I was thinking about how springs can be used to fly, and I realised that a bunch of cups on a spring would squeeze air out in such a way as to create thrust as a compression wave travelled through the spring, and those waves could in turn be created with sound.
I'd try and simulate this but I have no software to do that, so does /diy/ think it'd work?
And would there be a better way than a one-way valve of getting the cups to not suck themselves backwards when refilling with air?
Since the idea of this is to make a strange yet easily built aircraft, and one-way valves would be impractical to get in such quantity probably...
>I was thinking about how springs can be used to fly
Wat
Alternatively, it might be able to fly by wiggling if it used troughs instead of cups, but for that the airflow is more confusing so I'd definitely need a simulator that I don't have.
I don't follow. Are we talking about a tension spring here, pulling the cups together?
I don't think your sound idea is very workable.
So first off, jellyfish gather water from a large area by slowly expanding their bodies. They force that fluid out through a smaller opening than they gathered it.. Second, they rely on their buoyancy in water to keep from falling like a rock while they gather for their next push.
In your diagram you draw air in through the same opening you expect to get thrust with effectively identical force. You don't need a program to calculate this, you need to learn physics, statics, and dynamics.
>>1000512
as jellyfish these movements have to be coordinate
ALSO
the overall density/air ratio has to near the same as the animals
>>1000541
>A looser spring than that, able to compress and stretch.
Then how is it powered? The spring can't store energy unless you impart strain on it.
>I'm aware of the air drawing in negating the thrust
Not exactly.
https://en.wikipedia.org/wiki/Feynman_sprinkler
An inlet does not produce a substantial directional "suction" force in the same way that a jet produces thrust. There is SOME resultant force, but it is far smaller than that produced by the jet. So if you have a given orifice that you periodically ingest and expel fluid through, there will still be a net average thrust. This is how valveless pulsejets work, and pop-pop boats.
So IF you were able to get the cups to periodically squeeze together then spread apart continuously, then the arrangement still would produce potentially useful thrust. But I don't see how you're going to manage that with a simple spring.
>>1000557
Compressional waves from one end of the spring is how the cups are squeezed, and it might be possible to send a saw wave down the length to create that jet-then-intake pattern.
OP, I'm pretty sure half, or even all of the people in this thread have no idea what you're going on about.
Make a shitty animation to describe your invention.
>>1000512
with enough power you can make a brick fly:
https://www.youtube.com/watch?v=gJg_6YLLid8
>>1000571
I don't like that at all. What if instead of a gyrating beam on a servo, you had a linear actuator attached to a plate which held an accordion-shaped sheath to perform the jellyfish action?
Immediate problems I see are with the seams caused by the accordion.
However circular pumps in this fashion exist and are widely used (by hospitals)
![pic1[1].jpg](https://i.imgur.com/eqMum5y.jpg "pic1[1].jpg")
>>1000594
In particular this shit is made out of paper, could be light enough and able to support the stresses of being repeatedly stretched and compressed.
I still really want a good, easy to use aerodynamics simulator, because I want to try see if I can get something that's very good for hovering but not extremely large.
I'm pretty sure this guy just woke up from a dream that didn't quite make sense and then posted a question on this site as if he was still there.
I don't think we can help you.
>>1000594
That's no servo, thats a tiny motor.
More on it here
http://rsif.royalsocietypublishing.org/content/11/92/20130992
>> linear actuator
Then it wouldn't be able to move that fast, linear actuators also tend to be heavy.
>> accordian shape sheath
This has been tried in water and does not generate that much thrust.
>>1000595
I highly doubt that
I'm not sure are we talking mechanical or organic here?
If it was something besides. Aspring it'd work. Something like a bungee cord than can tighten and release itself.
It's be better if it went through in waves, e.g. there is part of it "pushing" and part of it taking in water the whole time, so you can consistent momentum. That makes sense right? If it could have a one way valve in the front (bottom) of the cup, it could draw water in and push out the back/opening of the cup, would probably be slightly more efficient.
>>1002370
Or go with the jellyfish example, have the cups in a stable position, but have the lip expand and contract, much like a jellyfish.
>>1002373
I'm more concerned though about whether it would actually be a significant thrust, since it turns out you might not even need the valves.
![pump-jet_by_zapata_human_dolphin[1].jpg](https://i.imgur.com/gxvWd3m.jpg "pump-jet_by_zapata_human_dolphin[1].jpg")
>>1002370
That's called a water jet.
I had to think about it for a bit, now I understand your idea.
It's going to be a very small amount of thrust. Something like this MIGHT work under water but that's it.
>>1002763
This.
With this kind on setup, in air at least, your thrust would be so tiny, at a point that it would be a pain in the ass to make the craft light enough to actually use this thrust in a first place.
Also since if it's light enough to float in the air, it will just be pushed by any litle amount of airflow around it, nullifying the thrust.
The ejected air would be too slow and the amount too light to propel it effectively.
In water on the other hand, or any denser environement it would work like a charm.
>>1002785
I don't see why thrust is limited though.
The maximum amplitude is if the cups have no gap between them (which would provide fair thrust at even a low frequency), and frequency has no limit.
i.e. you just need to drop the bass harder.
basically you want to make a flying air jellyfish
its a pretty cool concept, but
the main issues would be weight,
amountof thrust and control
>>1000541
Let the be a block. It has a surface with friction. Another block behind it moves in and out. A flap is draped over the side, zero mass, with some tension properties. The exhaust occurs and overcomes the friction. The intake flows not through the gill-like flaps but through a central conduit running through both cubes to a variable - volume reservoir. The momentum transfer rate of air must not be enough to overcome friction. Either fill the reservoir slowly, or else have higher friction coefficients. Problem solved.
Fuck all you morons in this thread who had their first reaction be, "no way you can't", fuck you down to hell. This is diy, not "durr hurr flabagastabad", fuck you, you fucking piles of fuck.
Ahem.
Imagine a sequence of such blocks with angular play and a "breathing" mechanism. Give its materials variable density, that is vary the external volume enclosed by the surface area of the machine. Configure the respiration with the aim of neutral buoyancy at all times (or exploit directional movement by non-constant buoyancy + moment arms generated by varying buoyancy along the path of a curve, the respiring snake.) Tada, no friction, well I mean practically little friction.
Now you fucking nimkapoops, go calculate the efficiency of this as a propulsion system, then go duck your linear - thinking minds for not realizing "agility" has just been granted to this new thing I now christen the Jellyfish-Lompoc.
Not the Jellyfish-Snake.
Or the Rattlefish.
...
ZOMG rattlers with lasers built into their eyes THAT ARE AQUATIC!!!! YES! Imagine releasing these on a horde of WASP NIMBYs!
>>1003405
Also for energy-mass conversion use good balloons in a chain for the reservoir, string electromagnets around them, and wala you now have a 98% efficientcy power transmission system. Incorporate energy harvesting from waves in the ocean. Be clever with your nozzles. Low friction surface on the snake. Sacrifice 4% energy efficiency for open-close controllable nozzles. Tada, a perpetual-motion Rattlefish.
Attach lasers and scoopers and build a thousand of them to slowly excavate through continental shelf underneath cities. Collapse the city, killing all WASPs inside. Casual and causal Civilian casualties are unavoidable.
Attach polonium and dump in sewers to poison water supply of millions.
Stick speakers on them and communicate with and control whales.
Attack sharks, bore into them, excavate them from inside out, and create zombie shark stealth robot. Because who is ever tracking sharks around a naval base?
Go on land and share military naval bases, because you can!
Replicate Megazone 23.
Grow algae and periodically harvest snakes at sea for your perpetual food supply. Genetically - engineered algae.
Attach seaweef to rattler. Harvest seaweed and sell to the last remnants of a waterworld for favors.
Inject mind+control drug in seaweed and dominate the waves.
I have been on /a/ far too much....
By the way, does anyone know what they call those starfish with several top-bottom layers of radiating arms? Bristlestats?
Another idea. Spiral reservoir. Less components, pinch it along its path as desired with a flow of magnetism. Less efficiency. Now the following actively-controlled variables dictate thrust:
- vent geometry
- vent clamping (magnetic field & latch/mechanical computer)
- vent shaping of gas flow (bristles normally parallel to the vent, attached to the vent, and sticking out based on more emails fields and more mechanical computers)
- reservoir exhaust rate
- reservoir exhaust pinching function
Come up with 5 or 10 more things and throw them all into a simulation of the snake traversing various obstacles. Throw a genetic algorithm at it and evolve your ideal and personalized Rattlefish.
This sounds like a toy for children you could buy at walmart!
>>1003413
Forgot picture.
>>1003405
Aren't those gills just an abstraction of one way valves though?
And I have no idea what is going on after "Ahem".
>>1003528
If this thread is still up after a week, I'll draw a simulation for the post-ahem and put it in webms for you.
Yes, the gills are abstractions of one way valves. These abstractions can also have controlled geometry of some sort, so I should say it's a one-way valve overlayed over an infinitely-thin variable surface right under it. The surface's behavior is couple'd to the valve, and the combined effects are supposed to give me not only thrust but also aspects relating to maneuverability.
For motivation, if I have a snake that wants to curve is body toward a semicircle arcing-in left, I would close the left gills, open the right gills, and breathe out. But if I opened the left gill a bit but prohibited a change in volume in its specific reservoir, I now have another source of dampening. The water took in during this dampening operation, as it accumulated, could be periodically collected and ejected from the respiratory tract. Another motivating example: it I attached a 4-member linkage at the lip of the gill and could dictate its configuration with servo motors (or wires + ratchets + one solenoid as I prefer), then the gill can be oriented, or I can even try to dictate properties of the air flow beyond merely the air flow through the gill. For example, I can try to dictate where eddy currents will form and either use that as an aid in maneuverability or to do something weird like kick up dust on the sea floor with minimal energy expenditure.
I can also avoid using gills all-together, instead perforating the snake everywhere with tiny holes and sticking one - way valves in there, but I would experience heavy energy losses by friction then.
I should also stop calling these gills. Maybe reverse-gills. Or ink jets.
>>1003686
Sorry, if i permitted a compression in the left gill's lung, not "if i prohibited a change in volume".
>>1003686
It would be very useful to be able to open the gill in some places but not others since if this is to work in the air, a continuous thrust is needed.
By the way, a random thought; if air flows very fast through a light body, could that light body become lighter than air?
Or does change in air speed just change pressure and not density?
