice  . it was refreshing to read this far into a post and not have 2 guys off topic and going at eachother throats. please continue its vary a interesting read.

[Strip]

Well, base bleed is a 1970s technology mostly (if not solely) used for artillery rounds. Normal tracer rounds also have slightly reduced drag due to the same effect, but not enough to offset the loss of mass (weight).

    Tracer rounds are, by their very nature, "base-bleed" type projectiles. In some tank rounds the effect is great enough to increase the range. Generally rounds without boattail's will benefit the most from this. A boattail decreases the base drag reducing the effect of the tracer or gas generator. Conventional tracer rounds can approach ten percent less drag than inert rounds. While tracers are lighter, and slow down quicker, they also leave the barrel faster. Most of this applies more to the big calibers,  beyond even the .50 BMG and out to the larger artillery rounds.

Strip

[Strip]

Here is a photo showing similar rounds I did some work with, the SLAP and SLAP-T. They are the two SABOT rounds towards the upper right hand side. Technically, while the SABOT's are different the bullets are identical in shape save the tracer cavity. They are solid, very dense tungsten rounds and fire at a velocity well north of 4000+ fps. Rather expensive to produce but they are extremely easy on barrel wear and have excellent downrange ballistics. Note the heavy crimp to help build pressure before the round unseats and heads down the barrel. Fun times....

SLAP....Saboted Light Armor Pentrator

SLAP-T.......Tracer Version

Around $8.00 a pop in quantities of over a million!!


Strip

[jdbecks]

either way, we found them to be less accurate than conventional bull point rounds

[Strip]

either way, we found them to be less accurate than conventional bull point rounds

This is due to manufacturing variations in weight, density, and burn time of the tracer material.

[Die Hard]

In some tank rounds the effect is great enough to increase the range.

Name one please.

[Die Hard]

(Image removed from quote.)

Here is a photo showing similar rounds I did some work with, the SLAP and SLAP-T. They are the two SABOT rounds towards the upper right hand side. Technically, while the SABOT's are different the bullets are identical in shape save the tracer cavity.

The two penetrators are clearly not the same shape. The one on the right is clearly blunter with the distance from point to full diameter being shorter than the one on the left. Also why do you capitalize SABOT like that? It's a French word, not an acronym.

[Strip]

The ones I were involved with were the same shape, the Winchester made SLAP(-T) might have a different design.

As for you other question, why would it matter, I could name ten? Without in depth test data you couldn't prove or disprove anything. I have some of that data for the SLAP rounds but frankly its never going to be posted on the internet.

The sabot bit was just a brain fart, lack of sleep and a crying two year can have that effect.

Strip

[Die Hard]

Well I was obviously asking for you to back up your claim that "in some tank rounds the effect is great enough to increase the range" with some documentation.

[Strip]

The documentation I have isn't even on computer with internet access, much less on the internet.

Suffice to say, any tracer round will have about 8-12% less drag than a identical sized inert round.

[Strip]

 Accession Number : ADB000431

Title :   Wind Tunnel Study of Base Drag Reduction by Combustion of Pyrotechnics,

Corporate Author : ARMY BALLISTIC RESEARCH LAB ABERDEEN PROVING GROUND MD

Personal Author(s) : Ward, J. Richard ; Baltakis, Frank P. ; Pronchick, Steven W.

Report Date : OCT 1974

Pagination or Media Count : 83

Abstract : It is well known that tracer rounds have longer ranges than comparable nontracer ammunition, and the ballistician seeks ways to degrade the tracer's ballistics to match the conventional round. Presumably the tracer reduces base drag by addition of heat and mass into the near wake of the projectile. Wind tunnel experiments conducted with well-defined gases at metered rates of injection showed that a hot, low-molecular weight gas would be the better drag reducer. It was also suggested that combustion in the near-wake could be advantageous. Fuel-rich mixtures of magnesium and inorganic oxidizers were investigated in this report as such gas generators (designated 'fumers'). The excess magnesium in such mixtures is to be the hot, low-molecular weight gas. Wind tunnel tests were performed at the Naval Ordnance Laboratory to see if fuel-rich magnesium propellants reduced base drag. These tests showed reductions on the order of fifty percent in combination with oxidizers that burn slowly enough to be used in small arms applications. The base drag reduction was also proportional to the quantity of excess fuel in the mixtures. Ignition of mixtures containing over forty percent by weight magnesium was impossible for all oxidizers tested. (Author)

Descriptors :   *TRACER AMMUNITION, *PROJECTILES, *GUN PROPELLANTS, EXTERIOR BALLISTICS, DRAG REDUCTION, DRAG REDUCTION, RANGE(DISTANCE), AERODYNAMIC DRAG, WAKE, COMBUSTION, BASE FLOW, MAGNESIUM, OXIDIZERS, SMALL ARMS AMMUNITION, PROJECTILE TRAJECTORIES, VELOCITY, WIND TUNNEL TESTS, PYROTECHNICS, FUMES, BASE PRESSURE, IGNITION, BURNING RATE, FLAME ARRESTERS, OXAMIDES.

Subject Categories : PYROTECHNICS
      BALLISTICS

Distribution Statement : APPROVED FOR PUBLIC RELEASE

[BrownBaron]

dude, go twittle urself, its like wrapping the round in paper and burning it...whatever the hell ur talking bout is more or less a small rocket propeled object, like an RPG r sum toejam, we are talking about the chemicals the rounds are coated in to give them visibilty, and in planes, the tracer rounds are often described as basket-ball orange, or blood-red, personally i like our white tracers....