What are the conditions to create fire?
Fuel, heat/spark and oxygen are needed to create fire. This is often called Fire Triangle.
What does that mean? Well for example, when creating camp without a lighter:
· The sticks are the fuel
· The friction of rubbing the sticks create heat
· And the oxygen is coming from the air
· When the heat from friction reaches the temperature for ignition of the specific material the fuel start to burn
So, let’s look at Luffy’s case and how does he fulfill the fire triangle conditions. From what we have seen until now, the process he creates the fire is covering his arm in Haki, extending his arm in a high speed then retracts it back at high speed and the fire just appear. In relation to the fire triangle the properties are as follow.
· The rubber is the fuel
· The friction of extending and retracting creates heat
· And the oxygen is coming from the air
· When the heat from friction reaches high enough T the rubber ignites
So, the process is very similar to the example with the camp fire, with one difference – the fuel in this case is rubber.
However, when we talk about highspeed friction with air, it’s not the friction with the air that produces most heat it’s the compression. Scientifically explained that’s how it sounds:
“At high speeds, it isn’t friction with the air that produces most of the heat, it’s the compression. Like a ship moving through water, you push a bow wave of air in front of you. The air molecules can’t get out of the way in time and they bunch up, banging into each other and getting hotter. Any parts of your body facing into the wind will be heated up.”
Then continuing the topic it was interesting to check how fast you must move in order to ignite yourself and the answer is Hypersonic
“Bodies are typically cremated at around 1,500°C and aircraft research from NASA reveals that you’d need to be running at Mach 5 (6,000km/h) to reach that temperature.”
However, this is about human bodies. So, lets continue.
“1,500°C is the temperature to completely incinerate your entire body – your clothes will catch fire long before you reach that point. Nylon has an ignition point of about 500°C and wool will catch fire at 230°C. Which means that with the right attire, you could trot along at a leisurely 2,500km/h and still burst into flames.”
The ignition rubber temperature can vary between 260°-316° (google) depending on the rubber.
So, from that statement it means that Luffy needs to move his arm around 2 times faster than the speed of sound in order to catch fire. But from we have seen in the animations from the fights with Hody Jones and Doffy, Luffy seems to extend his arms at normal speed.
However, this explanation is valid for the contact between the Air and other material. But what happens if we substitute the air with other material – then the friction coefficient between objects is higher.
When the friction coefficient is higher, bigger force is needed to move on this surface. When we apply the force needed, the bigger the load on the object, the more heat is being released from the friction. So, with higher friction coefficient and constant force we can reach a specific temperature faster.
With all these explanations and setup, can we speculate that Luffy is unintentionally using a basic awakening which turns the air around his Haki rubber arm into rubber to increase the friction coefficient and reach ignition without the need of supersonic speed???
To support that we have already seen a character who affects the air around him to use his devil fruit – Whitebeard.
When causing all the shocks it seems like he is breaking the air or grabbing the air making it physical object.
Also the pattern where Luffy actually uses a power without knowing its meaning has been shown before with his Haki against Duval’s Bull and in Marineford knocking people with CoC.
So this might be similar case where he went to such extend training his Devil Fruit in the island for 2 years so he discovered something by accident and dont know how exactly it works, but he is using it by instinct.
Interesting fact or an animation/drawing mistake?
Looking at the cases where Luffy has used the technique Red Hawk we can see a difference in one of the fights.
The first case is against Hodi Jones where it seems that his entire arm is ignited in fire.
Then the second time we see the technique is when Luffy fights Doffy and here it seems that actually the air around his arm is ignited. Or could it be actually the rubber air catching fire?
The third case is when Luffy tries to hit Katakuri and in this case his entire arm seems on fire again.
Is that a coincidence/mistake in drawing/animation or it is specifically made in the Doffy fighting scene where later Doffy directly reveals the awakening factor in Devil Fruits?
*Theory by Capt_NakedPanda