# Thrust to Power Ratios for Modern Propulsion Systems

• syberraith
In summary, the conversation discusses ballpark figures for thrust to power ratios in modern propulsion systems, including mechanical drive trains and various types of vehicles such as cars, trucks, propeller driven craft, boats, planes, and rockets. The conversation also mentions a reference that states a specific F/P ratio for a DC-9 jet engine and questions if it is accurate, as well as noting that efficiency numbers for propeller driven aircraft vary with air speed and can be represented by curves. The speaker expresses uncertainty about where to find this information.

#### syberraith

Does anybody know some ballpark figures for thrust to power, Newtons per watt, ratios for modern propulsion systems, mechanical drive train ie cars trucks, propeller driven craft, boats planes, and rockets.

I've found one reference that states the F/P ratio for a DC-9 jet engine is 0.016 N / W. Is that accrurate?

Thanks,

Fred

I'm not sure such a ratio has any meaning, since for most vehicles it varies with speed.

Yes, I've read that efficiency numbers for propeller driven air craft very with the vehicles air speed.

Curves would do just as well.

I just am clueless as to where to start looking for that information.

## What is a thrust to power ratio?

A thrust to power ratio is a measure of the efficiency of a propulsion system, specifically how much thrust (or force) is produced per unit of power (or energy) input.

## Why is the thrust to power ratio important in modern propulsion systems?

The thrust to power ratio is important because it indicates how effectively a propulsion system can convert energy into thrust. A higher thrust to power ratio means that the system can produce more thrust with less energy, making it more efficient and potentially more cost-effective.

## How is the thrust to power ratio calculated?

The thrust to power ratio is calculated by dividing the thrust (in newtons) by the power (in watts) of the propulsion system. This can be measured directly using specialized equipment, or it can be calculated using other known values such as fuel consumption and velocity.

## What factors can affect the thrust to power ratio of a propulsion system?

There are several factors that can affect the thrust to power ratio of a propulsion system. These include the design and efficiency of the system's components, the type of fuel used, and external factors such as air resistance or gravitational pull.

## How do different types of propulsion systems compare in terms of thrust to power ratio?

The thrust to power ratio can vary significantly between different types of propulsion systems. For example, electric propulsion systems tend to have higher thrust to power ratios compared to traditional chemical propulsion systems, which can result in greater efficiency and longer operating times.