The solution for hypersonic flight and space planes: rocket ramjet.

The answer to the problem of how to ignite the ramjet is the rocket ramjet. The system allows engineers to make the space plane. The aircraft that can operate the atmosphere and orbiter. 

The biggest problem with ramjet engines is the pressure. The engine itself doesn’t have moving parts. That means the aircraft that uses a ramjet engine must fly about Mach 1 so that the airflow into the engine can create pressure and heat that ignites the fuel-air mixture. There are introduced things like the rocket-ramjet hybrid system that uses an iris at the front of the engine. When an aircraft stands on the runway the system uses internal oxygen and fuel. The iris will be closed and the engine acts as a rocket engine. 

When the aircraft reaches Mach 1 the iris will be open and the internal oxygen injection ends. At that speed air that comes from the front of the engine can maintain burning. However, it is possible. The system uses pressurized air at the beginning of the flight. The system can store air in pressure bottles and then the same pumping system that is used for pure oxygen can transfer that air from the bottle to the engine. 

Above: Regular ramjet. 

The diagram of the ramjet engine that uses separated superchargers. The iris is open. 

The system can transfer air to the ramjet engine using centrifugal superchargers. That system allows aircraft to ignite ramjet engines at runways. There is a possibility that a rocket ramjet that turns the ramjet into a rocket engine can beat even a scramjet. If the compressor system can inject air to the combustion chamber at a speed that is higher than Mach 6 that system allows it to operate at higher speed and altitudes than traditional air-breathing ramjet and scramjet systems. The idea is that the system can take air and oxygen from the atmosphere but it conducts that oxygen to the engine in different ways than regular ramjets. 

The compressor system can fill those bottles with air, and then the engine system injects that air into the rocket ramjet chamber with fuel. The system can use hydrogen as fuel, which allows the system to ignite that fuel easier than kerosine. The system can also use an electric arc to ignite the fuel. The electric arc can be formed around the pressurizer cone that creates the pressure wave in the ramjet engine. The system can also use oxygen straight from the air. That means the system can replace those pressure bottles with centrifugal compressors. Those high-power compressors can be on both sides of the engine. Then they pump air at a very high speed from the front against the cone. 

Then, the hydrogen (or a hydrocarbon, such as kerosene) can be injected into the combustion chamber. If the iris at the front of the engine is closed, that system makes it possible to start and lift off the hypersonic aircraft straight from the runways. When the aircraft turns to move faster, that system opens the iris at the front of the engine. Then it can close the airflow to the compressor. If that kind of aircraft also had internal oxygen storage it could fly to space and operate at the orbital trajectory. The system can also dive into the atmosphere and utilize atmospheric air in its mission. 

https://en.wikipedia.org/wiki/Ramjet

https://en.wikipedia.org/wiki/Scramjet