Not a Jetpack
That's just a small hybrid power helicopter with no cabin. I was prepared to give them a technical victory if it used *jet* engines, but it doesn't. Nor is it a "pack", as in something even remotely backpack sized.
In a weekend of contradictions, New Zealanders have demonstrated technologies showing off the best and worst in fuel efficiency: a petrol powered personal jetpack joined the mile-high club, while a solar-powered ship made an unassisted trip from Monaco to Brisbane. A crash test dummy has returned unharmed after riding a Martin …
It is "just" a small personal helicopter, able to operate from a couple of square meters and extremely close to obstacles with no risk of rotor strike. It's the smallest practical man-carrying helicopter the world has seen (let's exclude toy quadrocopters, which this has a lot in common with, but which can't carry people).
Some are complaining about the 30 minute endurance. This turns out to be a legal limit for the class of ultralight aircraft it is being operated as. If you are a customer able to operate it under other rules then they could fit a bigger tank for you.
Of course you'd never get even close to that using a rocket or even a jet turbine. The old peroxide-powered Bell Rocket Belt (it's not a belt, it's a pack!!) has an endurance of 30 seconds.
A fundamental property of a rocket engine is the "Isp" (specific impulse). This has units of "seconds" and can be interpreted as the amount of time that the rocket could hover in 1 gravity, ignoring the weight of the engine itself, the tanks, and anything else on board.
Hydrogen peroxide monopropellant rockets have a theoretical maximum Isp of 160 seconds. The improved RB2000 Rocket Belt produces 145 kgf (enough to lift it's own 60 kg weight plus a human weighing less than 85 kg) for 30 seconds from 32 kg (23 liters) of fuel, implying an Isp of about 135 seconds, so there's not much room for improvement. The 1960's version had an Isp of about 100.
The very best chemical rockets[1] give an Isp of about 450, so you're unlikely to ever get a rocket belt with more than about three times the endurance (90 seconds), and it's certainly impossible to get more than 7.5 minutes even if it's carrying its own fuel and nothing else.
A turbojet can achieve an effective Isp of 2000 - 3000, which is much better, but still would give an endurance of no more than about 10 minutes.
It seems to me Martin is using the right technology for a practical machine, regardless of whether it fit's someone's Buck Rogers definition of what a "Jetpack" should be.
[1] 542 seconds was achieved in a rocket engine using liquid lithium, fluorine, and hydrogen but this is .. er .. expensive, dangerous, highly toxic, and just generally impractical.
All our power sources are solar sourced - nuclear comes from dead stars so I suppose may not count as 'Solar' in the strictest sense.
Wind is solar generated (what no sails !).
And of course all those lovely fossil fuels were all ultimate the result of solar energy impinging on the planet - mainly in days gone by when the CO2 concentration was many times higher than it is now.
To get from Monaco to Australia? They're doing it wrong. The old SAILING ships of 100+ years ago did that trip in a couple of months. Obviously the wind power we'd been using for hundred of years is somewhat superior to solar, not to mention a damn sight cheaper. Newer is not always better!
The very first steam ships were slower then the sailing ships going from the UK to the US, but now take a look at the world, all commercial shipping is done with powered ships, not sailing ships, i wonder why that is? Could it possibly be because sailing ships are as advanced as they can feasibly be developed, where as the steam powered ships were developed into more and more powerful ships able to travel faster and further and not be beholden to the mercies of the wind?
Give the technology a chance for f%&ks sake. This sort of thing could be a god send for your oil tankers and cargo carriers - theyve got a hell of a lot more deck space in which to layout massive arrays of panels, and so in time we might be able to do away with the huge amounts of diesel powering the worlds commercial shipping. Its not going to happen overnight, but early demonstrators like this pave the way...
The very first steam ships had substantial problems in that they were too small to carry enough coal to make the crossing, and no coaling stations existed because nobody else was using coal, so they actually made most of the crossing under sail and only used steam when becalmed.
The first "real" steam ships (in that they were only powered by steam, not mainly by sails with a steam engine as well) were also slower than a small ship, but you expect a ship of 1700 tons to be a bit tardy compared to the best sailing ships of 80 or so tons. If you wanted to compare this toy with anything you should compare it to Turbinia.
Except that Turbinia was actually groundbreaking, and led to lots of sales of steam turbines for ships. This, on the other hand is an application of one of the most inefficient electrical generation methods known to man to power a ship, and will not lead to mass sales or conversions of existing ships to solar power.
And no, I have no problem with technology. However, all you need is the slightest understanding of technology to know that solar will never be able to provide the amount of power required to propel a ship grossing over a hundred kilotons at any worthwhile speed.
I think you are missing the point .. we're unlikely to go to a totally solar powered ship, but as a fuel saving measure this could prove useful. As lglethal pointed out, some ships have a massive deck area. Electric propulsion is increasingly used with a diesel gen providing the power. Offsetting the fuel cost with something alternative such a s solar could be useful, but before you can do that, you need to test out how the technology works in anger, which is what this 'demonstartor' does.
Right.
A modern LNG carrier's engines deliver about 40MW of electricity, and likewise with the Royals Royce Marine Turbines. Yes, that's 40 MegaWatts, not 4MW and not a typo.
1meter square of marine solar panels gets you 65 watts according to the salesdroid in ideal conditions. VLCC ships could be up to 470m by 60m, an area of 28,200m. That means that covering the deck would give you at most 4.5% of the requirement in absolutely ideal conditions, which you will never actually get outside of the sales brochure due to the fact that the sun doesn't always shine, the panels don't track and at sea you get water, oil, dirt, bird shit, etc etc etc on the panels.
In the real world, if you actually produced 2% of the energy requirement then I think you'd be lucky, and frankly it's not worth the hassle to run the engines 2% slower because of the efficiency curve on the engines.
So yeah. Where did I miss the point?
Missed points?
You might consider the possibility of an energy multiplier, using one unit of electricity to get very many units of propulsion. It's called a rotor sail. Yes, you do need some wind, though with screw propulsion as a backup you'd never be completely becalmed. (The first use of steam on mostly-sailships was to escape from dead calm conditions).
Also the power needed to propel a ship rises as a high power of its velocity. Travel slower? Optimum velocity is an economic function of cargo and fuel costs. As for engine efficiency curve, that's an internal combustion problem. Electric motors can work efficiently over a wide range of speeds and power outputs.
Engine efficiency curve is indeed a internal combustion problem. That's because a combustion engine is generating at least 96% of the power used by the electric motors even if you did spend silly money coating the ship with solar panels. See my last post for how I arrived at that figure.
That's why I say solar is pointless on a ship. If the sums added up then i'd be supporting it, and so would most ship owners. However, the sums simply reinforce common sense, that solar on a ship is pointless.
You could travel slower, but seeing as we were looking at massive LNG tankers that would mean that in the longer voyage more LNG would evaporate, costing more than the fuel used.
Not that it actually has anything to do with solar panels on a ship, but Rotor sails failed to get into use because you have to put more energy into them to get any given speed than you would from simply putting the same power into a screw. If THAT changes then maybe they might get used for something.
This is a very poor design of solar boat. A test-bed for marine deployment of solar panels at best. Be a bit more ambitious!
The right way to go would surely be a rotor-sail ship with the rotors solar-powered. You'd be propelled by the wind whenever there was any, switch to direct propellor drive if becalmed. Rotor-sails use the Bernoulli effect to generate as much a 20 times more propulsive force than a sail of the same cross-sectional area as the rotors (which are vertical spinning cylinders). The amount of energy needed to make them rotate is small. They also need little manpower to operate them compared to sails, kite-sails, etc.
Also note that in a boat, crude lead-acid batteries should suffice to store solar energy. Weight isn't much of a problem for a boat. Indeed, many designs of boat require a considerable weight of ballast to stabilize them.
Sail plus solar has another advantage. Becalmed normally implies sunny, or at worst light overcast: a high-pressure system. Heavy cloud cover normally implies wind.
200km in a day!
Under favourable conditions!
WTF!
Really, which is the worst here? A backpack helicopter/jetpack or a solar boat that cost many more millions to build, goes abbhorently slow and would have created a lot of wasted chemicals in the manufacturing of solar PV cells?
Gimme a petrol jet pack any day at least then i can put some ethanol fuel in it.
Correct me if I'm wrong, but I'm pretty sure there are already some very tried, test and successful non-fossil/nuclear ways to move a ship through water...
Oh what are they called...
Damn my memory...
Oh yes, sails!
So stop messing about on the water (a clipper ship would embarrass you if you happened to meet one) and focus on getting enough panels onto a practical car!
Clippers were bloody fast ships for their day, and weren't massive bulk carriers (then again, nothing was in those days, compared to modern kit).
Bit like dropping a V12 from a XJ220 in the back of a transit and finding you can't get a palette in anymore; hull design limits load.
Agreed though - 200km a day is a bit slow, but glass half full an' all that - better efficiency and more panels should bump that up in version 2.0. Early days yet I suspect.
Though I doubt they'll ever look as good as the clippers...aye, I remember the day when...
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IIRC the endurance of the 1960s era jet packs was somewhere around 8-12 minutes.
Note One problem with *all* these personal flying gadgets is the fuel is such a *big* part of their mass that you have to keep constantly throttling down to stay level, *any* constant throttle level will cause climb.
As others have noted it's *not* a jet pack and it's pretty bulky.
But honestly it's pretty impressive. Like something DARPA might fund.
Now how much is $NZ8m in *real* money.
"Now how much is $NZ8m in *real* money."
Doesn't matter a lot .. it's a pretty trivial amount of money as tech development goes. But anyway, present conversion as at today is:
£4.0m
€4.6m
US$6.6m
They've only got to sell a few hundred to military or search & rescue or similar worldwide to get into profit.
200 KM per day? 8.3 MPH or 7.5 Knots?
Sorry, that's completely, totally and utterly pathetic for any ship of that tonnage built in the last half millennia. The most ungainly 16th (!) century naval construct, the First Rate Line of Battle Ship of one hundred guns and a crew of ~850 (such as HMS Victory preserved in Portsmouth) could do an average of 8 Knots with frigging sails on trade winds routes, and she weighs over two thousand tons in comparison to this piddling little thing weighing 85 tons!
Sailing ships (well, boats technically as a Brigantine or Ketch rig doesn't qualify as a ship) of 85 tons consistently logged up to 14knots. In my opinion, a modern ship failing to match the performance managed several hundred years ago by a sailing ship (you can't get anymore green than that!) is not impressive, it's pathetic. And it's meant as a demonstration of why we should use Solar? It's really a demonstration of why you shouldn't touch it with a barge pole.
The Cape of Good Hope is not a high latitude region. It is not even a low-latitude region (Southern hemisphere and all that...)
We do pretty well in terms of sunlight - over 3090 hours a year. Even the least sunny month, June, averages 174 hours of sunshine. Plenty of solar power, even in winter when the average daily low gets down to 7°C.
I suspect the big companies will still take the suez, based on the massive fuel cost saving it entails, and the insurance is still cheaper than going round the cape (what with it's propensity to ship ships an' all).
Risking the Somalia zone is just considered to be a throw of the dice...a calculated risk.
Quite a few boaties are moving over to diesel-Electric, with solar backup, with small diesel charging battery bank and electric motor driving propeller. However, current deployed panels are about 26% efficient, which is a bit shit. I' ve installed solar panels and wind turbine on my boat, with wind being far more efficient. Wind works a treat, but solar can barely charge handheld vhf, unless I'm very, very patient.
Still, boat is in Newcastle and I'm in Spain, so would get better results if I grow some and have a go at Biscay...
Ps, me and a mate are building a solar cooker and are planning a solar kiln are some stage. Google Scheffler + solar. Guy is a genius in all things solar.
Pirate, obviously...