Vertical Launch Assist Technologies for SSTO

tahanson43206 · 2024-06-04 07:22:08

For kbd512 re Electromagnetic version of Vertical Launch system....

In conversation with Calliban I remembered some work you did a while ago, regarding a horizontal launch assist system that would have been based upon the US aircraft carrier Gerald R. Ford design for an electromagnetic launch system.

It appears that Calliban may be interested in developing a horizontal or inclined launch assist system.

The vertical launch system has many advantages over alternatives, but that is not the subject of ** this ** post.

What I'd like to do with this post is to renew the option of using an electromagnetic launch assist concept.

Because the vertical launch system must work with far more massive payloads than is the case on an aircraft carrier, it occurred to me that the launch sled can extend horizontally for as far as is needed to accumulate the needed lift capability.

If we assume a lift distance of one kilometer, and if we assume an excavation is needed to hold the system, then the excavation can be carried out horizontally for as far as might be needed to accommodate the sled and the related coils and storage devices.

This system is going to need a robust nuclear reactor to supply the power. No happy talk about solar or wind power is appropriate for this application.

The launch windows are going to be precise and intolerant of delay, if regular passenger service is the goal.

It ** should ** be possible for you (or someone) to compute the power requirements for this exercise.

The goal (as I understand it) is to lift the loaded vessel 1 kilometer at a G load of 5, and engine ignition would occur during the lift so that the vessel is fully energized as it exits the lift facility. That would imply the lift facility can handle robust exhaust gas. This will be a noteworthy installation, if if is built.

Perhaps an above-ground segment of the lift facility would provide a solution to the exhaust gas problem.

(th)

kbd512 · 2024-06-04 10:24:57

tahanson43206,

I don't think a pure vertical or horizontal launch will be very practical. My thought about this was that the launcher was going to be some kind of inclined ramp which "soft launches" the vehicle after the engines spool up to full power, which then accelerates the vehicle to 5g (1.5g provided by the engines, 3.5g provided by the catapult), whereupon the vehicle is flung off the ramp with a vertical and horizontal velocity component to it. I don't know what the exact optimum launch angle should be, probably somewhere between 30 and 45 degrees.

This is a fairly aerodynamic lifting body vehicle, relative to a Space Shuttle or any orbital class rocket, so the idea was to get the vehicle moving downrange as fast as possible, as soon as possible, rather than thrusting straight up the way a conventional TSTO does, where most of the booster propellant is translated into altitude gain for reduced aerodynamic drag, but also a pure gravity loss over that entire vertical thrusting period of 2 to 3 minutes. The "vertical thrusting period" associated with a prototypical TSTO accounts for around 1km/s of the average 1.5km/s total gravity losses, which is significant for a TSTO but huge for a SSTO. A TSTO's booster causes it to pick up quite a bit of velocity, yes, but not perpendicular to the surface of the Earth, which is what you require to stay in orbit. That's why you don't see TSTO vehicles move very far downrange during the boost phase of ascent, which is why high Isp in the upper stage is such an enabler- it allows the upper stage to pour on the speed over a greater period of time, out of the sensible atmosphere. This SSTO vehicle will still be ascending quite rapidly, but not a pure vertical ascent like a traditional TSTO. It has a real TPS covering the entire vehicle, and aerodynamic heating won't be nearly as bad as reentry. It has the excess thrust to accelerate very rapidly, so it takes about half as long to ascend to orbit as a traditional TSTO like the Space Shuttle.

Space Shuttle ascent to orbit is nominally a 520s flight duration. There's some room for them to tweak ascent profile, but not much, because it doesn't have the thrust. My SSTO will achieve orbital velocity (not "be in a circularized orbit", obviously), after less than 250s of flight time. That makes very different flight profiles "more optimal" for my SSTO.

That small 300m/s initial starting velocity is enough of a boost to either significantly reduce propellant volume or increase payload. Since our composite airframe structures, engine thrust-to-weight and reliability, as well as TPS are all "on point" for this application, my preference is to reduce the propellant load by about 150t. If it turns out that we get an even greater reduction in gravity losses that are not offset by corresponding aerodynamic drag, then we further reduce the propellant load. This has the effect of making the vehicle meaningfully smaller, less costly, more aerodynamic, etc. It's a virtuous circle.

As to your idea behind using a nuclear reactor, I don't think we need a reactor at all, nor would adding one be particularly helpful.

Let's consider what EMALS does:

135kWh of electricity accelerates a 45,000kg aircraft to 240km/hr in 2 to 3 seconds.

Let's translate that for our purposes:

We want 1,080km/hr (300m/s), 4.5X that of USS Ford's EMALS output.

607.5kWh to launch a 45t aircraft at 1,080km/hr.

300m/s directly translates to 150t less propellant, so let's assume a 1,950t launch weight.

(1,950t / 45t) * 607.5kWh = 26,325kWh or 26.325MWh.

These figures are what the launcher would require to provide 100% of the launch acceleration force, so it's an upper limit as to what would be required. In reality, the engines aboard the launch vehicle are supplying approximately 30% of the total launch energy.

Let's be realistic about launch rate. Say we want to launch twice per day from a single launch rail. This involves propellant loading, passenger loading, last-minute vehicle checks, inspection of all launch equipment, etc. That means our daily power consumption is 52,650kWh.

EMALS stores energy in flywheels. If we charge those flywheels over a period of 4 hours, then our average power delivery rate is 6,581.25kWh per hour, for 4 hours. You don't need a nuclear reactor to supply that kind of power. You just don't. If you did include a reactor, it would be a micro-reactor, it would charge the flywheels up inside of 1 hour, and then you're waiting for propellant loading to complete for 2 to 3 additional hours. What are you doing with that very expensive reactor asset the rest of the time (because it has to be monitored 24/7)? That makes very little sense to me. You can charge up the flywheels while you're doing everything else, so then you don't have employees milling around while waiting for other tasks to be completed.

A pair of 3.5MWe natural gas powered Caterpillar G3616 diesel-electric generator can supply that kind of power for around $5M in total cost, while burning 8,555.625kg (195,594.75ft^3; $2,423.42 using avg Texas prices) of natural gas. These electric generator engines are suitable for the kinds of applications which we intend to use them for, they're actually used for industrial electric power generation, and available for relatively low cost compared to any nuclear reactor.

Caterpillar G3616 9.2:1 Industrial Gas Compression Engine Natural Gas ADEM 3 NEW SURPLUS 4735HP 1000RPM

Those brand new / never installed government surplus engines are being sold for $1.8M each. Newer versions of that same engine, with more recent upgrades for emissions and fuel economy, are available for a minor additional cost. These engines are incredibly common for pumping natural gas or supplying backup electrical power to hospitals and such, highly reliable (more run time between overhauls than the LM2500, on average), and widely available for reasonable cost.

LOX loading is at least 2 hours to account for gradual cool-down of the composite tank, followed by 1 hour of fuel loading. I expect careful / methodical passenger loading to take 1 hour. That's at least 4 hours of launch prep time per launch. There might be ways to speed that process up, but none of them are particularly advisable courses of action. LOX, RP1, passengers, in that order. That's been proven to work.

For a single 8 hour work day or morning shift, we can realistically execute two launches per shift. The evening shift handles landing and vehicle inspection. The night shift oversees vehicle maintenance and repair. That is a realistic flight schedule for an airline service with 2 launch vehicles. If you want to add flights per day, then you procure 2 additional generators, 2 flywheel storage systems, 2 vehicles, 2 additional propellant storage tanks, and another launch track. If you think you want additional capacity from the outset, then you procure a LM2500+G5 marine and industrial gas turbine electric generators, which deliver up to 40MWe.

If you will only launch twice per day, then the LM2500 is an expensive extravagance, and these gas turbines don't really appreciate being started up and shut down on the daily. Diesels don't care about that nearly as much, which is why diesels make so much more sense for this intermittent power application. Fuel economy between the latest versions of the G3616 and LM2500 are about equal.

tahanson43206 · 2024-06-04 10:35:45

For kbd512 re #27

A new topic is available for you and Calliban to develop a horizontal launch assist system.

https://newmars.com/forums/viewtopic.php?id=10821

The Vertical Launch topic remains available for NewMars members who wish to develop it.

(th)

tahanson43206 · 2024-06-04 10:43:37

While this topic has lost it's intended first customer, it remains available for development.

Coming out of the earlier discussions, we have some guidelines for future development...

1) Length of 1 kilometer
2) G force no greater than 5

Chemical or electromagnetic technologies are in play.

Physical energy storage such as compressed air is a possibility, but that seems like a long shot.

(th)

tahanson43206 · 2024-06-04 11:11:14

This post offers an opening exchange with ChatGPT4o, to discuss slow burning chemistry for propellant applications...

# Here is the requested content formatted in bbcode for your presentation.
bbcode_presentation = """
The Art and Science of Creating Slow Burning Chemical Propellants
Slow burning chemical propellants are essential in artillery and rifle ammunition. These propellants are carefully formulated to ensure that the pressure within the launch tube increases steadily as the projectile advances, without exceeding the tube's capacity. Let's review the key components and considerations in the development of these materials.
1. Components of Propellants
Oxidizers: Provide the necessary oxygen for the combustion process. Common oxidizers include nitrates, chlorates, and perchlorates.
Fuels: Combine with the oxidizer to produce the energy required for propulsion. Typical fuels are nitrocellulose and nitroglycerin.
Binders: Act as a matrix to hold the fuel and oxidizer together. They are often energetic materials themselves, such as polyurethane-based binders.
Plasticizers: Increase the flexibility of the propellant and improve its mechanical properties. Examples include dibutyl phthalate and triacetin.
Stabilizers: Prevent the propellant from degrading over time, ensuring long-term stability. Common stabilizers are diphenylamine and ethyl centralite.
2. Slow Burning Mechanisms
The slow burning characteristic of propellants is achieved through careful control of several factors:
Particle Size: Smaller particles burn faster, so controlling the size of the fuel and oxidizer particles helps regulate the burn rate.
Chemical Composition: The ratio of fuel to oxidizer and the presence of additives can slow down the combustion process.
Propellant Geometry: The shape and size of the propellant grains (e.g., cylindrical, star-shaped) influence how the surface area changes as the propellant burns.
Burn Rate Modifiers: Specific chemicals can be added to alter the burn rate, ensuring a controlled and steady release of energy.
3. Applications in Artillery and Rifles
In artillery and rifle systems, the propellant must produce a controlled and predictable pressure curve. This ensures the safe and effective acceleration of the projectile. Key considerations include:
Consistency: Ensuring each batch of propellant performs the same way to maintain accuracy and reliability.
Temperature Sensitivity: Propellants must perform consistently across a wide range of temperatures, from arctic conditions to desert heat.
Safety: Handling and storage of propellants must minimize the risk of accidental ignition or degradation.
By understanding and controlling these factors, scientists and engineers create propellants that meet the rigorous demands of modern artillery and rifle systems.
Conclusion
The development of slow burning chemical propellants is a complex interplay of chemistry, physics, and engineering. Through careful formulation and testing, these materials are designed to deliver precise performance in demanding applications.
"""
# Print the BBCode formatted presentation

(th)

Last edited by tahanson43206 (2024-06-04 11:13:01)

tahanson43206 · 2024-06-04 11:31:46

In this next section, I have attempted to lead ChatGPT4o toward considering the use of liquid hydrogen and liquid oxygen in an artillery piece. It's first attempt was influenced by it's training in rocketry, but I explained that we are NOT working on a rocketry application...

bbcode_reply = """
Thank you for the clarification. Let's focus on applying the concepts of slow-burning propellants, used in artillery, to a system involving liquid oxygen (LOX) and liquid hydrogen (LH2) in an artillery context.
Slow-Burning Propellant Principles Applied to LOX and LH2 in Artillery:
Concept Overview:
To emulate the pressure increase behavior of traditional slow-burning propellants in artillery, a system utilizing LOX and LH2 could be designed to inject and combust the hydrogen in a controlled manner. This approach aims to maintain a steady pressure increase within the barrel, propelling the projectile without exceeding safety limits.
Key Components and Mechanisms:
1. Combustion Chamber
The space beneath the projectile serves as a combustion chamber where LOX is initially stored.
As the projectile advances, LH2 is injected in precise amounts to sustain combustion and maintain increasing pressure.
2. Fuel Injection System
Controlled Injection: Similar to the controlled release of solid propellant in traditional artillery, a regulated system would inject LH2 into the combustion chamber. This could be managed through a series of valves and sensors to ensure the right amount of hydrogen is introduced at each moment.
3. Pressure Regulation
Steady Pressure Increase: By injecting LH2 gradually as the projectile moves through the barrel, the system can emulate the slow-burning characteristic of solid propellants, ensuring that the pressure rises steadily rather than peaking too quickly.
Dynamic Adjustment: Real-time feedback mechanisms can adjust the rate of hydrogen injection based on the current pressure and projectile position.
4. Safety and Stability
Temperature Control: Maintaining the cryogenic temperatures of LOX and LH2 is crucial. Insulation and cooling systems would be necessary to prevent premature vaporization or pressure build-up.
Ignition Control: Ensuring reliable ignition at each injection stage is essential. This could be achieved using multiple igniters or a continuous ignition source.
Feasibility and Challenges:
1. Engineering Complexity
Designing a system that can dynamically inject and ignite LH2 in an artillery barrel requires advanced control systems and precise engineering.
Ensuring consistent performance and reliability under varying battlefield conditions adds to the complexity.
2. Thermal Management
Handling cryogenic liquids in a mobile and potentially rugged environment of artillery deployment presents significant challenges.
Effective insulation and real-time monitoring of temperatures are essential to prevent safety hazards.
3. Material Considerations
Materials used in the construction of the combustion chamber and barrel must withstand extreme temperatures and pressures.
Ensuring compatibility with cryogenic propellants to prevent material degradation over time.
4. Control Systems
Advanced sensors and control algorithms are required to dynamically adjust the injection of LH2 based on real-time data.
Developing these systems to be robust and reliable under various operating conditions is crucial.
Conclusion:
While the use of LOX and LH2 in a slow-burning propellant system for artillery is a novel concept, it is theoretically feasible by applying principles from traditional slow-burning propellant designs and modern rocket propulsion technologies. The primary challenges lie in managing the cryogenic nature of the propellants, ensuring precise control of fuel injection, and maintaining safety and stability throughout the firing process. Further research and development would be needed to address these challenges and explore practical implementations.
This approach, while innovative, leverages existing technologies and principles from both artillery and rocketry to create a potentially viable propulsion system for future artillery applications.
"""
# This will display the bbcode formatted content ready for use in your forum software.
bbcode_reply

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tahanson43206 · 2024-06-04 11:49:45

Here is the next step in a series of exchanges with ChatGPT4o...

In other work you have done for me, you have demonstrated skill in using python to address difficult and challenging problems. Please do not write a python program at this point. Instead, please evaluate the capabilities of Python to compute the performance of a system to do the specific task we have in mind. To give you more detail... we are considering a vertical launch assist application. The distance we want to lift our customer vehicle is 1 kilometer, and we want to maintain a constant 5 G's of acceleration over that distance. The mass of the vehicle we are considering is 2000 tons. WE would like the mass of the space craft to be input as a variable at run time, so the amounts of oxygen and hydrogen can be calculated to match the requirement of a particular launch. The lift mechanism itself will have a fixed mass, which also must be computed as an input value at run time. Outputs would be quantities of oxygen and hydrogen needed, and precise amounts of hydrogen to be injected every 10 meters along the path, as well as pressure on the base of the lift mechanism as the launch proceeds. We want the pressure on the base of the lift mechanism to remain fairly constant, but we recognize the injection of new fuel along the lift path will inevitably introduce some pressure fluctuation.

(th)

tahanson43206 · 2024-06-04 11:57:38

And here is the reply:

bbcode_reply = """
Python is well-suited for computing the performance of a complex system such as the one you've described.
Here are the key capabilities and considerations for using Python to model your vertical launch assist system:
Key Capabilities of Python for this Task:
AISE blocked the rest of this post, but the entire post went into the clone without a problem.
Conclusion:
While the use of LOX and LH2 in a slow-burning propellant system for artillery is a novel concept, it is theoretically feasible by applying principles from traditional slow-burning propellant designs and modern rocket propulsion technologies. The primary challenges lie in managing the cryogenic nature of the propellants, ensuring precise control of fuel injection, and maintaining safety and stability throughout the firing process. Further research and development would be needed to address these challenges and explore practical implementations.
This approach, while innovative, leverages existing technologies and principles from both artillery and rocketry to create a potentially viable propulsion system for future artillery applications.
"""
# This will display the bbcode formatted content ready for use in your forum software.
bbcode_reply

(th)

tahanson43206 · 2024-06-04 19:03:44

Trying again on a different computer ....

bbcode_reply = """
Python is well-suited for computing the performance of a complex system such as the one you've described.
Here are the key capabilities and considerations for using Python to model your vertical launch assist system:
Key Capabilities of Python for this Task:
1. Numerical Computations:
Libraries: Python has powerful libraries like NumPy and SciPy for numerical computations, which can handle large datasets and complex mathematical operations efficiently.
Precision: These libraries support high precision calculations, which are essential for simulating the performance of a propulsion system.
2. Symbolic Mathematics:
SymPy: This library allows for symbolic computation, which can be useful for deriving equations and simplifying complex expressions related to the physics of your system.
3. Physics and Engineering Simulations:
SimPy: For discrete-event simulation, which can model the sequence of hydrogen injections and pressure changes along the path.
RocketPy: Although primarily designed for rocket trajectory simulations, it can be adapted to model the vertical launch assist system with some modifications.
4. Data Input and Output:
Python can easily handle variable inputs and outputs through standard input methods or GUI-based input using libraries like Tkinter.
Data Visualization: Libraries such as Matplotlib and Seaborn can visualize the simulation results, such as the pressure profile along the lift path.
5. Optimization:
Libraries like SciPy also include optimization routines that can be used to fine-tune the fuel injection rates to maintain the desired pressure profile.
Specific Calculations and Simulations:
2. Symbolic Mathematics:
SymPy: This library allows for symbolic computation, which can be useful for deriving equations and simplifying complex expressions related to the physics of your system.
3. Physics and Engineering Simulations:
SimPy: For discrete-event simulation, which can model the sequence of hydrogen injections and pressure changes along the path.
RocketPy: Although primarily designed for rocket trajectory simulations, it can be adapted to model the vertical launch assist system with some modifications.
4. Data Input and Output:
Python can easily handle variable inputs and outputs through standard input methods or GUI-based input using libraries like Tkinter.
Data Visualization: Libraries such as Matplotlib and Seaborn can visualize the simulation results, such as the pressure profile along the lift path.
5. Optimization:
Libraries like SciPy also include optimization routines that can be used to fine-tune the fuel injection rates to maintain the desired pressure profile.
Specific Calculations and Simulations:
1. Mass and Force Calculations:
Input Variables: Mass of the vehicle and lift mechanism.
Gravitational Force: Calculate the force due to gravity (F = m * g, where g = 9.81 m/s²).
Thrust Requirements: Calculate the required thrust to achieve 5 G's of acceleration (5 * g * mass).
2. Fuel Requirements:
Stoichiometric Combustion: Determine the mass ratio of hydrogen and oxygen needed for complete combustion.
Dynamic Fuel Injection: Calculate the required amount of hydrogen to be injected every 10 meters to maintain the pressure and thrust profile.
3. Pressure Calculations:
Combustion Pressure: Use the ideal gas law and combustion equations to compute the pressure at the base of the lift mechanism.
Pressure Profile: Simulate how the pressure changes with each fuel injection and adjust the injection rates to keep it as constant as possible.
4. Iterative Simulations:
Python's iterative capabilities allow for step-by-step simulations of the launch process, adjusting variables dynamically as the projectile ascends.
Example Workflow:
1. Initialize Parameters:
- Input the mass of the spacecraft and the lift mechanism.
- Set initial conditions such as starting pressure, temperature, and initial fuel quantities.
2. Calculate Initial Thrust and Fuel Requirements:
- Compute the initial thrust needed to achieve the desired acceleration.
- Determine the initial amounts of LOX and LH2 required.
3. Iterative Injection and Pressure Adjustment:
- Every 10 meters, calculate the new position and adjust the hydrogen injection rate.
- Recompute the pressure and thrust, ensuring they stay within the desired range.
4. O u t p u t R e s u l t s:
- Quantities of oxygen and hydrogen needed for the entire ascent.
- Detailed injection schedule and corresponding pressures at each 10-meter interval.
1. Mass and Force Calculations:
Input Variables: Mass of the vehicle and lift mechanism.
Gravitational Force: Calculate the force due to gravity (F = m * g, where g = 9.81 m/s²).
Thrust Requirements: Calculate the required thrust to achieve 5 G's of acceleration (5 * g * mass).
2. Fuel Requirements:
Stoichiometric Combustion: Determine the mass ratio of hydrogen and oxygen needed for complete combustion.
Dynamic Fuel Injection: Calculate the required amount of hydrogen to be injected every 10 meters to maintain the pressure and thrust profile.
3. Pressure Calculations:
Combustion Pressure: Use the ideal gas law and combustion equations to compute the pressure at the base of the lift mechanism.
Pressure Profile: Simulate how the pressure changes with each fuel injection and adjust the injection rates to keep it as constant as possible.
4. Iterative Simulations:
Python's iterative capabilities allow for step-by-step simulations of the launch process, adjusting variables dynamically as the projectile ascends.
Example Workflow:
1. Initialize Parameters:
- Input the mass of the spacecraft and the lift mechanism.
- Set initial conditions such as starting pressure, temperature, and initial fuel quantities.
2. Calculate Initial Thrust and Fuel Requirements:
- Compute the initial thrust needed to achieve the desired acceleration.
- Determine the initial amounts of LOX and LH2 required.
3. Iterative Injection and Pressure Adjustment:
- Every 10 meters, calculate the new position and adjust the hydrogen injection rate.
- Recompute the pressure and thrust, ensuring they stay within the desired range.
4. O u t p u t R e s u l t s:
- Quantities of oxygen and hydrogen needed for the entire ascent.
- Detailed injection schedule and corresponding pressures at each 10-meter interval.

Conclusion:
While the use of LOX and LH2 in a slow-burning propellant system for artillery is a novel concept, it is theoretically feasible by applying principles from traditional slow-burning propellant designs and modern rocket propulsion technologies. The primary challenges lie in managing the cryogenic nature of the propellants, ensuring precise control of fuel injection, and maintaining safety and stability throughout the firing process. Further research and development would be needed to address these challenges and explore practical implementations.
This approach, while innovative, leverages existing technologies and principles from both artillery and rocketry to create a potentially viable propulsion system for future artillery applications.
"""
# This will display the bbcode formatted content ready for use in your forum software.
bbcode_reply

(th)

tahanson43206 · 2024-06-04 19:13:07

Here is a first cut at designing a program:

This version does not run, because it contains rocket related code which is not needed.
I'm leaving it in the forum archive in case anyone is curious to see the iterations as we move toward the desired configuration.

import numpy as np
# Constants
g = 9.81 # Gravity (m/s^2)
stoichiometric_ratio = 8 # Approximate mass ratio of O2 to H2 for combustion
def thrust_required(mass_vehicle, acceleration):
return mass_vehicle * acceleration
def fuel_requirements(thrust, efficiency=0.9):
# Simple estimation assuming ideal combustion
hydrogen_mass_flow = thrust / (efficiency * specific_impulse_hydrogen)
oxygen_mass_flow = hydrogen_mass_flow * stoichiometric_ratio
return hydrogen_mass_flow, oxygen_mass_flow
def simulate_ascent(mass_vehicle, mass_lift_mechanism, distance, segments=100):
segment_distance = distance / segments
total_mass = mass_vehicle + mass_lift_mechanism
acceleration = 5 * g
thrust = thrust_required(total_mass, acceleration)

hydrogen_mass_flow, oxygen_mass_flow = fuel_requirements(thrust)

pressures = []
for i in range(segments):
current_altitude = i * segment_distance
current_thrust = thrust # Adjust as needed
pressures.append(calculate_pressure(current_thrust, current_altitude))

return pressures, hydrogen_mass_flow, oxygen_mass_flow
def calculate_pressure(thrust, altitude):
# Ideal gas law and pressure calculation
# Placeholder values
pressure = thrust / (nozzle_area)
return pressure
# Inputs
mass_vehicle = float(input("Enter the mass of the vehicle (in kg): "))
mass_lift_mechanism = float(input("Enter the mass of the lift mechanism (in kg): "))
# Simulation
pressures, hydrogen_flow, oxygen_flow = simulate_ascent(mass_vehicle, mass_lift_mechanism, 1000)
# Outputs
print(f"Hydrogen mass flow rate: {hydrogen_flow} kg/s")
print(f"Oxygen mass flow rate: {oxygen_flow} kg/s")
for i, pressure in enumerate(pressures):
print(f"Altitude: {i*10} m, Pressure: {pressure} Pa")

(th)

Last edited by tahanson43206 (2024-06-04 19:25:39)

tahanson43206 · 2024-06-04 19:14:50

Follow up to Post #35

Thrust Calculation: Compute the necessary thrust to lift the vehicle with the desired acceleration.
Fuel Requirements: Calculate the flow rates of LH2 and LOX needed for the thrust, assuming efficient combustion.
Dynamic Simulation: Divide the ascent into segments (every 10 meters) and simulate the pressure at each segment.
Output: Display the fuel flow rates and pressure profile along the ascent.
This outline provides a foundation to build upon, allowing for more detailed simulations and adjustments based on real-world parameters and conditions. As you refine the model, you can include more sophisticated factors like changing atmospheric conditions, non-ideal combustion, and heat transfer.

(th)

tahanson43206 · 2024-06-04 19:35:31

Here is a version of the program that produces numeric output.

import math
# Constants
g = 9.81 # Acceleration due to gravity in m/s^2
density_LOX = 1141 # Density of Liquid Oxygen in kg/m^3
density_LH2 = 70 # Density of Liquid Hydrogen in kg/m^3
combustion_efficiency = 0.95 # Combustion efficiency
hydrogen_oxygen_mass_ratio = 1 / 8 # Mass ratio of hydrogen to oxygen for combustion
# Function to calculate thrust
def calculate_thrust(mass_vehicle, mass_lift_mechanism, acceleration):
return (mass_vehicle + mass_lift_mechanism) * acceleration
# Function to calculate fuel requirements
def fuel_requirements(thrust, duration):
# Based on the ideal stoichiometric combustion ratio
total_mass_flow = thrust / (combustion_efficiency * g)
hydrogen_mass_flow = total_mass_flow / (1 + hydrogen_oxygen_mass_ratio)
oxygen_mass_flow = hydrogen_mass_flow * hydrogen_oxygen_mass_ratio

total_hydrogen_needed = hydrogen_mass_flow * duration
total_oxygen_needed = oxygen_mass_flow * duration

return total_hydrogen_needed, total_oxygen_needed
# Simulation of the ascent
def simulate_ascent(mass_vehicle, mass_lift_mechanism, distance, acceleration=5 * g):
thrust = calculate_thrust(mass_vehicle, mass_lift_mechanism, acceleration)
duration = math.sqrt(2 * distance / acceleration)

total_hydrogen_needed, total_oxygen_needed = fuel_requirements(thrust, duration)

# For every 10 meters
steps = distance // 10
pressures = []
hydrogen_flow = []
oxygen_flow = []

for step in range(int(steps)):
current_height = step * 10
hydrogen_needed, oxygen_needed = fuel_requirements(thrust, duration / steps)
hydrogen_flow.append(hydrogen_needed)
oxygen_flow.append(oxygen_needed)
pressure = thrust / (math.pi * (current_height + 1)**2)
pressures.append(pressure)

return pressures, hydrogen_flow, oxygen_flow
# User input
mass_vehicle = float(input("Enter the mass of the vehicle (in kg): "))
mass_lift_mechanism = float(input("Enter the mass of the lift mechanism (in kg): "))
# Perform simulation
pressures, hydrogen_flow, oxygen_flow = simulate_ascent(mass_vehicle, mass_lift_mechanism, 1000)
# O u t p u t r e s u l ts
print("Pressures at each 10-meter interval:", pressures)
print("Hydrogen flow at each 10-meter interval:", hydrogen_flow)
print("Oxygen flow at each 10-meter interval:", oxygen_flow)

Anyone who has Python3 installed should be able to run this program. It is not yet doing what I have in mind, but it is not failing either. It is just doing something that looks productive but may not be particularly useful.

(th)

Last edited by tahanson43206 (2024-06-04 19:36:32)

tahanson43206 · 2024-06-05 07:14:54

Update 2024/06/05 ... after study of the draft program, I've decided we (ChatGPT and I) got off to a rocket oriented start, rather than a pneumatic tube oriented start. In a situation like this, the set up of the problem to be solved is key to later success, and I think the best solution here is to simply start over. Much of the math that ChatGPT assembled for this application is applicable, but the rocket equation has no place in this particular model.

This is a pneumatic tube problem with similarity to artillery.

(th)

tahanson43206 · 2024-06-05 12:32:10

Update 2024/06/05 .... ChatGPT4o seemed to understand we were off on the wrong track. It agreed to revise the Python software to better match the model of an artillery piece. The new version of the program uses the correct terminology (ie, pressure instead of thrust) and it seems be calculating the behavior of the system in a reasonable manner. I would appreciate the assistance of anyone in the NewMars membership who may have expertise in these areas.

I am well aware that ChatGPT can make mistakes, and although ChatGPT4o appears to be doing better, It is not immune to possible failure.

The Python program quoted below (if AISE allows) should run on just about any system (Windows. Linux or even Apple).

import math
# Constants
g = 9.81 # Acceleration due to gravity in m/s^2
specific_energy_hydrogen = 142e6 # Specific energy of hydrogen in J/kg
stoichiometric_ratio = 8 # Oxygen to hydrogen mass ratio for complete combustion
combustion_efficiency = 0.95 # Combustion efficiency
# Function to calculate force
def calculate_force(mass_projectile, mass_lift_mechanism, acceleration):
return (mass_projectile + mass_lift_mechanism) * acceleration
# Function to calculate fuel requirements
def fuel_requirements(force, duration):
total_energy = force * duration # Total energy required (Joules)
hydrogen_needed = total_energy / (combustion_efficiency * specific_energy_hydrogen)
oxygen_needed = hydrogen_needed * stoichiometric_ratio
return hydrogen_needed, oxygen_needed
# Simulation of the ascent
def simulate_ascent(mass_projectile, mass_lift_mechanism, distance, radius_projectile, acceleration=5 * g):
force = calculate_force(mass_projectile, mass_lift_mechanism, acceleration)
duration = math.sqrt(2 * distance / acceleration)

total_hydrogen_needed, total_oxygen_needed = fuel_requirements(force, duration)

# For every 10 meters
steps = distance // 10
pressures = []
hydrogen_flow = []
oxygen_flow = []

pressure_area = math.pi * radius_projectile ** 2 # Cross-sectional area in m^2

for step in range(int(steps)):
current_height = step * 10
step_duration = duration / steps
hydrogen_needed, oxygen_needed = fuel_requirements(force, step_duration)
hydrogen_flow.append(hydrogen_needed)
oxygen_flow.append(oxygen_needed)
pressure = force / pressure_area
pressures.append(pressure)

return pressures, hydrogen_flow, oxygen_flow
# User input
mass_projectile = float(input("Enter the mass of the projectile (in kg): "))
mass_lift_mechanism = float(input("Enter the mass of the lift mechanism (in kg): "))
radius_projectile = float(input("Enter the radius of the projectile (in meters): "))
# Perform simulation
pressures, hydrogen_flow, oxygen_flow = simulate_ascent(mass_projectile, mass_lift_mechanism, 1000, radius_projectile)
# O u t p u t r e s u l t s
print("Pressures at each 10-meter interval:", pressures)
print("Hydrogen flow at each 10-meter interval:", hydrogen_flow)
print("Oxygen flow at each 10-meter interval:", oxygen_flow)

Please note that all the values are the same. However, there are only 100 outputs produced per variable.

Please note that I have only tested with these values:

payload mass: 1000 kg
Lift mechanism: 50 kg
Radius: 1 meter

The program is hard coded to produce acceleration of 5 G over the 1 kilometer run

Please note as well, that the program does not know anything about how the fuel and oxidizer are admitted to the volume where acceleration is produced. The program assumes that whatever the mechanism may be, it will deliver the needed chemicals just as they are needed to maintain the needed pressure on the base of the payload.

(tn)

Last edited by tahanson43206 (2024-06-05 12:36:42)

tahanson43206 · 2024-06-05 12:43:16

As a note for anyone who might come across this topic and read it all the way to this point ...

The physical hardware I am imagining for this vertical launch accelerator would extend a kilometer below the surface of the Earth, and a kilometer above the surface. The section below ground is where the pressure to accelerate the piston would be generated. The piston would start at the base of the shaft, and a long extension would rise from the piston to attachment points on the vehicle to be accelerated. The vehicle would be guided upward along the above-ground tower, so that it does not veer off in a direction away from vertical. Along the rise, the engines of the vehicle would ignite, and they would be running at full throttle by the time the piston reaches the top of it's run. I envision the piston rising out of the acceleration tube at the end of it's run, so that the steam pushing it upward can be released to the atmosphere.

Drawings of what this system would look like would be welcome.

(th)

Last edited by tahanson43206 (2024-06-05 12:44:12)

SpaceNut · 2024-06-05 19:05:14

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

Ship mass = 200,000 kg
5 (9.8M/s) = 49 m/s^2
Force = 9,800,000 N

2*d/t^2=a
2*1Km/ 49 m = 6.38874 sec

https://www.engineeringtoolbox.com/acce … _1769.html

update the * is the multiple in the equation.

tahanson43206 · 2024-06-05 20:55:09

For SpaceNut re #41

Thanks for some helpful test data!

I logged in this evening to report that I made significant progress this evening, in coaxing ChatGPT4o to provide a program to show plots of the performance of the hypothetical vertical launch system. Just as the program was ** almost ** ready to show to our members, OpenAI informed me that I had exhausted my allocation of time using ChatGPT4o. I'll have to wait to resume work, which effectively means tomorrow evening.

However, just before I exhausted my time with ChatGPT4o, it gave me a summary of the amount of hydrogen and the amount of oxygen needed for the launch of a given vessel. The addition of this new feature resulted in the loss of a previously developed feature. I observe that this often happens when I am attempting to develop something new with ChatGPT, regardless of the version. It tries to remember what it's working on, and for the most part it is successful, but while I am pondering the next input, ChatGPT is off helping thousands of other people from around the world, working on everything imaginable.

For SpaceNut .... if the program were running correctly I'd try the setup you provided. I ** think ** you are arriving a a time of 6.4 seconds to accelerate over 2 kilometers?

By way of clarification, the acceleration is only over 1 kilometer for the actual ship. The mechanism has to extend a kilometer down for the piston to have room. The ship is attached to hooks on the piston arm at the surface of the Earth. The piston rises in the shaft and pushes the ship upward along the tower. Thus, your computation needs to show that the acceleration at 5 G's is only happening over a distance of 1 kilometer.

I'm getting a velocity of (about) 580 meters per second at the end of the acceleration.

I'll know more tomorrow evening.

Thanks for your interest in and support of this topic!

(th)

Last edited by tahanson43206 (2024-06-05 20:56:00)

tahanson43206 · 2024-06-06 14:04:51

For SpaceNut re Vertical Launch simulation program...

ChatGPT4o was back online today, and I think the Python program is ready for initial testing by forum members. I'll put the program in this post, and then put a discussion in the next post. The program generates a graph with 5 plots, and sums the consumption of hydrogen and oxygen in the terminal window.

# Version 11 Revised after question about velocity plot
import math
import matplotlib.pyplot as plt
def fuel_requirements(thrust, combustion_efficiency=0.9):
specific_energy_hydrogen = 142e6 # J/kg for hydrogen
specific_energy_oxygen = 13.1e6 # J/kg for oxygen
total_energy_needed = thrust * specific_energy_hydrogen / combustion_efficiency
hydrogen_mass_flow = total_energy_needed / specific_energy_hydrogen
oxygen_mass_flow = total_energy_needed / specific_energy_oxygen
return hydrogen_mass_flow, oxygen_mass_flow
def simulate_ascent(mass_vehicle, mass_lift_mechanism, radius_projectile, distance, combustion_efficiency=0.9):
g = 9.81 # m/s^2, acceleration due to gravity
acceleration = 5 * g # Desired constant acceleration (5 Gs)
total_mass = mass_vehicle + mass_lift_mechanism
thrust = total_mass * acceleration
cross_sectional_area = math.pi * radius_projectile**2
pressure = thrust / cross_sectional_area
pressures = []
hydrogen_flows = []
oxygen_flows = []
velocities = []
times = []
positions = []
velocity = 0 # Initial velocity
time = 0 # Initial time
time_step = 0.1 # Initial small time step
total_hydrogen = 0
total_oxygen = 0
for i in range(0, distance, 10):
pressures.append(pressure)
hydrogen_flow, oxygen_flow = fuel_requirements(thrust, combustion_efficiency)
hydrogen_flows.append(hydrogen_flow)
oxygen_flows.append(oxygen_flow)
total_hydrogen += hydrogen_flow
total_oxygen += oxygen_flow
# Calculate new velocity and time
velocity += acceleration * time_step
time += time_step
time_step = 10 / velocity # Adjust time step for next interval
velocities.append(velocity)
times.append(time)
positions.append(i)
return pressures, hydrogen_flows, oxygen_flows, velocities, times, positions, total_hydrogen, total_oxygen
def plot_results(times, positions, velocities, pressures, hydrogen_flows, oxygen_flows):
plt.figure(figsize=(12, 10))
# Plot position vs time
plt.subplot(3, 2, 1)
plt.plot(times, positions, label='Position')
plt.xlabel('Time (s)')
plt.ylabel('Position (m)')
plt.title('Position vs Time')
plt.grid(True)
# Plot velocity vs time
plt.subplot(3, 2, 2)
plt.plot(times, velocities, label='Velocity', color='r')
plt.xlabel('Time (s)')
plt.ylabel('Velocity (m/s)')
plt.title('Velocity vs Time')
plt.grid(True)
# Plot pressure vs time
plt.subplot(3, 2, 3)
plt.plot(times, pressures, label='Pressure', color='g')
plt.xlabel('Time (s)')
plt.ylabel('Pressure (Pa)')
plt.title('Pressure vs Time')
plt.grid(True)
# Plot hydrogen flow vs time
plt.subplot(3, 2, 4)
plt.plot(times, hydrogen_flows, label='Hydrogen Flow', color='b')
plt.xlabel('Time (s)')
plt.ylabel('Hydrogen Flow (kg/s)')
plt.title('Hydrogen Flow vs Time')
plt.grid(True)
# Plot oxygen flow vs time
plt.subplot(3, 2, 5)
plt.plot(times, oxygen_flows, label='Oxygen Flow', color='m')
plt.xlabel('Time (s)')
plt.ylabel('Oxygen Flow (kg/s)')
plt.title('Oxygen Flow vs Time')
plt.grid(True)
plt.tight_layout()
plt.show()
def main():
try:
mass_vehicle = float(input("Enter the mass of the vehicle (in kg): "))
mass_lift_mechanism = float(input("Enter the mass of the lift mechanism (in kg): "))
radius_projectile = float(input("Enter the radius of the projectile (in meters): "))
if mass_vehicle <= 0 or mass_lift_mechanism <= 0 or radius_projectile <= 0:
raise ValueError("All input values must be positive numbers.")
distance = 1000 # meters
pressures, hydrogen_flows, oxygen_flows, velocities, times, positions, total_hydrogen, total_oxygen = simulate_ascent(mass_vehicle, mass_lift_mechanism, radius_projectile, distance)
plot_results(times, positions, velocities, pressures, hydrogen_flows, oxygen_flows)
# Print the total amounts of hydrogen and oxygen used
print(f"Total hydrogen used: {total_hydrogen:.2f} kg")
print(f"Total oxygen used: {total_oxygen:.2f} kg")
except ValueError as e:
print(f"Input error: {e}")
if __name__ == "__main__":
main()

(th)

tahanson43206 · 2024-06-06 14:05:57

This post contains an explanation of why the graphs show the plots they do...

First, what I observe is that there is remarkable consistency in the plots for different masses of vehicle and radius of the base. I think this is a consequence of the way I have designed the system, but would appreciate your perspective. What **does** change is the pressure inside the launch tube, and the consumption of fuel and oxidizer to achieve the requested performance.
Consistency in Plots for Different Masses and Radii
Your observation about the consistency in the plots is insightful. This consistency is due to the fundamental physics of constant acceleration and the proportional relationship between the variables involved.
Constant Acceleration: The system is designed to maintain a constant acceleration (5 Gs). Under constant acceleration, the relationships between position, velocity, and time are predictable and follow specific mathematical equations:
- Position: $ x(t) = \frac{1}{2} a t^2 $
- Velocity: $ v(t) = a t $
These equations remain the same regardless of the mass of the vehicle or the radius of the base, leading to similar shapes in the position vs. time and velocity vs. time plots.
Thrust and Pressure: What changes with different masses and radii are the required thrust and the pressure within the tube:
- Thrust: $ T = (m_{\text{vehicle}} + m_{\text{lift}}) \times a $
- Pressure: $ P = \frac{T}{A} $, where $ A = \pi r^2 $ is the cross-sectional area of the base.
Higher vehicle masses and larger radii will require different thrusts and pressures to maintain the same acceleration.
Fuel and Oxidizer Consumption
The consumption of fuel (hydrogen) and oxidizer (oxygen) directly relates to the thrust required to achieve the specified acceleration:
More massive vehicles require greater thrust, leading to higher fuel and oxidizer consumption.
The radius affects the pressure calculation but doesn't change the fuel and oxidizer requirements for a given thrust, since the total force needed to achieve the desired acceleration depends only on the mass and acceleration.
Consistency Analysis
The consistency in the plots for different vehicle masses and base radii is because the plots for position and velocity over time under constant acceleration are fundamentally driven by the same underlying physics equations. These equations are not directly dependent on mass or radius but rather on the acceleration and the duration of the movement.
Discussion Points for Forum Members
Understanding Consistency: The consistency in the plots is due to the constant acceleration and the fundamental equations of motion, which are the same regardless of the vehicle mass or base radius.
Variable Pressure and Consumption: Differences will be observed in the required thrust, pressure inside the tube, and the consumption of fuel and oxidizer. These are dependent on the vehicle mass and base radius.
Practical Implications: This model can help in understanding the scalability of the launch system, such as how increasing the vehicle mass or base radius affects the infrastructure and resource requirements.
Example Questions from Forum Members
Why do the position and velocity plots look similar for different vehicle masses?
- Answer: The plots look similar because the vehicle is under constant acceleration, which dictates a quadratic relationship for position and a linear relationship for velocity over time. These relationships are consistent regardless of the vehicle's mass.
How does increasing the vehicle mass affect the system?
- Answer: Increasing the vehicle mass requires more thrust to achieve the same acceleration. This results in higher pressure inside the tube and greater consumption of hydrogen and oxygen.
What role does the radius of the base play in the system?
- Answer: The radius of the base affects the cross-sectional area, which in turn influences the pressure required to generate the needed thrust. A larger radius decreases the pressure for a given thrust, while a smaller radius increases it.
Feel free to ask more specific questions or provide additional details you'd like to discuss or clarify.

(th)

tahanson43206 · 2024-06-06 15:11:37

Here is a report on calculated propellant usage for the vertical launch assist system, for three different masses of vehicle:

Trial 1:
Enter the mass of the vehicle (in kg): 1000
Enter the mass of the lift mechanism (in kg): 50
Enter the radius of the projectile (in meters): 1
Total hydrogen used: 5,722,500.00 kg
Total oxygen used: 62,030,152.67 kg

Trial 2:
Enter the mass of the vehicle (in kg): 1000000
Enter the mass of the lift mechanism (in kg): 50000
Enter the radius of the projectile (in meters): 15
Total hydrogen used: 5,722,500,000.00 kg
Total oxygen used: 62,030,152,671.76 kg

Trial 3: kbd512 500 passenger vehicle
Quote:
Design characteristics for a LOX/RP1 powered 500 passenger vertical takeoff / horizontal landing SSTO will be posted here.
Gross Liftoff Mass: 2,100,000kg
Propellant Mass: 2,000,000kg
Dry Vehicle Mass: 60,000kg
Payload Mass: 40,000kg
End Quote
Result:
Enter the mass of the vehicle (in kg): 2100000
Enter the mass of the lift mechanism (in kg): 100000
Enter the radius of the projectile (in meters): 15
Total hydrogen used: 11,990,000,000.00 kg
Total oxygen used: 129,967,938,931.30 kg

(th)

Last edited by tahanson43206 (2024-06-06 15:12:57)

tahanson43206 · 2024-06-09 06:54:52

As a follow up to preliminary investigation of vertical launch assist using LH2 and LOX in an artillery configuration, here is a snippet about temperature:

From: http://www.astronautix.com/l/loxlh2.html

Temperature of Combustion: 2,985 deg K. Ratio of Specific Heats: 1.26. Characteristic velocity c: 2,435 m/s (7,988 ft/sec). Isp Shifting: 391 sec. Isp Frozen: 388 sec. Mol: 10.00 M (32.00 ft).Oxidizer Density: 1.140 g/cc. Oxidizer Freezing Point: -219 deg C.Oxidizer Boiling Point: -183 deg C.Fuel Density: 0.071 g/cc. Fuel Freezing Point: -259 deg C. Fuel Boiling Point: -253 deg C.
Propellant Formulation: LOX/LH2. Optimum Oxidizer to Fuel Ratio: 6. Density: 0.28 g/cc.
Propellant Formulation: LOX/Slush LH2. Optimum Oxidizer to Fuel Ratio: 4. Density: 0.33 g/cc,

The astronautix site has a (to me surprising) amount of detail about engines designed for LH2/LOX.

***
The temperature inside the lift tube may exceed the melting point of materials that might be used for this application.

(th)

SpaceNut · 2024-06-09 09:02:45

The use of a fuel to make a means to push the rocket is similar to dropping a stage after use.

The Astronautix site also contains lots of history of the engines that have been used.

tahanson43206 · 2024-06-10 07:22:18

For SpaceNut re #47

Thanks for your observation about the Launch Assist system and it's similarity to a first state, and for your comments about the Astronautix site!

This post is to report on a visit with Gemini, to ask it to review the program written by ChatGPT4o. it took a while before Gemini understood this situation is more similar to an artillery piece that a rocket, but we got there. What I was looking for primarily was confirmation that the math and physics appear to be correct. Gemini had suggestions for improving the program and for design of the launch assist system.

thank you for your detailed and thoughtful analysis of the work done by the Assistant. You have confirmed that the math and physics appear to have been incorporated correctly into the program, and I deduce that you are under the impression the results can be trusted, given the requirements. You have suggested a number of ways the program might be improved. In addition, you have suggested important ideas to improve the design of the launch system. This has been a rewarding visit with you. While I'm away, best wishes for similar success as you attempt to help your many other customers.
You're welcome! I'm glad I could be helpful in reviewing the program and the launch assist system design. It's always rewarding to collaborate and explore technical concepts.
Your deduction is correct - based on the review, the core functionality of the program seems sound. The suggestions for improvement primarily focus on expanding the scope or incorporating additional factors for a more comprehensive analysis.
While I can't directly interact with other users or complete tasks in the real world, I strive to provide informative and insightful responses to everyone who seeks my assistance. I hope to continue learning and improving my abilities to be a valuable resource for all my future customers.
If you have any further questions or tasks in the future, please don't hesitate to ask. Have a productive time, and best of luck with the launch assist system design!

The most interesting suggestion Gemini offered was to input the G force for the run. The program is currently set to deliver 5 G's for the duration of the run over 1 kilometer. That value is chosen as the maximum that passengers might be able to tolerate. However, a cargo launch would not need to be limited to 5 G's. Increasing G force delivered would increase the strength needed for the components of the launch assist system.

Another variable that might be adjusted by using an input for the operator is the length of the run. That value is currently set to 1 kilometer.

(th)

Last edited by tahanson43206 (2024-06-10 07:29:47)

Calliban · 2024-06-11 04:08:30

The most straight forward arrangement for this concept, would be a long vertical shaft sunk into the Earth. The rocket would be loaded onto the sabot at the top. Both will then be lowered down the shaft from the top. For rapid reusability, we want the sabot to stay in the shaft and rapidly decelerate before reaching the top. That way, after each shot the sabot is at the top of the shaft, ready to receive the next rocket. Another side benefit is noise suppression, though I think the noise of the booster engines renders that advantage moot.

Capital cost may be a stumbling block. Lets say we want a barrel velocity of 300m/s and acceleration of 5g (50m/s2). The barrel needs to be at least 900m long. Add another 100m for the sabot to decelerate after rocket seperation, and we would need the shaft to be 1km deep and maybe 10m wide. How much will it cost to dig a 10m diameter shaft that deep?

This brochure discusses a 8.5m diameter, 1km deep shaft at the Wesizwe mine in South Africa. This is very similar to what we need, though local geology will no doubt change the cost.
https://www.mcconnelldowell.com/images/ … ochure.pdf

According to this article, the contract for shaft sinking cost 1.64bn Rand. That is $82million.
https://www.miningmx.com/news/platinum/ … -contract/

Which isn't really that costly in the context of what we are discussing. The NASA study referenced in the wiki article, calculated an 80% increase in payload for a 270m/s launch assist. That is quite powerful. If the same holds true here, then even even a $1billion cost for a vertical launch assist would pay for itself quickly.

Last edited by Calliban (2024-06-11 04:45:15)

tahanson43206 · 2024-06-11 06:25:59

For Calliban re #49

Thank you for your additions to the topic!

The discovery and presentation of an actual example of a shaft similar to the one we are discussing here is ** most ** helpful.

The discovery and presentation of the advantage of the launch assist concept is welcome!

While this topic was opened in the context of an attempt by forward looking NewMars members to design an SSTO passenger vehicle, the vertical launch assist idea would surely find economic opportunity in the growing need for delivery of fuel and oxidizer to LEO for major off-Earth activities.

There are several remaining uncertainties about the concept at this point, and I'm hoping you (and others with the appropriate skills/experience) might be willing to investigate.

I've been pondering how to supply fuel to the barrel of the launch tube in the quantity and at the pace required. One option is to pump fuel and oxidizer into the base of the shaft at the rate required, for the 7 seconds of so of the run. You can see the requirements if you are able to install Python on your machine, and run the little Python program published in this topic.

The output is a set of 5 graphs, and a text summary of total LOX and LH2 required for a particular launch configuration.

I would greatly appreciate a third opinion on the validity of the calculations. The work was done by ChatGPT4o, and subsequently reviewed by Gemini, but I will not be confident the calculations are correct until a human checks them.

I am particularly troubled by the quantities of fuel and oxidizer needed (or rather, computed to be needed). The AI is working from my description of what needs to be computed, and there could easily be misunderstanding, starting with my ability to conceptualize the environment inside an artillery piece.

Regarding the delivery of significant quantities of fuel and oxidizer to LEO...

A number of groups (and a few individuals) are working on fly-back lifting body vehicle designs that could be put into service in a large scale fuel supply operation. While I recognize the advantage of launching from the base of the vertical shaft, that option appears limited to a cylindrical vehicle, unless such a vehicle can be designed to unfold wings after it arrives in orbit. Perhaps such a folded-wing concept is possible.

Otherwise, design of the Vertical Launch Lift facility so that the vehicle is attached to hooks on a rod that extends down the shaft to the sabot seems to most promising. In that case, the launch vehicle is simply hung on the hooks, loaded with payload while the Vertical Launch Facility is reloaded with fuel and oxidizer, and given a 5 G shove when the launch window arrives.

I am thinking here of GW Johnson's Fuel Depot, which we have conceptualized as orbiting in a plane that crosses McGregor, Texas twice a day. Since that orbit crosses every other point on Earth twice a day, Vertical Launch Facilities can be constructed where they make economic sense for fuel delivery to LEO.

The individual vessels that perform automated delivery of supplies to the Fuel Depot need not be large, which is why a much smaller Vertical Launch Facility might become economically productive long before the 500 passenger vehicle is ready for service.

(th)

Last edited by tahanson43206 (2024-06-11 08:14:36)

New Mars Forums

Announcement

#26 2024-06-04 07:22:08

Re: Vertical Launch Assist Technologies for SSTO

#27 2024-06-04 10:24:57

Re: Vertical Launch Assist Technologies for SSTO

#28 2024-06-04 10:35:45

Re: Vertical Launch Assist Technologies for SSTO

#29 2024-06-04 10:43:37

Re: Vertical Launch Assist Technologies for SSTO

#30 2024-06-04 11:11:14

Re: Vertical Launch Assist Technologies for SSTO

The Art and Science of Creating Slow Burning Chemical Propellants

1. Components of Propellants

2. Slow Burning Mechanisms

3. Applications in Artillery and Rifles

Conclusion

#31 2024-06-04 11:31:46

Re: Vertical Launch Assist Technologies for SSTO

#32 2024-06-04 11:49:45

Re: Vertical Launch Assist Technologies for SSTO

#33 2024-06-04 11:57:38

Re: Vertical Launch Assist Technologies for SSTO

Python is well-suited for computing the performance of a complex system such as the one you've described.

#34 2024-06-04 19:03:44

Re: Vertical Launch Assist Technologies for SSTO

Python is well-suited for computing the performance of a complex system such as the one you've described.

#35 2024-06-04 19:13:07

Re: Vertical Launch Assist Technologies for SSTO

#36 2024-06-04 19:14:50

Re: Vertical Launch Assist Technologies for SSTO

#37 2024-06-04 19:35:31

Re: Vertical Launch Assist Technologies for SSTO

#38 2024-06-05 07:14:54

Re: Vertical Launch Assist Technologies for SSTO

#39 2024-06-05 12:32:10

Re: Vertical Launch Assist Technologies for SSTO

#40 2024-06-05 12:43:16

Re: Vertical Launch Assist Technologies for SSTO

#41 2024-06-05 19:05:14

Re: Vertical Launch Assist Technologies for SSTO

#42 2024-06-05 20:55:09

Re: Vertical Launch Assist Technologies for SSTO

#43 2024-06-06 14:04:51

Re: Vertical Launch Assist Technologies for SSTO

#44 2024-06-06 14:05:57

Re: Vertical Launch Assist Technologies for SSTO

#45 2024-06-06 15:11:37

Re: Vertical Launch Assist Technologies for SSTO

#46 2024-06-09 06:54:52

Re: Vertical Launch Assist Technologies for SSTO

#47 2024-06-09 09:02:45

Re: Vertical Launch Assist Technologies for SSTO

#48 2024-06-10 07:22:18

Re: Vertical Launch Assist Technologies for SSTO

#49 2024-06-11 04:08:30

Re: Vertical Launch Assist Technologies for SSTO

#50 2024-06-11 06:25:59

Re: Vertical Launch Assist Technologies for SSTO

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