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littlediamon

What about parachute-paragliding with a movable tail?

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Hello,
I'm the inventor of a new type of parachute-paragliding.
This new invention allows an unlimited autonomy of flight thanks to fact that it's possible to regain altitude just by flapping its movable tail. This is accomplished by moving legs up and down. Besides that, it also limits the possibility of crashes: there is a better control of manoeuvre and considering its tightened shape, it 's more difficult to get knots or suffer a tear. Moreover, elastic bands of reinforcements improve the stability.
You can find an animation here:
https://www.youtube.com/ watch?v=3BtPXtlC3hg
What is your opinion about it?

Regards,

Dario Tumazzo

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The part about flying prone, or using hands and feet and not just hands to control the canopy, that is possible. Don't know if it is needed, but one could certainly rig things up for more or different control inputs, whether to "brakes" or "front risers" or other variations.

The part about gaining altitude though, sorry, that's not going to work out as far as the energy balance goes. That's where it gets into fantasy not engineering.

Humans don't really have the power to keep an aircraft aloft -- unless it is say a slow, 30+:1 glide ratio ultra-efficient long span very lightweight glider, powered preferably by an athlete. Those are the kind of things that very clever teams have made fly. A 6:1 glide ratio paraglider isn't going to cut it....

(Eg, we humans can put out, what, 0.25 hp for a good bit of time if really fit? Strap a 0.25 hp electric motor with an efficient prop to your back while paragliding... and you aren't going to go up in still air.)

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I totally agree with all what was said above. In addition, the front riser turning I don't see happening. Any front riser input like will cause the canopy to frontal...they just fly totally different. I'm sure that's due to a combination of the lighter wing loading and the angle of attack being much different than skydiving canopies. Pulling those outer A's like in the video will put give you what's called big ears...or something similar to it. There goes all your lift.
my pics & stuff!

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According to very basic highschool science:
Not a chance.

Flying a parachute takes approximately 3 kW.
The source is the potential energy (height x weight), all of it eventually converted to heat.

E = mgh [J]
P = mgv [W]

m = 100 [kg]
g = 10 [m/s^2]
v = 3 [m/s] (vertical speed)

P = 100 x 10 x 3 = 3000 [W]


From wiki:
During a bicycle race, a well trained cyclist can produce / sustain close to 400 watts of mechanical power over an hour and in very short bursts over double that: 1000 to 1100 watts.


So you would be far from able to maintain level flight, let alone climb. Well, unless you can build a parachute with a very very very low vertical speed.

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>it's possible to regain altitude just by flapping its movable tail.

Nope. Not without a MUCH MUCH better L/D. So far the human powered aircraft that have worked have had astronomically high L/D's (36-45) - an efficient parachute has an L/D of about 4.

And unfortunately, your design significantly reduces the aspect ratio of the wing; this will reduce your L/D further.

> it 's more difficult to get knots or suffer a tear.

I don't think that's supportable without a lot more work. In general, the more lines, the more chance of tension knots. In addition, hard openings are going to be a lot more dangerous. Your body evolved to take impacts from your feet while in a standing position; if you take impacts from the front you risk nasty injuries from dissected aortas and the like (a common frontal-crash injury in cars.) And of course broken necks from hyperflexion.

>it also limits the possibility of crashes

Well, but even if that's true, the crashes that DO occur will be a lot more dangerous, since your feet and legs are much better at absorbing impacts than your face and neck.

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Agree with points above, humans produce nowhere near the energy needed to maintain level flight, much less climb.

Additionally, birds/insects/bats don't just flap their wings up and down - they flap them in a figure-8 motion, rotating the tips on both the upward and downward stroke. Just flapping something up and down will produce zero lift.

This looks like a strange wing with a low aspect ratio, so L/D ratio would also be not very good.

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billvon

Not without a MUCH MUCH better L/D. .


Technically, the required power is more dependent on downward velocity. Moving straight down at 1 m/s (terrible L/D) results in the same energy per second as moving down 1 m/s while simultaneously moving 10 m/s horizontally (pretty good L/D).
Therefore the trick to making this idea work is to design a very slow descending canopy, regardless of L/D. To be honest, I don't see this happening.


Until now I ignored efficiency; taking this into account makes things much worse.

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Are the lines to the back of the canopy the only ones on the back half? That's what I think I see from the video.

If so, it won't "flap" the back half of the canopy, it will just pull down the tail.

It won't add thrust, it will add drag.
"There are NO situations which do not call for a French Maid outfit." Lucky McSwervy

"~ya don't GET old by being weak & stupid!" - Airtwardo

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Answering to Your right doubt on the difficulty to flap and land without provoke a risk of a physical damage.
It's enough put the following changes (that it is a revamped):
there are lines that are tied up from the oval over the pilot and go throught the end of the tail to two mechanical wrappers with a steel spring. (Their weight doesn't influence the stability of the parachute-paragliding) . These last are bind to the ankles of the pilot.
So the pilot use his legs to activate their wrapping strength, enough to lower the tail allowing without doubts the flapping of the movable tail.
About the landing of it, the “seat” where is set down the body of the pilot (from his shoulders to his knees) is open to allow to his legs to glide until his hips and landing as a typical parachuter.

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dqpacker

***It's not April yet this is a bit early.



That’s what I was thinking.
I have never laughed so hard at an idea.
And your’re not a inventor. You’re a bad idea guy.

The bad idea just got badder.

"Madder than mad Mac McMad, winner of the madman of
the year award".
My computer beat me at chess, It was no match for me at kickboxing....

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It's certainly possible to make a contraption that allows you to pull down a huge tail. Pulleys are well known for being a force multiplier (at the cost of having to traverse greater length).

However, basic physics still dictates that this is very unlikely to work. In order to stay aloft, you need to replenish the energy in your system (pilot + wing) that is lost. Energy is lost due to drag, and for typical skydivers this energy is taken out of the amount of potential energy available. That's why we generally go down, not up.

Making such a thing viable means getting the energy loss below 400 watts, since that's about the limit of what a trained athlete can generate (for normal adults it is about 50 to 150 watts, according to Wikipedia). And this is still not talking at all about how to get that energy from your body into the pilot+wing system.

To get to 400 watts energy loss, assuming the entire system weighs 100kg, you need a descend rate at or below 0.4 m/s. (E = m*g*h for potential energy)

Let's look at paragliding wings, since they are among the most efficient non-fixed wings that I know of. The Wikipedia article on paragliding quotes glide ratios of 9.3 to 13 in extreme cases, and speeds from 20 km/h to 75km/h. Lets assume both the maximum glide ratio (13) and the minimum speed (20 km/h), since that will minimize the energy requirements. 20 km/h is 5.56 m/s, which at a glide ratio of 13 means 0.43 m/s downward speed. Sooo close, but not enough.

And oops, we made some very far-fetched assumptions (100% efficiency in getting the energy you generate into the wing, a top athlete that doesn't get tired, a highly efficient wing flying at very slow speed to minimize energy loss from drag). To succeed, you will need to design a wing that is significantly more efficient than a paragliding wing. If you can do that, I'm sure there are quite a few paragliding (and parachuting) manufacturers that would be happy to hire you onto their design teams. However, as it stands, I see a brighter future for you as an animator.

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Quote

Making such a thing viable means getting the energy loss below 400 watts, since that's about the limit of what a trained athlete can generate (for normal adults it is about 50 to 150 watts, according to Wikipedia).



I think 'trained' is underselling it. Sustained for more than a handful of minutes 400W is world class. For more than an hour it's approaching record breaking. Especially if the pilot's attempting to emulate the Grand Tour cyclists by stripping body weight as low as possible to get the watts per kilo up.
Do you want to have an ideagasm?

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You need to make a skydive and fly a canopy.
As you deflect the tail downward it produces drag the opposite of what you want. Otherwise when you pulled the right side of the tail of the canopy it would turn left not right. You will never overcome the the drag produced! But keep thinking and don't get discouraged you may come up with a good idea that may advance parachute or paraglider design.

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pchapman

Franz Reichelt going splat, now that's a little mean. :)



Franz's glide ratio was also a bit 'steep'. ;)

As for being "mean", I'm confident that our man's contraption will leave a similar divot. He'll just have more time to contemplate his folly.
Every fight is a food fight if you're a cannibal

Goodness is something to be chosen. When a man cannot choose, he ceases to be a man. - Anthony Burgess

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