Drone swarms. What's your thoughts on the tech and applications good and bad?

[Pommie]

I got loads of info why a tiny glow outdid the petrol engines, not easy to explain and i am not sure i see the reason, but the figures speak for themselves. Also this time i will dig up info on the motor i used as the generator.

The reason glow engines have a very good power to weight ratio is because they are very easy to tune to give lots of power - down side is they use lots of fuel. If you do the calculations including fuel, the 4 stroke petrol engines win hands down every time. A 2kW 8 hour generator can weigh just 10kg - 8kg fuel and 2kg engine and generator. Also, as the fuel is burnt the craft gets lighter and uses less fuel - so probably 12 hours flight time.

Mike.

 

[dknguyen]

The reason glow engines have a very good power to weight ratio is because they are very easy to tune to give lots of power - down side is they use lots of fuel. If you do the calculations including fuel, the 4 stroke petrol engines win hands down every time. A 2kW 8 hour generator can weigh just 10kg - 8kg fuel and 2kg engine and generator. Also, as the fuel is burnt the craft gets lighter and uses less fuel - so probably 12 hours flight time.

Mike.

I thought glow engines have a better power-to-weight ratio than gas engines because even though glow fuel has a lower energy density than gasoline, you can burn so much more it per stroke that you can actually get higher power from glow fuel than gasoline for a given engine size. This is because when glow fuel burns, it provides some oxygen which lets you burn even more of it. To get the same amount of power from a gasoline engine you need more atmospheric oxygen so you need a larger engine.

The downside is that because glow fuel energy has a lower energy density than gasoline and you burn more of it per stroke to take advantage of its higher power density, you run out of it very quickly. You get a lot more energy from the the same tank full of gasoline, but you can't burn through it as fast to get that same level of power as glow fuel. The result is that for the same amount of gasoline, not only does the gas engine run longer because you can't burn through it as quickly, it also provides more energy per volume burned so a gas engine runs much MUCH longer. I think for the same size of model helicopter, a glow helicopter might fly for 15 minutes with higher performance levels while its gas counterpart will fly for 4 hours at lower performance.

 

[unclejed613]

https://www.rc-airplane-world.com/model-jet-engine.html i found out recently that these exist, an actual gas turbine for RC models...

 

[dknguyen]

https://www.rc-airplane-world.com/model-jet-engine.html i found out recently that these exist, an actual gas turbine for RC models...

You should see the ones that use a turbine to drive a propeller to make a turboprop. Also used in high-end model helicopters to turn the rotor.

 

[Pommie]

Two stroke engines have a much higher power to weight ratio. However, they are atrocious at fuel economy. When the UK restricted 16 Y.O. teenagers to 50cc motor cycles, all the manufacturers went 2 stroke. Once the restriction was lifted they all switched to bigger 4 strokes. I don't think any car manufacturer produces a 2 stroke because of the fuel consumption.

Mike.

 

[unclejed613]

i just saw a demo online of a new rotary engine. instead of a triangular rotor inside an oval cavity, it's an oval rotor inside a triangular cavity. it solves the problem of the wear on the points of the triangular rotor quite nicely.

https://www.popularmechanics.com/military/research/a15233/liquidpiston-darpa-contract/

plus, i just noticed something i forgot, it has a sparkplug for each third of the swept volume.

 

[dknguyen]

Two stroke engines have a much higher power to weight ratio. However, they are atrocious at fuel economy. When the UK restricted 16 Y.O. teenagers to 50cc motor cycles, all the manufacturers went 2 stroke. Once the restriction was lifted they all switched to bigger 4 strokes. I don't think any car manufacturer produces a 2 stroke because of the fuel consumption.

Mike.

I'm fairly certain it's actually illegal to use two-stroke engines in cars they burn oil and cars use so much more gas and there are so many more of them than motorcycles that it's banned for environmental reasons.

 

[tcmtech]

I'm fairly certain it's actually illegal to use two-stroke engines in cars they burn oil and cars use so much more gas and there are so many more of them than motorcycles that it's banned for environmental reasons.

They are almost universally now but that was not true in the past. There were many small vehicles of countless applications that used 2 stroke engines specifically for their good power to weight ratios.

Not everyone cares about what the fuel efficiency of an engine is either. If that was universally true, emissions compliance would have went the way of the 2 stroke shortly after it came into existence and people started getting stuck en masse stuck with new vehicles that suddenly saw 20 - 50% reduction in fuel economy for it from one previous non compliant models numbers to the new complaint models numbers.

One size and one data point does not fit all as a universal point of truth.

 

[large_ghostman]

Mike there is a way around the petrol thing, this is the bit the model RC guys are convinced is over unity, i have just tried again and it isnt, True a glow uses more methanol fuel that a petrol engine, but a petrol engine is much heavier, also note a small diesel out does both by a long long way.

Now the over unity bit your just going to have to try yourself. You can run a 2 stroke GLOW engine with a GLOW plug and not a spark plug on petrol, seriously this is true because i have done it and done it again tonight, NO timing used no modifications to the engine except when power is applied to the glow plug at low rpm. If you know that Methanol burns on its own with platinum as a catalyst, then the reasons seem fairly clear, to lower fuel consumption i mix ethanol in. Its got more punch but dosnt burn as well on its own, also you need it bone dry, so 3A molecular sieves in the tank and fresh dried ETOH only.

Now add 3-5ml per 150ml of fuel of petrol, that 3-5ml of petrol adds some serious punch but the down side in a RC plane is speed, the engine cant run slow, in a quad it dosnt matter as your not landing with the prop. Heat is the big issue with this mix, I way trying all kinds of tings to try and negate the heat problem. Also the glow plug matters, i dont know the number of the one i used, i know its made by OS and i think its a number 3...... I need to buy a couple and try them again.

Engine size, i dont know much about RC engines, most the ones i tried (i got roughly 40 odd beat up ebay ones) range from .25 on the body to 10cc. The ones that work best are the medium ones, they have 65 on the engine body, no idea what that is in CC. I know its under 10cc because they are smaller. I will video my bench runs, GLOW plug and petrol and Glow plug and my fuel. Decent caps would help because my motor i use as the generator knocks out 75V, I dont remember the electric drive motors now, but they were from sil labs dev kits, i still have them. I do remember that full chat they pulled 14A and were nasty to get near. This is why i had to sequence them because the power consumption was high.

Let me get some work out the way, i will then do some videos. But i would honestly put my engine up against a petrol any day, I am positive fuel wise I would come out on top. Dosnt work with castor oil, not sure why but carbon is one issue and the burn isnt right, but normal mower synthetic oil works fine if mixed with a tiny drop IPA or Trichlor if i run out of IPA .

 

[large_ghostman]

I'm fairly certain it's actually illegal to use two-stroke engines in cars they burn oil and cars use so much more gas and there are so many more of them than motorcycles that it's banned for environmental reasons.

No i dont remember the silly bug eyed cars name, but the modern one is twin cylinder and 2 stroke, sits one and I only seen two of them.

 

[large_ghostman]

I dont mind where this goes, but for me the limits and point of it were/are.... no special timing gear, no spark plugs, petrol i have used with little problem in a un modified glow engine with a glow plug. I will video it as i am aware this is over unity talk to model guys!!

I cant help it, i didnt know when i did it that it isnt meant to work! I wasnt and i am still not up on model engines, but i did get it working and without alot of fuss.

 

[unclejed613]

i had an idea long ago for an engine that uses helium. when you ionize helium (or any gas, but helium, argon, and neon are plentiful and inert, you wouldn't want to try this with oxygen, chlorine or even nitrogen), it doubles it's volume, remove the ionizing voltage and volume goes back to normal. you could double the efficiency by having two opposed cylinders, one would be "on" while the other is "off. of course the cylinder and piston would need to be made of ceramic, maybe teflon coated, and not metal. i don't know how much mechanical work you could get out of it, maybe not a whole lot. the increase in volume of burning gasoline is much larger than a 2:1 ratio, partially due to the temperature increase, but also from the change in density from a dense molecules to simpler, lighter molecules.

 

[unclejed613]

try and get military frequencies for a drone swarm!

actually, with the right equipment, you don't need to. as they drilled into us in Army Signal school "Your operating frequency stops being a secret as soon as the radio wave leaves the antenna". so, with an SDR transceiver, the device listens, grabs all the frequencies used by the drones (and yes this would work against frequency hopping/ spread spectrum devices) and transmits on all of them.

 

[large_ghostman]

actually, with the right equipment, you don't need to. as they drilled into us in Army Signal school "Your operating frequency stops being a secret as soon as the radio wave leaves the antenna". so, with an SDR transceiver, the device listens, grabs all the frequencies used by the drones (and yes this would work against frequency hopping/ spread spectrum devices) and transmits on all of them.

Now Jim will correct my errors but, it isnt about frequency as such. these days its all coded and encrypted in a carrier signal. A massive amount of money goes into making radio systems that are anything but easy to jam. Think predator drone, if it was easy they wouldnt be so effective. Not contradicting you but those things are totally fly by wire so the communication side has to be robust. People think ISIS is stupid etc, but look at some the IED's and what they can make from scrap.

Not all of them are uneducated stupid gun fodder, i think underestimating the capability of modern signals is a mistake. I dont pretend to begin to understand it, but i doubt it would be easy to bring down a military drone by radio signal. Even my lash up channel hopped and swapped about if needed, keep in mind it isnt sitting doing nothing its looking around for you, so you wouldnt get alot of time.

 

[large_ghostman]

Right I am back to peaceful use, i dont have an interest in mass destruction. thats actually pretty easy, but personally i prefer to look for solutions to help people.
So with that in mind I am going to spend some my free time back on the drones.

I might stick it on my website rather than clutter this place up.

 

[nsaspook]

Now Jim will correct my errors but, it isnt about frequency as such. these days its all coded and encrypted in a carrier signal. A massive amount of money goes into making radio systems that are anything but easy to jam. Think predator drone, if it was easy they wouldnt be so effective. Not contradicting you but those things are totally fly by wire so the communication side has to be robust. People think ISIS is stupid etc, but look at some the IED's and what they can make from scrap.

Not all of them are uneducated stupid gun fodder, i think underestimating the capability of modern signals is a mistake. I dont pretend to begin to understand it, but i doubt it would be easy to bring down a military drone by radio signal. Even my lash up channel hopped and swapped about if needed, keep in mind it isnt sitting doing nothing its looking around for you, so you wouldnt get alot of time.

It can be jammed at close range with pure power. We used traveling wave tubes (TWTs that you can find on ebay fairly cheap) for active missile and radar jamming with chaff to protect against some pretty advanced systems for the time. I'm sure active jamming has kept pace with current technology.

 

[unclejed613]

there's a lot of stuff that SDR makes easy, that used to be very difficult with normal radio hardware. for instance, a drone swarm must have communication between all the drones in the swarm, or at least from one drone acting as the brains to the rest of the swarm. what would happen if the master drone's communications with the rest of the swarm were recorded, and just played back in an endless loop? playback attacks are very simple to do with SDR because you can catch the whole chunk of spectrum at once, and play it back exactly as it was received. if the swarm were being ordered to execute a left turn, what would happen if that set of instructions were played back repeatedly? the swarm would be flying around in circles. meanwhile, the master drone executes it's left turn and flies away. leaving the rest of the swarm with no further instructions. once the playback loop stops, the rest of the swarm, not being in contact with the master drone, would most likely head back to the start coordinates.

another possibility, and the technique is quite effective as a defense against drones, is GPS spoofing. since GPS satellites are hundreds or thousands of miles from the surface, it doesn't take much power to spoof GPS. GPS spoofing is used in Moscow to protect government buildings from drones, and i wouldn't be surprised if it's used here in the USA as well. the GPS spoof makes phones and other devices display that they are at the airport. since many drones have a "no fly" database that includes airports, if they see the airport's coordinates as their current location, they will either fly home, or shut down. even if a drone swarm (and since we're assuming the drone swarm is operated by a government entity, and would not have a "no fly" feature) doesn't stop at an airport boundary, if the drone swarm's target is a particular location, GPS spoofing can fool the swarm into thinking it's somewhere else. or if the elevation data were spoofed, the swarm could be caused to crash land.

 

[large_ghostman]

GPS is the domain of commercial toy drones, GPS isnt relied on or the sole means a drone finds position. In my own case when i looked at a RC solution for getting coms from wind turbine panels in places you couldnt reach easily, GPS was not great because of the hills and woods. And seriously if you got a killer drone it isnt going to kill you by flying into your head. You need something that will work at a minimum of 500 meters.

Our prisons are trying jamming, little success so far, hawks work better. Coms in swarm assumes you have a single master, why would you design like that? Why not more like a CAN system with multi master and the ability to switch, it started as a military drone (big budget) V a person. now we have dropped to avoiding commercial toys with a grenade on, my point still stands, if a drone is so easy to defeat how come predator drones are so effective?

Think sat mapping and terrain identification via a vision system, accurate time and compass techniques, GPS as add on. I have no idea what is available in a military sense, but i know several years ago with a pile of junk (literally) i built a self guiding and flying drone. it could pick people out no problem. I didnt use the same system as MIT, mine used tri colour vision and it switched colours and made things into blocks, its quicker and more accurate than the system they used.


I also forgot the 1000m long range blue tooth, you can that off the shelf
jump ahead a few years to the point that drones are real cheap and easy to get (hardly any around a few years back), I bet with a half decent budget you would have a hard time not getting killed by a small drone swarm. 1/4 mile with a decent one shot bullet system and guidance camera...... Gut feeling is you wouldnt know it was on you before it was over. The military special forces helping in places they shouldnt be, are finding shop brought drones with hand grenades on a problem.

If jamming is so simple why are both British and American special forces finding it hard to take those hand made commercial drones out? Its simply got to be high enough and in the sun or whatever and drop it, by the time it hits the ground you got what 1-2 seconds? Enough time to mutter Oh Sh.........

How directional is the jammer? you said swarm, so to me that means 3-4 minimum. What you going to do spin around in a circle all day?

1000 meter long range bluetooth would also be an issue

 

[large_ghostman]

Found what i was looking for! the site is awful!!
I used the pro kit which is old now, but look at the specs, i have several of these kits and one of the new mesh kits i havnt opened yet.
https://www.silabs.com/products/wir...-ism-band-transmitters-recievers-transceivers
https://www.silabs.com/products/wireless/multiprotocol-connectivity
https://www.silabs.com/products/wireless/proprietary/efr32-flex-gecko-2-4-ghz-sub-ghz
https://www.silabs.com/products/wireless/mesh-networking/thread

And finally, mesh networks. Game set and match .

 

[unclejed613]

if you have military drones snooping around, you've got problems that won't be solved by jamming the drones. if you have government agencies sending drones to spy on you, in your own country, it's likely that such things are either illegal, or have legal hoops to jump through before they can do that. here in the USA we have a Constitution that's supposed to protect We the People from such things, but it doesn't always work out that way. to paraphrase Mel Gibson "why worry about one tyrant 3000 miles away if there's 3000 tyrants one mile away". we have state and local governments that seem plenty willing to take on the job of spying on their citizens. however those same bureaucrats don't have billions of dollars to spend on technology. they're not going to be buying missile carrying Predator drones for millions of dollars each. i'm equally sure they're not going to Walmart to get their drones either. even so, they likely will be getting equipment that either operates in the ISM bands, or through a cell phone link, or maybe in the public service bands (except there's not a whole lot of bandwidth available there). such drones are very likely to either be controlled from a remote location (maybe within a 1 or 2 mile radius) or pre-programmed, which requires GPS. even remotely controlled drones rely on GPS to report position. the drones need bandwidth to send any video and audio back to the controller. encrypted or not, frequency hopping or not, the radio link is a weak point. so is the GPS. another weakness is that federal, state, and local agencies must file flight plans, even under 200ft AGL. private companies must also file flight plans. there are simple ways to get flight plan data, since it must be publicly available. also publicly available is the FCC database of radio licenses for any equipment that isn't using ISM or cellphone bands, so any drones operating outside the cell and ISM bands will have a license on file.