David Tubb introduces a new DTAC 115gr 6mm bullet with Noseringtm

[EdHarley]

How about some pictures of bullets shot and expanded? You do any testing of this theory? Actual shot bullets pics would be nice to see.

Isn't Kurz last picture a fired bullet?

 

[davidjoe]

Sounds like that's the claim. Assuming it works, I would guess it's the same principle as dimples on a golf ball reducing drag

The golf ball dimple and scuffed boat bottom examples have come up a few times. They actually do create turbulence. “How stuff works” answered this way:


“If you want to get deeper into the aerodynamics, there are two types of flow around an object: laminar and turbulent. Laminar flow has less drag, but it is also prone to a phenomenon called "separation." Once separation of a laminar boundary layer occurs, drag rises dramatically because of eddies that form in the gap. Turbulent flowhas more drag initially but also better adhesion, and therefore is less prone to separation. Therefore, if the shape of an object is such that separation occurs easily, it is better to turbulate the boundary layer (at the slight cost of increased drag) in order to increase adhesion and reduce eddies (which means a significant reduction in drag). Dimples on golf balls turbulate the boundary layer.

The dimples on a golf ball are simply a formal, symmetrical way of creating the same turbulence in the boundary layer that nicks and cuts do.”

 

[dcali]

I'm skeptical of the claimed drag benefits. If the ring creates a turbulent boundary layer, it's going to increase drag. I also don't like the idea of cutting the jacket like that. Surely, it's not going to improve balance.

 

[dcali]

Sounds like that's the claim. Assuming it works, I would guess it's the same principle as dimples on a golf ball reducing drag

Yes and no. If the ring makes for turbulent flow, then that's what the dimples do as well. But unlike a golf ball, where that's a positive, for a bullet it's a negative (and a significant one).

Here's a very detailed explanation for the curious:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

 

[Ranger188]

I don't know if I'd be willing to add more damage to a jacket and hope
it doesn't blowup prematurely.

 

[dcali]

I don't know if I'd be willing to add more damage to a jacket and hope
it doesn't blowup prematurely.

It's my understanding that blowups tend to originate at the bearing surface, but yeah - I'm not sure I buy that anything good happens when you start cutting rings into a jacket.

 

[RustyPin]

Yes and no. If the ring makes for turbulent flow, then that's what the dimples do as well. But unlike a golf ball, where that's a positive, for a bullet it's a negative (and a significant one).

Here's a very detailed explanation for the curious:
http://www.aerospaceweb.org/question/aerodynamics/q0215.shtml

I'd be more willing to accept projectile theory is closer to Compressor Dynamics than Aircraft flow do to high twist rates of Projectiles. Without a complete understanding of the Article it appears it support the transonic transition for long range applications.

 

[Brians356]

I also don't like the idea of cutting the jacket like that. Surely, it's not going to improve balance.

But, is it surely going to degrade balance?
-

 

[PRR1957]

OK. If dimples work on a golf ball, why not try dimples on the nose of a bullet ?

 

[linebaugh]

Marketing 101 for those easily swayed.

Where is the proof of expansion on game or accuracy or bc or whatever else is being claimed here?

 

[Kurz]

Isn't Kurz last picture a fired bullet?

No, that's the base of the new version of the 115 DTAC taken from David's website.

 

[urbanrifleman]

David and I shot pdogs and he was shooting 77 Sierra MKs with the nose ring cut into them. They really blow up way better.

And yes, David will be selling the cutter. It is quite cool.

 

[urbanrifleman]

I don't know if I'd be willing to add more damage to a jacket and hope
it doesn't blowup prematurely.

Has no effect on that, any more than having a plastic tip would cause a bullet to fail. Bullet fail from tearing the jackets from the rifling.

 

[dcali]

But, is it surely going to degrade balance?
-

I have more faith in the machine punching out the jacket than I do in the machine cutting that groove. But that's admittedly based on nothing other than speculation.

 

[urbanrifleman]

I have more faith in the machine punching out the jacket than I do in the machine cutting that groove. But that's admittedly based on nothing other than speculation.

Tubb is cutting the ring at his shop.

 

[rogn]

Sounds like someone has discovered a break thru and 33. % of us are trying to explain it, 33. % are trying to disprove it and the remainder are just quietly using it.

 

[urbanrifleman]

Sounds like someone has discovered a break thru and 33. % of us are trying to explain it, 33. % are trying to disprove it and the remainder are just quietly using it.

Right????

I will give you guys a little tip.

If Tubb does it, it works.

Here endeth the lesson.

 

[Hohn]

I'm skeptical of the claimed drag benefits. If the ring creates a turbulent boundary layer, it's going to increase drag. I also don't like the idea of cutting the jacket like that. Surely, it's not going to improve balance.

Indeed it will at subsonic flow speeds.

A turbulent boundary layer is really only helpful at preventing flow separation. For example, many fighter planes have "air hockey table" like pinholes supplies with bleed air that will reduce flow separation at very high angles of attack for aggressive turns. (also why many planes have side strakes that induce vortices that pull flow over the top of the wing to also increase the angle of attack before separation.) Flow separation is why a golf ball benefits from dimples, but why dimpling an arrow would do nothing helpful.

Unless you are experiencing flow separation, the turbulent boundary induces a drag penalty at subsonic speeds that you don't need to pay.

But the rules change for supersonic flow, and I'm not sure what benefits of the nosering would accrue at supersonic flow where it would likely be tucked in behind a shock wave cone.


It seems to me that the location of the "ideal" nosering would vary a lot with speed because speed determines the cone angle of the shockwave and where it would be relative to ogive.

In any condition, the slight shift rearward in CoM would seem helpful.

 

[Hohn]

Right????

I will give you guys a little tip.

If Tubb does it, it works.

Here endeth the lesson.

This goes against my nature to admit, but I think it's pretty much bang on. I prefer to be data-informed and be able to put of accepting things until I can explain them.

But some things just ARE, whether we can explain them or not.

All of the Tubb products I have purchased have performed exactly as claimed.

 

[Hohn]

OK. If dimples work on a golf ball, why not try dimples on the nose of a bullet ?

No flow separation on the nose of a bullet.