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Comment by purpleidea | Hacker News Reader

I didn't read the whole article, but if they even mentioned how long it will fly for, they sure hid that carefully. Stop wasting my time until you have a decent product!

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They mentioned 83 kWhr battery, a peak power usage of 80 kW, and a "normal flight", whatever that means, usage of around 20 kW.

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.

While doing circuit training, a student pilot can do 5 training circuits of 6 mins each using 30 minutes of battery. They'll probably be so overwhelmed and fatigued afterwards (well, I was anyway) that their day's training is over. That's five or six exhausted student pilots per exhausted battery. :)

3 hours of flight time is more than adequate for training purposes. Not only is it a huge win for fuel savings, but safety is the number one reason I can see primary trainers going 100% electric over the next decade. Learning to deal with the intricacies of an ICE across the full range of flight conditions is half your training time wasted, and the myriad of things that can go wrong simply wont exist anymore.

> Learning to deal with the intricacies of an ICE across the full range of flight conditions is half your training time wasted

I'm not familiar with flight terminology or flight training, so could you elaborate on the meaning of that sentence?

ICE = Internal Combustion Engine.

ICE = Internal combustion engine

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

And when descending, you have to be sure not to shock cool it etc.

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.

A lot of that "mess" is due to a couple of critical requirements. Namely, low engine weight and reliability.

At this point it's mostly certification cost and liability insurance cost that's keeping the tech back. You can easily modify modern aircraft engines to be more reliable and efficient (PMAGs) but you need an STC (certification procedure) to make the switch so the experimental home builders are the only ones who actually benefit.

Rotax seem to be doing pretty well, they're used in a lot of popular trainers

Shock cooling as a concern for cylinder cracking is a fairly well debunked myth at this point, IMO, short of crashing your airplane into a cold lake.

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%.

> carburettor

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?

Most flight schools have much older aircraft-- think 70s and 80s-- that have carbs. Newer aircraft are fuel injected, but often more expensive per hour.

VW Golf are fuel injected since 1975.

But they've only been able to fly since 2016.

Cars are different, though you could have pointed out that the Messerschmitt BF-109 had fuel injection in the 1930s.

An average car company makes millions of cars. Probably millions of a given model. Cessna has made ~44k 172 Skyhawks. It's one of the most produced aircraft, and it's been in production largely unchanged since 1956. I think Tesla is going to make more Model 3s this year than Cessna is going to make Skyhawks.

Don't they cost hundreds of thousands of dollars? Surely you're going to find an engine manufacturer that can build you an engine that's not half a century old.

If it ain't broke...but the 172[R and S] has been using a fuel-injected engine since 1996[0]

[0]https://en.wikipedia.org/wiki/Lycoming_O-360

And the flight hour cost of one of these is double the price of a 1970s/80s carbureted 152. Guess which one the majority of student pilots are learning on.

Of course, and if you want something like that, you can find aircraft manufacturers using more modern engines. Want a car engine in an airplane? You can have that. Want a fuel-injected digitally-controlled turbocharged water-cooled diesel? Step right this way.

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.

What's this "engine management software" you speak of? :-)

Seriously, GA aircraft engines are seriously old tech.

You can indeed get engine management computers, but the thinking in the aviation world is that this would be just another thing that could go wrong. In any case, if the computer were to fail, the pilot would have to know how to manage the engine manually. Aircraft engines have various design choices designed to make the things more reliable, such as dual independent ignition systems that are isolated from the battery. The pilot deliberately has independent control over things like fuel/air mixture for good reasons.

Wasted? Isn't that exactly among the things you need to learn?

So you can have an electric plane for primary training, and ICE as the next step?

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?

Sure, but that hardly means it is wasted.

And perhaps that is true, but hardly the case in the near future.

Unfortunately that defeats the purpose of a trainer, because "real" planes, which the trainer is supposed to prepare you for, won't be electric for quite a bit, so you do need to learn all about the intricacies and issues which can crop up on those planes.

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.

Of course, this means a student can start in this electric trainer, and focus on learning the flying right off the bat.

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.

Except that in countries where stick shift dominates, you start off learning to drive a stick right away.

Unlike airplanes, cars have no stall speed. You first lesson involves driving at very low speeds, away from traffic. If you have any trouble shifting you can just stop. Airplanes are less forgiving.

Electric vs ICE trainers won't have much in the way of differences. The main procedural differences will be engine start (just follow the checklist) and low power conditions where carb heat is required (becoming slightly less common now that fuel injection is available and relatively cheap). The most common trainer is the C172 which is high wing and therefore doesn't need an electric fuel pump or tank switching so that's about it.

That's why you have an instructor.

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.

It hardly "defeats the purpose." You'll still learn to fly. You just won't learn to manage engines, which you can learn later on. Learning the two things separately is probably a good thing, since it'll let you focus on one thing at a 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.

>Unfortunately that defeats the purpose of a trainer, because "real" planes, which the trainer is supposed to prepare you for, won't be electric for quite a bit, so you do need to learn all about the intricacies and issues which can crop up on those planes.

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.

> We designed the aircraft for the niche application of pilot training, where the inability to carry a heavy payload or fly for more than 3 hours straight is not a problem and where cost is a major factor.

So a little less than 3 hours, I'd imagine.

> I didn't read the whole article

You should have stopped right there.

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