isn’t better for planes on carriers to start at the top of the ramp and get more speed down for takeoff instead of climbing the ramp?
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The ramps at the end of small carriers are not very high compared to the speeds that the airplanes go at. The problem they are there to solve is that the ships are too short for the airplanes to get up to enough speed to fly. If there were no ramp and the aircraft would just launch straight ahead off the deck of the ship they would not get enough speed to fly before hitting the water. The ramp is there to make sure the airplane is at least going up for a bit so they have more time to gain speed. You could argue that the airplane might have a tiny bit more speed if they were winched to the top of the ramp and took off in the reverse direction, but that would still not be enough speed to take off before they hit the water.
Yes it would help the plane gain speed but it would do so at the sacrifice of traction and controllability. Also how do you get planes to the top of this ramp? The only way up would be back up the ramp itself. Now you’ve severely limited the frequency at which you can launch planes.
You can transform height into speed.
The problem is:
Potential energy = weight x height. If you double the length you go downhill, you just double the energy you receive.
But what you need for speed works with this equation:
Kinetic energy = mass x (speed squared)
Let’s say the energy needed to go 1 km/h is 1 energy unit.
If your target is 2 km/h, you need 4 energy units.
If your target is 20km/h, you need 400 energy units.
If your target is 200km/h, you need 40000 energy units.
At that point, any ride downhill is negligible in achieving speed.
So, what they do is to get to high speed by massive engine power, then take the ramp, and the ramp converts that speed into some vertical speed. It’s not about getting more energy, is to direct the energy toward a better direction.
Then by the time the plane loses the vertical boost that it got from the ramp, the engines have added more speed to the plane and it can hopefully be fast enough for safe flight.
Ah but, if you are on a ship and pointing downwards, how much distance do you have before hitting water?
Answer: not enough! Your plane would have to jam it into a powered climb anyway to keep from just crashing there and then.
Planes do not ‘take off’ from nor ‘land’ on aircraft carriers.
Planes are ‘thrown’ and ‘caught’.
100% of the speed a plane attains until it reaches the end of the deck is due to the steam-powered catapult. They only run up their engines so that they will have sufficient thrust to continue flying after they leave the catapult.
Speed and altitude are both energy and can be traded for each other, and the more time you have before you hit the water, the less power you need to build up enough energy. Taking off going upward increases the amount of time you have in the air on a ballistic trajectory.
Pulling up out of a dive will also mean additional induced drag.
Lets say you’re 100 feet up and throw a ball 30 degrees up at 50mph. On the way back down, the ball will be moving 50mph at 30 degrees when it gets back to the starting altitude, ignoring air resistance. That extra time for your engines to accelerate you is what you’d be giving up.
Looks like we’ll have to stick with the ramp for now, unless someone wants to crowdfund a few catapults!
It works fine the way they do it. If the aircraft they launch need more airspeed, making the runway longer would be easier than having any ramp at all, so they would just do that. But they dont need it currently because they’ve designed both the carriers and the aircraft to be able to work with each other. Carrier designs are all old except for the US Navy’s Ford class and those are already designed and being constructed. The F35 is the only new aircraft. So we have what we have for now. Future carrier and naval aircraft designs may evolve, but those are decades away at least.
Worth noting that the UK operates F35B from the Queen Elizabeth class carriers with ramps while the US operates the same aircraft from Wasp and America class amphibious assault ships with no ramps. The ramp allows the F35 to take off with more payload or fuel for the Brits, but it also reduces flight deck space for helicopter operations.
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