Thread: Dutchman flies by flapping his arms

1. Hi all

Originally Posted by PELHAM
...Please go and study the physics and aerodynamics behind flapping wings and you will realise there is something very wrong with this. It's fake, an early April Fool.
Then it is a damn good fake.

But I will wait and see.

Kind Regards walker

2. If you apply a little bit of logic, you realise it's fake. The "power assistance" just looks way too dinky to handle the torque that would be required to move those arms that help power the wings. But, even if the assistance is strong enough, the lift is still cancelled out on the upstroke on the wing and once he is airbourne, his legs are off the ground and there is no longer any forward force.

Not to mention the fact that this would have been done years ago, if it were even remotely possible.

3. Originally Posted by PELHAM
Here's the science bit, anything flapping a wing has to reduce the air resistance on the upstroke or it cancels out any lift produced on the downstroke. Flapping a flat wing up and down will get you nowhere. The most obvious thing in that video is even if the wing motion was feasible, the range of motion wouldn't produce a force to get a human off the ground. He is gliding with powered assistance of some kind e.g. a hidden winch (could even be lifted by a crane out of shot).

Please let me have a list of projects you have worked on, I would like to avoid travelling on those aircraft. LMFAO
I see your video and raise you mine:

Maybe you can explain your "cancelation of lift" theory to the bat. I did enjoy the MS Pain parrot though. Which institute was it produced in? Maybe where you got your own "wing flight theory" Ph.D? I don't claim to know whether its real or fake, I didnt make any calculations on it, just saying that I think its possible. If its fake, then its disappointing. You are just a smug troll apparently.

on the dutch news:

The motion controlled servo's

4. Yes I was right, in the videos hes says he mimics bats with the help of elektro motors...hes deos not power it with his muscles its electricalyl assisted...it's like a wii controller he uses. A bat decreases the ost in lift by decreasing not the wing area but the angle af attack since the skin is flexible liek the artificial wing we see here...but effect is minimal and the video must have ben shot under optimal conditions...a good head on wind is needed. The motion pattern the motors and rods produce mimics indeed bats or albatros flight.

5. The dutchman's wings are far from being as advanced as a bat wing. Here is a nice article I just read, going into more depth:
http://www.sciencedaily.com/releases...0118161402.htm
http://www.sciencedaily.com/releases...0229135215.htm

And a much much better windtunnel video, representing bat wing movement:

Also, take note that a bat flaps their wings like 15 times a second.

6. Originally Posted by Soul_Assassin
Maybe you can explain your "cancelation of lift" theory to the bat. I did enjoy the MS Pain parrot though. Which institute was it produced in?
It's not my theory, it's a well known scientific fact (welll I thought it was). By folding, or twisting the whole wing or parts thereof, the air resistance is reduced on the upstroke. If that didn't happen the lift produced on the downstroke would be cancelled out. That is how lift is produced in a flapping wing, simple. Flapping flight works on that principle in any wing, man made, insect, mamalian and avian. If you look really closely at the bat video you will see the bat folds it's wing on the up stroke and extends it on the downstroke.

The fake flight video can't work on any level, the wings don't twist or fold, the electric motors are not powerful enough, it doesn't have the right range of motion and does not flap fast enough. Something is bothering me about the trailing edge too. If that wing was producing lift the loose material would flutter caused by turbulance over the top of the wing. So it isn't gliding. I say it's clever CGI or he is being lifted by a crane or winch.

You guys are starting to worry me! You sure you aren't pretending to believe this nonsense? Is this the new April fool joke? We all pretend to believe some outragous crap as a clever reversal? If so you have my admiration, you fooled me.

7. Possible or not, in my opinion, that video is not even close to being a good fake. The footage from about 30 to 40 seconds and the landing do not look like flight to me. Maybe I'm wrong, and maybe this isn't an april fools prank or some other fake, but that video does not convince me at all.

8. Hi all

...Also, take note that a bat flaps their wings like 15 times a second.
The bat flaps its wings faster because it is smaller. The smaller a flying animal is the faster its wings beat. Among other things it is a function of inertia which scales inversly on mass. Newtons Second law of Motion F = ma.
http://en.wikipedia.org/wiki/Inertia#Mass_and_inertia
And also on Radius, simplified and generalised using ballistic physics, what is the radius of a bat?
http://iontrap.umd.edu/teaching/phys...tofInertia.pdf

In general the smaller an object both mass and dimension the less inertia it suffers, so in this case the faster it can flap its wings. You also have to throw in energy source in the case of animals that is food, of which the quality of the food and its ability to be converted into useful work is what is important. So a Humming bird feeding on nectar can support a high speed of engine flap and the smaller it is the less inertia affects it.

So in this case an albatrosses wings or those of Fruit bat which I do not think beat at 15 times a second are more appropriate analogues, even more appropriate are things like condors, buzzards and vultures none of which are renowned for high speed flapping of their wings.

Kind Regards walker

9. Originally Posted by walker
Newtons Second law of Motion F = ma.
Newton's third law: The mutual forces of action and reaction between two bodies are equal, opposite and collinear. Exactly same thing happens on upstroke and downstroke.

You see, this is a really basic concept of physics that even a small child can understand. Say you're in a rowing boat and just move the paddles/oars (wing oarss if you must) backwards and forwards without taking them out of the water or twisting them... Nothing happens. Now, change the paddles to wings and change the water to air... What happens?

edit:

• http://i.imgur.com/bcox5.gif
• http://i.imgur.com/9sLbx.jpg
• 0:45 GoPro view﻿ shows his helmet in frame. 0:58 has no helmet in frame.
• Who filmed him taking off when there appears to be no cameraman ahead in the first scene? (already ran past man on far right / camera angles don't match.)
• At 01:09 his body keeps disappearing like he is running 10 meter infront of the wing.
• ~100m / ~30s = 3.3m s^-1﻿ or 12km h^-1 (rofl gliding that thing at 12kmph / 7.4mph)
• The wingspan in proportion to the man's body gets bigger as he moves further away. (incorectly resizing the cgi wings)

------

Also, an extra argument he does not have enough forward motion to be able to lift his legs up straight. The mass displacement would change the centre of gravity and cause the man to tilt upright without enough drag created to counter it. + don't forget the other thousand things already mentioned in this thread. And, I'd like to add to the fact that a hand glider takes ~25kph to glide, this design is much weaker with less wingspan, tension and surface area... For this to work i'd speculate that it'd take at least 50kph for it to even glide (assuming he has the correct aerodynamics), which he is clearly not achieving.

10. 0:35 movement looks really fake and cheap fx.

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