Diesel in NASA's hydrogen fuel cell plane
 

http://ecomodder.com/forum/attachmen...1&d=1508968625

Somehow people think that spoilers make cars aerodynamic. I have read many comments on here that downforce is drag.

Well, so is lift. NASA says that if we reduce the lift\drag on a plane at cruise, we drastically reduce the energy needed to propel it. Popular Mechanics explains that the huge wings are only needed for takeoff and landing, but the X-57 uses the six motors on each wing to provide lift on takeoff and landing, larger motors on each wingtip to actually propel the craft, and until battery technology improves, "you don't need hydrogen fuel to power a fuel cell—you can use diesel."

"The energy density of Hydrogen is 120MJ/kg. The energy density of gasoline is 31 MJ/liter × 3.8 liter/gallon = 117 MJ/gallon." Gasoline is 29/30ths as energy dense as diesel, so diesel is closer to hydrogen.

Measuring one by weight and the other by volume...sigh. :rolleyes:

A US gallon of gas weighs 2.83 kg so you get 41 MJ/kg (link you posted says 44). Considerably less energy per kg. You could use gasoline (or diesel), you just have to pay a weight penalty.

I can't imagine doing an "engine out" in that thing. Can you say "Auger it in"?

The Electroflight, they are developing in the UK, has a handle on the panel. Pull it and it deploys a parachute for the entire aircraft!
https://www.youtube.com/watch?v=Xe1g1JrRRkY&t=4s

That makes sense because using hydrogen fuel in any thing other than space vehicle lift is pretty stupid.

What about the weight penalty for the compressed hydrogen container or insulation for liquid hydrogen?

When I first heard of solid-oxide fuel cells, they were being tested on ethanol. But it doesn't really surprise me to find out some tests of fuel cells with Diesel fuel.

Japan had diesel powered fuel cells when I was over there back in 2003.

What else would you expect from Japan? Anyway, I'd be curious to find out why they just didn't try to make it commercially available instead of trying hydrogen. Considering that most of their animal protein intake is fish and other seafood, could even rely on fish liver oil as a feedstock for biodiesel :D

I've sometimes thought that fuel cells running on sugar would be a better solution, as it skips the whole conversion to ethanol step.

Which is why most airplanes have flaps &c, and some have swing wings. They increase lift at the price of creating more drag.

I find the airframe more interesting than the powerplant[s].

Nice if you can make that work reliably. They should be shaped like whale tubercles to help with span-wise flow when they're off.

That's a sweet all-flying elevator.

Not sure if that would be so easy, since a liquid would flow more effectively. Maybe molasses? :thumbup:

Obviously you'd have a sugar solution. Molasses probably not, because of all the impurities that give it its flavor. Maybe high fructose corn syrup, though.

That would be interesting to say the least, but due to the lower viscosity (and therefore an easier flowing) I'd still believe ethanol to be more commercially viable as a fuel.

The first diesel motorcycle I ever saw claimed you could run it on bottles of vegetable oil from the supermarket.

That military one from Hayes or some random custom built? Indirect injection is more suitable to use veg oil as fuel, and surprisingly it actually gets more fuel-efficiency than running on regular Diesel fuel.

I don't recall. It was maybe in the last century, but it was billed as a world first commercial diesel motorcycle at the time.

There had been at least one variant of the Royal Enfield fitted with a locally-developed Diesel engine (not sure if designed in-house or outsourced to Greaves Cotton, the largest independent engine supplier in India), but I'm not sure about its suitability to straight vegetable oil usage.

In unrelated news...
 

NASA allegedly designed a super-efficient plane with one giant engine behind the plane. But wait! There is more! To power the engine, they put generators on the wings!

Windmills don't work that way?
NASA's New Plane Design Could Save Fuel and Money

I think it's unfortunate wording. The tail location may have some advantage over the usual stuck-in-the-rudder solution. It may rely on new carbon-fiber fuselages that have less attached turbulence.

But starting at a high altitude, at high speed, there is a lot of energy to be regeneratively captured descending to rest. Which can be reused by the efficient tail engine back at cruise, after the extra wing engines idle back after the climb.

Considering that sometimes in case of a flame-out the inertia and the impact air flow are enough to drive the rotating mass while the engine is re-started, that sounds like a quite good opportunity to try some sort of hybrid setup for the aircraft.