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vishnu2315
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i have planned to make a human powered aircraft.For that i want to know about the problems on making that.
For one thing, assuming you can build a craft capable of flight, it's exhausting work keeping the thing aloft.vishnu2315 said:i have planned to make a human powered aircraft.For that i want to know about the problems on making that.
The main problem is low power to weight ratio.vishnu2315 said:i have planned to make a human powered aircraft.For that i want to know about the problems on making that.
That's easy to overcome. Simply use lighter than air.russ_watters said:The main problem is low power to weight ratio.
The air is not thick enough.vishnu2315 said:What are the problems on human powered aircraft?
2milehi said:Humans are weak. Imagine lifting 550 pounds a foot every second, that is 1 horsepower. A person could sustain lifting ~30 pounds a foot every second for a sustained period. That is ~1/20 of a horsepower.
You can't do much with 1/20 of a horsepower.
cjl said:That's a fairly pessimistic estimate of human power output - most reasonably in-shape people can maintain 150 watts for a period of an hour or more (which is about 1/5 of a horsepower), and professional athletes might be able to do more like 350-400 watts (1/2 horsepower or so). Of course, even with half a horsepower available, the power to weight ratio is still a hugely limiting factor for a human powered aircraft.
2milehi said:Your numbers are optimistically unrealistic and you can't back it up with data. You are stating that an "in shape" person can maintain a consistent exertion of lifting 110 pounds per foot per second for hours on end (no rest, consistent energy output like a motor can do). Say a 110 pound person ascended stairs at the rate of 1 foot per second (1/5 of a horsepower or 110 pound⋅ft per second). In one hour that person would have climbed 3600 feet. Simply stated - in eight hours that person could be at the top of Everest.
I challenge you to produce 1/10th of a horsepower for 15 minutes (consistent power output, no breaks). Think of it in imperial units.
I agree with CJl's numbers and this is easily googlable, but you should also try looking at it another way (comparing it to real exertion) to make it lot easier to see.2milehi said:Your numbers are optimistically unrealistic and you can't back it up with data. You are stating that an "in shape" person can maintain a consistent exertion of lifting 110 pounds per foot per second for hours on end (no rest, consistent energy output like a motor can do). Say a 110 pound person ascended stairs at the rate of 1 foot per second (1/5 of a horsepower or 110 pound⋅ft per second).
When I wrestled in high school at 120 lb, we would run stairs or stadium steps for 45 min at a time. At a 120 step/min pace, that's about 240 ft-lb/sec on the up-steps.In one hour that person would have climbed 3600 feet.
There's a big, big difference between "an hour or more" and 8 hours. Not to mention the cold, snow and gear. Not a realistic comparison.Simply stated - in eight hours that person could be at the top of Everest.
You're really really far off base here. 1/10th horsepower is a pretty light bike ride -- I'd barely even consider it exercise. If you want a photo of my exercise bike's screen I can provide one for you.I challenge you to produce 1/10th of a horsepower for 15 minutes (consistent power output, no breaks). Think of it in imperial units.
How far off do you really think being uncalibrated means? 10%? 20%?2milehi said:Let's ignore the uncalibrated bike screens and look at the physics of it.
You've upped the horsepower from what we were discussing before. Since you aren't a pro it makes it harder for you to use your intuition to see it.Say a pro bike rider weighs 137.5 pounds. That rider would have to lift an additional 137.5 pounds (that is three plates of 45 pounds and a 2 1/2 if you ever lifted weights) one foot vertically every second and sustain that to create 1/2 horsepower.
Not sure what else can be said here other than now that you've seen others provide sources, it is your turn to start doing some of your own research. Your intuition/imagination is not providing you the right answer.I don't see a bike rider being able to do that, they are too scrawny.
That is a useless test because moving an object horizontally doesn't require applying any power to it.I submit to cjl - go to Home Depot and move 10 eighty-pound bags of concrete about 50 feet, then move 'em back to where you found them. I am sure that is no more than 1/10th of a horsepower.
I would add that there's a huge difference between lifting with arms and efficient use of leg muscles.russ_watters said:How far off do you really think being uncalibrated means? 10%? 20%?
You've upped the horsepower from what we were discussing before. Since you aren't a pro it makes it harder for you to use your intuition to see it.
In any case, as said before you can easily verify this stuff via a quick google:
http://www.bicycling.com/training/2015-tour-de-france/you-versus-tour-de-france-pro
Not sure what else can be said here other than now that you've seen others provide sources, it is your turn to start doing some of your own research. Your intuition/imagination is not providing you the right answer.
That is a useless test because moving an object horizontally doesn't require applying any power to it.
Yes. Lifting an object up, carrying it, then putting it back down is a zero output, zero efficiency process. There is basically nothing calculate about it. And even if it is useful to know the input energy, it's impossible to calculate with any accuracy.Jeff Rosenbury said:I would add that there's a huge difference between lifting with arms and efficient use of leg muscles.
But aircraft still consume fuel when flying horizontally.russ_watters said:That is a useless test because moving an object horizontally doesn't require applying any power to it.
2milehi said:Let's ignore the uncalibrated bike screens and look at the physics of it.
Say a pro bike rider weighs 137.5 pounds. That rider would have to lift an additional 137.5 pounds (that is three plates of 45 pounds and a 2 1/2 if you ever lifted weights) one foot vertically every second and sustain that to create 1/2 horsepower. I don't see a bike rider being able to do that, they are too scrawny. So the other extreme would be for the bike rider to lift himself 2 feet vertically every second. That is 7200 feet in an hour and I don't see that happening either.
Anyway we are arguing over a fraction of a horsepower. I submit to cjl - go to Home Depot and move 10 eighty-pound bags of concrete about 50 feet, then move 'em back to where you found them. I am sure that is no more than 1/10th of a horsepower.
1. What are the challenges of designing a human powered aircraft?
Designing a human powered aircraft poses several challenges, including ensuring the aircraft is lightweight, aerodynamic, and strong enough to support the weight of the pilot and sustain flight. Additionally, the aircraft must be designed to minimize drag and maximize lift to achieve efficient flight.
2. How do human powered aircraft overcome the limitations of human strength?
Human powered aircraft typically use a combination of lightweight materials, such as carbon fiber, and efficient aerodynamic design to overcome the limitations of human strength. Some aircraft also incorporate mechanisms, such as gears or pulleys, to increase the power generated by the pilot.
3. What are the safety concerns with human powered aircraft?
One of the main safety concerns with human powered aircraft is the risk of crashes and accidents due to the lack of onboard power and propulsion. Additionally, the lightweight and delicate nature of these aircraft can make them more susceptible to damage and turbulence during flight.
4. How do environmental factors affect human powered aircraft?
Environmental factors such as wind, temperature, and air density can significantly impact the performance of human powered aircraft. Pilots must carefully consider these factors and adjust their flight strategies accordingly to achieve optimal flight conditions.
5. What are the current advancements in human powered aircraft technology?
Recent advancements in human powered aircraft technology include the use of advanced materials, such as graphene, to make the aircraft even lighter and more efficient. There is also ongoing research into new aerodynamic designs and propulsion systems to improve the speed and range of human powered flight.