This should be taking off. Why doesn't it?

[Failatlaunch]

Image :

I've tried to make some kind of helicopter, but it doesn't lift.

Edited September 10, 2014 by Claw
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[Whackjob]

Too much weight, not enough lift. Try making the wings longer, and even angling them up about twenty or thirty degrees. Like the blades on a propeller.

[worir4]

Also that top adapter thing is just dead weight. Attach the parachute directly to the pod.

[Random Tank]

Nice whirligig... It needs more spirals though

[Kasuha]

Wings are horizontal so they produce no lift. And the ring of control surfaces below them is placed the wrong way, they act in opposite direction.

Give those wings a little tilt and it will go up.

Edit: and it also needs more wings

Edit2: longer wings help as they meet higher airspeed and therefore have higher lift at ends.

Edited September 10, 2014 by Kasuha

[Taki117]

Wings in KSP are weird and will only generate lift with a Positive AoA (Angle of Attack) Meaning if you are trying to make a copter you need to angle your wings about 5 degrees (More will generate more lift)

Edit: Ninja'd by Kashua...

[Kasuha]

Wings in KSP are weird and will only generate lift with a Positive AoA

Any wings with symmetric airfoil do the same. Symmetric airfoils are used e.g. for aerobatic airplanes.

[Taki117]

Any wings with symmetric airfoil do the same. Symmetric airfoils are used e.g. for aerobatic airplanes.

Did not know that, thank you.

[Wanderfound]

Did not know that, thank you.

Likely to be educational: http://www.explainxkcd.com/wiki/index.php/803:_Airfoil

[-Velocity-]

Wings in KSP are weird and will only generate lift with a Positive AoA (Angle of Attack) Meaning if you are trying to make a copter you need to angle your wings about 5 degrees (More will generate more lift)

Edit: Ninja'd by Kashua...

There is an increasing trend within science education to do away with using Bernoulli's principle in explaining how wings work. The Bernoulli's principle explanation is over-complicated and usually explained incorrectly. It is also not intuitive. Most people are coming to realize that it's much more simple to teach that wings produce lift by pushing air down. So it is the angle of attack that creates the lift. A non-symmetrical wing, if angled so that its geometric average direction is parallel to the air flow (instead of the bottom surface) will also produce zero or almost no lift (maybe even negative lift).

Basically, wings push air down, and so they get pushed up. Very, very simple, and it's a correct explanation of the forces at work. Whoever is responsible for mixing Bernoulli's principle into the explanation should be shot, as they left at least two generations of people not understanding how wings actually work. That included me, until I played enough flight sims (where the relationship between angle of attack and lift was made clear to me), and looked up enough resources, to realize that the Bernoulli explanation was bull!@#$.

To demonstrate how wings work, just stick your hand outside your window while driving your car fast. First, angle your hand so that it is directly into the wind. You'll feel no lift. Next, angle your hand upward, so that your hand pushes down some of the air streaming past. You'll feel your hand (rather strongly) being pushed up. Really, that's it. Lift is that simple. It's a travesty that they over-complicated it to the point that they did.

Oh and by the way, the reason that wings are curved and not flat isn't because of Bernoulli either. It's so that there are less vortices generated- less drag.

Edited September 10, 2014 by |Velocity|

[Aethon]

When I first saw a wing as kid I thought wings create lift by pushing air down and was promptly told that was wrong. Are you saying the turbulent vortex at the trailing edge has no effect on lift?

So is the wing ( sail ) on a sailboat all about angle of AoA as well? When I'm sailing it sure seems like I'm being semi sucked into the dead air, low pressure vortex.

[Wanderfound]

When I first saw a wing as kid I thought wings create lift by pushing air down and was promptly told that was wrong. Are you saying the turbulent vortex at the trailing edge has no effect on lift?

So is the wing ( sail ) on a sailboat all about angle of AoA as well? When I'm sailing it sure seems like I'm being semi sucked into the dead air, low pressure vortex.

Wing/sail curvature, vortex effects, etc. have some influence. But they're massively outweighed by AoA, and are totally inadequate for takeoff. The main effects of the non-AoA lift forces is that they allow you to reduce AoA in level flight, thereby reducing drag.

Ditto for sailing; a flat sheet of plywood works just fine as a sail, just not as well as a curved one.

[Pecan]

There is an increasing trend within science education to do away with using Bernoulli's principle in explaining how wings work...

That would be the trend that parallels making kids feel good by winning prizes, regardless of their performance then.

Basically, wings push air down

Basically, they don't.

they left at least two generations of people not understanding how wings actually work

As opposed to the hundreds of previous generations that couldn't make a plane fly?

To be very clear - there is a difference between a flat surface 'pushing air down' due to angle of attack and an aerofoil (wing, sail) that works by acceleration of the air over one side. True; many wings work best with a positive angle of attack but no - any flight simulator that told you it was pushing air down needs to be deleted.

The classic example must be 'whisper' helicopters (stealth without the radar-hiding) - their rotors actually deflect air UP, taking a lot of the noise with it. Nevertheless, because of their shape they manage to generate lift, otherwise the thing would fall out of the sky!

[Pecan]

Ditto for sailing; a flat sheet of plywood works just fine as a sail, just not as well as a curved one.

No it doesn't. It works just fine as a wall that stops the wind and can deflect it but even with a good keel you ain't going to windward.

[Wanderfound]

No it doesn't. It works just fine as a wall that stops the wind and can deflect it but even with a good keel you ain't going to windward.

...as with most sailing ships through history. With all but the best square riggers, sailing upwind was mostly just a matter of trying to hold position while you waited for the wind to change. Leeway eats your upwind progress.

When I was sailing HMB Endeavour, the highest we we could point was about 80° off the wind, and you'd actually go backwards at a fair clip if you tried to do that.

Endeavour was admittedly a bit of a pig even by square-rigger standards, though. 18th C oil tanker, basically.

[Pecan]

...as with most sailing ships through history.

Exactly - most ships used sails as walls to block the wind and just waited until the wind was in the right direction. It's only because a fore-and-aft rigged sail IS a wing that it allows a boat to go upwind. While it's possible to fly relying on angle of attack if you have enough power that is not the principle that, for example, gliders rely on nor is it the 'secret' that allowed us to capitalise on powered flight.

(And I should probably add - and that I used sailing yachts across the Atlantic 3 times, amongst other trips during 10 years as a boat bum [RYA Coastal Skipper, never bothered to take yachtmaster]).

Edited September 10, 2014 by Pecan

[Wanderfound]

Exactly - most ships used sails as walls to block the wind and just waited until the wind was in the right direction. It's only because a fore-and-aft rigged sail IS a wing that it allows a boat to go upwind. While it's possible to fly relying on angle of attack if you have enough power that is not the principle that, for example, gliders rely on nor is it the 'secret' that allowed us to capitalise on powered flight.

(And I should probably add - and that I used sailing yachts across the Atlantic 3 times, amongst other trips during 10 years as a boat bum [RYA Coastal Skipper, never bothered to take yachtmaster]).

Did you see this, BTW: http://forum.kerbalspaceprogram.com/threads/92653-K-S-S-Kraken-three-masted-sailing-ship

[Pecan]

Did you see this, BTW: http://forum.kerbalspaceprogram.com/threads/92653-K-S-S-Kraken-three-masted-sailing-ship

LOL, no, I hadn't seen that. Next Friday - 19th September - is International Talk Like A Pirate Day ;-)

[godefroi]

The "wings just push air down" explanation is just as over-simplified and wrong as the "bernoulli's principle makes airplanes fly" explanation. Turns out it's much more complex than that: http://www.allstar.fiu.edu/aerojava/airflylvl3.htm

[Xavven]

That would be the trend that parallels making kids feel good by winning prizes, regardless of their performance then.

Basically, they don't.

As opposed to the hundreds of previous generations that couldn't make a plane fly?

To be very clear - there is a difference between a flat surface 'pushing air down' due to angle of attack and an aerofoil (wing, sail) that works by acceleration of the air over one side. True; many wings work best with a positive angle of attack but no - any flight simulator that told you it was pushing air down needs to be deleted.

The classic example must be 'whisper' helicopters (stealth without the radar-hiding) - their rotors actually deflect air UP, taking a lot of the noise with it. Nevertheless, because of their shape they manage to generate lift, otherwise the thing would fall out of the sky!

Could you explain what you mean by "basically, they don't," referring to the downward deflection of the air? I find http://en.wikipedia.org/wiki/Lift_(force) to be pretty confusing once I get past the first couple of sections and into the math, but some of the earlier explanations make plenty of reference to downward deflection.

"But as the angle of attack increases, the air is deflected through a larger angle and the vertical component of the airstream velocity increases, resulting in more lift."

"Cambered airfoils will generate lift at zero angle of attack. When the chordline is horizontal, the trailing edge has a downward direction and since the air follows the trailing edge it is deflected downward."

"Lift involves action and reaction at the airfoil surface and is felt as a pressure difference. The airfoil shape and angle of attack work together so that the airfoil exerts a downward force on the air as it flows past. According to Newton's third law, the air must then exert an equal and opposite (upward) force on the airfoil, which is the lift.[14][15] The force is exerted by the air as a pressure difference on the airfoil's surfaces."

That last bit got me thinking, are Pecan and Velocity really saying the same thing -- that the vertical component of the action/reaction against the airfoil and air IS a pressure difference?

[Xavven]

The "wings just push air down" explanation is just as over-simplified and wrong as the "bernoulli's principle makes airplanes fly" explanation. Turns out it's much more complex than that: http://www.allstar.fiu.edu/aerojava/airflylvl3.htm

Excellent link. I read the whole thing. But... the conclusion I draw from it is that it's very much a pro-"wings push air down" explanation. What do you mean by "over-simplified and wrong"?

[godefroi]

Excellent link. I read the whole thing. But... the conclusion I draw from it is that it's very much a pro-"wings push air down" explanation. What do you mean by "over-simplified and wrong"?

Sorry, it would be more clear if I'd said, "wings deflect air down". Yeah, air gets pushed down, but there are more things going here on than a piece of plywood.

[DrMonte]

Please get some basic aerodynamic book and stop arguing on simple physics. Anyway in KSP this is not implemented. Wings generates predefined lift when placed horizontally. You can get more if you'll rotate them but you'll also increase drag drastically.

Main thing to note that in KSP wing speed is calculated at the connection point. So in construction like this speed would be near zero. You should think of something like Kasuha model with wings further from the core.

Have a nice fly.

[Xavven]

On the contrary, there are such helpful and knowledgeable users on this forum that I'm glad the topic came up. http://www.allstar.fiu.edu/aerojava/airflylvl3.htm was a pretty nice link, thank you very much. I don't think I would have ever found that if not for this forum. Thanks! I've got the basics now and I don't have to read a whole aerodynamic book.

[SRV Ron]

Steerable fins, exception the advanced Canards, will make your rocket float, different from a aircraft or glider, if you start steering it near zero acceleration. Infinaglider effect. In fact, with some experimentation, you can actually fly such a contraption with some degree of control. An eight pair, one stacked above the other is stable enough to point vertically hands and SAS control off. This bug is due to how KSP implements aerodynamics on steerable fins and would never happen for real.

It also caused this problem when landing a booster.