What's the deal with the sketchy "PDF viewer" that they tried to force Chrome users to install? This is an example where a site actually worked better in Firefox and Edge.
NASA's exhaustive Kite index which covers the physics and Math of Kites. There is even a KiteModeler and interactive simulations for anyone who is interested
Before drones were widely available, I attached an inexpensive camera to a kite to take some aerial photographs. I'm a little surprised that wasn't more common, given how popular drones are now.
Perhaps the limiting factor was the lack of inexpensive cameras, not the lack of drones. There was only a short window of time between when remotely controllable lightweight cameras became cheap enough for people to not worry about crashing them into rocks, on the one hand, and when drones became widely available, on the other.
Agreed. We got around this by hacking the single use CVS/Rite Aid cameras according to the below guide. Dropping one of these in the water or on some rocks didn't feel quite so devastating.
Not that narrow. I remember in the late 80's / early 90's Estes had a model rocket that would pop a picture (onto film) from the nosecone when the chute charge went off. I have no idea what the quality was like (my parents refused to buy me one).
I spent a bunch of allowance money on one of those. It used 110 film cartridges, and had a pretty cheap plastic lens. Quality wasn't really that good (and wasn't helped by the cheap film I had to use), but it didn't matter to a 10 year old -- I had a rocket that took pictures!
The stability of that kind of platform is a severely limiting factor. The 3-axis gimbal had a lot to do with making aerial photography a thing as much as the drone itself. I was part of a group where we launched a helium balloon to ~90,000' with 2 GoPros attached. The footage is so unstable in much the same way that I imagine being attached to a kite would be. The weight of the camera is at the end of a length of "string" which essentially makes it a pendulum. It just swings and swings and swings. Oh, and it also spins as it twists up the tension in the string, and then releases to spin back the other way. Just about the time all of the swinging and spinning relaxes, the balloon reaches max altitude and bursts.
That looks interesting for other purposes I'd like to try. I love builds that let gravity do the work.
I have been wanting to try it again using a swivel in the line to allow the balloon to spin freely, but then use a tail/fin type of attachment to keep the rig oriented. It seems like anything would have to make it better.
Kite photography is still used at some archaeological sites for aerial photographs: some countries, particularly in the Middle East, are wary of people using drones with cameras.
One of the lectures on YouTube from the Oriental Institute had beautiful pictures of early (Old Kingdom?) Egyptian military and trading sites on the Nile in southern Egypt or possibly northern Sudan, and described the problems they had and why they used kites.
I was thinking recently that kites could make great signaling mechanisms for backpackers. It would be relatively light in your pack and can get a location noticed if you got lost. I'll have to dig through this site for simple designs that are easy to keep up in the air.
When I think of kites, I always think of my dream of a kiteboat for long term cruising around the world.. purely kite powered, with maybe a small stabilizer sail if necessary.
My understanding is that there are a variety of advantages: the kite flies in cleaner air; the thrust from the kite is applied at one point, with less heeling moment than from a sail; the design of the boat is not constrained by the structural requirement of a mast
IIRC A kite powered boat called Jacobs Ladder held various sailing speed records at one point
I’ve a feeling that upwind performance would be lackluster. A modern Bermuda rig can be highly performant at all points of sail in a variety of conditions.
It works the same way, the kite acts like a wing and provides pull and something (kiteboard, fins, hydrofoil, etc.) resists that pull and provides a perpendicular force to the force from the kite power line.
"The rig consists of a triangular sail set aft of the mast with its head raised to the top of the mast; its luff runs down the mast and is normally attached to it for its entire length; its tack is attached at the base of the mast; its foot (in modern versions of the rig) controlled by a boom; and its clew attached to the aft end of the boom, which is controlled by its sheet."
If you're not familiar with sailing rigs, you probably don't even notice it as anything other than, "that's what most modern sailboats look like." This is precisely because it is a extremely efficient at sailing upwind. And their fastest speeds are roughly doing perpendicular to the wind.
Boats like you see in pirate movies and such have what is called square rig. These boats will sail their fastest downwind, but struggle much more in other directions.
EDIT: So I just realized that the Wikipedia article does not have a great explanation on the actual physics here. I'll do my best, though this is all subject to my (mis)understanding.
Obviously, just putting a sail on a raft with no other modifications will just push your raft downwind. You have some ability to control direction with the rudder, but that's it. To sail perpendicular, you need to start leveraging other forces. The main ones are lift force from the sail shape, and drag from the centerboard. [0]
Bermuda rigging uses a triangular sail that is rigged along the axis of travel. (Compare to square rig, where the sails are perpendicular to the axis of travel.) The sail has enough slack that, as wind fills it, it curves. The sails then begins acting as a vertically-oriented wing, using the airflow over the surface to generate lift -- though, in this case, the lift pushes the sailboat sideways.
So you have the wind attempting to push your boat sideways... That is not helpful for moving forward. Enter the centerboard, which resists this push by simply increasing the surface area of the boat under the water. In order to move sideways, the water has to be moved. So you have two opposing sideways forces, and the result is a bit like pushing a wedge -- the boat moves forward.
Also of interest in the physics is speed. So a boat sailing downwind can never go faster than some fraction of the wind speed. Because if it was, the apparent wind would either be zero or a headwind. However, a boat moving perpendicular or upwind can actually move faster than wind speed, because it is utilizing more forces than just the raw wind. And, in fact, the faster a boat moves upwind, the faster the apparent wind is, moving it yet faster.
Really small boats might get away without one. For example, a Hobie Cat (around 16 feet) is using a combination of its hull and a large rudder surface to achieve the same effects.
Wow. I couldn't get over how flat the thing sat in the water... no heeling at all. I guess that is a joint property of removing the mast (ie. reducing unnecessary vertical offset prior to thrust distribution across the hull) plus curved foils / mini-keels visible a the start and end of the video. Impressive stability given the low profile in the water.
Yeah, I'm curious why these are not more widespread. Maybe it's not as "cool" when it doesn't heel? And probably not possible to run in any regattas with that kite.
Kite building is actually fairly easy, and can be very inexpensive. With just wooden dowels, fabric, simple sewing and simple rope & knots you can have something flying in a few hours.
Takes a while to get the hang of troubleshooting the problems of flying, but the basics aren't complicated. Good cheap fun.
Kite building is a hobby I've always wanted to get into.A buddy of mine has build a few of the NASA-style Regallo kites. He uses them with his icebuggys. Apparently, they're not too difficult to make and icebuggys are a blast to pilot.
Don’t forget the middle. There are many excellent spots for flying kites away from the coast.
One of my favorite kite shops is out of Boulder, Colorado: Into The Wind[0]
I’ve only bought from them once or twice, but I used to spend hours paging through their paper catalog as a kid. I also visited their shop in Boulder as a teen — that was really fun.
When I was 10, the Into the Wind catalog lit my imagination in so many ways. It was a fantasy novel crossed with a science book.
A couple years ago I wandered past their store in Boulder and was floored that there was a real, physical incarnation of that magical catalog. I took my little kids there this winter and it was like passing a spark between generations.
My brother got his daughter a kite from there. The wind didn't cooperate on the first day we went to fly it, but her dad and I still tried getting it into the air by running with the string to see if we could get it high enough that it'd catch what wind there was higher up. We failed, but my niece saw us running with the kite, so she wanted to run with the kite. She had a great time running around the park with the kite bouncing on the ground behind her.
The kite survived that & flew fine on later occasions. Now that she's seen it fly, though, she has lost interest in kites that won't fly.
Maybe in market value with all the gear that comes with it, but unlikely by numbers. Regular kite festivals still draw massive numbers anywhere in europe and casual or kid kites are still at thing. Regular kites where really huge in the late 80s and 90s for some weird reason, with any bigger town in Germany having at least one dedicated kite shop.
i always feel slightly bad for websites like this that HN brings hugs to death, even though ad supported, its normal users are unable to access their content
Why? It's not like this will be permanent, a few hours probably. And many sites exist without ads. What's there to support? A few dollars a month in fees?
For personal sites like that, curators often do it for the love of the subject rather than a financial reward. Hence why some personal sites are hosted without any adverts.
Edit: I see I’m getting downvoted a lot for this comment. I appreciate creating content for the love of it might seem like an alien concept to many HNers but not everyone is driven by the motivation of turning every hobby into a start up. In fact once upon a time, in an era before Facebook and Google, the majority of an average persons surfing time was spent on non-commercial personal web sites.
That’s how my sites are run. No ads, no tracking. I put free 3D printed robot designs up as well as my personal writing. I do all of that stuff because I want to and I want others to have it. Ads are gross.
So I don’t know why you’ve gotten downvoted, but your comment rings true for me.
Edit: I can accept that kite plans can be on topic for HN. I also don't mean to stifle anyone's curiosity about kites or kite building.
I suppose I expected something more akin to "Kite Plans, Experiments, Observations, and Results that SoAndSo ran" or "Specific Kite Plan and Notes" to be linked on HN.
If you're new to kites, good news, it's a lot more fun than it should be.
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Original Post:
I am confused, why this link is on HN?
I enjoy kites and have used this site before, but what makes it worth the front page of HN? It's nothing new, their site hasn't really changed in years, and it is somewhat off topic.
Was the poster just fired up about kites? Am I missing something?
Stuff that is old-hat to members of a subculture tends to be really interesting to people who didn't even know that the subculture existed.
The last time I flew a kite was in elementary school. I guess I knew in the abstract that people actually put thought and engineering into kites, but I never actually thought about it. Posts like this remind me of the enormous breadth of human hobbies, and they're really interesting.
As always, there's a relevant xkcd[1], and today, I'm one of the lucky 10,000.
It definitely meets the “satisfies intellectual curiosity” criteria for me! I think we’re giving it the HN hug of death right now (or my phone internet sucks here), but I’ll definitely be checking back later and maybe building one this weekend.
Kites are pretty cool and, as this site points out pretty dramatically, can go from super simple to technically very complex and interesting.
Apart from being fun, there is a good amount of engineering in designing kites.
For example, NASA has been experimenting with designing simple parachutes [1] and it turned out that the parawings (or Rogallo wings) are pretty good traction kites, too. The NPW kites are still popular kites as they are cheap to make and long-wearing in use.
Yeah. you've been around here for a while, so i suspect you know the answer. But hey, maybe this will help.
The first part is the boring answer
> On-Topic: Anything that good hackers would find interesting. That includes more than hacking and startups. If you had to reduce it to a sentence, the answer might be: anything that gratifies one's intellectual curiosity. [1]
So anyhow, given you'd actively used the kite site it the past, you should be able to see how it satisfied your own intellectual curiosity in the past. Clearly, it's not relevant to you today, but perhaps you can see how it's relevant to others. Also, your experience can help drive some conversation with new kite makers.
the second part is some gentle advice - please don't take this as a criticism, just an observation. Try to take joy in other people being one of the 10,000 [2].
