Ramjet Ignition Airspeed: What You Need to Know

In summary: I have been reading about ramjets. I was wondering what airspeed is required for a decent efficiency. And if you don't mind say the vehicle weighs 500 pounds and is carrying 1,000 pounds of fuel (1,500 pounds total weight) how long would it take it to accelerate to maximum efficiency. What is maximum efficiency for a state of the art ramjet? And are they rated in specific impulse or pounds of thrust?Thank-you for your question. From what I've read, a state of the art ramjet would need a velocity of around 1,650 m/s to achieve a 60% efficiency. And they are not rated in specific impulse, but in terms of pounds of thrust.
  • #1
joaquinwalkin
3
0
What airspeed do I need to ignite a ramjet?
 
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  • #2
Are you asking "what is the required velocity of air inside the combustion chamber in order for it to ignite with a decent efficienty?" This is a tough question, I could write an essay about it just in this post.
 
  • #3
I was thinking about the airspeed of the vehicle, but both airspeeds would be appreciated (vehicle and combustion chamber). So with a state of the art ramjet what would be those speeds to ignite with 60% efficiency. And if you don't mind say the vehicle weighs 500 pounds and is carrying 1,000 pounds of fuel (1,500 pounds total weight) how long would it take it to accelerate to maximum efficiency. What is maximum efficiency for a state of the art ramjet? And are they rated in specific impulse or pounds of thrust?
Thank-you very much.
 
  • #4
joaquinwalkin said:
I was thinking about the airspeed of the vehicle, but both airspeeds would be appreciated (vehicle and combustion chamber). So with a state of the art ramjet what would be those speeds to ignite with 60% efficiency. And if you don't mind say the vehicle weighs 500 pounds and is carrying 1,000 pounds of fuel (1,500 pounds total weight) how long would it take it to accelerate to maximum efficiency. What is maximum efficiency for a state of the art ramjet? And are they rated in specific impulse or pounds of thrust?
Thank-you very much.

Welcome to the PF.

Have you been doing any reading on your own so far? Here is an intro article:

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

.
 
  • #5
Thanks, but I don't consider wikipedia a reliable source of information.
 
  • #6
Wikipedia = Anonymous editors writing articles
PhysicsForums = Anonymous posters answering physics questions

In theory they aren't any different in terms of potential for being wrong.
 
  • #7
joaquinwalkin said:
Thanks, but I don't consider wikipedia a reliable source of information.

LOL. About ramjets?

Well, what other reading have you been doing?
 

1. What is a ramjet engine?

A ramjet engine is a type of air-breathing jet engine that operates by using the forward motion of the aircraft to compress incoming air without the use of rotating compressor blades.

2. How does ramjet ignition work?

Ramjet ignition works by using the compressed air from the inlet to ignite the fuel. As the air enters the combustion chamber, it is mixed with fuel and ignited, creating a continuous cycle of combustion.

3. What is the minimum airspeed for a ramjet engine to operate?

The minimum airspeed for a ramjet engine to operate is typically around Mach 2. However, this can vary depending on the specific design and size of the engine.

4. What are the advantages of using a ramjet engine?

Some advantages of using a ramjet engine include its simplicity and lightweight design, as well as its ability to operate at high speeds and altitudes. Ramjet engines also have a higher thrust-to-weight ratio compared to other jet engines, making them more efficient.

5. Are there any limitations to ramjet engine technology?

One limitation of ramjet engine technology is that it requires a high initial speed to start operating, which means it cannot be used for takeoff and must be accelerated by another engine. It also has a limited operating range and is not suitable for use in low-speed or stationary applications.

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