Forums: Skydiving: General Skydiving Discussions:
What about parachute-paragliding with a movable tail?

 


littlediamon

Dec 5, 2017, 1:33 AM
Post #1 of 12 (1614 views)
Shortcut
What about parachute-paragliding with a movable tail? Can't Post

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


piisfish

Dec 5, 2017, 2:38 AM
Post #2 of 12 (1584 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

https://www.youtube.com/watch?v=3BtPXtlC3hg
Sure looks different. Looking forward to seeing it flying


pchapman  (D 1014)

Dec 5, 2017, 4:57 AM
Post #3 of 12 (1513 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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.)


linestretch  (D 21060)

Dec 5, 2017, 7:20 AM
Post #4 of 12 (1427 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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.


evh  (D License)

Dec 5, 2017, 7:27 AM
Post #5 of 12 (1423 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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.


Premier billvon  (D 16479)
Moderator
Dec 5, 2017, 10:08 AM
Post #6 of 12 (1340 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

>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.


aonsquared  (C 110922)

Dec 5, 2017, 10:16 AM
Post #7 of 12 (1336 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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.


evh  (D License)

Dec 5, 2017, 12:16 PM
Post #8 of 12 (1267 views)
Shortcut
Re: [billvon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

billvon wrote:
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.


wolfriverjoe  (A 50013)

Dec 5, 2017, 4:31 PM
Post #9 of 12 (1129 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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.


platypii  (C License)

Dec 6, 2017, 6:58 PM
Post #10 of 12 (812 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

How about something like this? A paraglider that flaps like a bird:



Human energy output is still a problem, but I think this would be closer.
Attachments: paraglider2sm.gif (109 KB)


Quagmirian  (C 110392)

Dec 7, 2017, 5:12 AM
Post #11 of 12 (633 views)
Shortcut
Re: [littlediamon] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

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


dqpacker  (D 32043)

Dec 7, 2017, 7:17 AM
Post #12 of 12 (557 views)
Shortcut
Re: [Quagmirian] What about parachute-paragliding with a movable tail? [In reply to] Can't Post

Quagmirian wrote:
It's not April yet this is a bit early.

Thats what I was thinking.
I have never laughed so hard at an idea.
And yourre not a inventor. Youre a bad idea guy.


(This post was edited by dqpacker on Dec 7, 2017, 7:21 AM)



Forums : Skydiving : General Skydiving Discussions

 


Search for (options)