Venus Aerospace Inc. created the Mach 6 engine. That can start on runways.

Image via Hermeus

It's possible to send a shuttle from the regular runways to space using the ramjet engines. The biggest problem is how to make air travel through ramjet. Because that engine does not have moving parts. 

In the most conventional solutions, the ramjet engine will start at Mach 1. The aircraft can accelerate to Mach 1 using regular jet engines. When the speed is high enough, the system closes the engine compressors and lets the fuel-air mixture travel to the ramjet. 

The main problem with Ramjet engines is that they do not involve moving parts. One solution that can solve this problem is the pulse ramjet. The pulse ramjet is a similar system to the pulsejet, but its engine tube is transferred to the ramjet engine. In pulsejets, the flap system allows the engine to create thrust even if the aircraft doesn't move. 

There is the possibility of installing pulsejet separately from ramjet. The pulsejet accelerates the craft to a speed of about Mach 1. Then the system puts aerodynamic shields on the pulsejet. And injects fuel into the ramjet. There is the possibility that the pulsejet is installed in the ramjet engine tube. The system's purpose is to put air flow backward. 

There are tested systems like the flap system that are similar to the system that was used in the WW2 German V-1 missile. 

The flap ramjet uses a differently shaped engine tube that the V-1 missile's engine uses. And that allows the system to start on runways. This engine system requires a separate ignition system until the speed is so high, that the airflow from the front of the engine can create so high temperature and pressure that the fuel-air mixture burn turns self-sustaining. 

Illustration of Venus Aerospace's Rotating Detonation Rocket Engine for hypersonic travel. Image generated by AI. (Sustainability “Mach 6 From a Runway”: US Unveils Hypersonic Jet Engine That Could Redefine Military Airpower and Global Strike Speed)

Pulsejet

Diagram of a valved pulsejet. 1 - Air enters through the valve and is mixed with fuel. 2 - The mixture is ignited, expands, closes the valve and exits through the tailpipe, creating thrust.3 - Low pressure in the engine opens the valve and draws in air. (Wikipedia, pulsejet). One of the most promising variants of the pulsejet is a pulse detonation engine (PDE) 

"A pulse detonation engine (PDE) is a type of propulsion system that uses detonation waves to combust the fuel and oxidizer mixture. The engine is pulsed because the mixture must be renewed in the combustion chamber between each detonation wave and the next. Theoretically, a PDE can operate from subsonic up to a hypersonic flight speed of roughly Mach 5. " (Wikipedia, Pulse detonation engine)

"An ideal PDE design can have a thermodynamic efficiency higher than other designs like turbojets and turbofans because a detonation wave rapidly compresses the mixture and adds heat at constant volume. Consequently, moving parts like compressor spools are not necessarily required in the engine, which could significantly reduce overall weight and cost. Key issues for further development include fast and efficient mixing of the fuel and oxidizer, the prevention of autoignition, and integration with an inlet and nozzle."  (Wikipedia, Pulse detonation engine)

Ramjet

Simple ramjet operation, with Mach numbers of flow shown (Wikipedia, Ramjet). 

Rotation detonation engine (RDE)

In some cases, the system can use separate compressors and acoustic systems that form pressure waves. Like pistons in the engine. That kind of high-pressure system can create so much heat that the fuel-air mixture can ignite. 

The system works in a similar principle to a diesel engine, where a piston that goes up creates pressure and temperature that allows fuel-air-mixture burn. There are also plans to use the small hypersonic wind tunnels that pull air through the ramjet or scramjet. That makes it possible to ignite those engine systems on runways. Things like explosives behind the engine tube are tested for making the airflow. If the hypersonic engine can start on the runway that makes the ramjets more effective and decreases their weight. 

The system called rocket ramjet can transport spacecraft to orbit from regular runways. The air-breathing ramjet engine transports aircraft to the high atmosphere. There the engine closes its iris. Then the system will start to inject fuel and oxygen into the engine. That gives the spaceplane or antipode aircraft the capacity to operate variously in the atmosphere and space. 

The main problem with ramjet and scramjet engines is the compressor. The compressor's mission is to make air flowing through the engine. Hypersonic technology is challenging because the compressors might not stand the airflow. There is the possibility to make metal rings where the turbine wings are connected. The magnets pull the ring to the axle, and that helps to resist the centripetal force. 

The other version is the rotation detonation (rocket) engine (RDE, RD(R)E). That system base is in the screw-shaped structure in the engine tube. The special compressor and maybe acoustic systems send a fuel-and-air mixture to travel in the screw-shaped structure. One of the solutions that can allow the use of the compressor to operate at the speed of Mach 6 and above can be the "umbrella solution". 

The system turns the engine compressor's wings against the axle when the speed turns high enough. The system can use some kind of electric system. That makes the electric arc in the engine. The compressor is needed to aim the airflow in the right direction. 

The idea is that the friction in that screw or riffled structure ignites the fuel. The system can use some kind of electromagnetic system to heat up the fuel. The ability to start on the regular runways makes those new hypersonic systems travel. At every point on Earth in 90 minutes. The system can revolutionize warfare and transportation. 

https://militaryembedded.com/unmanned/test/hypersonic-drone-to-take-first-flight-later-this-year

https://www.sustainability-times.com/research/mach-6-from-a-runway-us-unveils-hypersonic-jet-engine-that-could-redefine-military-airpower-and-global-strike-speed/

https://wccftech.com/nasa-test-rare-supersonic-rocket-engine-with-circular-combustion/

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

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

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

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