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Comment by tylerchilds | Hacker News Reader

Anecdotally, I never got into drones because of the batteries. Everyone I met that had them absolutely loved them, but had like 4 batteries they needed to keep charged for about 15 minutes of flight time.

And quite a few tried pushing that a little too long an ended up with crashed drones. So my half cent is that batteries need to get better before people like me even consider them. Mentioned 0 times in that article.

Alternatively, drones need to get efficient enough to be solar powered, which is maybe the intent behind the acquisitions by PrecisionHawk Inc.

https://www.precisionhawk.com/blog/media/topic/precisionhawk...

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Even more generally, when I've thought about getting a drone, I imagine flying it around my house a few times, take some video, and then what?

I don't really want to take it out into nature environments. That seems obnoxious where it's even allowed.

I suppose I could find clubs that fiddle with the things but I don't really have the interest.

So, basically, I have trouble imagining how I'd use them for more than a couple days.

I have a DJI Spark. It's loud when it's close but as soon as it's a few hundred feet away you can barely hear it. I primarily use it in nature and usually use it at 200-400ft elevation. At 200 ft it's quieter than standing next to a running car. At 400 ft you really have to try to hear it.

It's loud when it's close but as soon as it's a few hundred feet away you can barely hear it.

If you're in an open area. And if there is only one drone.

A couple of years ago I was in a serene canyon in Utah enjoying the peace and watching nature when three drones decided to scare away the bighorn sheep.

People don't hate drones because they hate drones. That's why many seem to like the idea of Amazon/UPS drone deliveries. They hate drones because of what the drone pilots do with them.

"Quieter than standing next to a running car" isn't a good criterion for subjecting strangers to noise in a public place they're probably visiting at least in part to get some quiet and seclusion.

I don't mean to be a dick; I've been flying R/C for ~25 years and I know how difficult it can be to find fun places to fly and how frustrating when other people get in the way of that. But I also really appreciate quietness and because I live in a city it's a rare gift for me when I do get out into nature. Please have some consideration for others and don't unilaterally decide what noise level is acceptable for them unless there are already significant sources of noise present or you're really sure nobody else is around.

The guys with their ATVs and dirt bikes and those dumping trash everywhere are also huge problems.

Yeah but mostly on BLM land, and that's kind of what it's for? As long as the local USFS rangers are writing tickets, they mostly stay out of national forest. I'm never seen them at national parks, wilderness areas, etc.

BLM land is most certainly NOT for dumping trash...

I was trying to think of something to compare it to that others would relate to. A car wasn't a good example since the dB level varies significantly. I was trying to make the point that it's quiet at that distance. If you were having a conversation with someone you wouldn't notice it.

> At 200 ft it's quieter than standing next to a running car.

Really very loud then for the people around you in a nature environment.

For me, standing next to a running car is already sort of noise polution, especially if the car could be turned off as well.

Last time I heard a drone fly overhead, I definitely felt anoyed. People tend to overlook the impact their toys have on other individuals

Maybe you have to try to hear it, but I spend a lot of time in large public parks and, without fail, hear drones flying overhead.

This just started in the last year or so, where virtually every time there's a drone off in the distance.

I don't have great hearing either (especially in one ear), after playing some musical instruments that you hold close to one ear to play. Those things are just loud and stand out when the other noises are the wind in the trees, birds, and the rustle of small animals in the underbrush.

I imagine if you get an FPV headset it's quite a fun activity.

If people can spend thousands of hours playing flight simulators on the computer, surely there's a lot of replay value of doing the same thing with an RC quadcopter through a forest or around your home/neighborhood w/FPV.

This. This is the main thing I want to do.

I havent bought one yet, but have flown a cool DJI/FPV setup around a local mountain. It was really fun

Yeah, it's on my list. Though I'm more interested in getting a powered electric glider w/FPV instead. It won't annoy the neighbors as much.

I made my own flying wing for about $300 all in (the controller and goggles are usable with any other open-hardware drone, though). It's really fun, I recommend it, and it's not as loud since it only has one motor.

Did you document the build or put info about it online? :)

No, it is a fairly stock one. However, tell you what, if you want you can follow me on https://www.instagram.com/stavrosware/ and I'll document it there (I'm rebuilding it).

Wow, that is impressive. I thought I would have to spend around double or triple the amount to get started with this. Would be really interested if you could share some details on this.

Certainly. I am also rebuilding the wing and another commenter asked for info, so I can post photos and details on https://www.instagram.com/stavrosware/ if you want.

I bought a Taranis QX7 remote controller (~$100), which is amazing and I love it and you can use it with any other RC vehicle you want. I even hook up the receiver to my hardware projects so I can control them remotely.

You also need an FrSky XSR or R-XSR receiver (~$10), a Beitian BN-220 GPS (~$10), a motor and ESC (be careful, get a plane ESC, not a quad ESC, the plane one is larger and has better heat dissipation, ~$30). You need two small servos for the elevons, those cost about a dollar each. You also need a good soldering iron (the TS100 is $35 and is amazing.

For the controller, the Kakute F7 is fantastic and costs $45ish. It can fly in modes ranging from manual to completely autonomous (you get a Google Maps interface and mark where you want it to go and it just flies to those points). This may be a bit overkill, as it's the best board around, you can get a cheaper one (or maybe one that is made specifically for planes) no problem, but it's only $10 cheaper.

The FPV goggles can cost around $30 for some cheap ones, adjust those to taste.

I think that's it for components, although I should probably do a proper writeup if people are interested. There's much info out there already, but it might not be concentrated in one place. Let me know if you have any more questions!

I think the biggest point might be the Wing itself. Did you built that on your own or did you use a pre-made model?

Oh oops, I forgot about the body. I bought an AR.wing, I think it was $80. I was wondering why the total only came up to about $200...

Looked into the AR.wing yesterday and that seems to be a great model. I will totally look into this, thanks for all your information!

Anecdotal, but the FPV drone pilots I've seen are much more responsible and aware than photography drone pilots (I'm a part of both communities).

Photography drone pilots will do all kinds of stupid shit that horrifies me, like fly near people, near obstacles, under trees, in crowded places, etc etc.

I blame it on the fact that a Mavic is super easy to get and requires no knowledge, whereas it took me two hours of reading just to figure out how to start my racing drone.

I usually get into stuff like this for professional reasons. However, as someone in the aerospace industry, it’s not very common that we go through the hoops to get a drone out at the airport. We’ve talked about using one strictly inside of our hangars, but at that point a gyro does just as well.

I’ll stick to writing code.

Have you ever been to go karts? To me flying a drone is much like that. I have never had an expensive drone only flew the 50$ or less drones I have gotten my young children. Flying around the yard avoiding things trying to land in different spots is a heck of a lot of fun with no real purpose. I can only imagine the countless hours of fun I would have with first person view flying. So for me I like drones just for fun. Though I do not fly every single day, every once in a while I will go out for a fly. The drones with the ability to take pictures is a lot of fun. A drone getting away on you and almost crashing but adrenaline kicks in and you run after it and save it in the nick of time is a thrilling experience. This some of the best fun I’ve had playing with my kids toys.

I've had a couple of <$50 drones which I've played with a bit. It was fine for the money--though very fiddly, at least the ones I've had. Hard to actually use the camera.

Fun enough for a few hours punctuated by recharging but not really something I see myself spending $500-$1000 on. I don't have kids. I can see them being fun toys. I spent many hours as a child playing with balsa wood gliders for example.

I feel much the same way. The one I have came with 2 batteries and with a couple more I think you could continually swap out and it only takes second with no tools required. The charge time was under half hour. But like you say I don’t know if I could push myself to pay 1000$ for a drone. I mean with one like that you can do a lot more and the range is a lot farther but at that price I would be terrified to lose it if it ever left my sight. The 50$ drone I push for my own adrenaline’s sake, over the water, through the trees, over the death spot if it dies. But if 1000$ falls into the water I will be swimming and I don’t like getting wet!

It depends on how you use them. I travel full time so I primarily use mine for nature photography. 15 min is usually plenty of time and if not I have a 2nd battery that takes no time to swap. It would be nice to have longer battery life but it's not a deal breaker.

The only cases where needing more time would be a big deal would be for filming something that lasts longer than the battery.

This. I recently worked with a company that produces drones among other things, and spoke with the head of research there.

More or less, they said they had given up on putting money into drone R&D until battery technology caught up, as they had plenty of ideas that they believed in but were unfeasible due to battery life.

As RC vehicles {car|helicopter|plane} get larger they reach a certain mass where liquid fuel - usually a petroleum - is preferable to battery. Why is this not an alternative for drones?

Indeed this has been done since WWI. https://www.warhistoryonline.com/military-vehicle-news/short...

Let me rephrase: why would companies consider battery life a limit when liquid fuel is a viable way forward for range, time-aloft or size?

Nobody wants to risk the liability and noise of a flying lawnmower.

Repeating my post above:

Given the line of sight limitation for drones, gas power does not add much value. Batteries are usually sufficient to map/photograph the area within range of the operator. Given this legal limitation, it is often more economical to hire a small plane like a Cessna with an avionics package and a 400 mi range.

And then use it for what?

They exist, but they are expensive. https://www.youtube.com/watch?v=wS0Hr2lw604

It certainly has been done, and on small drones too.

It's been done, but it's expensive. Not many people can drop $30,000 on a drone: https://www.bhphotovideo.com/c/product/1416171-REG/walkera_q...

It's hardly $30k to buy a gas drone. You can buy a Cox .049 engine for $50 or so.

You're looking at a fixed wing aircraft though with one of those. What's made the quadcopter drone possible is the high torque and instantaneous throttle response of small electric motors, combined with fast control electronics. The conventional way to fly a small helicopter is just like a full sized helicopter, with a main rotor and a mechanical swash plate.

With the right control electronics, these can easily be made into drones, but people tend to not like them as much anymore because they're mechanically complex and finicky. The electric motors are simple, and when one goes bad you just drop in a new one.

Could you couple one of those engines to a generator, and use that to power the electric motors? You'd need a battery or supercapacitor to handle change in throttle demand that outpaces generator response too.

Weight is the limiting factor. Try to find a generator that can output up to 400amps at 25V (what my big drone draws) and yet weighs less than five pounds including fuel.

I think that’s a more impossible goal than increasing power density in batteries is.

400 ampere??

Thermal to mechanical to electrical to mechanical. That’s a lot of energy conversions and with each conversion you lose a lot of efficiencies.

https://youtu.be/7zMPodObo-Y

This guy tries to make gasoline powered generator for large drone.

I've watched people fly RC airplane and helicopters with gas engines. They still exist, and there are air fields for them. I've seen them since the 90s as a kid. They aren't expensive but, are bigger and require an actual landing and takeoff area.

https://www.hobbytown.com/gas-rc-airplanes/c7574

Those aren’t usually gas, but rather a nitromethane mix, runs off glow plugs (saves all the issues of timing, spark plus, distributors...)

Controls are more complicated if you're not using electric motors where a microcontroller can easily adjust the RPM. Someones already linked a hybrid drone with a gas powered generator but it's not cheap. In high volume it could probably come down a lot but I don't know how much demand there is for it.

The electric motors used can change the speed of 4+ independent propellers extremely quickly.

This is hard to do with petrol engines, without costing a lot of extra weight or mechanical complexity, in a system where any single failure means a crash

I wonder if there's some simple variable transmission that could be electronically controlled to deliver power from the motor to the propellers in highly controlled fashion.

A generator and four motors. Efficiency would probably be around 70%. It's about 90% in diesel-electric locomotives where more weight and money is spent on efficient conversion hardware.

That adds weight of 4 beefy electric motors to the system.

There's differential based continous variable transmission that varies according to resistive torque on a control shaft: https://makezine.com/2012/08/10/lego-continuously-variable-t...

This might enable electronic control witout using any motors just one simple coil per propeller. Energy generated through this way of control could be stored to power onboard devices.

For me, it’s the FAA notification requirements that seem daunting. It looks like the situation may be better than it used to be, but it’s still confusing at a glance.

Get your Remote Pilot license and you’ll understand that process inside and out.

With petrol’s energy density, why not make gas powered drones? Gas engine → generator → small battery (backup power) → electric motors. This is what manned drones (still in development) do.

Great idea if you have robust controls! Terrible idea if you don't, because a crash can handily result in a fire or an explosion.

Heavier fuels (kerosen, a/k/a jet fuel, diesel) have equivalent energy density to petrol, but are far less flamable. You might get a small fire, but not an explosion. And there are a lot of RC aircraft already.

They are noisy, however. Drone buzz now is simply from spinning fans. Adding a reciprocating motor to the mix is all the louder.

The alternative is lighter airframes and solar power. For quads / octos, probably not viable, but for a prop-driven fixed-wing craft, a very small amount of thrust to counter gravity could be quite effective. Expanded polystyrene or similarly light body, solar cells over all horizontal surfaces, and an ultra-lightweighted controls and imaging payload. That would allow for long-duration flights at least in daylight.

The low-energy use would also make battery-powered night flights more viable, certainly beyond 15 minutes.

The principle cost is loss of hover capabilities.

Yes, but the motor (turbine) to run kero is more expensive than the motor (piston) to run petrol.

The motor to run the drones was expensive till they became mass produced and dropped in price. Same for the batteries. DJI Drones aren't exactly cheap either.

also I believe if you want to be pedantic, if it runs on combustion it's a engine. if electric then a motor.

> also I believe if you want to be pedantic, if it runs on combustion it's a engine. if electric then a motor.

I think that might be less general than you think: General Motors hasn't exactly been known for their electric motors the last few decades.

Also see: https://en.wikipedia.org/wiki/Engine

"Motor" is commonly used for rockets too, eg:

https://en.wikipedia.org/wiki/Model_rocket_motor_classificat...

The motor/engine dichotomy is blurry at best.

However "reciprocating engine" has a clear usage preponderance over "reciprocating motor":

https://books.google.com/ngrams/graph?content=reciprocating%...

Given the line of sight limitation for drones, gas power does not add much value. Batteries are usually sufficient to map/photograph the area within range of the operator. Given this limitation, it is often more economical to hire a small plane like a Cessna with an avionics package and a 400 mi range.

> With petrol’s energy density, why not make gas powered drones?

They exist and are used for long distance drones.

My brother used to have RC airplanes. Gas is messy, and starting even a single prop was a massive pain. Motors are also less laggy, and probably easier to precisely control than engine throttles.

Now, that's for small scale drones flying 15 minutes. For, say, commercial airplanes that can fly 18 hours, energy density becomes a major factor.

Tech Ingredients YouTube channel guys did this. They used two two-stroke RC engines to reduce vibrations, and can apparently get close to 2kW.

Build: https://www.youtube.com/watch?v=1yB49G756OI

Generator tests: https://www.youtube.com/watch?v=7zMPodObo-Y and https://www.youtube.com/watch?v=uf78udpz3aI

Not sure how well it'll work in practice but fun build.

This one is better: https://www.youtube.com/watch?v=wS0Hr2lw604

Longer flight times are possible, if an engine is used instead (plus servos to change prop pitch). I'm just not sure why it hasn't been pursued much (can't be the noise - electrics aren't exactly silent)...

People have used fuel-powered drones extensively before Li-Po batteries got good (including me). My take on why they haven't taken off as much as the modern quadcopters: they are quite a bit scarier.

The main two types of flier before quadcopters were fixed-wing model airplanes, and helicopters. They are both riskier to use than quadcopters: fixed wings can't be stationary and need a large area to fly around, while helicopters have large dangerous blades. This is why either of these are less attractive to the mass market.

On the flip-side, I think converting a quadcopter to use an engine is expensive because controlling 4 blades at once is not as simple as with 4 electric motors. Either they need to have 4 gas engines (expensive, not as responsive as electrics) or they need to have a variable pitch mechanism (now you need an intricate/expensive mechanical system of levers and servos to transfer the control).

Curtis Youngblood, the OG Heli god himself, actually has 2 stroke collective pitch drones: http://www.curtisyoungblood.com/platforms/tdp-mr/

It's a scaled up version of his stingray.

It has, just in the form of Helicopters. Its been known for a while that moving a lot of air slowly with a bigger blade is more efficient than moving less air faster with 4 props.

The issue is that stability and control is easier to do with 4 blades rather than with one that has a swash plate.

Seems like graphene batteries are just around the corner and safer than lipo, with a few time the charge, that'll be interesting to see!

Seems like graphene has been around the corner for a decade or more - are there any real world applications yet?

Suncream (sunscreen)

I never got into them for the same reason I never got into football or (before I had to for professional reasons) Linux - everyone who is into it turns it into an evangelism project.

I’m sure I would love them if I tried them, but I don’t want to be seen as the type of guy who owns a drone (like how I don’t want to be known as the guy who uses Linux or the village Libertarian, even though those words might describe me reasonably well).

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