Rocket-Jet Hybrid, Rocket + Ramjet

In summary, a thrust augmentor can significantly increase the efficiency of a jet engine. It is sort of like a ramjet, only the cold air is being sucked in along with the hot air that's being forced into it from the previous stage.
  • #1
I read that a thrust augmentor can significantly increase the efficiency of a jet engine (http://www.pulse-jets.com/phpbb3/viewtopic.php?t=931). Now from my understanding, the thrust agumentor is sort of like a ramjet. Only, in this case, the cold air is being sucked in along with the hot air that's being forced into it from the previous stage (like a jet jump). The hot air heats the cold air instead of burning fuel like in a ramjet.

So...

Could a low-force rocket pump cold air into a ramjet to provide high force? I don't think I understand all this correctly. I would appreciate any help. Please point me to where I could read about this (someone has already built it I'm sure).
Here is my Frankenstein image in case my words are worthless:
Rocket-_Ramjet.png
 

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  • #2
Julian Erickson said:
I read that ...
Read where? Do you have a link? You will get more and better answers if we have a better idea where you're starting from.
 
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  • #4
IMHO, you would get more benefit by altering the intake shape, as was done with the 'Blackbird'. Ramp, cone, spike or whatever.

You may need that rocket to kick-start the main jet, but I reckon the thrust augmenter belongs at the back, where it cannot compromise the intake's airflow. IIRC, a pulse-jet enthusiast in the Antipodes found a real-neat way to put a wide, tuned pipe over the exhaust, creating the equivalent of a high-bypass ratio jet engine. His research publishing was hampered some-what by the possible application to build inexpensive flying-bombs...

If you want a cutting-edge jet-rocket combo, with inter-cooling yet, check out Reaction Engines' fascinating work.
https://www.reactionengines.co.uk/
Disclosure: Some years ago, when I first read about their micro-filament heat exchanger, I asked them if they'd considered diagnosis via Fourier analysis of the 'Aeolian Harping'. Their reply was a BIG smiley...
 
  • #5
Have a look at this video to see the same principle of jet pumping in action with a rocket motor.



You can also see the effect of entrainment from a rocket engine in this example.

Starts test firing at 8min into the video.



Perhaps it may be possible to redirect some of the exhaust from the jet back into the intake so as to bootstrap the flow too.
 

1. What is a Rocket-Jet Hybrid?

A Rocket-Jet Hybrid, also known as a Rocket + Ramjet, is a type of propulsion system that combines elements of both a rocket engine and a jet engine. It utilizes a rocket engine for initial acceleration and a ramjet engine for sustained supersonic flight.

2. How does a Rocket-Jet Hybrid work?

A Rocket-Jet Hybrid works by using a rocket engine to provide initial thrust and accelerate the vehicle to supersonic speeds. Once it reaches a certain velocity, the ramjet engine is engaged and uses the vehicle's forward motion to compress incoming air and mix it with fuel for combustion. This creates continuous thrust for sustained flight.

3. What are the advantages of a Rocket-Jet Hybrid?

The main advantage of a Rocket-Jet Hybrid is its versatility. It combines the efficiency and high thrust of a rocket engine with the fuel efficiency and high speed capabilities of a ramjet engine. This allows for greater range and speed compared to traditional rocket engines.

4. What are the potential applications of a Rocket-Jet Hybrid?

A Rocket-Jet Hybrid has potential applications in both military and civilian sectors. It could be used for high-speed and long-range reconnaissance and surveillance missions, as well as for launching satellites into orbit. It could also be used for commercial travel, such as hypersonic passenger planes.

5. What are the challenges of developing a Rocket-Jet Hybrid?

One of the main challenges of developing a Rocket-Jet Hybrid is the complexity of the technology. It requires precise control and integration of both rocket and ramjet engines, as well as the fuel systems and air intake. Additionally, the high speeds and temperatures involved in the combustion process pose engineering challenges and require advanced materials.

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