How to incorporate a Hydrogen fuel cell into an electric aircraft for Homebuilders?

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Aesquire

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Here are some read them & weep numbers.

Hydrogen needs 7 times the volume as E10 gasoline, at 10,000 psi. for equal energy. For IC. But only 3.5-4 times for the same range with a fuel cell.

1.3 kilowatt hours per liter for hydrogen @700 Bar vs. 9 kilowatt hours per liter for gasoline.

And worse, in an IC engine you get about half the power per displacement, unless you supercharge. Not sure what the market really is for 40 horse Rotax 912H engines.

Assuming a small plane with 24 gallons of gas, you need to design for 96 gallons of high strength composite, heavy pressure vessels to get the same range, assuming you have the optimized motor, fuel cell, and every other system down to the same as the ( gasoline ) Rotax 912 you are replacing.

As a certified scuba diver, I'm nervous enough transporting 3000 psi tanks of harmless air. In a car.

And since we are talking cylinders, in a wing, I'm guessing you need to orient them span-wise... I'm reminded of the discussions on flying between trees in a crash to absorb energy, and separate the fuel carrying wings from the sturdy cockpit structure. In the case of high pressure storage, those wings may fly much farther that you did to get to the crash site.
 

blane.c

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I flew with wing tanks typically capable of 5404 gallons 100LL (usually carried much less) and bulk fuel tanks of 5000 gallons more or less depending on whether you where delivering gas, diesel or God knows what. So sitting on that kind of fuel mass for eleven years the hydrogen thing isn't really that scary to me. It is a matter of doing it properly as with all else in aviation we are only as safe as we make it.
 

Aesquire

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The cube square law helps a lot when dealing with fuel. I'm thinking a Kitfox vs. a DC-8.

At the silly extreme, I saw a video where a paramotor had an EBay nitrous kit using whipped cream cartridges. It made only a tiny difference since there was no added fuel, ( as I yelled, uselessly, at the screen ) but take that as a data point on your study. I don't know what the hydrogen tanks in a car weigh, and the difference in mass empty vs. full isn't as much as gasoline, but it's obvious the two eternal problems apply to any alternative power plant in aviation. Cost & weight.

Science Fiction has many handwavium power plants. The 2 most realistic off the top of my head are...

From the Honor Harrington series, by David Weber, fusion using gravity pinch. Highly recommended, the title character is a sailplane/hang glider/starship pilot. Often called Horatio Hornblower...in space.

From the Schlock Mercenary online comic by Howard Tayler, "Annie plants" that produce prodigious amounts of power from direct annihilation of He3, inside spheres of Platinum group heavy metals, which are slowly consumed.

What makes it "reasonable" is that scarce resources are needed to make it work, so unlike lazy writers who just technobabble free power, you can have your plasma lance, but you gotta pay to run it, and not only can you run out of fuel, the investment in a slowly decaying ball of Iridium/Platinum alloy is significant, even with asteroid mining. The biggest human warships are "Battleplates"
 

Vigilant1

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Honda Clarity: RIP
If you guys find an automotive fuel cell that you want to use in an airplane, better buy it before the OEM pulls the plug. Honda is ceasing production of its only hydrogen fuel cell vehicle model.

Honda Clarity Going Out Of Production Due To Weak Demand: Report

Honda Clarity Going Out Of Production Due To Weak Demand: Report

Fewer than 1000 hydrogen vehicle of all types were delivered in the US in 2020, down over 50% compared to 2019. It is not a technology that is practical when realistically compared to alternatives.
 
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Martin W

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Hydrogen has never been practical for cars etc .... this whole situation is "fueled" by global warming politics .... which we are not allowed to discuss here .... but mark my words .... a few years from now all the hydrogen-windmill-solar will be proven just as unpractical.
 

Bill-Higdon

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The cube square law helps a lot when dealing with fuel. I'm thinking a Kitfox vs. a DC-8.

At the silly extreme, I saw a video where a paramotor had an EBay nitrous kit using whipped cream cartridges. It made only a tiny difference since there was no added fuel, ( as I yelled, uselessly, at the screen ) but take that as a data point on your study. I don't know what the hydrogen tanks in a car weigh, and the difference in mass empty vs. full isn't as much as gasoline, but it's obvious the two eternal problems apply to any alternative power plant in aviation. Cost & weight.

Science Fiction has many handwavium power plants. The 2 most realistic off the top of my head are...

From the Honor Harrington series, by David Weber, fusion using gravity pinch. Highly recommended, the title character is a sailplane/hang glider/starship pilot. Often called Horatio Hornblower...in space.

From the Schlock Mercenary online comic by Howard Tayler, "Annie plants" that produce prodigious amounts of power from direct annihilation of He3, inside spheres of Platinum group heavy metals, which are slowly consumed.

What makes it "reasonable" is that scarce resources are needed to make it work, so unlike lazy writers who just technobabble free power, you can have your plasma lance, but you gotta pay to run it, and not only can you run out of fuel, the investment in a slowly decaying ball of Iridium/Platinum alloy is significant, even with asteroid mining. The biggest human warships are "Battleplates"
Sadly Sgt Schlock has ended :(
 

Aesquire

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. It is not a technology that is practical when realistically compared to alternatives.
It's practical in context! Consider, the 91 Octane booze free premium I fill my motorcycle and Mom's Prius with ( because both go for months without running ) requires a planetary infrastructure including the World's biggest ships, pipelines across continents, refineries in every hemisphere, millions of workers, and teams of lobbyists to grease the palms to make it all Work. ( Not a Political statement! If you want a deep water port or to build a gas station, you need the cooperation of the local bureaucracy. They don't work for free. )

Hydrogen Economy requires a similar infrastructure, multiple nuclear power plants, ( and solar farms the scale of cities, ditto wind, water, etc. ) and CHEAP POWER. You use Hydrogen as a BATTERY FUEL. Power in-power used. Physics applies. It's renewable! Meaning You Make More.

Go ahead, make gasoline! Get back to us after you've buried that forest under lots of rock & waited for it to ferment. Like a fine wine.

Simply the infrastructure doesn't yet exist, and cannot work except for the Rich unless Power is both Cheap and plentiful.

You can't build an airplane without mines to dig up the ore, lots of Power to make metal from that, factories to make tubing and engines from the metals...etc. Etc.

Composites need their own civilization infrastructure.... Including the metals industries. And the Power industries. And the Chemical industries. And...

So... Hydrogen not practical? Absolutely. It CAN be, with a massive investment and some time, but Only if you check ALL the boxes on the form building the roads there.

The current trends in political religion are not going to make that investment in the Basic underpinnings for Hydrogen, In My not so humble Opinion, and are beyond the scope of this thread.

But as an intellectual exercise, for a few wealthy guys who like technology toys, and like to solve problems, ( like how to carry high pressure flammable gas in a lightweight airplane ) it's cool stuff. ( and unlike Antimatter, a mistake isn't likely to cause an Apocalypse )
 

BBerson

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Hydrogen powered airships worked for decades. Modern flameproof fabric could be used with separated compartments for each ventilated gas bag.
 

Aesquire

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Airships also offer a storage solution that only requires a really big hanger and a willingness to limit flying to low wind days. And money, lots of that.

I spent a very entertaining 45 minutes watching the Goodyear Blimp go about a mile against a headwind to land at the Rochester Airport. We were on the Barge Canal bike path directly below and could easily see the control surfaces moving as it struggled in the turbulence. Great pilots, working Hard.
 

Saville

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Go ahead, make gasoline! Get back to us after you've buried that forest under lots of rock & waited for it to ferment. Like a fine wine.

Um.....they have found a quicker way. Was used in the 1940's. You make gasoline(and other petrochemical products) from coal.

So... Hydrogen not practical? Absolutely. It CAN be, with a massive investment and some time, but Only if you check ALL the boxes on the form building the roads there.

And one box that has to be checked is whether or not there's a market for it.

But as an intellectual exercise, for a few wealthy guys who like technology toys, and like to solve problems, ( like how to carry high pressure flammable gas in a lightweight airplane ) it's cool stuff. ( and unlike Antimatter, a mistake isn't likely to cause an Apocalypse )

I'm all for rich guys playing around and even garage inventors trying to make something work. But any solution that doesn't have a market is destined to be tossed on the trash heap of ideas (e.g. steam powered cars)>
 

Aesquire

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I'll point out the coal is also long buried forest. ;)

And Steam cars are cool! External Continuous combustion has much less problem with Oxides of Nitrogen, and no Octane requirements. Modern flash boilers can run fine on Hydrogen, Methane, Methanol, Chanel #5, or wood gas.

Weight is always an issue. :)
 

blane.c

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Still say pregnant women with broken water ain't waitin' for no steam boiler to get to temp. Well they ain't waitin' in silence that is for sure.
 

tallank

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It's practical in context! Consider, the 91 Octane booze free premium I fill my motorcycle and Mom's Prius with ( because both go for months without running ) requires a planetary infrastructure including the World's biggest ships, pipelines across continents, refineries in every hemisphere, millions of workers, and teams of lobbyists to grease the palms to make it all Work. ( Not a Political statement! If you want a deep water port or to build a gas station, you need the cooperation of the local bureaucracy. They don't work for free. )

Hydrogen Economy requires a similar infrastructure, multiple nuclear power plants, ( and solar farms the scale of cities, ditto wind, water, etc. ) and CHEAP POWER. You use Hydrogen as a BATTERY FUEL. Power in-power used. Physics applies. It's renewable! Meaning You Make More.

Go ahead, make gasoline! Get back to us after you've buried that forest under lots of rock & waited for it to ferment. Like a fine wine.

Simply the infrastructure doesn't yet exist, and cannot work except for the Rich unless Power is both Cheap and plentiful.

You can't build an airplane without mines to dig up the ore, lots of Power to make metal from that, factories to make tubing and engines from the metals...etc. Etc.

Composites need their own civilization infrastructure.... Including the metals industries. And the Power industries. And the Chemical industries. And...

So... Hydrogen not practical? Absolutely. It CAN be, with a massive investment and some time, but Only if you check ALL the boxes on the form building the roads there.

The current trends in political religion are not going to make that investment in the Basic underpinnings for Hydrogen, In My not so humble Opinion, and are beyond the scope of this thread.

But as an intellectual exercise, for a few wealthy guys who like technology toys, and like to solve problems, ( like how to carry high pressure flammable gas in a lightweight airplane ) it's cool stuff. ( and unlike Antimatter, a mistake isn't likely to cause an Apocalypse )
Some simple numbers to consider. A hydrogen fuel cell is 40% efficient. The most economical way to "make" hydrogen is from natural gas. When you consider the losses in making hydrogen, the energy required to compress it for storage, and the weight and expense of the storage tank, it makes more sense to use a 33% efficient diesel engine.
 

Aesquire

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True. Here's a slightly dated explanation on the efficiency problem.


and electric planes... also dated.


But... ( there's always a but... or a compromise )

Compared to batteries, Fuel cells win on mass, depending on storage tank weight. Weight is the flight killer. So, for a "range extender" or replacement for batteries in an already electric plane, Hydrogen fuel cells make SOME sense.

Might not be affordable, but once you've backed into that corner of the fuel tank ( battery ) costing more than the engine, and possibly the entire plane, you are well into "sunk cost fallacy" and other "compulsions" that compel you to spend far too much money for poor performance.
For the engineering aspects, those shouldn't matter, but motivation/mission always DOES in aviation. If the customer wants a SST for 8 passengers for the LA-Tokyo commute, he may settle for a Jetstream and give up some speed, but he won't take a T-38 which simply can't make it to the next island without aerial refueling.

The Hydrogen Economy Idea is a package, the Mission is to get off fossil fuels. It may be good for Carbon Cult Credits or Green Self Esteem Bragging Rights, or even save a puppy, and you may be able to Sell it with those side reasons, but that's Not The Core Mission. The Hydrogen Package accepts the efficiency problems with LOTS more, possibly an order of Magnitude More, generated power.

Going... near completely... to electric vehicles, even just cars & motorcycles, is going to take a massive increase in Grid generated power to charge all those batteries ( or make hydrogen, on a small scale ) or it will fail. Society collapse. Famines. Dogs and cats living together. Mass Hysteria! WILL NOT WORK. Without more generated power. Ignorant or ideologically blinded electric fans deny that, or ignore that, or believe they can put windmills on the cars to charge the battery as you drive. ( or cover Antarctica with solar panels.... )

The Hydrogen Economy is even "worse" as the power needs are even higher. But it might accomplish the core mission, which is replace the petrochemicals we burn with Grid Power. ( which is being attempted now with Lithium Ion batteries )

At best it's a competing vision for the future and it's been around as an idea and experimentally a long time.

I like the idea, but I'm Not blind to the drawbacks, and as of today, drawback #1 is cost and availability.

And really, I WANT ONE OF THESE!!!!!!


Which, apparently uses a "hybrid" system, that, being from Rolls Royce, is awesome, insanely complex, and costs more than.........
 
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