Strangest Places for an empeg?

...Paul Allen and submarines, I've read somewhere he intensd to order one of these.



I bet not.

After looking over the description and specifications, I'm thinking this thing looks pretty bogus.

There is no way they can cut a bunch of seven foot diameter holes in a 26' diameter pressure hull, fill those holes with plastic windows, and then take the thing down to it's rated operational depth of 1000 feet. At least, not with any expectation of ever bringing it back to the surface! Anybody know how many PSI water pressure would be on those windows at 1000 feet? Each window would have 5541 square inches...

The electric motor specs are a bit suspect as well.

We're looking at a total of 3280 KWH of electrical storage, but assuming that these are lead-acid batteries (and I don't know of any other technology suitable for such a large-scale application) at best you will only be able to use two-thirds of that capacity without risking irreparable harm to the batteries. So call it 2150 KWHs available. The motors themselves have a maximum output of 740 KW, that's almost exactly 1000 HP.

They're claiming a maximum submerged speed of 10 knots, which I assume would require all 740 KW. They claim a six hour endurance at that rate, which would require 4440 KWH, more than double the amount of onboard capacity availabale.

Further, they claim a 140 hour submerged endurance at 2.5 knots. To get 140 hours from 2150 KWHs would be a continuous draw of about 15 kilowatts, or about 20 horsepower. I would be very surprised if 20 HP would propel a 213 foot long 26 foot diameter craft with all the protrusions shown for bridge acoutrements etc. at a speed of 2.5 knots -- while submerged! In fact, I'd be surprised if basic life support (lighting, heating, air circulation, cooking, oxygen generation) could be done on 15 kilowatts, leaving nothing left for propulsion.

There is also a discrepancy in maximum claimed speeds submerged vs surfaced. On the surface they are claiming 16 knots, from two 1100 horsepower diesels. Submerged they are claiming 10 knots from 1000 horsepower. Just guessing here, but my gut feeling is that total drag submerged would be about two times the drag experienced on the surface. It's been a while since I knew these things for sure... but I think power required for the same speed goes up as the cube of the drag (double the drag requires 8 times the power for the same speed.) So if that is right, and 16 knots on the surface requires 2200 horsepower, that same speed submerged would require more than 17,000 horsepower. It doesn't seem reasonable that if it could theoretically go 16 knots submerged with 17,000 horsepower, that it could go 10 knots (60% of that speed) on just 6% of that power.

I've decided that I'm not going to send them my $78.000,000 unless they can answer these discrepancies. Of course, the real deal breaker might be if I demand they install an empeg at no additional charge.

tanstaafl.








"There Ain't No Such Thing As A Free Lunch"

What the heck? So we kill off the super-rich. No big loss

DiGNAN

I get the vague feeling you know something about this, Doug...

One of the few remaining Mk1 owners... #00015

I was lookin to install my empeg on to my motorbike. Apparently vibration isn't an issue, but mounting position is difficult, either face up in a pannier (which i've been told is a no no) or horizontal under the seat. Would still need to find some form of amp to power the headphones, and some form of remote control. Anyway, too manys problems and not enough time so the project's bee shelved for the time being.

Anyway preasure;
1000ft = 304.8m
preasure at 304.8m = 30.48 bar + 1bar for atmospheric preasure.
so preasure would be 31.48 bar or 456.47 Psi (if you like it in old numbers)

Ah, here is Doug again earning his sig .

Well, they do actually build some submersibles (but with far less spectacular specifications)...

BTW, don't some modern nuclear submarines actually sail[1] faster when submerged (due to lack of drag component caused by generating bow wave)? Then again, this $78M contraption looks like semiplaning when on surface, which should require far less power than diving with all those sticking bits...

You think those foot thick lexan hemispheres could not withstand 30*2.2*2.54*2.54 psi? Well, perhaps not, especially at joins with the rest of the hull :-(

Anyway, heck, Doug, you have spoiled my daydreams

[1] Is 'sail' the right word when there is not a periscope or snorkell, not to mention mast or sail, above water? It's similar to ancient Informix DB admin question: is Informix-OnLine online even when it is offline?

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green

don't some modern nuclear submarines actually sail[1] faster when submerged (due to lack of
drag component caused by generating bow wave)?

Yes, they do go faster submerged. But I think it is because at depth, as the water becomes more pressurized, the propeller can do more work, put more energy into the water before it begins to cavitate.

I have heard that a modern nuclear submarine can attain speeds approaching 50 knots submerged. Of course, they have a bit more than 740KW of power available for propulsion.

You think those foot thick lexan hemispheres could not withstand 30*2.2*2.54*2.54 psi?

At more than a million kilograms total load on each one, I think not.

Just for my continuing education, though... what is the formula behind your math "30*2.2*2.54*2.54"? Let's see... the 2.54*2.54 is no doubt going from square centimeters to square inches... what's the 30*2.2? I think I used to know how to calculate water pressure at depth, but it's been such a long time...

tanstaafl.





"There Ain't No Such Thing As A Free Lunch"

what's the 30*2.2

1000 feet ~ 300 m
pressure rises approx 1 atmosphere (1kg*g/sq cm) per 10 m depth (g=9.81 m/s/s)
1 kp (kg-force, kg*g) ~ 2.2 lbf
so, pressure rises approx 2.2 pounds per sqare centimeter per 10 m of depth

(I should have used furlongs somewhere, but I could not remember how much is that - 220 yards?)

Cheers!

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green

(I should have used furlongs somewhere, but I could not remember how much is that - 220 yards?)

Stop it, you're encouraging him.

Doug, pretend you didn't read that.

___________
Tony Fabris

I get the vague feeling you know something about this, Doug...

Not really... I like novels about submarines ("Run Silent, Run Deep" has to be the all time classic) but mostly I am cursed by an overly analytical temperament. If I read a sci-fi novel, and the heroes go to the moon at a continuous acceleration of .7G, I have to stop reading and work out the math to see if the author got it right (4.2 hours assuming zero velocity when they arrive). Watching a movie where the bad guy takes off in his car, tires squealing on a dirt road makes me crazy. And when I see claims involving numbers, particularly numbers that have to correlate with other numbers, I can't rest until I check them out. A little Newtonian physics, a bit of knowledge about drag and power from my flying days, and a bit of common sense, and suddenly things don't add up so well.

One of my all time favorites is the pirate move, where the pirates pick up the chest full of gold bars and load it in their dinghy and row across the bay. Well, if the chest were three feet by two feet by two feet (12 cubic feet) it would weigh... let's see, 3*2*2*(1728/231)*167 pounds, or close enough to 15,000 pounds (about 6800 kilograms) as not to matter. About $45 million worth at modern prices.

Now, I challenge anyone to figure out what "3*2*2*(1728/231)*167" is all about!

It's a good thing we never get off topic on these threads, isn't it.

tanstaafl.



"There Ain't No Such Thing As A Free Lunch"

In reply to:

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Anyway preasure;
1000ft = 304.8m
preasure at 304.8m = 30.48 bar + 1bar for atmospheric preasure.
so preasure would be 31.48 bar or 456.47 Psi (if you like it in old numbers)

---

But pressure differential would still be 30.48 bar in medium old numbers, or around 3MPa (megapascals) in new numbers (our weathermen report air pressure in hPa - hectopascals - secret aliases for millibars).
(1 bar ~ 1 kg * 9.8 m/s**2 / cm**2 = 9.8 N/cm**2; 1 Pa = 1 N/m**2 ~ 10/1000**2 = 1e-5 bar)

As everibody has guessed by now, I am procrastinating. I have a report to write for tomorrow. Ah, well...

Cheers!

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green

Not really... I like novels about submarines ("Run Silent, Run Deep" has to be the all time classic) but mostly I am cursed by an overly analytical temperament. If I read a sci-fi novel, and the heroes go to the moon at a continuous acceleration of .7G, I have to stop reading and work out the math to see if the author got it right (4.2 hours assuming zero velocity when they arrive). Watching a movie where the bad guy takes off in his car, tires squealing on a dirt road makes me crazy. And when I see claims involving numbers, particularly numbers that have to correlate with other numbers, I can't rest until I check them out. A little Newtonian physics, a bit of knowledge about drag and power from my flying days, and a bit of common sense, and suddenly things don't add up so well.

This makes us two (besides seeming to be among this list seniors ). I will look up the novel right away. I enjoyed Clancy sub-novels well enough (real Clancy's, of course, 'Hunt for Red October' and 'Red Tide Rising' or something, not garbage like 'SNN'), so I suppose I will like your favourite.

Several friends of mine have 20-something year long custom of comunal video (now DVD) watching, once a week or so. Whenever the movie has anything to do with technology or science (including mechanics of driving or flying, as you mentionend), the hostess jokes I have to keep my mouth full of food, beer or something, so that I cannot complain at goofs all the time.

One of my all time favorites is the pirate move, where the pirates pick up the chest full of gold bars and load it in their dinghy and row across the bay. Well, if the chest were three feet by two feet by two feet (12 cubic feet) it would weigh... let's see, 3*2*2*(1728/231)*167 pounds, or close enough to 15,000 pounds (about 6800 kilograms) as not to matter. About $45 million worth at modern prices.

Now, I challenge anyone to figure out what "3*2*2*(1728/231)*167" is all about!

Well, 3*2*2 is volume in cubic feet, additional factor od 1728 gives cubic inches. Now, just to figure out what has volume of 231 cubic inches and how do we know it weights 167 pounds if made of gold...

Dragi "Bonzi" Raos
Zagreb, Croatia
Q#5196, MkII#80000376, 18GB green

Yes, but what would it weigh on the moon?



Reg #2845: Mark 1 #00173, Mark 2 #119

(I should have used furlongs somewhere, but I could not remember how much is that - 220 yards?)

I'm not sure about a furlong, but by my calculations the pressure increase with depth is approximately
68.364 stone to the square Mesopotamian great cubit, per fathom. This gives a pressure rise on those
windows of about 1169.297 stone each, per fathom, or almost exactly 939241 stone per standard
Imperial Roman mile.

I could go on, but I won't

Patrick.


Opinions expressed in this email may contain up to 42% water by weight, and are mine. All mine.

Don't you just love this board?

I was scared it has been getting a bit tame of late, but this thread has just restored my faith.

PS To return to something like the original thread, I have a friend here whose father is considering installing a Mk 2 in his CAT Land tractor, to while away those dull hours spent trogging up and down spraying meadows. At the moment he is undecided about whether to go for for Alpine or MTX amps, though - he's not sure that 200W/channel is going to be enough in the cab...

PPS Farmers here are rich....

One of the few remaining Mk1 owners... #00015

In reply to:

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PPS Farmers here are rich....

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and their cabs are more sound proofed than the average car, so 200 watts would be plenty. He should be spending the time considering the best position for the bass speakers

- --
Rod, UK Mk2 64gig Red S/No.341

In reply to:

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but this thread has just restored my faith

---

Paul Haigh, Reg. 4120
(mk1) 6GB, Blue, 00254
(mk2) 12GB, Red, 00357

I'm not sure about a furlong...

If memory serves me right, there are about 402 Mespotamian great cubits in a furlong.

This gives a pressure rise on those windows of about 1169.297 stone each, per fathom

Hmmm... are you sure about that?

Let's see...

we know that there is 1 kilogram per square centimeter increase in pressure for each 10 meters of depth.

That would give .1575 stone weight per square cm increase in pressure for each 10 meters.
That would give .1575 stone weight per square cm increase in pressure for each 5.468 fathoms.
That would give .0288 stone weight per square cm increase in prressure fo each 1.0 fathoms.
That would give 72.01 stone weight per square cubit increase in pressure for each 1.0 fathoms.*

Since each window is 14.297 square cubits, that would be 1,029.55 stones pressure per fathom.**
At a depth of 1000 feet (=166.67 fathoms) total pressure would be 171,595 stones per window.

*Given the standard assumption of 1 cubit = 1/2 meter
** 7' diameter window = 4.267 cubits diameter = 14.3 square cubits.

I'm guessing you used a different value for cubits than I did... something in the vicinity of .002184 furlongs, instead of the more properly accepted .002485 furlongs, perhaps? That might account for the discrepancy in our figures.

Hey, let's you and I get together and design an airplane next week!

One Egyptian says to another: "You may be right, Pythagoras, but they're all going to laugh at you if you call it a hypotenuse."

tanstaafl.







"There Ain't No Such Thing As A Free Lunch"

Sigh. I told you guys to quit encouraging him. Now look what you've done.

___________
Tony Fabris

Okay i know that i might be a bit late in replying to this but i had mine with me at work.

My work is on a VLCC oil tanker weighing in at 350685tons displacement

I had the empeg installed on there does that count.

My work is on a VLCC oil tanker weighing in at 350685tons displacement. I had the empeg installed on there does that count.

Sure.

Imagine the space you'd have for subwoofers and amps.

___________
Tony Fabris

probably most powerful as well with 27000Bhp

probably most powerful as well with 27000Bhp

Yeah, but I'm sure its 0-60 times suck.

___________
Tony Fabris

depending on its overall length, its quarter mile times might be instantaneous

____________________
Murray 06000047