Items tagged with: gizmo

Okay, so I've decided to actually work on a Space Carrier VARUHARA board game system, even if only to help me study tactics and strategy for the story.

I'm adapting my ideas to line drawing, because that lets me keep a record I can refer to and refine.

That means drawing lines on millimeter graph paper; each map consists of multiple 8.5x11 sheets (with margins, since printers don't print edge-to-edge). So each sheet is just 20x25cm.

Scale is designed for Earth out to GEO, or a bit more than 80,000km across. At a scale of 1cm:1000km, that's about 80x80, or 5x5 sheets (100,000km x 125,000km).

SCALE = 1cm to 1000km

SHEET = 20cm x 25cm

MAP = 5x5 sheets (100,000km x 125,000km); without corners this is 21 sheets

Earth is the center sheet, consuming about 64% of the width. The area within Earth's circle is optionally used for orbit inclination tracking, for true 3D movement.

Earth is surrounded by rings indicating gravity strength.

The use of millimeter graph paper enables really good precision - down to a fraction of a millimeter, or less than 100km.

An intercept is registered if two line segments cross (and optional inclination indicates close enough Z match). This is a bit of a fudge, but I think it's close enough for my purposes.

However, to achieve greater precision I use a "Tangent Vector Movement System". A ship's position is implicitly defined by a tangent between a PAST dot and a FUTURE dot. The line segment between these dots is tangent to the ship's true position and path.

The way it works is that time is broken into "measures", and the dots are projections of the ship's tangent into the PAST and FUTURE times, on measure breaks. Each measure is broken down into four quarters.

MEASURE = 4000 seconds (about 1 hour)
QUARTER = 1000 seconds (about 17 minutes)

Using this tangent system makes it easier to visualize future positions, and reduces how much work is needed because units orbit without thrusting most of the time.

The actual position of a ship is implicitly designated by a point along this tangent. For example, on quarter 2, the ship is at the midpoint of the tangent. But you don't actually draw this point if you don't want to.

More thoughts later ...

#gizmo #worldbuilding #SpaceCombat #SpaceTechnology #SpaceCarrierValhalla

Space Carrier VARUHARA notes - Stealth tactics in space

I've redesigned the spacecraft in Space Carrier VARUHARA to emphasize stealth.

The Valhalla is a late war carrier designed for rapid production at the expense of redundant systems and flexibility.


Valhalla's angular shape assists radar/lidar steatlh.

The short side is the main sunshade; it's mirrored to reflect sunlight into a narrow cone. Most of the time, the ship hides in the shadow of this sunshade.

The long side is also a mirrored sunshade. This allows aiming the catapult when needed.

The other sides are black, to eliminate reflections of moonlight/planetlight.

All sides are cooled by liquid helium or liquid hydrogen. Liquid hydrogen is used in interplanetary space because it has much better heat of vaporization, but liquid helium is used when it's necessary to "bottle up".

The main thrusters are hidden within tunnels, so they are only visible in a narrow cone. They use pulsed operation to increase expansion ratio so the exhaust is cold. The propellants used are:

1) (Molecular) hydrogen - this is the main propellant used, heated by fission reactor. Hydrogen is hard for enemy sensors to detect, but easier than helium. Specific impulse is 850s.

2) helium - this propellant is used when extra stealth is needed. It is also heated by fission reactor. Specific impulse is 600s.

3) LH2/lox - Hydrolox is used in situations where relaxed stealth is practical, because LH2 consumption is halved and LOX is a conveniently dense fuel. In particular, it's used for the main transfer burns at planetary periapsis. The exhaust is normally very visible because ice particles reflect sunlight. But this isn't a problem when thrusting in the night shadow of a planet/moon. Specific impulse is 450s.


When in orbit in contested space, the ship "bottles up" during most of the orbit. This means cooling the outer surfaces with helium, and melting ice to absorb internally generated heat. If helium supply is low, hydrogen is used instead - although this makes the ship warm enough to see with helium cooled sensors.

At periapsis, the ship refreezes the ice with liquid hydrogen. This hydrogen will be difficult to see against the background of the much warmer planet.

At all times, the boiled off helium and hydrogen will be run through the reactor before being expelled out of a main thruster. You might as well get some maneuvering thrust out of it, to hopefully throw off enemy predictive tracking. Even when the reactor is shut off, the core will remain hot.

Even though most military spacecraft have similar stealth abilities, a completely unseen approach is rare. The occasional detection by sunlight beam or star occultation is enough to provide a rough idea of where enemies are located - but this data isn't frequent or precise enough to provide a firing solution. Pre-war theory was "there is no stealth in space", meaning that an approaching attacker will always be detected and always be tracked well enough for lasers to prevail. Long range stealth missiles destroyed many laser battleships until crews changed tactics to emphasize stealth. New warship builds tended to be missile bus carriers to save costs compared to laser battleships and to reduce minimum reactor waste heat generation.

The perception is that laser battleships were made obsolete by missile bus carriers, but in fact the case is not so clear cut. At the time of the war, stealth had an edge over sensors. But if sensors regain the edge, then high power beam weapons could regain the advantage.


Valhalla's main sensors are:

Helium cooled thermal telescopes. These can see anything that isn't itself helium cooled, although not against a planet/moon.

Optical cameras - occultation sensing. These stare at the background stars and detect the dimming or distinctive diffraction pattern of a passing object. This can see anything, but at limited range and can't track.

Optical cameras - sunlight/thruster sensing. The cameras may also get lucky seeing reflected sunlight or a thruster. In this case, the detection may last long enough to get a rough heading.

Scanning Electron Beam/Telescope. Shine an electron beam onto a target; observe with a telescope. This can see anything at short range, including against a planet background. Electron beam telescope is particularly useful for stealth spacecraft because they are deflected by ambient magnetic fields. As such, the target has a much less precise idea of where the beam is coming from. In contrast, radar and lidar give the target a precise angular location and thus a precise direction to point tracking sensors back.

Neutron beam. The neutron beam is a weapon, but it can also be used to find out stuff about enemy targets. In particular, they can be used to distinguish decoys and detect nuclear warheads and materials.

Valhalla lacks radar, depending entirely on fighters/drones for radar sensing. Most military spacecraft have radar stealth, so this limitation is accepted.


Valhalla's main weapons are:

Valhund fighters. Valhalla can catapult a Valhund up to 250m/s in 5s; it can slow down incoming fighters with a volley of reusable bullets. Each Valhund is armed with a hydrogen/hydrolox gas gun that launches small triple missile burgers. Hydrogen is used for low muzzle velocity; hydrolox is used for high muzzle velocity at the expense of stealth. Each missle burger can immediately split up into three short range missiles, or it can act as a single two stage missile. The "buns" act as the first stage, but retain a small amount of fuel so they can act as orbital "space mines". The "meat" acts as the second stage.

Hydrogen gas gun. Valhalla has a gas gun which can shoot reusable bullets at an extremely high rate. It's optimized for use in fighter braking, and mounted near the reactor. However, it can be used as a short range weapon.

Neutron beam. Neutron beams were developed just before the war, using plasma wakefield acceleration within a solenoid magnetic field. The solenoid means that the ambient electrons rushing into the plasma wake "miss" the exact center of the beamline and form a strong magnetic field at the beamline. This moving magnetic field accelerates the neutrons (which have a magnetic moment). Neutron beams are not very efficient, so few countries anticipated their importance in the war. But they would be able to disable nuclear warheads and cause most guidance electronics to fail.

Valhalla lacks electron beam armament. The neutron beam is powered by an electron accelerator parallel to the catapult, but this electron beam has too much self repulsion to be a practical weapon. It does, however, use the electron beam in a low power mode for the scanning electron beam telescope.

Valhalla lacks laser armament. Pre-war warships typically had heavy laser armament, but this required them to use large hot radiators and/or large solar arrays. Either way, they were highly visible and the advances in stealth missiles made them too vulnerable. Late war warships would typically have much smaller reactors insufficiently powerful for heavy lasers.

Valhalla lacks missile launchers; it depends entirely on its fighter wing to launch missiles.


Obviously, the main defense is stealth - avoid detection, and try and throw off tracking. But there's also Whipple shielding - 3 layers of metal sheet to defend against random space debris and small bullets/fragments. Additionally, burger missiles are used to shoot incoming missiles (Valhalla lacks missile launchers, but at least one Valhund should normally be nearby defending the ship.) The neutron beam has limited effectiveness against late war missiles, but the ability to neutralize nuclear warheads alone justifies its continued use. The gas gun is not really an effective weapon, with a low muzzle velocity and light unguided bullets. But it's better than nothing as a last ditch defense.


Apparently this isn't obvious to everyone, but it's actually really easy to dock and receive supplies from supply ships in space. Here on Earth's ocean, ships can't just dock with each other due to the way the ocean moves. But in space, there's no ocean. So, Valhalla was not designed to carry a bunch of long term supplies on board. Stealth supply drone ships are bigger, and are shaped like square base obelisks. Despite being larger, supply drones are less expensive than warships.

Even less expensive are civilian supply ships and stations. Usually Valhalla breaks stealth to directly receive supplies from civilian ships, relying upon stealthy hydrogen propulsion later on to throw off tracking. It's also possible to tug cargo containers and tanks with a Valhund fighter, using a large sun shield for some semblance of stealth carrying the containers/tanks to/from Valhalla. However, this is more time consuming and costly, so Valhalla doesn't bother. It's currently patrolling in the Jupiter system, where hydrogen fuel supplies are not so available (most spacecraft only pass through the Jupiter system for its gravity boost). So its operations heavily emphasize conserving hydrogen.

Valhalla's current patrol orbit passes by Callisto, given the crew a view of its namesake crater about twice a month. Before the war, Callisto had LH2 refineries, but these were destroyed in the war. Most of Callisto's current industry revolves around cheaper and more storable methane fuel, along with lox, water, and carbon dioxide. These supply civilian stations just fine, but neither Valhalla nor its Valhund space fighters can use methane fuel. In contrast, its Dauber scouts use pre-war modular booster packs. Methane-lox boosters aren't very stealthy, with water and CO2 ice particles in the exhaust. So, Dauber scouts from Valhalla try to only make mid-course return thrust maneuvers in the shadow of Jupiter or Callisto. (The initial catapult boost and gas gun braking are stealthy enough, but a mid-course maneuver is usually required to return back to the carrier.)

#gizmo #worldbuilding #SpaceCombat #SpaceTechnology #SpaceCarrierValhalla

Dragon Hunting Notes: Sailback Dragons

As an aside, Sea Dragons exist in my dragon hunter setting. However, humans do not really hunt them, so whatever. They:

1) Have a body plan similar to an oarfish

2) Fly like nothing on our Earth, using their entire body as a flying wing

3) Use sidewinding to move on the ground

4) Swim like a snake or eel

Sailback dragons are legless reptiles. They were initially somewhat small, and developed stickle-back spines as a defense from constrictor snakes. These spines became a spiny neural sail from head to tail.

Forest sailbacks began to glide from tree to tree using their bodies for lift like flying snakes. However, flying snakes are flattened horizontally, while sailbacks are flattened vertically. This means sailbacks can fly, even though flying snakes can only glide. The natural snake-like undulating motion produces thrust like flapping wings.

Ironically, sailbacks did not last in forest environments. Their flying wing body plan may have been fine for wrapping around the nearest tree, but pterosaurs could nimbly maneuver between branches for longer flights. Pterosaurs and snakes muscled out sailbacks from forests.

Sailbacks moved to coasts and rivers, occupying mostly seabird niches. They were excellent divers and swimmers, much better than pterosaurs.

Sadly, the K-T event almost wiped out sailbacks. Birds flooded into their niches, leaving the remaining sailback survivors as evolutionary relics. By the time humans arose, a sailback dragon was a rare and spectacular sight.

It will be a long time before humans understand how sailbacks fly. They look like snakes magically suspended in the air; their undulating motion looks nothing like flapping wings. Foreign scientists will be skeptical of their existence. Even after dead bodies will force them to admit that these wingless dragons exist, they will long refuse to accept they can fly.

Actually, when viewed from directly below, the body wing is apparent, but most of the rare sightings would be from an angle where the undulating motion would be the most visible thing.

Regardless of foreign skepticism, natives celebrate sailback dragons as noble magical creatures. This contrasts with the (well earned) reputation of pteropod dragons as cruel and evil. Dragon hunters are skeptical of their existence, so obviously they have no interest in hunting sailbacks.

OTOH, sailors worldwide fear giant flightless sea serpents, which occupy the niche of our large toothed whales, such as sperm whales. In myths, these sea serpents are often regarded as related to pteropod dragons, but in fact they are only distantly related. Even though dragon hunters dismiss sea serpents as mere sea stories, most will go along with the myths if they can get a "free" ride for protecting a ship.

To get some idea of how this would look, see this video:

The drone in the video only waves incidentally, but that wave motion is how a sailback dragon would fly.

#gizmo #dragons #pterosaurs #RPG #WorldBuilding

Paduka Bipod Foot Bow

The bipod foot bow is a simple DIY flat bow for target shooting. It's a precision challenge like bipod rifle, but the "bipod" is literally two feet.

You lie on your back, with your right foot resting on top of your left foot.

The bow is a simple plank of wood with tapered tips and a paduka knob in the middle. You wear the knob between your big and second toe.

You thumb draw by leaning forward to reach the string and then lying back down. This doesn't use your arm muscles much.

You knock the arrow using your left hand, resting the arrow between your big and second toe.

That's all there is to this gizmo. Obviously it's not traditional archery, but it does have a primitive feel.

#gizmo #archery

Simplistic Dryer design

I've been having frustrations with my dryer, so here's my idea for how I wish a dryer were designed.

Almost everything is accessible from the top or front, and the front is bolted on with visible bolt heads.

There are no belts or traditional gears. Instead, the main drive is an electromagnet that tugs on a steel hoop. The hoop has a few teeth that engages holes in the main stator cylinder and the rotor. This type of drive has an extreme gearing ratio but it does make vibrations due to shimmying around like a hula hoop. So what? A dryer inherently has vibrations anyway due to the load tumbling around.

So, for example, there might be 4 teeth, where the stator has 100 holes and the rotor has 96 holes. Each electromagnet pulse, each tooth will advance 1/26 revolution. Thus, it takes 26 pulses for a tooth to make a full revolution. Completing a full revolution advances the rotor by 1/24 revolution. So, it takes 624 pulses to complete a rotor revolution - a 624:1 gearing ratio.

The steel hoop is easily replaceable by sliding it out the front.

The electromagnet is easily replaceable via an access port on the top.

The heater, exhaust, and fan are accessible from the top also.

Basically, it's built to last, with a strong steel hoop instead of a belt drive. But things will eventually fail so everything can be easily replaced.



Minicyclodrone is inspired by the CycloCrane, a blimp which rolls continuously like a gigantic propeller. This drone solves the prop speed problem.

See, an off-the-shelf motor/prop is designed to push a small diameter of air at a high speed, but a blimp needs to be pushed by a large diameter of air at low speed. This normally involves reduction gearing, adding mass and losses ...

Most blimp drones simply live with the sluggish pathetic performance of tiny props unable to propel the blimp well.

Minicyclodrone solves the problem by mounting the motor/prop to a waist fin. The entire blimp rolls continuously, so the fin orbits around the waist. It's like a small airplane flying circles around the blimp. The fin is angled so the fin acts like a slow moving rotor blade.

The fin is a strip of plastic cut from a soda bottle, and is attached by tape. Theoretically, a straight wing sticking out the waist would be more efficient, but it might be more challenging to make/maintain, and mount to the bag.

To control, you pulse the motor as it goes around the waist.

Bottom line? Prop spins fast. Fin spins slower. No mechanical reduction gearing.


Scanning Electron Telescopes vs Hard UV Lidar vs RADAR

So, I'm working on my Space Carrier VARUHARA setting, and have decided the ships and fighters and such will use stealth after all.

The Valhalla looks like a trapezoid slab, with a mirror sun shield on the shortest side and the catapult along the longest side. This side is also mirrored. The other four sides are black to absorb light from a nearby planet/moon.

The main thrusters use helium propellant when operating in contested space, which is really hard to see, but also hydrogen at periapsis where the planet/moon makes it hard to see.

Nevertheless, it's possible to sporadically detect the Valhalla when a sensor is in its reflected sunlight beam, or due to occultations.

But sporadic detections aren't good enough to directly hit a target with weapons.

What could they use for tracking? Here are a few candidates I've thought of:

1) Radar Radar stealth is good, but is it ever going to be perfect? Maybe just amp up the power enough, and radar's still the best option?

2) Hard UV Lidar Mirrors might defeat optical lidar, but hard UV or soft X-rays will produce backscatter no matter what. Is this a better option than radar?

3) Scanning Electron beam I'm not sure precisely how this would work, but basically the idea is to shine an electron beam at the target, and use telescopes to detect photons produced when it hits. Even if self repulsion might make an electron beam unsuitable for use as a high power weapon, it may be good enough to use in a sensor system?

Any ideas how these would compare? Any other good ideas?


#SpaceWarfare #SpaceTechnology #SpaceCombat #gizmo #Space #Astronomy

Stealth in Space - Helium propellant instead of LH2 propellant?

Hey, question for @Luke Campbell or @Rhysy or anyone who knows astronomy and stuff ... how visible would cold helium or cold molecular hydrogen exhaust be?

I know interstellar molecular hydrogen is notoriously difficult to detect; would that apply to hydrogen lit by sunlight from 1AU away? I'm guessing helium would be practically impossible to detect. Is that right? Or is it actually easier to detect due to its spectral lines?

Assume we're in interplanetary space vaguely near Earth. Would the exhaust get warmed up by sunlight, or scatter sunlight enough to be visible? I figure hydrolox exhaust would be visible due to the ice particles reflecting/refracting sunlight.

The stealth missile has a helium cooled mirror sunshade to reflect sunlight away in a narrow cone. There's also a side port to receive a laser which warms a heating element. The hot element does radiate light back toward the power laser, but it's unlikely enemy sensors will be lined up with that. OTOH, the laser path might be visible thanks to zodiacal dust? (I'm not sure.)

Anyway, small pulses of helium go through the helium element to produce thrust with a large expansion ratio. I think helium exhaust will be cool without an excessively bulky thruster, whereas that may be difficult with hydrogen due to the multi-atomic molecule. Specific impulse is perhaps 600s, which is more than enough for interplanetary missions.

Of course, liquid helium is going to be a lot more expensive than liquid hydrogen, and logistically challenging due to the increased boiloff. Liquid helium doesn't have much heat of vaporization, and of course its boiling temperature is colder.

If helium exhaust is practically invisible, then there may be no defense against these stealth missiles other than foiling enemy detection and/or tracking.

#SpaceWarfare #SpaceTechnology #SpaceCombat #gizmo #Space #Astronomy

Solid Rocket Space Missile Guidance Reconsidered ...

Most current space missiles use four liquid/gas divert thrusters arranged up/down/left/right.

But the old ASM-135 ASAT used a bunch of solid rocket thrusters with nozzles arranged around its waist.


You can see that the 64 solid rocket tubes are actually parallel to the body, but their nozzles are pointed outward sideways from the center of each tube. 56 of the thrusters are high thrust, while 8 of them are lower thrust for more fine adjustments. The entire MHV rotates at 30 revolutions per second, so continued thrust in a single direction is possible.

The Strix anti-tank mortar round uses a similar divert thruster system, with 12 solid rocket waist thrusters.

Well, for future space combat missiles, why not return to this style of solid rocket guidance? Compared to liquid/gas thrusters, I think solid rocket units could have better acceleration, and the delta-v is not necessarily much worse when you consider the 45 degree penalty of thrusting "between" the four cardinal directions.

Instead of a single layer of somewhat flattened nozzles, I imagine two staggered layers of bell nozzles, one slightly angled forward and the other slightly angled rearward so they all point through the center of mass. And each solid rocket chamber could be partitioned into 4 charge pulses. That way, you could have 64 efficiently large nozzles and 256 charges - some bigger and some smaller.

Compared to a liquid/gas thruster system, this is perhaps cheaper to mass produce and less maintenance. It might also be more compact. But I think the really interesting advantage is that it could be used for a gun launched projectile rather than boosted by a rocket. The projectile might have a stealthy flat face. Note that a gun would typically need to lead the target by a lot in space, so this face will not reflect radar/lidar beams directly back to the target. The face might be pointed, say, 30 degrees away from the target.

This could be an extreme challenge to defend against. It might be impossible to target an incoming guided projectile until it lights up a divert thruster. You might be compelled to perform an occasional evasive maneuver simply to force incoming projectiles to divert.

For guidance, a rear facing receiver could be used for command guidance and/or receive navigation beam data. For example, a beam spiral scanning around the target could implicitly guide multiple projectiles by informing of their relative location compared to the target.

More thoughts on implications for space combat maneuvering and engine/weapon layout to come...

#SpaceWarfare #SpaceTechnology #SpaceCombat #gizmo #Space

Stump Saw

I wonder if any sort of curved saw similar to this "Stump Saw" exists. I have a bunch of bamboo stumps clumped together that I need to deal with, and I'd like to cut them below ground level.

So, I wish something like this exists. The blade is very thin, to minimize the amount of material that needs to be sawed (in contrast, a chain saw is relatively thick). It uses its curved shape to keep the blade perpendicular to the desired cut direction - which is "sideways". The idea is to cut below ground level by sawing a shallow "scoop" shape.

In the design pictured, the saw belt has holes for engagement with a sprocket belt. The sprocket belt is thicker, with teeth to engage the saw belt, as well as a toothed edge that the motor engages. The sprocket belt is wider than the saw belt, so it prevents the saw teeth from rubbing against the guide.

You hold the tool by the belt guide, giving you good control and letting you operate the tool without bending over too much.

I'm guessing I could DIY a crude hand powered version which is simply a flexible saw blade between two handles, but I figure it would be hard to get the thing going without some sort of guide. Maybe a cylindrical drum could serve as a guide ... first hold the drum down against the stump, and wrap the saw around it. Maybe first hammer a nail into the stump to help hold the drum in place ...


Dragon Hunting Notes: Pteropod Dragons

Here's my take on dragons for a dragon hunter setting. They:

1) Fly like pterosaurs

2) Run like tyrannosaurs

3) Have armor like crocodilians

4) Spread fire like firehawks

In this fantasy world, pterosaurs had scute armor because they evolved from crocodyliforms. Stronger winds, increased air density, and reduced gravity helped increase their max weight and size beyond Quetzalcoatlus.

Some pterosaurs survived their K-T event. These evolved from quadrupedal pterosaurs into bipedal "pteropods" ("wing feet"). The pteropods took over niches left behind by large theropods. Bipedalism let them get even bigger than before, thanks to running launch.

Pteropod arms are powerful, used for both flying and running. Their hind legs are almost vestigial, being used only to help shape the wings for maneuvers in flight, and help fold away the wings on the ground.

The "knees" are actually wrists. The "ankles" are actually finger roots. The "feet" are actually fingers, ending in hooves.

The stiff armor scutes are like an exoskeleton. This makes the body pretty stiff, but the neck can still bend well side-to-side so the pteropod can preen itself.

Different pteropods had different lifestyles. Some spent most of their time on the ground; some went flightless. These went extinct when their megafauna food sources were killed off by hominids. Others were vulture-like, but they shrank along with the food supply. The remaining giant pteropods are the "true" dragons - dragons that can "breathe" fire.

Dragons don't project fire like a flame thrower, but rather they hold burning brush/twigs in their beaks which they use to set other things on fire. They control the fire by exhaling through the mouth to fan the flames, or closing their beak to keep it from burning too hot.

Dragons strategically set fires, like firehawks, to flush out and trap herds. Then, they can slay the concentrated animals left and right on the ground, expending little effort for a lot of food. Thus,they don't depend on megafauna like their extinct relatives. (This strategy would have been too risky for flightless pteropods, but the "true" dragons can fly if needed to escape the fire.)

These dragons are very intelligent, as fire hunting requires a lot of intelligence to pull off. Some use flint to initiate fire on demand. Others use lava if available; others may maintain ongoing fires. In all cases, fire hunting only works in dry conditions with a herd in a position within suitable fuel. Dragons can rest in a reduced energy state to wait out wet conditions, and then soar to scan for a herd in a good position.

Ironically, hominids caused dragons to increase in size. Before hominids, dragons were mostly social pack hunters. But these smaller dragons were vulnerable to hominids with spears. The bigger solitary dragons were too tough for hominids to take on, and they got even bigger and tougher without food competition from the pack hunters.

These dragons are an utter terror for humans. Obviously livestock and humans are easy snacks, and this is a big problem when a dragon hasn't been able to fire hunt in a while. But also, dragons like to randomly set human stuff on fire just to see them scurrying around. This isn't just malice, it's an evolved play behavior to practice fire setting and study how fire propagates and corrals prey. However, the human victims just see a dragon taking sadistic pleasure in watching them suffer.

So, these dragons are tough, they're big, and they're cunning. And the humans have incentive to hunt and kill them ... if they can ...

#gizmo #dragons #pterosaurs #RPG #WorldBuilding

Fantasy equipment musings: Sandwich shield armor

I'm pondering fantasy setting equipment for a small party of adventurers, and traditional military armor may not be the best thing. In particular, a shield wall is great when you have a large group of soldiers. But with only a small party? It doesn't work.

So, how about providing all around coverage by wearing two shields? You wear them like a sandwich billboard; they're supported by shoulder straps. You have storage bags to provide some spacing between the shields and your body (historical arrows could penetrate a few inches through a shield, so you don't want it flush against your body).

To augment protection against thrusts, you could put plates and stuff in your storage bags.

This is much less expensive than plate armor, as fantasy adventurers would likely get their hands on lots of pieces of armor metal and pots and stuff, but not a set of properly fitted plate armor. Another advantage is that the sandwich shields can be a lot quieter than alternatives like plate armor.

Obviously there are openings to the sides, but you could mitigate the vulnerability with extra plates of stuff stored in side pouches, and jack chains on your arms. Also, you could wear a large poncho over the shields to make it more difficult to see where the protection gap is, as well as the positions of your arms.

#gizmo #whatever
Does anyone know of a battery powered "infinite bouncing ball" toy? What I mean is a steel ball bearing that bounces on wood base; the base uses magnetic force to keep the ball bouncing forever (as long as the battery lasts).

An electromagnet powered pendulum is common enough, but what about a bouncing ball?

I'm thinking it could use a microphone sensor and a permaelectromagnet. An electromagnet is wound around a permanent magnet so applying current reduces the magnetic force. When the microphone detects a "click", current is applied. This reduces the attractive force on the ball on its way up.

I don't know how the electronic circuit would work exactly, but it's got to be really simple I'd think. The natural "ringing" of the click should provide enough duration to make the device work.


Hanging Arm Trebuchet

This trebuchet is portable and very easy to make. There are no hinges or tight tolerances.

The two main parts are a tripod and the swing arm. The tripod is three poles tied together at the apex. The swing arm is tipped with the weight and sling. A rope is tied to the apex and swing arm tips.

It's portable - you can bundle together the tripod legs, along with the swing arm.

To launch, you plant the swing arm slightly into the ground and let it fall toward the tripod. The rope arrests the arm's fall, causing the sling to swing upward.

That's pretty much it. I think this design could be efficient, with barely any friction losses and low final weight velocity. The real kicker is ease of construction, though.

Oh, I think this design follows principles of tensegrity, albeit dynamic rather than static.

Isaac Kuo 9 months ago
Diaspora has an awesome hashtag capability, though. I organize my posts on stuff with hashtags, like my #gizmo hashtag. Of course, there's nothing preventing someone else from spamming #gizmo but it seems to work fine in practice. Unless I get targeted by a crazy harasser, of course.
So, here’s my DIY practice meteor hammer. Budget = $0.00.


1) Two pill bottles

2) Plastic shipping strapping

The shipping strapping was a bit wide, so I tried splitting it down the centerline. Seemed to work.

To secure a pill bottle, I simply placed a knotted tip in the bottle and screwed the top on. I don’t think the knots are even needed; the threading already bites into the strap.

It’s fun to swing around and whip into a bean bag chair, but it would take a lot of practice to master. I’d like to add a couple PVC pipes or some other kind of tubes to make a prototype of “meteor sticks”, which should hopefully be easier and more fun to smash stuff with. Maybe I can do a $0.00 prototype if I can find something suitable lying around ...

Random buying stuff questions:

1) Where to buy 2 Ounce Tungsten Fishing Weights?

2) Where to buy strong thin ribbon?

I'm making "meteor sticks" - a flail-like weapon which I'll whale on old bricks with. So, I prefer unpainted tungsten weights because they're going to get severely abused.

The two sticks will just be 3/4" PVC pipes, 2 feet long. I can get them off-the-shelf at Lowe's. If they're too long, I can cut them down for something handier.

I'll run maybe 3-4 yards (3-4m) of line through the pipes, and tip the line with the two tungsten weights. The idea of meteor sticks is to whip the weights forward with a drum stick motion. The line will slide through the sticks as one weight goes flying forward toward the target and the other weight returns.

The "strong thing ribbon" is a big question for me. Obviously I want something strong enough that I don't have to worry about it snapping. But also I don't think the required strength is so high, maybe.

1/4" satin decorative ribbon would be great. It's very lightweight, and it slides smoothly with little friction. It's also colorful and a bit shiny, so it'll look nice swishing around. But is it strong enough? I don't even know where to find relevant data.

If I look up DIY slings, they use paracord, which I think may be too heavy. But it's possible to reduce weight by using just some of the inner strands.

Any ideas or thoughts? Thanks!


Meteor Sticks

I've been pondering a fun weapon or musical instrument inspired by the kusarigama and kama.

Nito Shinkage-ryu Kusarigama-jutsu - 43rd Japanese Kobudo Demonstration (2020)


The kusarigama and kama are sickles; one sickle is attached to a ball-and-chain like a flail. Kusarigama requires a lot of skill and practice to use effectively.

My "meteor sticks" are mainly for fun. They can be used like a less-lethal version of kusarigama+kama, but the basic technique is more like casting a fishing pole. You whip the sticks as if drumming a wall or odaiko. This slings the weights forward to strike targets.

So, the idea is to have fun "shooting" targets with a BAP-BAP-BAP barrage of strikes. For music, the targets can be drums or chimes.

The sticks are PVC pipes, with a line running through them; the line is tipped with weights. The basic casting technique is to whip a stick forward like casting a fishing pole. This slings its weight forward, while tugging the other weight rearward. When the other weight arrives you whip the other stick forward. When you get a good rhythm going, the retracted weight will do a tight 180 just as you're whipping its stick. This efficiently retains kinetic energy going into the next strike.

You can either aim both weights at the same target, or you can get fancy with aiming at two different targets. Either way, you get a satisfyingly rapid sequence of strikes. In contrast, stabbing with a spear involves fighting inertia as you alternate between pulling back and thrusting forward. Meteor sticks let you just BAP-BAP-BAP in a continuous onslaught.

A more advanced technique is to use one side as a flail - like a kusarigama and kama, but with an extra option to tighten up the radius by moving your hands further apart. The sweeping motion can hit harder and can be hard to defend against. It can also be used to wrap around a leg to trip the enemy onto the floor, or tangle a weapon. Then the other stick can be used to attack. This technique is more advanced due to the skill and practice required for anticipating and controlling the motion of the weight, the need to get in close for followup direct strikes, and the complex combination of attack and defense possible with the two sticks. In contrast, the basic casting technique allows you to keep a distance and just try to overwhelm the enemy with endless attacks.

For a practical weapon, each stick could have a kama blade and some sort of hand guard. In a fantasy setting, a curved spike might be the best option for spiking through mail between armor plates. Or for less lethal use, the sticks could be shaped like jitte or sai to parry swords/spears/etc.

But for modern use, I think it's just a fun way to whale on stuff at a distance. So - no need for blades or spikes or crossguards. Just a couple PVC pipes, a rope, and a couple weights.

Anyway the name "meteor sticks" is obviously inspired by "meteor hammer". Also, drumsticks are meatier sticks.


Buddy Line System

I've thought of a good alternative to overhead lines, suitable for electric trams, trains, etc. The idea is to invert the overhead line system, so the wire is attached to the trams and the transverse carbon bars are fixed. Advantages:

1) Lower cost per kilometer. You only need two power supply arches per km, assuming 500m lines.

2) Much less visual impact than overhead wire system, particularly if the arches are integrated with street lighting and/or traffic lights.

3) Lower running costs, because the power supply arches don't suffer as much storm damage.

4) Less affected by weather. The small contact area of the carbon bars take less energy and time for friction to de-ice, than overhead lines. It's also more practical to put covers above the bars to reduce icing in the first place.

The idea is to use pairs of trams, or "buddies". Each buddy has a trolley pole to support a wire between them. There's a reel in the front buddy to keep it taut. Thus, one can move while the other is stopped.

Power is supplied by arches. Each arch is two poles straddling the path, with a carbon bar strung between them. It's like the popular pantograph system turned upside-down.

The buddy line system is suitable for trams which share the road with other vehicles, so long as the arches are safely taller than the road vehicles.

For buses, you might want to have two wires instead of one. In this case, the power arch has two transverse power lines, from which hang the carbon bar contacts. The carbon bars are held inside C shaped frames to "trap" the buddy lines. This power arch is more complex and can't handle higher voltages, but there's no need to figure out a separate ground return.


Anti-Bird Rocket Armament for Airliners

So, there are numerous reasons why airlines don't put mesh grills on intakes. Therefore, the solution is ROCKETS.

There is a rocket launcher tube near one engine. If you're about to run into a flock of birds, FIRE. The rocket launches, spewing bright sparks behind it. The birds dodge this blazing trail of flares, flying themselves out of the path of that engine. The birds might still take out the other engine, but one engine will sustain safe flight.


MonoArc Bike

Another whimsical bike idea - the MonoArc. This attempts to solve the problems with the Monowheel:

1) Heavy due to large rigid wheel

2) Complex construction with 3+ rollers

3) Gerbiling problem

4) Centerline visibility problem

The MonoArc replaces the large wheel with a bunch of small wheels in an arc.

1) Lightweight due to minimal frame and small wheels

2) Simple construction with few moving parts

3) No gerbiling due to very flat arc. It's a shallow arc from a much larger radius.

4) No visibility problem

For propulsion, there is a larger wheel in front. It's fixed, so you lift it for steering (shift your weight rearward to lift it). The wheel is flanked by plastic cones that you engage with rubber friction rods strapped to your calves and heels. You "push" the rod along the friction cone to drive the wheel. Gear ratio varies with the radius of the cone where you engage it.

Due to the limited grip of friction, this system is more for casual riding than speed or power. A more powerful version would use sawtooth rails engaging gear ridges on the drive axle. Either way, this direct drive system minimizes complexity, weight, and transmission losses.

To help you shift your weight, there's a vertical handle between your legs. You push/pull to shift your weight.

Construction is very simple. It's just two plates, held together by the seat and axles. The handle is attached to one plate.

Compared to a normal bicycle, the MonoArc has some potential advantages. It could be lighter due to the minimal frame. It could have lower air resistance. It could be simpler to maintain - no flats. It might be less expensive. It might carry and store more conveniently, hanging on a wall.

#Gizmo #MyArt
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