“Japanese Student Takes Flight of Fancy, Creates Flying Bicycle” [https://www.youtube.com/watch?v=ZJrJE0r4NkU](https://www.youtube.com/watch?v=ZJrJE0r4NkU)
*Edit: Far beyond regulations and air traffic control issues, only regarding to physics:*
I’ve just seen this video of a Japanese student that has achieved making a flight of about 200 or 300m with a mechanism that turns the pedalling we normally do in a bicycle to the turning of a propeller.
Now, if we as humans and a very great bike can reach 40-50 mph (and very light planes such as cessna can take of with only 60mph – not to mention Bush Planes – all of these weighting easely 4 to 5 times the weight of a person + an extra light airplane design, specifically created for that porpouse) – why does this seems too hard to achieve/sustain? I can only guess its a matter of efficiency (or the lack of it), but which one of them?
In: Physics
Biological muscles are demonstrably capable of powering flight. The capability has evolved 4 times, after all. But all flying vertebrates have had to evolve lots of tricks to ensure their muscles are capable of generating enough lift. Most commonly known of these is “hollow” bones. Not exactly right, and they have more purposes than just keeping weight down. But the trade off is still there – fragility. Humans have solid, less fragile bones, as well as denser bodies and more fat.
There have been aircraft powered by humans, as others in this thread have mentioned. But they aren’t practical for regular use. Not on this planet, anyway. Maybe you could custom-build one for an incredibly lean and fit, but still very small person to use regularly in very flat terrain. But they wouldn’t be able to carry cargo, and would be pretty wiped out after any extended flight.
For impractical, recreational uses, larger people who are nevertheless still fit could probably use them for short flights, especially if you could find a safe place with good thermals to fly at. But if you’re going to do that, hangliding exists, and doesn’t require such engineering or specific environmental conditions – just a cliff and a well-constructed metal and cloth piece of equipment.
Now, a flying e-bike might be plausible. You can get a bunch of power out of an electric motor, and just keeping moving while in the air requires less energy than taking off or performing complex maneuvers.
It’s big.
And if everyone has one, it’s dangerous.
Everyone would need radios like in airliners and communicate with a tower to coordinate flights.
You can reach relatively high speeds on a bike, but you couldn’t get to the same speed if you added the drag associated with cessna sized wings (assuming we’re talking about a flat surface).
On top of that, wheels are really good at transmitting energy to the ground. The moment you take off, you would lose efficiency (maybe someone can confirm how efficient propellers are).
Physically? that would be gravity. Its quite energy demanding to fight gravity all the time. Much more demanding than cycling down a nice flat road.
Human powered aircraft have been built and flown, with a number of flights over reasonable distances. The basic demands of flight, in terms of the relationship between lift and drag, put a minimum power requirement to lift a certain weight and keep it in the air. For a very light weight aircraft with a human occupant, that minimum power requirement is right at the limit of what a human body, if well trained athletically, can sustain. You would be looking at Tour de France level of cycling ability rather than I ride my bike to the shops level of cycling ability to be able to power such an aircraft. There are a few people who can achieve this, but there is little reason to actually do so other than for the achievement of having done it. It is certainly not a practical way of travelling.
The government is very touchy about us being in the air. Let us run around on the ground as much as we want. Anything in the air is a big production.
Pysically it’s the density of air. If air was denser? No problem. Lower gravity would help, too.
I see two big issues with your question. For one, you are vastly overestimating the speed a person can ride a bicycle. For example, the most famous tour rider who tested positive for PED’s and rode on bicycles that cost more than most cars only averaged 26mph. But the biggest issue is, you watched a video of someone doing a thing, and then asked why can’t people do this thing? Is your question, why don’t more people do this? If that’s the case then it’s obvious from the video, it’s not practical.
The biggest issue is energy. The amount of energy required to move a person along the ground on a bicycle is incredibly small, the amount of energy required to lift a person is incredibly big in comparison. In order for a person to power a vehicle to fly it takes much, much more energy since you have to create lift using the air. This is very inefficient but also creates drag which is another force you have to fight against to create that lift. This is just to keep you in the air, you also have to expend *even more* energy to move in any direction and since you have to move air in order to do that it adds another layer of energy expenditure and inefficiency.
Could you lift your body weight directly? Could you also lift your body weight in a much more difficult and inefficient way? Could you do that while also propelling yourself forwards in an equally inefficient way? That’s why there are no human powered vehicles for air travel for the masses. Most people couldn’t even come close to getting off the ground, let alone going any kind of real distance.
It’s not so much that we can’t. We definitely can and have made human-powered airplanes and even helicopters. The trouble is that they aren’t terribly practical or safe. In order to be light enough to fly with just the power of a person, a plane has to be made of extremely light-weight materials, and even then, you still wouldn’t be able to carry much cargo, even compared to a bicycle. As a result, the plane ends up rather flimsy, even when made with expensive composites and alloys. This means that a crash from any appreciable height will be much more dangerous than a typical bicycle accident. Human-powered planes also tend to be very slow, so they can’t get you to most destinations any faster than a bicycle or kayak would, and being so light, wind is a major factor as well, so a human-powered plane might struggle to even reach a destination upwind of its start point. Add in the requirement of a runway to take off and land, and you end up with a vehicle that’s bigger, more expensive, more fragile, less safe, and less practical than a bicycle. Those are the main reasons so few have been made.
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