Parabolic Drag

I may be wrong, but I'll just think out loud about it here.
A shock wave is formed in front of our bullets, which is in the shape of a parabola. It is by itself traveling at the speed of sound (Mach 1).
The bullet picks up the shock wave while passing Mach 1. This is a big drag load, and I think of it like running with an open umbrella.
With each higher bullet speed over Mach 1 the umbrella closes a bit, reducing it's relative load. While the bullet slows to transonic, the umbrella opens more & more, becoming a bigger and bigger load.
That's how I functionally see it.

For each incongruity presented by the bullet's surface, where laminar flow is harshly disrupted, another parabola is formed.
That would be drive or crimp bands, and sometimes nose or base transitions. This only existing at supersonic velocities.
By subsonic the umbrella is fully released, letting go of that load.
My umbrella collapses way before transonic or mach 1--- maybe I need a higher quality umbrella?
 
There is no parabolic drag. There's your oddly worded to some, patent PDR…which makes sense to me. Not to be confused with rotating bands like on a 155.

Then, there's parabolic drag polar as mentioned above which is a aircraft physics term, as it relates to models/in a vacuum expressed in mathematics and focused on lift (to over simplify it, for the purposes of this forum.)

They have nothing to do with each other.
Ok, I'm a bit scared to ask this because you very well may be able to answer it, which in turn means I will be obligated to read said answer and then I will need another drink, but how do you solve an equation on lift or drag when an object is in a vacuum? Aren't lift and drag absent in a vacuum?

Give me a couple minutes while I grab the Whistlepig and a glass!
 
Ok, I'm a bit scared to ask this because you very well may be able to answer it, which in turn means I will be obligated to read said answer and then I will need another drink, but how do you solve an equation on lift or drag when an object is in a vacuum? Aren't lift and drag absent in a vacuum?

Give me a couple minutes while I grab the Whistlepig and a glass!
How is whistlepig, what's it similar to? It's one of the few stops I never got off on when I lived in a state with real selection.
 
How is whistlepig, what's it similar to? It's one of the few stops I never got off on when I lived in a state with real selection.
I like them quite a bit. Tonight was 15 year, but every one is delicious. I was gifted a 18 year, but haven't worked up the nerve to open it yet. The 10 & 12 year are the sweet spot for price/drinkability. If you like a rye Old Fashioned the 6 year Piggyback is great. they are very smooth rye whiskeys with good notes and not just overly spicy.
 
I tried to get an answer in another thread to no avail.

Can anyone tell me what parabolic drag is? Evidently it is caused by drive bands? I have never heard of it.
Steve,
Try reading this article and pay attention to the hyper-links regarding Bryan Litz' articles on drag, towards the end of the article.
Bullets that have grooves or drive bands might be covered there.
You might call or message Bryan if there are questions not answered in the links.
A CNC machined bullet certainly has consistencies unmatched vs cup and core which is helpful. After that, you need Bryan or an aero dynamics study.

 
Ok, I'm a bit scared to ask this because you very well may be able to answer it, which in turn means I will be obligated to read said answer and then I will need another drink, but how do you solve an equation on lift or drag when an object is in a vacuum? Aren't lift and drag absent in a vacuum?

Give me a couple minutes while I grab the Whistlepig and a glass!
Haha
There are equations, but it's easier to speak plainly that your gripe with what I said is, correct.

Air craft that require lift cannot fly in a perfect vacuum, technically. I was over simplifying it to keep on track of my point.

To your question and more to my point, what I was referring to but not elaborating on, is partial vacuum. Think of a spy aircraft R&D trying to reach say, 100 km.
 
I like them quite a bit. Tonight was 15 year, but every one is delicious. I was gifted a 18 year, but haven't worked up the nerve to open it yet. The 10 & 12 year are the sweet spot for price/drinkability. If you like a rye Old Fashioned the 6 year Piggyback is great. they are very smooth rye whiskeys with good notes and not just overly spicy.
Ooh nice. I do like a rye. The best I can get right now is High Plains from nearby in Park City. They're a reliable blender/bottler but they tend toward wide open throttle and 6-8 years as far as I can tell. Thanks. Hijack over.
 
Steve,

Generally, a lot of analysis on drag is part of "fluid dynamics" ... a projectile spinning through the air at 3000+ fps is a concern of fluid (air) dynamics.

How you model drag is a function of lots of things including the chaos/turbulence of the fluid flow.

When we tried to design airplanes that could break the sound barrier, for example, we found that the drag models used for sub-sonic flight were not adequate to model the drag at supersonic speeds.

Here is an university class introducing students to the concepts related to drag:
 
Not to talk for him but, It's not physics term "parabolic drag. "

It's parabolic (as in on the bands of the projectile/bearing surface) are parabolic and in doing so, (it alleges reduced drag.)

It sounds cool for marketing but it's horribly worded, I have to admit.
This is the first thing I've heard that makes sense thank you
 
Steve,
Simply put, the link you shared is describing the relationship between lift and drag for an airfoil over a range of angles of attack; the relationship is parabolic. That is, as angle of attack goes up from zero, lift increased faster than drag for a short time, then drag starts to increase much more quickly than lift. Instead of plotting lift against angle of attack and then drag against angle of attack, they plotted lift and drag (coefficients) against one another, which is much less intuitive to follow.

Try it for yourself if you like: put your open hand out the window of your car while driving, and hold it flat. You feel a little bit of drag and no lift. Now start rotating your thumb upwards relative to your pinkie finger. At first you start to feel your hand want to rise (lift), with only a little more force backwards (drag). By the time you get your palm facing into the wind, your hand is producing only drag, with no lift. The relationship of lift to drag you just felt is parabolic - once you rotated your hand too far, it slowly stopped producing more lift and rapidly started producing more drag.

Hope that made sense and helps. While drag is obviously important to bullets, we generally are not trying to produce lift, so this topic may not be especially relevant to your goals as a bullet maker...
 

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