Pilot Navigation around felarya.

Jasconius wrote:

*Tunneler Worm erupts out of soil, followed by an Ice Wyrm.*

Ya... I don't think the underground is much safer either, Pendragon.

*slaps* Take the zone when these are found into consideration. Do you see an ICE Wyrm dig all the way to a desert of the volcano?

I can't help it, they were all I could find in 30 seconds

Talking to Cauldronborn24 (who knows this stuff) we've established that, even though predators aren't effected by some of the normal laws of physics, it doesn't mean everything is possible.
A harpy will never go supersonic, nature just can't design an animal to do so. Why? There are a few reasons:

• In order for a bird to accelerate it has to flap its wings. This means that for a few second the flat side of the wings is facing forward, which means that it produces drag. This drag would prevent a harpy reaching anything near supersonic speed, as it attempts to go faster, more drag would produced.
  tl;dr: harpies can't achieve huge speeds due to drag and the inability to produce constant thrust.
  
• An object approaching the sound barrier is subject to a series of shockwaves. These would either kill on hugely injure the harpy.
  
• During WWII, pilots were sometimes unable to pull out of a dive because the the air pressure over the control surfaces was so great that they couldn't be moved. This would also happen to harpies, they would HAVE to keep their wings in and therefore be unable to pull out.
  
• If a harpy entered a super fast dive and then attempted to abruptly pull out of it, their bones would break due to the gees and pressures involved.
  

Anime-Junkie wrote:

Talking to Cauldronborn24 (who knows this stuff) we've established that, even though predators aren't effected by some of the normal laws of physics, it doesn't mean everything is possible.
A harpy will never go supersonic, nature just can't design an animal to do so. Why? There are a few reasons:

• In order for a bird to accelerate it has to flap its wings. This means that for a few second the flat side of the wings is facing forward, which means that it produces drag. This drag would prevent a harpy reaching anything near supersonic speed, as it attempts to go faster, more drag would produced.
  tl;dr: harpies can't achieve huge speeds due to drag and the inability to produce constant thrust.
  
• An object approaching the sound barrier is subject to a series of shockwaves. These would either kill on hugely injure the harpy.
  
• During WWII, pilots were sometimes unable to pull out of a dive because the the air pressure over the control surfaces was so great that they couldn't be moved. This would also happen to harpies, they would HAVE to keep their wings in and therefore be unable to pull out.
  
• If a harpy entered a super fast dive and then attempted to abruptly pull out of it, their bones would break due to the gees and pressures involved.
  

Once again, you're thinking too much real world. And that statement is pretty hilarious, coming from this pessimistic realist. For instance, any predator with magical abilities would be able to use the newtonian laws of motion to their advantage, not their derision. While gee-forces could break their bones or cause them to suffer redout/blackout, that would only occur if the forces were being enacted on said creature. If the forces that are actually generating lift and ability are magical in nature, then the force is not directly applied to the physical body. Even if the force isn't being generated entirely by either physical or magical yields, but rather shared between the two, one could easily argue that even a rock harpy could achieve such flight patterns. They are often masters (or at the least strong wielders) of powerful wind magic - which at its base is just the variance of different temperature layers, in and of itself a manipulation of energy and therefore also allowing a predator to manipulate matter/energy conservation to their advantage as well, as heat generation is one of the concerns of such flight. I can't imagine any good reason why a predator would need to travel at such speeds, and the stresses would be rather large. I don't think it would kill them though, unless they were attempting it solely by physical means. For short bursts, I wouldn't have any issues believing they could do it. Sustained? No chance. The amount of energy required to safely pull it off would not be worth it.


Using real world examples, in the peregrine falcon, we see a bird that has been clocked at 68mph horizontal cruising speed, and up to 242mph in swoop. That's roughly 32% sonic speed right there, unassisted. Ideal speeds of the falcon are even higher, especially at high altitudes and thin atmospheres (such as that near mountain peaks, which do exist in Felarya). More importantly to note, however, is that the falcon has been clocked doing 90mph UP. I personally do not see harpies 'catching' aircraft by flying along side them, but I do believe they could strike down an aircraft. Peregrines can protect their bodies while striking at such high velocity speeds, so there is no reason to think a harpy could not do so either, even if they had to result to magic in order to do so. Applying the resultant 'speed conversion' argument to predators allows for even more wiggle room.

Anime-Junkie wrote:

rcs619 wrote:

In a good dive, I think they'd be pushing supersonic.

No, terminal velocity does not allow supersonic dives. Supersonic would probably kill them. The sound barrier was called a "barrier" for a reason.

Supersonic speeds probably wouldn't, in and of themselves, kill harpies. People have ejected from aircraft traveling at supersonic speeds and survived with minimal or no injuries. Now if a wing got caught poorly or something like that, then I could see serious problems occurring. (Supersonic shock waves have much more energy than a normal sound wave, but considerably less energy than some of the things we encounter in everyday life, and a lot of the energy in the shockwave is not transmitted but is instead reflected off of a surface it hits. See the mythbusters episode where they shot a supersonic bullet between two very closely spaced panes of thin glass, yet didn't break them.)

Anime-Junkie wrote:

Also, a diving harpy colliding with a jet... Messy, to say the least.

Maybe, depending on how the harpy and the jet collided. If the harpy grazed the jet's wings with a talon, the jet's wing would likely disintegrate. The talon would be roughed up, but it probably wouldn't be ripped off or anything. If the harpy "dropped" down on top of the jet while traveling at the same forward velocity, the jet would almost certainly disintegrate, and so long as no piece of the jet accelerated fast enough and hit the harpy, the harpy would be essentially untouched.

Or, to explain more completely, consider this longer explanation.
A harpy and a jet are both traveling in the same direction at the same speed, with the harpy flying above the jet. The harpy dives down on to the jet, hitting it roughly enough to cause it to have a structural failure and break up. At the moment of impact, both the harpy and the jet are traveling at the same speed in the same direction. Each piece of the broken aircraft also starts out traveling in the same direction and velocity as the jet it came from, so each piece is not moving relative to the harpy. Each piece of the jet has a different mass and a different aerodynamic profile, so each piece will interact with the air around the jet differently. The really heavy pieces will not not slow down very quickly at all, and so will continue to travel at the velocity of the jet before it broke up (which is the velocity of the harpy as well). Since they are traveling in at the same speed and direction, they are essentially harmless to the harpy, since the relative velocity between the harpy and that object is essentially zero. It's like how you are not injured simply by touching your car seat, even though your car is traveling at 60 miles an hour, because you are also traveling at 60 miles an hour.

However, some of the pieces have considerably less mass and more drag than the others, and these pieces will decelerate rapidly (from the point of view of someone sitting on the ground. From the harpies' point of view these pieces will accelerate rapidly towards the back of the jet.) How dangerous these pieces are depends on a great many factors, with the major three being how sharp and pointed the object is, how quickly it accelerates, and how heavy it is. All three of these factors interact with each other.

The location of the harpy hitting the jet is of high importance as well. If the harpy only breaks a wing off of the jet, the jet will still crash but the harpy might be in front of all the dangerous pieces and thus be completely safe. On the other hand, a harpy that smacks into the back of a jet and causes it to break up will be showered with pieces from everything in front of her... many of which have the entire length of the aircraft to accelerate into lethal projectiles. (From her perspective. From the perspective of someone on the ground the dangerous pieces slow down very rapidly and it is the harpy that flies into them at high speeds.)

Anime-Junkie wrote:

During WWII, pilots were sometimes unable to pull out of a dive because the the air pressure over the control surfaces was so great that they couldn't be moved. This would also happen to harpies, they would HAVE to keep their wings in and therefore be unable to pull out.

Maybe. It is important to note that the reason WWII planes had this problem was because of where their flaps were placed; modern supersonic aircraft have their control flaps placed differently, still in contact with the super sonic air stream but out of any shock-cones, thus enabling the control surfaces to still function properly. We would need to model/test a harpy at super sonic speed to determine just how affected their control surfaces are. In an additional complication, it is likely that how functional their wings would be at controlling their orientation at supersonic speed would depend greatly on just how they are holding their wings; a slight change in the angle of attack might be enough to deprive them of control... or give control back.


Also, while I am not a hydrodynamic/aerodynamic engineer, I want to point out that it should be possible for an object to have a terminal velocity high than the speed of sound, if it has the proper aerodynamics. If an object is streamlined enough, it will fall faster and faster. As it reaches the speed of sound, supersonic shockwaves will form, which require energy and increase drag. For an object that is aerodynamic enough, however, even this increased drag will not bleed off energy fast enough, and the object will continue to accelerate past the speed of sound.

Anime-Junkie wrote:

If a harpy entered a super fast dive and then attempted to abruptly pull out of it, their bones would break due to the gees and pressures involved.

This depends on just how strong their bones are... if their bones were really strong then if they jerked their wings open at supersonic speeds not much would happen other than that they would begin to slow down very rapidly. Even if their bones are not very strong, they could still slowly pull out of a supersonic dive... by very slowly opening their wings, thus increasing their drag and slowing them down.




I was curious about just what the terminal velocity of a harpy might be, so I did some quick research.


The formula for terminal velocity is equal to sqrt((2*m*g)/(p*A*Cd)), where m is the mass of the falling object, g is the acceleration due to gravity, p is the density of the fluid through which the object is falling, A is the projected area of the object, and Cd is the coefficient of drag, which tends to increase for objects that are traveling at supersonic speeds.

The acceleration due to gravity is presumably 9.8 m/s^2 , and the density of the air is presumably around 1.3 kg/m^3. The other three variables have a wide range of possible values, so the result is likely to be somewhat variable. From the two harpies in the wiki (Erica and Belletia), I have calculated an average height of 89 feet. This is 14.8 times as tall as a 6 foot human. If we assume (a big assumption) that a harpy is essentially just a scaled up human, then we can just scale up a human's weight too. Not by 14.8, but by 14.8^3 (because the harpy is bigger in all three dimensions (x,y,z)). If the average human female weighed 74 kg, then the scaled up harpy would weigh 239892 kg. Assuming a head first dive, I don't think a human would have a projected surface area any wider than his chest to back distance, nor any longer than his shoulder to shoulder distance. This is roughly 0.12 square meters of surface area. Scaling it up (by multiplying it by 14.8 twice, once for each of the dimensions involved) gives a frontal area of 26.2 square meters. The last parameter is the most difficult to guess, as it varies depending on other factors. However, it tends to go UP when an object is traveling at supersonic speeds, so if I do my calculations using a higher than average coefficient of drag, then I will be underestimating the terminal velocity of a harpy, which is preferable to overestimating it. Some quick googling suggest a subsonic Cd for a bird of about 0.4... I am going to play it "safe" and quadruple that to 1.6 to get a supersonic coefficient of drag.


With all those number, I plug and chug and get the result of 293 meters per second, which is about 655 miles per hour. Since the speed of sound is roughly 768 mph, a harpy under those condition cannot generally exceed the speed of sound (maybe if they went really high were drag is less and dove they could exceed the speed of sound, though they would slow back down to 655 miles per hour after a bit.)

This result is very sensitive to the values you choose though; if the supersonic coefficient of drag is 0.8 instead of 1.6, then the terminal velocity is 928 mile per hour, clearly supersonic.

Since this is about to go way off on a tangent, I request that a new thread be made and the relevant posts from this thread be moved by a moderator.

Wow I'm quite speechless by all those demonstrations o.o
though I admit for the most part it's like chineese to me

Anyway, the thread is here : https://felarya.forumotion.com/harpies-and-sphinxes-f10/supersonic-flight-t2146.htm

Karbo wrote:

Wow I'm quite speechless by all those demonstrations o.o
though I admit for the most part it's like chineese to me

Anyway, the thread is here : https://felarya.forumotion.com/harpies-and-sphinxes-f10/supersonic-flight-t2146.htm

But I thought you had family in China.

Karbo wrote:

Wow I'm quite speechless by all those demonstrations o.o
though I admit for the most part it's like chineese to me

Trust us, we know what we're taking about.