Hmmh, a centrifugal propelling system. Who would have thunk it.

Hope your hand is feeling better, John...

Oi! Wot's 'is? I thought you told JOnah that the DREAD system was almost impossible a while back? He didn't say who sent him that but I figured it was you he was posting on the Corner about how a vehicle born system would have a serious problem with physics(equal and opposite reaction was the gist of it).
Well?

Not I, sir. The centrifuge eats the recoil, so to speak. Just like a trebuchet doesn't recoil, or a mangonel... except in the case of the mangonel, movement occurs when the arm hits the bar... which is a transfer of momentum.

Something about the physics of that centrifugal weapon doesn't seem to make sense. 40" long, 32" wide, 3" high. This thing has to spin in a horizontal direction. You are then going to put a dimpled ball projectile in it (the reason balls are dimpled is to create more air resistance).

Can you say slice?

Slice??? Don't think John wants to hear that word anytime soon.

Bwa-ha-ha-ha-ha! Nor stab, either!

MM - I thought the balls were dimpled to *reduce* flow-induced drag. Shows how much I pay attention to golf... I'm guessing this is like a pitching machine (which might have been the inspiration, who knows?) where you can control the spin, and do so with a uniformity that duffers can't match... how you account for that over time when shooting would certainly be interesting...

Sorry I missed it yesterday, oh master armorer. I hope that your hand is feeling better and that SWWBO doesn't make you where the helmet and knee pads ALL the time.

John - I hope your hand is not feeling too bad. I'm sure that Beth being home will make you feel better than anything else.

Kat - I'm pretty sure that Beth will not require the wearing of protective gear ALL the time, unless they *add* to the fun.

[*in the corner, the PG-17C unit twitches in its sleep*]

LOL...Barb...well, you never know if it's needed under certain circumstances (glances at chandalier). Always good to keep it handy.

PS...studiously ignoring work and reading the US ARmy Detainee Doctrine piece and it is very interesting since I just finished reading about half of the FBI redacted unclassified files fron interviewing detainees in 2001 and 2002.

I will try to post something on this this weekend.

Barb, You really shouldn't tease PG-17C like that. He might get confused and bash Neffi just because.

*retreats to LOW flying chandelier after topping off pink rita*

Well you know, with one hand out of commission, holy institution that is the Donovan household, may need the aide of a mechanical friend for a while.

Looks like Papa Gulf-17 MOD C may be pulling double duty tonite.

swing.... swing.... swing.....

My goodness... I do love a good swing from the chandelier...

and John, dear... that looks NASTY BABY! EWWWWWW

Barb, It is not nice to tease PG-17C. He might just haul off and twitch at Neffi just because.

*tops off pink rita and returns to low flying chandelier*

Eeep. Bill musta snuck in the bedoodlewhoopies again. They're making that delayed echo thing again.

*tops off pink rita again*

Boq ... ROFLMAO!!!! Yer killin' me!

Oh.My.GAWD! Boq pulls one outta thin air and floors the Denizen crowd!

Now I HAVE to go to a BBQ at your house.. LOL

That was pretty good, Boq.

On a more serious note, John, do you know if this study on Army Detainee Doctrine was passed around to the commanders and units and a lower lever?

This seems to have all the historical issues that continue to plague us today. Just thought I'd ask.

Ewww, coo-I mean-gross! Wound Pr0n!

On the slinger-flinger: Have thought on somethin like that for years, see my comments on the golf threads. The dimples are to trip the boundary layer and make the flow turbulent, because at some (small) Reynolds' numbers, the flow stays attached more and you get less drag. Also (maybe?) you get better Magnus effect that way. Back when I was trying to think of a way to play golf with a mortar, I kept wondering how the inside of the barrel should be shaped, in order to put the necessary backspin on the ball to get the circulation lift.

The reaction issue was discussed to death on Jerry Pournelle's site last week, with mention of [shudder] the Dean Drive. Dr. Jerry agrees with my High School Physics teacher, in that "Momentum IS Conserved!"

Ket, this isn't really that kind of a higher headquarters, but yes, it has been made available to everybody in the detainee business - and, perhaps more importantly, the doctrine writers and trainers.

And is in fact available on the web, too, I believe from outside the .mil firewall, but my thumb hurts too much when I space for me to go hunting for it.

HI ALL!

Sorry your hand is hurting John... I'm sure Beth will help you forget all about it though... *grin*

What is so weird about this is that I managed to negligently wound myself in almost the exact corresponding place on my left hand, with a similar stupid knife trick. I was working for a tree-surgery outfit, and had bought myself a sailor knife (Buck "Yachtsman") because we were always working with rope. It's true what they say about no points on the sailors' knives, but this thing has a lockback marlinspike.

Anywho, I was trying to untie a knot in a big rope which had been used to jerk down a huge tulip poplar, and fingers just weren't working. I gets out me trusty pirate knife, extends spike, and jabbed it Deep, deep, deep, into just that part of the Southern Paw.

They made fun of me at the Doc's office, and I got no stitches, no nice drugs, just a tetanus shot and instructions to keep it open and let it ooze.

I do think that marlinspike could be a good weapon into somebody's temple or eyeball, if I could get over the laziness (oughta learn and train) and squeamishness (gotta de-sensitize, it's nasty out there.).

What? The somnolent, snoring, been-up-for-24-hours person over to my right?

Mebbe tomorrow!

Glad to know Beth is home safe and sound. :)

And sleeping like a baby, surrounded by her critters.

What FbL said, and I trust you're using a silent keyboard.

I could be using an old IBM clackey-type and she wouldn't notice!

Aww! I mind my (unfortunately, now, ex-) sweety, and how cutely she snores. Like all women, she claims she doesn't, but I don't care, she does SNORE CUTE!

Just, well, awww!

Your resident scientist checking in here. After checking the link I declare the DREAD to be a hoax.

Let us put aside Newton’s second law which everyone here seems willing to violate. (Note to interested readers, there will be recoil)

Let us concern ourselves with the energy requirements. The stated specifications are a 0.308 inch steel ball accelerated to 8000 feet/second. The quick math tells me that each ball needs 5856 Joules of energy. So where does that energy come from? Let us assume it comes from Diesel. The energy density of diesel is 39.4 MJ/L so that comes out to 25,462 balls per gallon of Diesel. Wow, only two gallons of Diesel to fire off a mag of 50,000 balls.

Now comes the hard part. How do you get the chemical energy in Diesel to the kinetic energy of the ball? The engine in a Hummer is less than 30% efficient, the alternator is less than 60% efficient. (And when I say “less than” I mean waaaay less than) So now we are talking about more than 10 gallons of gas just to provide the electricity to the unit. (the real value would be about 40 gallons of diesel but I’m being generous) So, just how long does it take to process 10 gallons of diesel through a Hummer?

Actually the above was the easy part. The real problem here is how do you store massive amounts of energy from a slow generating source and release it quickly. In other words, you have to store the energy you build up for hours from your alternator and release it in seconds in your gun. Let me state unequivocally that it cannot be done in the package size they are presenting. There are lots of ways to proceed, but none of them are small. Batteries, ultra-Capacitors, flywheels they all would be too big to be practical.

By the way, this is the same reason the rail-gun never made it to the battle field. Nothing beats gunpowder for a large burst of energy.

Full disclosure, I have a Ph.D. in thermodynamics (physical chemistry). Don’t try to tell me that there is some miracle energy storage device out there.

Good God, man...

How can I drink myself (and my liver cells) into Oblivion in decent peace and quiet if you are going to flail about, stabbing yourself with bayonets in the Interim?

Can you not have some consideration, now?

I hope it is healing cleanly and you're not in too much pain.

Well done Mr. Pinguin. On the well expoused treatsie on physics.

Do we have a cubby open by the tool shed, where we can open up a physics research lab? I'm sure PG-17C won't mind colocating his shop with Mr. P.

Oh and BTW, Crab Season is starting soon. Everyone is welcome to come on down. We shall have ourselves a big pile o' crabs n' beer with our BBQ.

Boq... you are KILLING ME... crab season.... I can't stand fish, but I absolutely LOVE crab.

I think we need a Castle Blog Ball at Boq's house, with PLENTY of crab, beer and BBQ. Where do you live? And how far is it from Cincinnati....

*sooo hungry now, thankyouverymuch*

Chilly - I am *completely* unable to rebut, dilettante that I am. So I'll run off on a tangent. I'm not willing to 'set aside' anyone's currently accepted laws of anything... but can you explain (that's not a snark) recoil effects in this?

I did leave open the issue of practicality just in case anyone missed that...

As noted in another comment - the fraud flag was waved in other venues.

Cassandra, to be *precise* it was a kitchen knife. I didn't bayonet myself *this* time. I reserved the right to do so in the future.

And, as firearms *not* in the collection are starting to outpace the buying power of the Arsenal, I'm thinking of shifting a bit to spears and lances, so the possibilities are *endless*. Think of the self-mocking post that begins...

*I ran myself through today...*

SWWBO (looking over shoulder) sez "Hi!"

Boquisucio - SWWBO is toying with the idea of allowing the Arsenal to get one of these...

It could be the first project.

Were-Kitty, the Admiral of the Moat Fleet resides in Maryland or its environs.

*I ran myself through today...*

I can't bear to watch... :)

Hi Beth - I'm glad you got home safely, and even happier someone is there to supervise you-know-who around sharp kitchen implements :)

So, does Beth snore cutely, or not? I betcha she does, and you think warm fuzzies about her when hearing her go sngggrrk, ahhfggghh, sngggrrk, etc and so forth. If you love your woman, you love the way she snores.

According to my experience.

Oh yeah Were K, just head on East on I-70 and you will find me on the People´s Republic *er Free State* of Maryland.

“but can you explain (that's not a snark) recoil effects in this?”

What Newton’s second law really says is that the net chance in momentum is zero. Momentum is mass times velocity. This is true for both angular momentum and linear momentum.

I am now going to invoke one of those high math hand waving techniques. And that is that we can greatly simplify our life by assuming that angular momentum and linear momentum are orthogonal to each other. In other words we can cleanly separate the variables and solve our problem as two separate equations.

Linear momentium part.
This is the felt recoil part. The rule says that—
Mass_gun x velocity_gun = mass_ projectile x velocity_ projectile.

Mass of gun = 50 Kg
Mass of projectile = 2 g = 60 grains
Velocity of projectile = 2000 m/s

So velocity of gun = 0.08 m/s in the opposite direction, which isn’t too bad. To put this into real world terms since the projectile has about 1/12 of the mass of a .50 BMG round you would get about 1/12 the amount of momentum transfer per round. A 12 round burst would have the same momentum transfer as a single round of .50 BMG.

But felt recoil is not the same as momentum transfer. Felt recoil is a human perception that is more closely related to impulse, which is the derivative of momentum. So the longer it takes to transfer the momentum the lower the impulse will be. This is why air-bags in your car work. The mass of your head remains the same, the velocity change is the same, but the time it takes to make to make the velocity change goes from microseconds to milliseconds, which is enough to save your life. In the case of the gun a 12 round burst would have less impulse than a single shot of .50 BMG because the momentum transfer takes place in 12 steps instead of one.

So the manufacturer is correct, felt recoil would be very light. (but not zero)

Angular momentum part.
Herein lies the BIG engineering problem. A quick question for the aviators. How long does it take for an unbalanced rotor (prop, turbine, whatever) to destroy a set of bearings?

When the first round of our gun is fired it will change the center of mass of the rotor ever so slightly. This new center of mass will remain until an equal amount of mass is lost on the opposite side of the rotor. If we assume that we want all of the rounds to go the same direction then the gun is going to be out of balance for half of a revolution for each two rounds it fires. In other words it is going to have a shimmy as it fires.

This is no problem at less than 5000 rpm, difficult up to about 20,000 rpm, catastrophic after 50,000 rpm. These guys want to take this up to 120,000 rpm. I wish them luck.

JTG - you ask the oddest questions, dude. I never considered snoring from that angle. I'm not sure I find it "cute" so much as it just doesn't bother me...

Chilly - Hmmmm. Now I'm curious... almost curious enough to go watch the pitching machines at the local batting cages, which I suspect operate in a very similar manner to what DREAD is alleged to do.

With Memorial Day family functions to attend, I wish I could linger, and lob in a rejoinder or two.

Have fun everyone!!!

The concept they have is sound, I just don’t think they can scale it up from the “less than lethal” prototype they have now to a “way lethal” version. Making something spin 10 times faster is harder than it looks.

The real problem is the one I first outlined, energy transfer. How do you store up massive amounts of energy and release it quickly? You just can’t do it from the alternator and batteries in a HMMWV.

This is a problem all over the defense industry. Solid state lasers are better than chemical lasers in almost every respect. The reason that the missile defense system has chemical lasers is that you just can’t provide the solid state laser with enough electricity in the time frame required. A rail gun would out perform a 120mm tank round, but how to generate the energy is a problem that has yet to be answered.

The civilian sector has similar problems. You could see massive improvements in the efficiency of the power grid if you could store as little as 1% of capacity in a “float” you could instantly access. As it is all of the electricity on the grid is being generated in real time. Any over-generation is wasted, as there is no way to store it.

There is hope. Batteries are getting better and capacitors are getting better. The old problem with hybrid cars has always been having enough stored electricity to provide the “surge” needed during acceleration. Increasing the energy storage means you can down-size the engine improving weight and fuel efficiency. The problem was that battery weight increased faster than engine weight decreased. We are at the point now where the technology to make it work is there but the cost is not.

Okay, I can buy that, especially from the energy aspect. Which then leads me down and different path... wonder if there *is* something useful in there for non-lethal crowd control... though I suspect not, too easy to blind people, knock out teeth, etc. The "nausea ray" is probably a preferable alternative and that works, though I'm sure all the little monkey-wrenchers are trying to figure out a cheap way to defeat it.

I think DREAD would be an excelent way to launch Super-Balls at 300 feet/second. Talk about a mighty big welt.

Back in for a Sec.

Been thinking, and welts is exactly what's on my mind. Make them balls of pliable rubber, or fill them up with Oleum Capsicum or CS Powder, and you got your self a great Crowd Behavior Modificator.

Or, on the Lethal Side of the equation, fill them balls with a couple ounzes of A5 Comp, and you have your self an excellent fire suppression device.

Back to Memorial Day Officiating.

Well, JoA, when I was watching, and listening to, my ex-sweety snore, I was so fascinated by everything about her that I thought everything she did was 'way cool and super cute. Just got off the phone with her. She was telling me I need to get a newer system and load some version of gentoo on it.

On the golf balls and rotary launchers. A golf club is a rotary launcher, it just doesn't make a complete revolution. As I wrote in a comment here a while back, an auto-golf-ball-launcher would be an excellent crowd-control device for two reasons:

1. Golf balls bounce funny, and hurt when they hit you.

2. If the golf balls come off the launcher with no greater speed than is allowed by the Rules of Golf, yer liability is pretty much covered. Crazy incompetent golfers around here hit golf balls in all directions all the time, and are never called on carpet for the damage they do.

Remember Gerald Ford and Spiro Agnew beaning folks with golf balls?

JTG, I'll leave the science to ChillyWilly, but it strikes me that the golf club is an impact launcher, but I suppose the only difference between that and the sling is in effect that a sling (trebuchet) simply does the energy transfer more slowly than a golf club. Carp, if I'm not careful you guys are going to drive me into taking some physics classes to try to catch up.

Back when I could (and was required to) run, I used to run around the golf course at Fort Leavenworth (not on the course, (it has sidewalks all around the periphery with is a two-mile run) I got beaned by a duffer who thought it was funny, until I picked up his ball, and jogged on into the post hospital, where I got one stitch. I have a rule - anything fired at me that doesn't kill me - I keep it.

I have a question for the aviators in the house. Is there a rule of thumb about how much more energy is required when something goes from sub-sonic to super-sonic? In order to launch a projectile super-sonic the DREAD has to be spinning super-sonic. (I ask because the math is stupid hard if you want to do it from first principles.)

Also, wouldn’t this thing be making a whole lot of noise once it goes super-sonic? Does a propeller have a marked increase in noise when the blade tips go super-sonic?

Poppin' in for another sec.

$189.00 for a FEARSOME WARWOLF? I figger, at 20 shots per week-end day, times 52 weekends a year that comes at under a dime per shot.

We got to get ourselves some of dat!!!

Hmm, reminds me why mortars are cool, the recoil absorption is provided by Mother Earth, and the piece doesn't move much, meaning that more of the energy goes into the projectile.