Need a Rocket Scientist!

[fletcher]

"There are more things in heaven and earth, [insert skeptics name here], than are dreamt of in your philosophy."

Very true. To those who are jumping on the "something for nothing" bandwagon, keep in mind there are a lot of things that may appear at first glance to be "something for nothing", but in fact it's a simple reaction that just needed a little boost of activation energy, like a fire.

 

[XD Fan]

No real input here, but I am impressed with the extensive covnersational physics knowledge on this board. Wow guys? I do not know if any of you guys know what you are talking about, but it sure sounds impressive.

 

[Noxx]

Very true. To those who are jumping on the "something for nothing" bandwagon, keep in mind there are a lot of things that may appear at first glance to be "something for nothing", but in fact it's a simple reaction that just needed a little boost of activation energy, like a fire.

A fire has to consume something along with oxygen. When you're talking about funneling and compressing air at the speed of a bullet, with nothing but the projectile itself available as fuel, you'd be out of projectile in about, oh.... now.

I'm all for new technology, and having an open mind to new possibilities. I mean I've worked with linear induction motors, which began life in science fiction as "mass drivers", and today run roller coasters all over the world, HOWEVER... some laws cannot be set aside. If you impart X energy to X mass, inertia does the rest, unless you convert mass to energy along the way to provide additional thrust. With little or no mass available, in whatever form, energy is not coming out of thin air. Can't happen.

 

[Noxx]

No real input here, but I am impressed with the extensive covnersational physics knowledge on this board. Wow guys? I do not know if any of you guys know what you are talking about, but it sure sounds impressive.

You know what's really great about that? I'd bet green money that *most* of the people with a sound working knowledge of the principles discussed here get their hands dirty for a living in one way or another. Nothing makes my morning like setting aside a stereotype.

 

[fletcher]

A fire has to consume something along with oxygen. When you're talking about funneling and compressing air at the speed of a bullet, with nothing but the projectile itself available as fuel, you'd be out of projectile in about, oh.... now.

The projectile itself may or may not be the fuel. The issue is someone who is not working on the technical part of the project trying to explain it to another person. Who knows how much information may have been lost. There may be, as I mentioned in an earlier post, some coating designed to burn off as a fuel in this process.

This may be bogus, it may be real. There just aren't enough facts to know with certainty which it is at the moment. I'm leaning towards bogus, but wouldn't bet on it.

 

[Noxx]

I'll happily give you that, that something may be lost in translation.

I'll say, without calling the notion impossible, that if that is the case however, I'd have a very hard time believing that any potential "fuel" for the design presented would A) have a difficult time paying for it's own cost in inertia, and B) as we are positing combustibles, be almost assuredly consumed by the powder charge at the time of ignition.

I won't say, given that there may be missing critical information, that it's impossible, but the simple answer given everything, is that someone wanted to tell the OP a nifty story, and did.

 

[Mal H]

Conversation overheard about 64 years ago:

"I'm sorry, but you guys are full of it. You can't get something from nothing. You're trying to tell me this thing will blow up a city? No way! Look at it - all you've got is about 200 pounds of TNT in it. Sure that'll do a lot of damage, but a whole city? Fagiddaboutit! There just isn't enough explosives in it to do what you say it can do.

Say, what's that shiny little 4" sphere in the middle of the contraption?"

 

[Noxx]

Mal while I appreciate the humor, that's a bit disingenuous.

Whatever the research is onto in this project, I doubt it's on par, in the world of physics, with the realization of a chain fission reaction.

 

[mickmten]

Well, lets add a bit of fuel to this thing and it might work. Let's say that the interior of the bullet is coated with some type of material that would actually combust or undergo some type of chemical reaction when heat is added, i.e., from the heated bullet casing. In that case, you've got a projectile that would be gaining energy as the fuel is burned off up until the point where the fuel is gone. Then it would act as a regular dumb bullet. Need to design it so that the combustion within the rifle/cannon would not start the fuel to burn, so you'd have to pay attention to "packaging" and you'd have to have a stable enough burn so that one side of the bullet wouldn't get heavier than the other during flight (thereby causing instability), but like I said at the beginning of this, it might work.

Mick

 

[benEzra]

Forget burning fuel to heat the air. What if the bullet itself is hot enough?

Given the melting points and heat capacities of real-world materials, a bullet could not store enough energy as heat to propel itself. If you could heat it to a million degrees, you could--but it stops being a bullet at a thousand or two.

 

[Mal H]

Mal while I appreciate the humor, that's a bit disingenuous.

Not at all, and you misread my intention. The main thing I was saying is that there's a heck of a lot of energy to be found in reactions that are not combustion reactions. Fission is one, and maybe a super heated plasma rocket is another. To those looking for convention in new inventions, you may not find what you're looking for, but that doesn't mean it isn't there. (The convention most are looking for is fuel. If you don't have fuel, you can't have combustion which is required for a motive reaction. I'm saying stop looking for fuel when it is contained in the atomic bonds themselves.)

My little "skit" was the man on the street's reaction to claims that looked impossible to him.

Don't get me wrong, I'm almost as skeptical as most everyone else here. But, I have learned long ago to never say never.

Apparently no one bothered to read what I posted about plasma and the required speed of the projectile. No ordinary rifle is going to propel a bullet fast enough to create the slightest possibility of a plasma reaction inside the bullet. Yet, it seems most everyone is envisioning a hunting rifle carrying out this miracle.

 

[ArfinGreebly]

Plasma

A fire has to consume something along with oxygen.

My physics is a bit rusty, but I don't recall plasma requiring an oxidizer.

Most of the mechanisms for which I've seen diagrams are kind of clunky, but I won't pretend that I know for sure that someone can't trick a metal into "doing the plasma thing" under the right conditions.

Of course, once you get a plasma reaction going, you have little things like extreme heat and probably serious pressure with which you now have to deal.

I also don't know at what rate which materials would be consumed in such a reaction.

Would be cool, though, imagine such a self-consuming projectile striking a target . . . what would the terminal ballistics be?

 

[ConstitutionCowboy]

Has anyone thought that it might be a miniature RPG with the rearmost compartments filled with ignition mediums and the froward facing cone to be filled with a Thermite type substance, or poison, or some such nasty thing - all designed to ignite/eject upon impact? What we have here could just be the "shell" for such a device.

Eh?

Woody

 

[molonlabetn]

Unless the core of the bullet was comprised of a catalyst which would react with the properties of air at temperatures which could be sustained by supersonic heating, and the geometry of the inlet, chamber and nozzle could be held to reasonable tolerances... this would not work. Also, the transfer of heat to air particles at that small scale would be very inefficient, requiring tremendous heat. If this heat must be sustained through friction/drag on the projectile, the losses would be greater than the thrust. There is no such thing as perpetual motion with an excess of energy.

Scientists would be better off spending the research money on more efficient propellants and low-drag projectiles which could reliably achieve hypersonic velocities without burning up the barrel of the firing mechanism.

If anything, it would be more beneficial to simply pack the base of the projectile with a slower burning propellant, and a nozzle... creating a rocket projectile which is accelerated using the component cartridge, and sustained using carried propellant. This method would wear out barrels quickly, and the loss of projectile mass through propellant expenditure would reduce the impact energy of the projectile anyways, even in the most efficient model.

It's not worth it.

 

[glockman19]

I have concluded that if you coat the interior of the prohectile with a solid fuel the concept could work. I propose that a diamods coating on tehinside will ignite at the high temperature.

Isaac Newton first suggested that diamonds might be combustible. Early in the 19th century diamonds, like graphite and other forms of carbon, was found to burn in excess air or oxygen and produce carbon dioxide.​

furthermore,

Sir Humphry Davy, wrote a vivid and largely unpunctuated first-hand account of such a demonstration: “Sr H took the opportunity whilst here of making many experiments on the diamond with the great lens of the Grand Duke a noble instrument belonging to the academy and in these pursuits as in every other his attentive mind observed and demonstrated new facts. In the first experiment on the combustion of the diamond it was placed in the middle of a glass globe of 18 or 20 cubical inches capacity supported in a cradle of platinum fixed on a prop of the same metal. The cradle was pierced full of holes to admit a free circulation of air, i.e. oxygen for the globe was filled with the gas procured from hyperoxymuriate of potassa (KClO3). On placing the apparatus thus arranged in the focus of the lens it (the diamond) shortly entered into combustion and on removing it from the instrument the combustion was observed to continue for above 4 minutes during this time the diamond gave off intense heat and a beautiful vivid scarlet light it diminished rapidly in size and became at last a mere atom when it ceased to burn but on placing it again in the focus the whole rapidly disappeared​

I believe a projectile made of Titanium & molybdenum and coated inside with a carbon, Diamond, fuel could support the hypothesis. The Titanium/Moly bullet would have the weight & Strength and the diamond at high enough temperatures would/could provide the fuel. The only addition needed might be a small amount of ignightor to begin the fuel burning process. The addition of micro turbines could concieceably offer a self sustaining cycle.

All theory, but...it would be interesting to see such ammunition. It would likely be so expensive no one could afford it.

 

[fletcher]

One of the problems with using metals at such high temperatures is that they aren't solid. Plasma is VERY high energy, and plasma torches are used to cut steel all the time. Something like tungsten would be your best bet. Otherwise, time to move into the realm of ceramics.

 

[Claude Clay]

hollow

conventional ammo works underwater, in the rain & even in a vacuum ( not however in a Hoover--damned if i know why). IF.....IF this concept could fly, would it not be a tad less versitial?

 

[benEzra]

I believe a projectile made of Titanium & molybdenum and coated inside with a carbon, Diamond, fuel could support the hypothesis. The Titanium/Moly bullet would have the weight & Strength and the diamond at high enough temperatures would/could provide the fuel. The only addition needed might be a small amount of ignightor to begin the fuel burning process. The addition of micro turbines could concieceably offer a self sustaining cycle.

At that point, it would be cheaper to send in an F-35 dropping 250-lb guided bombs, though...

 

[Dave Markowitz]

Nah...you don't need unobtanium ........you need dilithium crystals.

I have some Folger's Crystals. Think they'll work?

 

[Noxx]

I have concluded that if you coat the interior of the prohectile with a solid fuel the concept could work. I propose that a diamods coating on tehinside will ignite at the high temperature

Ignition is not the problem, mass is.

I don't want to beat a dead horse (altho I am anyway) but it's pretty straightforward here.

In a conventional reaction, a common size projectile does not have even 1/100th of the mass necessary to derive significant additional power from it's consumption.

In the unconventional reactions department, plasma being the most mentioned, the heat generated by such a reaction pretty much negates the entire existence of the projectile.

I'm not saying it's not interesting, but let's stay grounded in reality.

 

[230RN]

what if the bullet is hot enough to do what?

where is the energy that drive the bullet faster coming from?

The energy would come from the heat of the bullet itself.

Why is everyone locked on to the idea of a "fuel" being needed to heat the air?

If the bullet were hot enough, the energy to heat the incoming air could come from the bullet itself.

It just so happens that the usual ramjets heat the air with burning fuel. But did they not try to build a ramjet engine using a nuclear reactor as a heat source*? All the reactor did was heat the air, and there was no combustion involved.

In this case, the air comes in and heats up, not from the burning of a fuel or from hot rods in a nuclear reactor, but from the heat of the bullet itself.

As I said in Post #10, plausible enough to dink around with, but not to invest in yet.

Someone said that you could not get the bullet hot enough.

OK, maybe, but I think perhaps if one used a highly refractory material (W, Mo, maybe even Ti) as the bullet material, filled the cavity with something like thermite which ignited from the firing of the bullet, which burns up a short way from the muzzle, thereby opening the tube, the bullet would probably end up white hot.

Is this "hot enough" to produce a ramjet effect when the tube opens up? I don't know. And neither does the poster who said you could not get the bullet hot enough.

But I think it may be possible... at least to the extent of slowing the deceleration of the projectile....maybe.

As I said, worth tinkering with, but not to sell stock in yet.

------------------------
* Google "nuclear ramjet"

See also:

http://www.ilpi.com/genchem/demo/thermite/index.html

 

[jerkface11]

My ears did perk up at the mention of depleted Uranium. It's pryophoric, and it will burn under intense friction or kinetic impact. (which is one of it's properties that make it useful as an anti-armor shell in the first place.) And with Uranium's incredible mass for a given volume, ejected Uranium vapor would have an incredible specific impulse, making it a highly efficient reaction mass to be squirting out a nozzle at high pressure.

I doubt spraying uranium vapor all over the battlefield would be a good idea.

As for those of you who think that the heat and speed of the bullet would be enough to produce a jet of superheated plasma. If it were THAT easy we'd be using it on aircraft and missiles and not bother with bullets.

 

[JohnKSa]

The projectile itself may or may not be the fuel.

That's a possibility but I'm still having significant problems with the idea that they can achieve the velocities required to create plasma...

 

[physics]

Unfortunatly we have the laws of Thermodynamics which basically state - you never get something for nothing. If you get energy out, then you have to put that energy in. So if you're creating a state change from gas to plasma, then mechanical/thermal engergy needs to be put in to do it.

Agreed . This would, as the OP described it, be a violation of the first law of thermodynamics, aka conservation of matter/energy. You can't get something for nothing... IT'S A LAW.

Also, where are you getting this energy for a plasma? You don't just GET plasma. Again, you need to put energy in. For example for a glow discharge plasma, you need roughly 100 V, minimum. Also, according to lecture notes, a plasma is created by an electric field, which I'm not seeing here.

I'm not saying that it's impossible, but there would have to be a whole lot more going on than what I've seen on here. Also, show me the math, and I might believe you. I will admit, my plasma experience is with semiconductors, so there may be some type of plasma I haven't heard of, but that seems farfetched.

 

[zoom6zoom]

It won't work until we perfect the flux capacitor.