Gas Thruster Controlled Drone

[@BPSspace]

PSHHH PSHHHHHH, PSHHH! (That says “Great work, Tom!” in RCS)

[@TomStantonEngineering]

Google translate won't help me write a reply

[@CaptainJohn]

Tom Stanton lol

[@DickyBenfield]

I follow you both. It was really cool to see Joe on your channel! Keep up the great work and content guys!!

[@leveckfamily8841]

Or "HOW DARE YOU SIR!"

[@shivamvaid601]

You low key look like Elon. 😂

[@PracticalEngineeringChannel]

So cool! The idea to convert the throttle values from a standard flight computer was really clever.

[@TomStantonEngineering]

Thanks Grady!

[@power-max]

I was surprised a simple, naive threshold worked so well!

[@alphaforce6998]

Yes, exceptionally clever considering nobody else anywhere, ever thought to do the same thing. An original comment for an original idea.

[@calebsherman886]

@@alphaforce6998 This feels alot like sarcasm

[@alphaforce6998]

@@calebsherman886 I think we can build a test rig to help determine that conclusively.

[@frederickevans4113]

2 words: pressure regulator. Tune the system for (pulling numbers from thin air), say, 40 psi. Install a pressure regulator and set it to the aforementioned 40 psi. Fill the bottles to the max pressure your compressor can output: 116 psi, IIRC. The regulator should regulate the 116 psi down to 40, giving you constant, predictable & repeatable thrust until the bottles drain to below 40 themselves. Problem might be finding a pressure regulator with a low enough mass to not overload the drone.

[@Trzpsq]

Frederick Evans 72 words actually

[@None_x934]

@@Trzpsq lol

[@DannySullivanMusic]

yup. completely right dude

[@hateWinVista]

So much this, pressure regulators are required for any gas system. Micro pressure regulators do exist and the lightest one seemed to be from landefeld. Their R M5 series is lower than 50 grams and rated up to 8 barg(2L PET bottles seem to hold up-to 150psi which is around 10barg, he tests the flights with 100psi) but additional setup will certainly be higher than 50g.

[@laramie371]

The mass is the problem here. He would probably get less flight time then he would gain from them.

[@btw04]

Whoever wrote the subtitles deserves a medal.

[@Faldrian]

"Yes I'm typing this by hand"

[@RCP-1136]

@@Faldrian when does this come up? did not see it-.-

[@stjepanbrkic3215]

@@RCP-1136 19:50

[@Faldrian]

@@RCP-1136 Look for the flight test part. :)

[@TheJustinsmurphy]

You need to have a converging nozzle. Diverging nozzles like the rocket nozzle are for supersonic flow!

[@forestdenizen6497]

This. Thrust comes from acceleration of the fluid. Even better, use the air supply to drive an air multiplying housing instead of using it directly. For those who haven't heard of air multipliers they are industrial devices with no moving parts, powered by compressed air and used to move air for ventilation. The Dyson fan uses this concept.

[@ultra881]

That entire part of the video was so frustrating to watch!

[@Paul-ev5wf]

You can see at 6:22 he uses a converging nozzle. He probably changed the design after being told but didnt explain it in the video.

[@mcsons13]

He does have supersonic flow. Going from 6 bar to 1 bar will give you supersonic flow at the nozzle throat.

[@slowpnir]

He can't have supersonic flow at all, no matter what the gas pressure is. The reason rockets have supersonic is the fuel is burned, producing the shockwave, which is funneled through nozzle.

[@grillsidepickin2397]

The pure joy on your face @ 12:14 when it's working is absolutely heart warming. I love seeing this level of human emotion. Especially during moments of triumph. Keep at it brother! You're awesome!

[@mrbrianbray]

"Let's just admire how little thrust this system actually produces." Love it.

[@onidaaitsubasa4177]

If it was in space though a little thrust is all it needs, it could actually go quite fast.

[@psycopirla1]

You need a converging nozzle cause you have a subsonic air flow passing through it. The higher the pressure in the tank the narrower has to be the nozzle and the more thrust you'll get out of it. This is true until you hit mach 1 in the nozzle narrower section, at that point you'll have to start increasing the nozzle section in order to further accelerate the air flow.

[@Zaros262]

6:18 he did end up using a converging nozzle

[@junovzla]

@@Zaros262 but he didn't use the expanding nozzle after the converging section

[@sullivan3503]

@@junovzla It likely doesn't reach Mach 1 anyway, so it would actually be bad to have a diverging section.

[@docostler]

I recall that years ago there was a small group (I've forgotten the name, unfortunately) in B.C. or Washington state that was sending soft drink water rockets over 1000 feet. They modified the bottles by wrapping carbon fibre around them using epoxy. These bottles were pressurized to as much as 2000 psi. Part of the success at reaching such heights was that they used dilute water/dish soap along with air for propulsion. They just poured it into the pressure vessel bottles before charging. As I recall, the most difficult problem was coming up with a reliable and safe way of setting them off. Another observation for this project is that you don't need a separate bottle for each nozzle, in fact it may be counterproductive to do so. Interconnecting the bottles would provide a more consistent pressure at each nozzle. Or add more bottles. Or make a custom bottle that utilizes all the dead space currently existing between the separate bottles.

[@misium]

De Laval nozzle. A narrowing of the flow increases speed of the flow and thus thrust (that's how subsonic jet nozzles look like). The widening is only needed if your flow reaches the speed of sound at the throat (supersonic jets and rockets). Wikipedia has a good overview.

[@DaveMody]

It should be able to go sonic when the pressure is roughly twice atmospheric.

[@alphaforce6998]

Thanks for chiming in with what you read on wikipedia. Clearly all it takes for anyone to become an expert on any topic is a cursory scan of wikipedia, and off you go to a comments section to dispense qualified advice.

[@dapz]

@@alphaforce6998 Wikipedia is not always wrong, or even wrong half the time, and he never admitted to being an expert. Anyways this not even anything complicated, it's like if the guy was asking what 2+2 is, and this guy replied 4, you don't need to be a mathematician to be able to learn that or even find it out yourself.

[@alphaforce6998]

@@dapz Well, that's the thing - nobody was asking anything... And he would have first consulted wikipedia's entries about the number 2, addition, and basic arithmetic.

[@misium]

@@alphaforce6998 What seems to be the problem? Looks like the only thing wrong here is your attitude.

[@ryanm.191]

This guys playing kerbal space program in real life Edit: if you edit a comment you lose your heart.

[@epicwarredpanda0155]

*JEB NOOOOOOOOOO* **Boom**

[@alphaforce6998]

What's a "space program"? Some new computer simulation?

[@ryanmarshall8925]

Oh hey Ryan M, it's me Ryan M

[@martindinner3621]

Needs moar boosterz.

[@IkKorp]

@@alphaforce6998 its fun try it kerbal space program

[@ejtliu]

Is it a bird? Is it a plane? Is it a flying submarine? No, it’s just one of tom’s creative inventions

[@eestaashottentotti2242]

It is a drone. (Or if you mean that man there? He is Superman.).

[@welshsteve2009]

It would be great if you attached an LED at each corner connected to each valve. That way you could slow down the video and watch the valves operating 🤔😜

[@cenabitednbfpv587]

Wow awesome idea For slow motion tuning like a black box for your eyes to see what's taking place or needs to.. u guys are amazing

[@welshsteve2009]

@@cenabitednbfpv587 Exactly!

[@chrismofer]

for a better control system: pulse the valve on and off at (relatively) high speed and you essentially have throttle control. instead of a simple gate you could have more like a minumum and from there to maximum it scales the pulses.

[@arnavjain7564]

Not sure if solenoid valves are that fast

[@KnowledgePerformance7]

I don't think the valves can move that quickly

[@murdelabop]

Pulse width modulation? If the valves can react fast enough that would work.

[@chrismofer]

​@@arnavjain7564 to expand on why I said relatively, there is an absolute minimum time to open the valve and another time till closed, which will result in a limit to the maximum cycle frequency. I understand this reality. It certainly won't maintain RC PWM freqs, but something alike PWM done in Hz frequencies is what I have in mind. I'd keep the gate on the input, but make it trigger lower. if the input > gate, then the thruster should start a cyclical pulse who's duration is proportional to the magnitude of the input (up to 100% duty cycle for a 'full throttle' command). Many smaller pulses should use the same amount of air as a few big pulses, so I don't think we'd see a huge drop in efficiency or anything. These are test bench questions to answer. In full size rockets utilizing RCS's in space, they don't deal with any of this because they're not inherently unstable balancing broomsticks quite like a wingless thruster in an atmosphere is. The RCS activity looks like a few 'pings', followed by silence as the ship rotates for a minute, then a ping or 2 more to stop that rotation. our implementation would need to differ in this regard to account for wholly different stability circumstances. I also implore Tom to revisit the nozzle. the bell of a rocket nozzle is useless without first accelerating the gasses supersonically with a throat restriction. The bell was also simply too big, in my estimation. The bell of an Estes rocket motor is smaller, and that motor produces hundreds of times the thrust. just saying, possibly a lot more efficiency could be squeezed out by looking back at the de Laval design principles. It is also 3D printed with FDM, meaning the inside is ribbed with a repeating half circle pattern. this will mess up your boundary layer flow which means turbulence which means loss in efficiency and thrust. Tom, if you come up with another nozzle design I can print it with an MSLA machine, threads and all, polish the interior surfaces with a lathe and ship them to you. Otherwise I'd look into acetone vapor polishing the nozzles printed in ABS. I also have the setups for doing this if you need.

[@Charlie90071]

@@chrismofer yea a couple hertz like say 5Hz should be possible i think

[@ChaseMadden]

Love how encouraging your dad (I'm assuming that's your dad) is in so many of your videos... He has every reason to be incredibly proud.

[@maxmorelikewantedfortaxeva2366]

Can we be best friends

[@landroveraddict2457]

Add a pressure sensor to the tanks, create a lookup table for each pressure level that adds or removes bias from your valve timing values.

[@eltimbalino]

The exact pressure is not critical, so maybe the weight and complication of a pressure sensor can be avoided. If you started with variables for pressure and volume, then you could calculate how much gas comes out of a nozzel during its on period. Updating a remaining-volume variable would enable you to predict the remaining pressure which feeds into the calculation for the next nozzle release. In this way you could compute the pressure to use when compensating for loss of thrust. The arduino board that is converting a gradient signal to on/off might be able to manage this between thrusts.

[@babydaddy4257]

Are either of you guys control systems engineers?

[@babydaddy4257]

@Jonny B i asked bcause i had a PLC question

[@fenderrexfender]

pid values*

[@fenderrexfender]

less gas more time.time must be scaled !!!!

[@Nuovoswiss]

There is a simple way to have a compressed fluid that doesn't change pressure as it is vented: use a liquid that boils below room temperature. Propane should work (though the pressure gets sketchy-high for 2 liters on warm days). If flammable propellants aren't your thing, then "canned air" should also work. Using boiling liquid has the added benefit of being able to carry much more propellant in your tanks.

[@ARVash]

dry ice would definitely similarly very high pressure, a pressure release valve might help mitigate that

[@HungrysitesRu]

maybe chemical gas generator? CaC2+H2O or something like that?

[@RCLoversan]

Well spotted! Propane has a density of 493kg/cm3, while compressed air has just 1.2 kg/cm3, that's why using compressed air you need an unbelievable amount of pressure to stabilize anything (rockets/drones/etc., etc.). Please check the propane gas thrusters created 5 years ago by Amazingdiyprojects. He created this system for his steam model rocket motor. If BPS will use propane, booya, we are going to see some serious fireworks. :-)

[@Codebreakerblue]

oh goodness, i just realized what would happen using propane with a solid rocket propulsion mechanism

[@alphaforce6998]

Did someone actually suggest venting propane for thrust instead of igniting it? We must be at a genius convention here... Maybe you can just power the drone by getting an extension cord and plugging it into itself for abundant free electricity.

[@Devvy996]

This guy looks like a hybrid of Elon musk and Mcauley Culkin

[@tolishaws]

Lol

[@sephjfox]

Nailed it

[@sometimesChris01]

My exact thoughts

[@prettypointlessvideo]

Steve Buscemi haha

[@boxyguy3681]

And he runs like Dr. Evil

[@thejayjay154]

Elon living a second Life as a de-aged clone. Man is rich enough

[@1.618_Murphy]

Most underrated comment on this video! He sure does look like ELON and also trying to do basically the same thing ELON is conducting, which is to say, bringing back and landing a rocket on its own!

[@darkracer1252]

i am convinced this is actually the truth. @elon musk. what did we win?

[@atmanbrahman5296]

I cannot deny that .. looks suspious

[@isetta4083]

This guy isn't an evil supervillain however

[@Alimentasable]

Except Elon isn't an engineer and hasn't really done anything worthy in terms of engineering.

[@Stigstigster]

When he flicked that self level switch on the controller it made me smile from ear to ear. That was really very cool to see working for the first time. This whole thing is amazing.

[@arkadiusztrzesniewski4237]

15:35 I love that sci-fi sounds this drone emits during liftoff attempts.

[@blitzvinnigFPV]

No ways, you never cease to impress me Tom!

[@pcislocked]

0:42 i literally JUMPED from my couch when i see joe im huge fan of his rockets

[@prachethire812]

The joy of getting a project behave as expected is unparallel. Great work, this will help engineering students who are studying control systems and have no idea where it's going to be applied.

[@patrickmihajlovic4112]

Best part of vid was to see you giggling and enjoying every little step to the final success !!👍💪!! Nice to observe pure dedication !

[@muh1h1]

i love how he called one of his rockets "Thrusty McThrustface" :D I'm guessing this is a community effort? :D

[@Forgotten_Foods]

yes, muh macmuhface

[@thejupitergod5687]

There is a submarine named boaty mcboatface

[@Bibibosh]

muh1h1 mc blank face , comes from the idea that when u insult someone you call them a FUCKFACE! the mc comes from .. mc lovin. so. mc *insert word* face

[@hgwells1899]

The creators of a polar research ship invited a public vote to name it. A prank name, Boaty McBoatface, suggested by a radio dj, went viral, and won. But the owners rejected it in favour of 4th place vote, RSS Sir David Attenborough. They did, however, give the name to a small, unmanned research submarine. It's a well known story here in the UK, hence the jokey Thrusty McThrustface

[@muh1h1]

@@hgwells1899 i know the story. I've also heard about a city who introduced a new machine to throw salt and gravel on icy roads and asked the public for names. The winning entry was something like "itsy gritsy teeny wheeny yellow anti slip machiney" :D

[@gavin_wer_customs6431]

Can we all take a second to appreciate the fact that tom typed all the subtitles in this video by hand

[@Frisenette]

You could probably gain some efficiency by also ducting the nozzles. Venturi effect etc.

[@andrewakrause]

The venturi effect may increase the velocity of the gasses, but it doesn't change the mass, therefore doesn't change thrust. The nozzles actually increased the surface area which increased drag which reduced thrust.

[@Frisenette]

Andrew Krause you trade pressure for mass flow. Just what you want. The ducts around the nozzle would work somewhat like the duct around the prop.

[@Infaviored]

@@andrewakrause p=m*v F=dp/dt

[@14aartis]

@@andrewakrause Yes but the trust equation is a function of mass, flow, and velocity. Thus it would increase.

[@dreggory82]

Try it, let us know.

[@jleadbetter29]

Love it...happy nerd. One suggestion...fill it with smokey air. Then you can see the thrusters actuate. Still great...keep it up.

[@renemunkthalund3581]

Smoke! Great idea

[@piotroledzki2331]

smoke and a red led together...

[@isaackay5887]

Correct me if I'm wrong, but if my calculations are correct, you're adding anywhere from _9.97382 grams_ to _10.5526 grams_ *OR* _16.6230 grams_ to _17.5876 grams_ *PER BOTTLE* - depending on if you use 60psi or 100psi compressed air in each bottle with 0.002m^3 volume (2 Liters), respectively. *This means you're adding at least **_29.9215 grams_** or **_49.869 grams_** to your aircraft.* However, *_you're dispelling this mass UNEVENLY!_* This will cause the Center of Mass (CoM), the Center of Gravity (CoG), and intended Moment of Inertia (MoI) to shift in the direction toward the side with more mass/gas. You can solve this 1 of 2 ways, how I see it. 1) You need to connect all 3 of the pressurized 2L containers together via open, fixed valves so that they form a single container of pressurized gas - this way the air is much more uniformly distributed when expelled. 2) Adjust your thrusters' flow rate to compensate for the changes in CoM, CoG and MoI - this would be significantly more challenging since you'd need to add pressure sensors (that withstand 60-100psi) to take these measurements and write more complex logic to even start testing. • *_m_* (mass of Air): *TBD* • *_M_* (Molar Mass of Air): 28.9674g/mol => www.engineeringtoolbox.com/molecular-mass-air-d_679.html • *_V_* (Volume of container): 0.002m^3 => (2L == 0.002m^2) • *_p_* (pressure of compressed Air): 413685.4374Pas or 689475.729Pas => (convert 60 or 100 PSI to Pascals) • *_R_* (Universal Gas Constant): 8.314 • *_T_* (Temperature in Kelvin): 273.15K or 289K => (0˚C or 15.6˚C) Using the formula for the Ideal Gas Law: *_m_* = ( *_M_* • *_V_* • *_p_* ) / ( *_R_* • *_T_* ) *References:* • en.wikipedia.org/wiki/Standard_conditions_for_temperature_and_pressure • physics.stackexchange.com/questions/268419/how-to-find-weight-of-compressed-air#268442 • www.calculateme.com/temperature/kelvin-to-fahrenheit/300? • www.engineeringtoolbox.com/molecular-mass-air-d_679.html

[@atomatopia1]

For some of these drones, you may want to consider designing the arms at a slightly upward angle. This is commonly used to improve a drone’s stability and, even though it’s mostly only for propeller drones, may help your case a bit.

[@MouseGoat]

He also does look like jr version of Elon musk lol just saying XD

[@electronicdawg]

He looks like some sort of Neanderthal

[@MrJustin2105]

thought that aswell lmao

[@agentsmith9708]

his friend looks like baby of Mask and Zuckerberg 😊

[@irchonite1953]

I know, right? I realized that myself after a few minutes of looking at him, then it clicked

[@carlosvelasco999]

He might be a elon clone who knows

[@RobBulmahn]

I love your work, and this is another awesome example, but I wanted to also praise you for something that most people probably don't even notice: putting on safety glasses. Always gotta have the right PPE!

[@JohnDoe-rl9pp]

And he took them off when the pop bottles were at 100psi...

[@Crustyislooking]

I absolutely love seeing two KZbinrs I watch independently collaborating

[@ematt622]

5:43 2 years late to the game here, but it makes sense that the straight through nozzle worked best. Rocket nozzles only work well because the fluid reaches >= mach 1 at the throat, so the expansion of the fluid afterwards increases the speed. In subsonic fluid flow, fluid expansion causes it to slow down, and the bell nozzle expands fastest, losing the most velocity in the escaping fluid. If you wanted the escaping air to go even faster, invert the bell nozzle so that it tapers down to the throat.

[@atluxity]

Now what I want to see is using flammable gas, and igniting the gas when fireing the thrusters.... THAT would be awesome....

[@andytaylor1588]

I would like to see heavier fuel, to perhaps set stuff on fire.

[@kadmow]

why not hypergolics??

[@astrofox2409]

@@kadmow Hypergolic fuels are, to say the very least, quite toxic.

[@kadmow]

@@astrofox2409:yep, I realise.. but... think of the Coolfactor with a hydrazine and di-nitrogen tetroxide mix. Lol. (It was a joke "obviously")

[@vonn1334]

You should put diy ice in the bottles it will make that cool smoke affect while also giving you TONS of pressure

[@ipodhty]

Co2 pressures will burst those bottles

[@infinitescales4013]

@@ipodhty not with a pressure regulator....i think you could have sort of a manifold who let some reactions occurs at a selected low pressure threshold...., by timing the chemical reactions.dry ice with air might be touchy to control in time since it active with oxygen. im no chemist but neutralizing some acid in little timed quantities might be a pretty neat iea .you make the reactions take place one at the time in a 4 thicker bottle that feed the 3 others and have a pressure regulator...Still you will have weight that's reduce in flight to program in the arduino.

[@SamFisk]

If the valves can open and close fast enough you could use Pulse Width Modulation instead of a plain threshold. I imagine it'd just give a bit finer control when under the threshold for plain on/off (but above another threshold defined by how quickly the valves can pulse).

[@dirkjanvanvliet]

I don't know if the bottles are connected to each other, but if they aren't it's probably a good idea to do so. This way you don't have differences in pressure per nozzle. I know it might be obvious but it's just something I thouht of. It's really cool to se a drone being controlled this way, you just keep being amazing!

[@jessecoc6247]

Yeah if it is windy and the drone is trying to tip the one bottle gets used way more

[@integza]

Cool project! I really like how you use test stands instead of simulations.

[@e6ensperception]

0:32 "Let's talk to someone that knows more than I do" *Elon musk enters chat* 🤣

[@fatitankeris6327]

Yep, that guy is looking like Elon Musk and does simmilar things.

[@projectdelta50]

Not gonna lie, legit had me for a solid second thinking Elon Musk was the skype call... (watches video more...) Close enough...

[@babblarn5598]

Same

[@ghostrunner2138]

for a second I was really surprised

[@petermckenna8462]

He does kinda look like a young Elon.

[@dr.shalabhsaxena4420]

Same

[@kens97sto171]

Same.. looks very much like a young Elon Musk..

[@wktodd]

Great stuff Tom. expanding nozzles need a gas with energy to do the expanding , compressed air has little additional (heat) energy.

[@nirodper]

@Rick Lokers IF it comes at high pressure, which is not the case here

[@Zorbeltuss]

Yeah, also for any nozzle you want speed for pressure which is why the constricting worked best, though it could probably be optimized a bit further. The exceptions for the energy rule is entropic explosives and low speed deflagration combustion, in essence the actual rule is that the bell nozzle and aerospikes wants supersonic flow of propellant, which in essence mean combustion products.

[@leveckfamily8841]

Wouldn't it work better if he reduced the flow BEFORE the expansion nozzle? So if he used a 2mm supply line that fed into a nozzle that first reduced to 1.5mm THEN expanded to 4mm wouldn't that work better? I'm not sure what the most efficient numbers are but you get the idea, right?

[@Zorbeltuss]

@@leveckfamily8841 Not if the flow isn't supersonic, if it is super sonic there are other reasons to avoid it sometimes like structural integrity, but in general then it's a good idea, in those cases you need a different type of restriction though.

[@nirodper]

@@leveckfamily8841 the best would probably be a diverging nozzle with a small throat like the one he settled on (≈2mm) and that expands to 4mm or 5mm. Also it would probably be a good idea to sand it smooth to decrease drag/turbulence

[@garrybrewster5821]

my first and only thought was air flow being drawn down around the bottles causing un-even disturbance with the thrust, was this looked at with your testing. ...cheers Tom. i'm enjoying this

[@nathanksimpson]

Guy owns a rocket called "Thrusty McThrustforce." ㅋㅋㅋ

[@theredstonehive]

*face

[@thatyoutubechannel6379]

No dip, Have you ever seen his channel!! "In thrust we trust"

[@sebastianwlodarczyk]

I remember my professor saying something along the lines of "that's the method of tuning the PID controller, but to be honest, you'll probably end using trial and error"- I guess aerospace buisness holds better standards than some backwoods uni:] That drone flew quite well for "eyeballed" values! I saw some drone projects using 3 motors instead of 4 and I was wondering why it isnt't a standard configuration- you managed to clear this up with one sentence about propellers induced yaw change:D

[@oo44wo93]

It isn't even about holding higher standards - it is absolutely normal to make informed guesses with control systems. It's just that cost of making mistake with rockets is incredibly high. Properly and precisely calculating right control parameters is incredibly complicated and time consuming, for even simplest of cases.

[@murdurer333]

It's sad that he already had the test bench setup to measure minimum thrust at minimum opening time for the valves. It would have been easy to setup a reference table in the Arduino, and given better control at near-zero pitch/roll

[@overklift]

I love how you get enjoyment out of the "failed" attempts.

[@electronron1]

NASA's flying bedstead DIY style. Just needed a pilot to eject prior to the crash. :-)

[@umbra1016]

Looks like you need in-line pressure sensors and variable solenoid valves instead of binary. Great job man! Really impressive.

[@TheJohnreeves]

He can do the pressure part in software. The computer knows how long it was firing, and he can separately figure out pressure vs time. Then it would of course need to be started at a specific pressure. But it saves the weight. Maybe I just see everything as a software problem because I'm a software developer.

[@umbra1016]

@@TheJohnreeves In this video he already tried adjusting the PID values to vary the release time and didn't work as well as my suggestion would. He needs a hardware-based gradient valve solution that would change based on the relative pressure after it's released more and more.

[@martindinner3621]

@@umbra1016 The problem is that flow and pressure are linked when using a fixed nozzle. A pressure transducer linked to the throttle gate value should help though.

[@joseespinoza2687]

Maybe you can make your own lighweight central pressure regulator.That should allow you to control the outlet pressure from your tanks and give you a constant PSI for your drone...at least until it drops past the regulated pressure. The only caveat would be that you would need to run lines from the central outlet back to the nozzels.

[@LeonardChurch33]

Really awesome concept Tom! To fix the stability issues at different pressures you could incorporate a small gas pressure transducer and use the value to adjust the threshold tuning on the fly.

[@ZactasticGaming]

Your first nozzles (divergent )were based on supersonic flow, i don't think the exit velocity is supersonic, you might need to try convergent nozzle.

[@benniehavenga1689]

Add: pressure sencor to read back pressure to arduino, two to three nozzles per arm at diff distances. In high pressure deliver pressure to inner nozzles and as pressure drops let compressed air channel to outer nozzles.

[@pieterpretorius1014]

put dry ice in one of the bottles should keep the pressure much higher and more constant

[@RageAZA]

would the super cold temperature not affect the pressure capability of the plastic?

[@runforitman]

You could have the Arduino lower it's gate over time, or install a pressure sensor and have it lower the gate depending on that

[@jackpaine8461]

The bell nozzle is designed for supersonic flow where the velocity of the air is mach 1 at the throat. U should look at subsonic nozzle designs that's why the straight nozzle was the best. U need a convergent nozzle instead of a diverging nozzle

[@jasonpatterson8091]

Love the message in Joe's mirror: "Subscribe to Tom!"

[@slickfast]

Those bell nozzles sucked because they only work for supersonic flow, where Bernoulli's principles are essentially reversed. What you don't see in those nozzles is further upstream, where the transonic region occurs at what's called the throat. Further upstream of that is actually a converging portion, which follows the rules of subsonic flow in order accelerate the flow up to the throat. That upstream portion is what you were essentially looking for, so it makes sense you went with a teensy hole!

[@thomasg4324]

*See.....the straight nozzle has the most thrust. The converging nozzle is a straight nozzle...you're just increasing pressure before using a straight nozzle.* Very nice video so far. Back to the build.

[@z4zuse]

Add bright LEDs on the 3 arms to show the valve open/close status. The noise of the motor is too loud for the clicking to be heart

[@Boi-ii2lm]

You couldn't see the lights especially in day also its just extra weight the motor barely caries current weight

[@NelsonBrown]

This is great! I think you could put the same bottles, valves, and micro-controller on an air bearing (like an air hockey table) and maneuver like a satellite in 2D.

[@un65tube]

The problem that the drone will not lift off directly from the ground seems to be caused by the air that is escaping underneath the curved downside of the bottles. Similar to the wing of a plane this causes a drag, but in this setting the drag is pointed towards the earth in the opposite direction of the thrust generated by the propellers lowering the overall lift of the vehicle. Great video, love your channel. Stay healthy! Many greetings from Germany.

[@thisismarkrogers]

He looks like Elon too 🤷🏼‍♂️

[@Morgow1]

Talk and act like him too. If he sounded like him... then wow.

[@AlkalineGamingHD]

"Hey they got discount Musk!"

[@chemgreec]

he has his manerism which i think is lame..ok i see that he admires elon musk but..fuck off mate have your own personality

[@VinceTibo]

@@chemgreec this comment is so uselessly mean the fuck

[@VinceTibo]

I KNOW, the way he moves too it's kind of insane!

[@tacticalpoet]

Why not treat the flight controller's motor speed output as a frequency? So the gas is outputted in pulses of increasing frequency as more thrust is requested. Would improve your fine control.

[@jamnchips]

Might be hard with the solenoids limited speed

[@oskarkrogsgard3014]

I thought about that as well, but i dont think the solenoids can turn on and off quickly enough

[@luongmaihunggia]

@@oskarkrogsgard3014 I wonder if it's possible to have faster solenoids.

[@oskarkrogsgard3014]

@@luongmaihunggia Most likely is. But they are probably also more expensive. But I think it's easier to make a variable valve though, like the throttle in a carburetor. There is a problem with making air tight though, but I'm sure some clever engineers have already figured that out

[@DFX2KX]

@@oskarkrogsgard3014 more expensive and heavier, yes. variable valves like that are available, but also rather heavy for something like this.

[@yoashuain1]

A good attempt is never a failure. It is merely one more step to the goal. Keep it up, I want to see it fly.

[@bioshift1]

You could try three CO2 or nitrogen cartridges. Should be enough volume and psi to give a prolonged flight.

[@wojciechsosna9230]

Yeah, im sure he want to use nitrogen to BLOW UP HIMSELF

[@robduquette8537]

What if you made a gas thruster controller blimp? Then you get cool noises lol

[@newmoon54]

At around 17:45 I believe what is happening is ~simple inertia buildup~ defeating the ~air thruster's~ ability to manage any control over the inertia created by the swaying "back and forth",, which with each additional sway motion, the air thruster(s) aren't a match enough to maintain any stability! The solution in simple terms is, how do you increase ~air thruster response~ to the increase in simple inertia created by inertia and gravity!?! Increase the psi in the air bottles??? But air pressure availability is finite! Unless you maybe try ~vectoring the lift air~ somehow,, or,, maybe add a sort of ~Kites Tail~ directly under ~dead center~ of the fan motors and maybe the kites tail will give a natural control over the wavering side to side motion???!!! Love your work!!! Cheers! Sonny.

[@minetubequest]

The drone gas thrusters are awesome! The sound tho, it's very satisfying! Its like a spacewalk when people carry thrusters to control their direction. Exactly sounds like that.

[@Kaxlon]

Hi Tom. Congrats on the success. =) Modern turbo charged cars comes with a solenoid valve called Boost Control Solenoid (BCS). The job of this BCS is to gradually taper in/out the boost pressure from the turbo to the throttle body. Most of valves use PWM at a frequency at about 16 Hz. The frequency choosen is based on how fast the BCS can open/close. i.e. how much mass the plunger has. You can run these valves almost at any air throughput from 0% to 100%. You could try using this method to improve the performance of your drone. Great work as always! PS. The BCS valve is very similar to the ones you use. So you should be good to go without upgrading your valves.

[@USWaterRockets]

A really high performance turbo might run at around 30PSI of boost. Joe is running 60-100PSI or more for his thrusters. Care must be taken with choosing a valve for a thruster, because they tend to fail if you use more than their rated pressure. The failure modes can be leaks, failing to open, failure to close, or destruction of the valve itself.

[@jessecoc6247]

@@USWaterRockets they run civics at 60psi

[@-_-5352]

I agree with you,but I see another one say p =mv. F =pt. So its just like the fuel injector.fuel flow decide by the pulse wide . I think it's a easier way to control the force. Bad English . :-p

[@Kaxlon]

@@-_-5352 Yes agreed. I was thinking F=mass of air/time But there could be a problem with the amount of time and deadtime of the valve. Your English is just fine. =)

[@Kaxlon]

@@USWaterRockets Yes agreed. Keep the valve he has. It's made of metal. Many car BCS are made with plastic bodies and prone to crack and leak over time. On my project car I switched from a PWM valve to a ball and spring type manual one. It holds shut until desired boost is achieved. The boost comes on hard and datalogs show no leaks. Tom should keep the metal ones he has. But if he tries the PWM method he can add a hard cut of airflow once the desired angle is achieved. That minimizes the over compensation. You could even taper by ramping the PWM width and/or time at the end.

[@Anvilshock]

15:56 - Ladies and Gentlemen, may I present: The Venturi effect, courtesy of the large curved surfaces of the bottles.

[@benfillman4049]

I'd say it's a coanda induced ground effect as the Venturi effect is mainly used to describe air pressure's relation to velocity inside a tube or pipe

[@tmapaman7080]

@@benfillman4049 accelerated air underneath the bottles, making a low pressure, sucking the drone to the ground. venturi effect

[@softb]

@@benfillman4049 dumbass read what you said again

[@MrDaewen]

The Venturi effect is the reduction in fluid pressure that results when a fluid flows through a constricted section (or choke) of a pipe. Coanda effect is the phenomena in which a jet flow attaches itself to a nearby surface and remains attached even when the surface curves away from the initial jet direction. You Decide.

[@Anvilshock]

@@MrDaewen Phenomena is plural. "is the phenomena" is nonsense. You decide. No, wait. No discussion.

[@tevapetiteau5729]

How in the world did that thing worked that well on the first try!!! Awesome job and project Tom! And thank you for explaining everything the way you do, it really make the difference

[@ArchieHalliwell]

You could use pressure regulators to keep it at or below a certain pressure at the output

[@mintxovlz9861]

So that way the air would last longer and the thrust would be more consistent. That's a good idea.

[@itburnswhenip]

"Psstt Pshhhh Pssssssh" (Yes im typing this by hand) best CC ever. @19:58

[@veinalpha1944]

Fuck you bitch

[@veinalpha1944]

itburnswhenip Bitch

[@okboing]

Idea: Entirely mechanical RC car? With a series of universal joins between axles, up to a handheld controller? If that makes any sense...

[@adamjackson9988]

Maybe it’s childish, but the funniest part of these is hearing Tom giggle when things work.

[@adamjackson9988]

Ken Romero, no, I agree, just funny watching the smile break and transform into a giggle.

[@CheapCheerful]

Great job man, its inspiring that smart but relatively everyday people can do such relatively groundbreaking new things.

[@farkelstein8396]

its relatively amazing

[@PacoOtis]

Excellent! From here in the States, Bravo! It sure is green where you are! Thanks for sharing and the very best of luck.

[@dontuno]

I always found binary control a difficult concept in practice. Wonder whether pulse pause modulation could be considered?

[@bobvincent5921]

Nice project. If the air jets are rigidly fixed then I think more predictable forces would result .

[@alexanderbeck5998]

0:45 I definitely did not expect that, but I love it 🚀🤟

[@raishen1516]

Me: What is Joe's last name Joe: It's Musk, Joe Musk

[@LordDecapo]

Projects like this make me happy and proud to be a patreon :) keep up the great work dude!

[@polarisukyc1204]

The bell nozzle, correctly called a de lavel nozzle (hope I’ve got the spelling right!) only works if it contains a constriction between the bell shaped bit and the feed pipe

[@Simey2wheels]

Joshua Bardwell has a video on pids adjusting with battery voltage. This would do what you need i think, you'd just need arduino to send pressures to the fc. Cool project 😀

[@merijnvinea3546]

Amazing project! Loved every second of the video! Idea for V2: the Arduino has a pressure sensor and lowers the solenoid actuation throttle. Thank you so much for the amazing content!

[@martindinner3621]

Solid concept!

[@nonnodacciaio704]

0:32 I was expecting a "Hullo, Scott Manley here"

[@dean3184]

Wouldn't you need pressure regulators so when the pressure drops,the output stays the same?

[@pboytrif1]

12:22 keep it going I’ll spit some bars

[@XavierBetoN]

5:22 pausing the video. Blue one is the legit one for pyrodynamics, as the walls cool down with the unburn gas. I'd go with green one. It's more feasible at supersonic speeds (if the nozzle reaches supersonic) it will ease the escape velocity. Edit: your end results suggest the escape velocity is subsonic (optimal choice: straight)

[@mitchd949]

Your "thrusters" are simply expelling the air that you have contained in a fairly low pressure vessel. Spacecraft use propellants in space such as MMH and NTO which are hypergolic and explode when combined. You have no explosive propellants at all, you're just seeing air escaping the tank at ever decreasing pressure. You're just pushing the air through an orifice that's why your 2mm had longer "thrust" than your 4mm (it was 1/4 the opening). You will get no benefit by nozzle shape. The traditional rocket nozzle shape you show is shaped that way because it's a combustion chamber.

[@cosmonaut2644]

RCS thrusters use single propellants at high pressures, not hypergolics

[@cosmonaut2644]

Also, nozzle shape does have effect here, as it lets the gas expand whilst still being forced out

[@T2D.SteveArcs]

13:38 GEEKGASM looool love your vids man one of the best youtubers ever....

[@jwayneair]

If you used “canned air” cleaner duster, you could possible extend flight time. When sprayed upside down, the liquid sprays out. Spray that liquid into a soda bottle, and cap to capture liquid before for it flashes off, and the pressure will be maintained at about 70 psi as long as liquid is present, as that’s about the saturation pressure of that liquid. The downside, however would be having liquid sloshing around which could introduce bigger issues, you know, like a constantly shifting center of gravity.

[@_VEKTA]

Screw the drone, I'm in love with your yard lol

[@manas1743]

This is the stuff I wanna do in my life!

[@fiskgames7020]

for added stability, you can fuss around with some fancy software and make the computer understand the torque difference between the positioning of the 3 arms and give it the capability to spin on the yaw access or understand the pressure difference by using other hardware, but id recommend using a 4 arm drone just for the sake of simplicity.

[@staplafara]

What about a fixed light weight landing gear to keep it off the ground a bit? Greetings from Germany.

[@CarlosDuarte2007]

The flexibility of the hoses, the flexibility of the arms where the hoses are hold and the ON-OFF control type make the system very unstable.

[@adasdasdasdasdasd9678]

Try putting smoke in the compressed air (at the input of the compressor), just to visualize how the stabilizing works :) The high motor speed is probably due to the second propeller not being very efficient in the fast airflow of the first one. For the compensation of the pressure drop, try a counter to monitor the valve time, and decrease the PID gate threshold when the counter increases.

[@kerbalcrashtestdummy4742]

I wonder if having smaller thruster nozzles would help? Keep the thrust consistent for longer? Love your videos by the way!