Sun Flyer, an Electric Trainer Aircraft
spectrum.ieee.org
spectrum.ieee.org
A broad torque curve isn't really useful since aircraft engines are already optimized for sustained operation at cruising speed and the range of speeds you can operate at is limited by the propeller and physics. There's no need to have a ton of torque at 1800rpm and at 6000rpm
>At 20 kilograms (45 pounds), the motor can be held in two hands, and it measures only 10 centimeters deep and 30 cm in diameter
And what's the horsepower rating and duty cycle rating on this motor? Power density is not an area where electric motors have a large advantage over ICE unless you're trying to build a cylindrical package. The article talks about doing away with durability requirements that impede a lightweight design.
>with no power-sapping transmission
Most small aircraft are direct drive.
Electric power certainly has advantages but this article may as well be a marketing brochure full of fluff.
Battery airplanes that carry the full weight of the batteries all the time have worst-case takeoff, climb, and landing performance on all flights.
It's easy to notice even 100 pounds difference in loading on light airplanes. That's a little under 17 gallons of avgas or about 90 minutes' fuel burn for a typical trainer.
If I want to take 2 extra 175# adults on a local flight, I can just leave off 60 gallons of fuel and have the same performance for a short flight.
A land-based launch system would have a lot of advantages; lower peak power would be needed from the motor and batteries, the engines could be made smaller, the energy used to take off doesn't have to be stored on the plane, everything gets lighter and more efficient.
"We designed and built a pneumatic rail launcher so that the plane does not have to take off under its own power."
In the spirit of everything old being new again, the Wright Brothers' original 1908 flyer also used a catapult to launch the planes. https://simanaitissays.com/2012/08/13/vintage-aero-wilber-wo...
Aircraft carriers (some of them) use catapults because that's a case where runway length is, by far, the limiting factor.
Perhaps if aircraft could use some sort of funicular system so that one aircraft taking off could get a "boost" from one slowing down to land?
Or planes could land on giant inflatable runways at 30,000ft, with the passengers and cargo taking a lift down to ground level?
From a straight lifting standpoint, lifting 910K pounds to 37K feet takes about 45 billion joules, which is the energy content in about 320 gallons (~2200 pounds) of jet fuel (if consumed perfectly efficiently).
A 747 burns about 1 gallon of fuel per second, meaning the straight lifting fuel consumed represents about 5 minutes or 1% of the fuel consumption on the flight.
2. Typical aircraft takeoff roll is under 30 seconds, and most aircraft have 3hours+ endurance, so you'd be extending the range of the aircraft by < 1/360th.
While it is true that you "nail the throttle" during takeoff in a little general aviation Cessna, the same is not true of jet-powered heavy metal. The big planes that account for most passenger miles are limited by engine noise regulations and scaring passengers, and run the engines at a fraction of peak power during takeoff.
You can find implausible-looking-but-true videos of big ungainly airplanes taking off near the edge of the flight envelope in ways that look very surprising.
Flight instruction is currently about $100-120/hr for aircraft rental and $40/hr for the instructor (not paid if you are soloing). This would likely halve the rate for the aircraft as fuel is currently averaging about $4.50/gallon and a C172 burns on the order of 6-8 gallons/hour and requires more maintenance. Insurance on electric aircraft will likely be cheaper too given the lower mechanical complexity, though this has yet to be seen.
In my humble opinion, the FAA does a lot more than an air regulatory agency should[0].
Since plane crashes are rare enough, the government litigates against everyone who ever worked on your plane if somebody ever dies in connection with it, and unless you can prove it was user error (expensive in its own right), you will end up paying millions in settlements and process. These costs are added at every level of the supply chain.
The FAA process could seem to make aviation safer if aviation technology never had to change ever again; but because there is so much to be done in private aviation that won't ever be done because of the cost of certifying craft with new technology; there's a good chance that safety devices have been held up by the process as well.
[0]: https://fee.org/articles/how-the-faa-brought-down-uber-for-p...
Roughly, they consider these groups, from lowest to highest priority in terms of keeping them safe:
1. Pilots. These are the lowest priority because they're the most in control and best understand the risks. If a pilot wants to turn himself into a red splat, that's his own concern.
2. Knowledgeable passengers. These are people who may not be pilots but understand aviation to some extent and have an idea of what they're getting into. They can't necessarily evaluate all the risks completely, but they can do a pretty good job of it. The FAA can't directly determine this, of course, but they use "for hire" as a proxy: if you're just taking people for fun or as a favor, it's assumed they have some idea of what they're getting into. If they're outright hiring you to fly them around, it's assumed they don't.
3. Passengers who are random members of the general public. Most of these people know little about airplanes and about the risks. They can't be counted on to evaluate things for themselves. People paying random pilots/companies to fly them around are assumed to be in this category. (And people buying tickets on a regularly-scheduled airline flight are assumed to be even more random than people hiring a charter, for example.)
4. The general public on the ground. These people aren't even involved in the process and have no choice in the amount of risk they're exposed to.
This is why the requirements get steeper as you move from recreational flying to commercial flying. If you want to fly solo over empty land, they don't care too much if you get yourself killed. If you're going to carry a hundred vacation travelers who just want to get to the beach, things are more strict.
(And I don't know that it is actually hard to find ones doing it now. Certainly the airlines are almost ludicrously safe, but the context here is GA, where things can be much more lax.)
When people get upset about the FAA's safety stance in GA, it has less to do with the part 61/91 regulations (airman certification/operating procedures) and more to do with the equipment certification standards. A common example is the reliance on vacuum driven gyroscopic instruments when MEMS technology provides better performance with a much lower probability of failure. Up until recently the FAA made it almost impossible to retrofit old aircraft with generic glass panel systems even though these systems provide vastly greater safety margins when used correctly. I personally have experienced a vacuum system failure, but luckily not while in IFR conditions.
Beyond instruments, the bulk of the fleet of 30-50 years old and beginning to show it's age, but it's prohibitively expensive to certify new designs that incorporate more safety features like CAPS (parachute systems), composite energy absorbing seats/fuselages or digital engine management systems. We're also still entirely reliant on leaded fuel (100LL) due to cost hurdles in certifying engines that can run on JetA or anything else for that matter.
The other big factor is the construction. Cars are largely stamped and then welded together. Aircraft are either stamped/milled aluminum that is then manually riveted together (production volumes are orders of magnitude lower than cars so no robots are used) or they are made of fiberglass/carbon fiber composite which is even more labor intensive to form. The issue with the comparison with cars is that they're way cheaper than they reasonably should be because of the sheer volume that they produce. In the time it takes cessna to build one plane, ford can pump out 1000 new cars.
Here are some LED landing lights for a C172 for the low low price of $227: http://www.knots2u.net/categories/cessna-single-engine-model...
Yikes, trainers don't have turboprops yet? I get that the initial cost would be higher (though not that much, I would think), but engine on time is the commodity that training airfields sell, it seems ludicrous that they would accept the piston tax.
The dirty secret they don't tell you is that turboprop's have miserable efficiency. A 1950's era carborated piston will outperform them every time in terms of fuel economy. The Cessna caravan or Pilatus PC12 will burn on the order of 50gal/hr of jet fuel at cruise and as turbine engines get smaller, they lose further efficiency.
A good rule of thumb is that nobody is going to be getting more than twice the flight time of a state of the art quadcopter.
Trains and long distance busses are still around for routes that are also trafficked by airplanes. Presumably because they are often cheaper.
Well, so does a hybrid plane, if it's fueled with biofuels. Zero net CO2 emissions anyway. I would imagine other emissions are less problematic since it happens far away from populated areas.
I'm not sure why hydrogen is desirable. Hydrocarbons have higher energy density and is easier to store and fuel.
I can imagine that the closed loop of H2O + electricity <-> electricity + H2 + O is more efficient than the hydrocarbon equivalent. But neither technology is near their theoretical limits, so it's a bit hard to say yet.
Regardless, if we build hybrid planes, we can use whatever technology makes the most sense. It shouldn't be too hard to swap out the energy storage mechanism. Who knows, maybe we'll invent a good rechargeable aluminum-air battery and replace everything with that.
http://www.ipcc.ch/ipccreports/sres/aviation/index.php?idp=6...
But if you're producing the hydrogen with zero emissions, then it's a 100% cO2 free process, isn't it?
Similar for making ethanol.
Every goddamn time HN gets an aerospace post....
The only time I could see wanting net regenerative power is on very short final (the last 50 feet of descent) or for braking on the runway (especially on contaminated runways). But neither of those will be effective for regen/extending range.
So a little less than 3 hours, I'd imagine.
I'm not familiar with flight terminology or flight training, so could you elaborate on the meaning of that sentence?
Off the top of my head:
- At certain temperatures and pressures you have to consider icing in the carburettor, which will block air flow into the engine.
- You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Some more in-depth examples at http://philip.greenspun.com/flying/engine-management
Airplane gasoline engines are a mess, the technology is ~1950s at best and just hasn't advanced at all, with a few exceptions that, pardon the pun, never really took off.
Agreed the tech is old, but the uncommanded in-flight shutdown rate for pistons is also very low. Part of that is driven by high maintenance demands (some of which introduces failures themself), but a lot is due to the simplicity and redundancy.
Would I like variable spark timing (beyond impulse couplers for starting)? Would I like more automated starting, especially for hot starts? Would I like thermostatic cooling of cylinders? Yes, but not if they came with any substantial increase in failure modes. When I'm taking the family 700 miles at night in a single-engine airplane to grandma's for christmas, I'll suffer with arcane checklists and having to manually manage the engine if it reduces the chance of an uncommanded shutdown by even 5%.
Excuse me? Carburettor? In 2017?
> You have to tune (lean) the fuel input to reduce fuel consumption and prevent spark plug fouling, but not lean it too much that you overheat the engine.
Can't the engine management software take care of this?
The big, old manufacturers like Cessna tend to be really conservative, though. They have something that's Good Enough and they have little incentive to make radical changes. Part of this is because a light aircraft's powertrain is safety-critical, unlike automobiles. In a car, if your engine explodes, you're stranded. In a small airplane, depending on where you are when it happens, you're probably hurt or killed. If you make a radical change to your engine, and that change results in a failure that kills a customer, it looks bad. Newer manufacturers seem more willing to push the envelope in this respect.
Seriously, GA aircraft engines are seriously old tech.
Lots of people learn to drive automatics and not manuals. Perhaps electric planes will become viable enough that many people will never need to progress to ICE?
And perhaps that is true, but hardly the case in the near future.
Even assuming a rather speedy pace of improvement in battery tech, the power/weight ratio won't be there for quite a while. Batteries also don't get lighter as their energy is consumed, like fuel does, and many planes cannot even land with the same weight they are allowed to take off with.
When a student has that down, they can graduate up to a trainer with an ICE, and then learn all of that stuff.
Exactly like learning to drive a car in an automatic first, then once you have the actual vehicle control/traffic/etc down, you graduate up to a stick shift.
Just as a decent driving instructor won't let you blow a red light, a decent flight instructor (who has the ability to take control of the aircraft, unlike a driving instructor) isn't going to let you enter an unplanned stall, or leave you on your own to deal with more than you're ready to handle at any given time.
This isn't a new concept, either. It's relatively common to learn to fly gliders before transitioning to powered aircraft. The US Air Force Academy has the largest glider operation in the world, for example.
Not at all. The vast majority of primary flight training is best spent on so called "stick and rudder" skills. The basics of flying do not change at all from an electric powered ultralight to a Boeing 777.
You should have stopped right there.
I should note that a conventional airplane rarely cruises at less than 50% power, 65-75% would be more common.
But even an hour endurance, plus reserves, is okay for a trainer airplane, so this product is pretty decent already, and your outrage over the waste of your precious time probably was not warranted.
If this thing can recharge in ~30 mins, then it would be a pretty good option for a flying school, where pre-flight briefings and checks will consume a part of this time.
And given the pre-orders and options, it seems the flying schools in fact agree that this is a pretty good product.