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back to article Personal jetpacks and solar-powered ships

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 …

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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.

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Not a Jetpack, but who cares?

It's still pretty damn cool and I'd like one! :)

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yes that's right

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.

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Heli?

I don't see a rotor. It looks like it uses 2 ducted fans.

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It looks like it uses 2 ducted fans

There are rotors in them thar fans...

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Coat

but

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.

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He doth protest too much methinks.

How many Hummers in the garage I wonder?

I note that you didn't mention that we're all made of star-stuff, but that would have been gilding the lily somewhat, so it's probably for the best.

:-)

ttfn

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Anonymous Coward

tidal energy

isn't solar either ... it's gravitational.

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Boffin

Tidal Energy

Well Technically it's the rotational momentum of the earth... eventually the earth will stop spinning and face the moon, just as the moon already has (same side facing earth).

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Boffin

Except that

The moon is moving away from the earth so it's tidal pull on the earth is steadily diminishing and it will escape earth orbit before it has extracted enough energy from the earth's rotation. So it isn't going to happen unless you can magically keep the moon where it is.

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FAIL

It took that boat 8 MONTHS

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!

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Mushroom

Iits called a technology demonstrator, you tit...

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...

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And it's demonstrating the technology is crap...

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.

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@peter2

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.

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Solar is pointless on a ship...

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?

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Stop arguing

Just ask someone at Greenpeace. They will suggest to use dolphins to tow the VLs and ULs. Just like some Greenpeacenik a wihile ago who suggested to me that horse-driven generators are the solution to the world energy needs - you see, horses, natural, organic, romantic...

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Meh

A totally solar boat could do a LOT better!

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.

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Energy multiplier

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.

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The title is required, and must contain letters and/or digits.

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.

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Anonymous Coward

>"basking in the turnaround from ridicule and skepticism [ ... ]"

..., no small part of it due to El Reg's very own Mr. Wrong....

(apologies for the form-tampering. only having a laugh, nothing malicious)

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Solar power on a ship....

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!

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The wind isn't always there when you need it.

Having just spent 4 days bobbing off the coast of the Azores with a dodgy engine and no wind, some solar powered means of propulsion would have gone down a treat.

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re: The wind isn't always there when you need it.

Ummm, neither is the sun ;-)

At least when there is no wind, you have some nice clam weather to sit about in

Glad you bobbed back intact.

Now go fix that engine!

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Anonymous Coward

Er...

If your engine was dead, how would solar have helped?

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re: Er...

You silly billy, he could have dismantled his mast, and used it to fashion some oars with the solar panels as the paddles.

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Anonymous Coward

untitled

Well, I suppose that solar panels do have a use on a ship after all!

I can't help thinking that packing oars to start with might have been a better investment though...

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Hmm

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.

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Black Helicopters

Search and rescue is an application...

or a requirement?

"Yes, I've located the shipwreck, the crew are safe. Can you pick me up first, this bloody thing doesn't float!"

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Pirate

Returning via the suez canal?

Certainly hope their giant solar collector doubles as a death ray to see off those Somali pirates.

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Stop

Only for dummies.

The crash test dummy managed to hold itself rigid on landing. I suspect that a real 'pilot' would flop around and get their head scraped along the ground.

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You think so?

I suspect that a real 'pilot' would land the thing upright after a controlled powered descent.

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tidal isnt solar powered

It's lunar powered.

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It's both

Actually...

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Anonymous Coward

8 Months, Monaco to Queensland...

...is that any faster than a 19th century clipper (which also used no additional energy)?

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Anonymous Coward

re: 8 Months, Monaco to Queensland...

Nope.

Clippers could push 30km/h

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Boffin

Clippers

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...

<OLD_MAN_MODE=ON>

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Stop

(untitled)

Clippers were bloody fast ships for their day. They weren't massive bulk carriers, but they did mass about a thousand tons.

This was a 80 ton ship and would probably have fitted in the hold. The Clipper wins.

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Wind

I seem to remember Sir Francis Chichester doing a solar-powered circumnavigation decades ago. Or did Gypsy Moth have an Axilliary engine?

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ship power

A solar powered ship!

Well blow me down, what will they think of next, a wind powered one perhaps?

http://en.wikipedia.org/wiki/SkySails

Can this solar ship not make the west to east return journey, or does it have to keep going round the world to get back to where it started?

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Good for tourists

Solar powered boats should be compulsory for tourist locations. The pollution from conventionally powered boats is killing what we all want to go and see. Keep a generator onboard just in case the sun goes in.

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JDX
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re:All our power sources are solar sourced

A pedant on El Reg forums? That's a new one.

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Speeds

200 km in a day compares to the commercial sailing-ship record of 861 km. In 1866 the trip from China to London was made in 102 days, by way of the Cape of Good Hope

The downside is that you need a lot more crew.

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Solar powered, would a rotor ship not be a better idea?

http://en.wikipedia.org/wiki/Rotor_ship

Use the solar to power the rotor motor, let wind do the rest

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Happy

30min on a jet pack would be *impressive*

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.

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exchange rates

"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.

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Meh

7.5 knot solar ship of 85 tons?!

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.

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Solar Ship

Taking the Suez canal means that they will be traveling through the high piracy area off Somolia.

Most circumnavigations go around the Cape of Good Hope, and some go around the Cape Horn region. Those are high latititude regions, so the amount of sunlight there is significantly less.

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Anonymous Coward

It would work here

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.

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Anonymous Coward

@ fisherman

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.

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Pirate

Mmmm...

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...

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