Spaceport Darwin Low Risk Business Model

Point Stephens NT General AreaA Staged Business Model

by Robert Brand. To be clear, I will not go into the long term business model details, profit and loss figures in a public forum and I will not be exposing any business plans other than a general outline, but the nature of why it is a low risk for the Northern Territory government and my company will be clear. There is almost nothing needed other than to reserve this land until developers wish to fund the development of private launch pads.

I proposed a site for Spaceport Darwin in yesterday’s post and by today there were several people that liked the site, but needed a business model to fully accept that this could happen. I understand that desire to see everything so this morning I am posting the basis of the business model. I was going to wait a week to be able to report more, but to get some credibility, here it is.

Spaceport Darwin will be a staged approach that would see investment grow over time and facilities established as needed. The failure of the past is that massive investment was needed on day one. Another factor is that we can establish credibility over time for the site and with those wanting i invest in launch facilities. With almost zero cost, agreements can be put in place for the first part of the operation and sounding rocket launches can take place before the main area sees a shovel of dirt moved.

Why does our Business Need a Spaceport?

Simply because in two years we expect to test fire our booster / sounding rocket to space. I have worked with CASA and with other groups that would have plenty of objections to where I can launch from. There are also few places to launch to orbit. Insurance companies prefer a water launch and costs are lower if you can lower the risk. Since our long term goals are orbital space, it makes sense to look to a long term site to save money. My company also has an interest in being involved in the running of a spaceport. My background is founded in the civil aviation sector and my education was focused on Civil Aviation electronics and systems. I have also a flying background and interact with CASA on balloon flights to the stratosphere. In our company (being set-up now) I am currently heading a group to build spacecraft and rocket technology. All small points, but with the right people, it makes me ideal to kick start such a business. We also need an area away from major air traffic to launch heavy payloads to the Stratosphere. As a Spaceport is not in constant use, this makes Spaceport Darwin ideal as a launch point for 2-3 ton payloads for stratospheric space observation. With a 2 year start date on a couple of these items, now is the time for me to secure a site for a Spaceport and negotiate an outcome.

Potential Spaceport Services

Apart from fuel storage, gas storage, water, power, staff and other background essentials, I am talking about the end product/ services. The first three below my company requires in two years:

  • Sounding rocket – non orbital – straight up and down
  • Sounding rocket – launched to the east. Payload landing 190km away
  • 2-3 ton payloads sent by balloon to the stratosphere.
  • light to heavy rocket launch facilities – increasing over time
  • 5km runway for landing winged space vehicles
  • Up to 4 launch pads – as demand requires. We are seeing the establishment of private pads in the US at the Kennedy Space Centre
  • Equatorial launches – near polar launches
  • Launches for space tourism
  • Other operations as required

Why be in this business? The current worth of the Space Sector is US$330,000,000,000 per year and Australia is only earning money from the radio astronomy and the space communications service. It is a small player, well positioned to player a bigger role servicing launches, but to be competitive, we must keep our operational costs low and that means being close to a major town. With these requirements met and adequate competition for supply of services to the facility, Spaceport Darwin could well see a significant business in the future. We will eventually have a Space Agency and they will be promoting such objectives. Even securing 1/3 of one percent of the space business would see about US$1B income annually with much of that injected back into the local economy through wages, spending and government fees. It is clear that we can secure much more than this if all services are met.

What is the Proposal underpinning the Business Model?

Stage 1

Legal: The Northern Territory (NT) government would need to place a 15 to 20 year hold on any other development in the proposed area while services are put in place and expanded over time. Stage one also requires the clearing of a future car park to be used as a temporary launch pad. Once stage 2 is implemented, all launches can be moved to their permanentlocation

Technical: A clearing of the Car Park area and a concrete area for launches and testing. The concrete area will be suitable for small launches and balloon launches. The access road, although gravel, should be suitable for large trucks in the dry season. A bunker house with no equipment would be built on the west side of the future Car Park to facilitate a safe house during launches. Not equipment will be left between launches and the building secured and patrolled. Balloon and rocket flights to space will occur from time to time. PlusAerospace (expected name of the company) will manage the site from a launch perspective. That will be source of most of the income

The Car Park clearing will be paid for by grants and other funding. PlusAerospace will look after the mobile plant and other setup as required for launches and will bring shipping containers ready to deploy for the electronics and fuel mixing. The ingredients are of a safe nature until combined and are safe without an ignition source. Only large balloons, sounding rockets and small orbital rockets could be launched from a temporary site.

Point Stephens NTStage 2

Legal: This would only proceed with finance, partnerships and most importantly with customers. A solid commitment from the Northern Territory (NT) government and other legal entities would be needed at that time for long term tenancy and a permanent arrangement for continued services put in place with PlusAerospace as the customer. The government would be responsible for build a sealed road suitable for heavy loads and a 400m bridge suitable for the same heavy loads.

Technical: It would require a large pad for launches and completion of a security perimeter (and fence) that would be easy to patrol and cleared areas for a large concrete launch pad and launch structure. Like the US Kennedy Space Center (KSC) it would need a bunker-like launch control centre 5km away from the launch site with adequate protection. This would need sealed roads from Darwin to support the area. Gas and fuel facilities would be needed and it should be noted that much of the specialist gases used are plentiful in Darwin as they arrive by boat for distribution around Australia. It is likely that facilities would grow for a crawler and fabrication centre and although these items may be a long way away, such assets and pathways will be included in plans for the site ensuring adequate land is available for the service and safety.

Other Business Model Information

It is too early at this stage and some discussions are private in nature, but this staged approach to a business model will also allow a real growth and need dependent expansion that is very low risk. Government partnerships will ensure that risk is kept low and it is expected that a permanent arrangement will be in place with CASA that has to regularly pass review, but will allow launches without jumping through massive hoops each launch. ie, some permanent restrictions at all times. It should be noted that the proposed runway would be built in a location that would be suitable for operation near the Darwin. The current suggested location may be too close to the airport and will need to be located further away. The launch of the tourist flight (rocket motors) could be positioned in the appropriate airspace for the rocket flights.

Comments

I would seriously love your comments on this approach and will respond as needed. I will begin some serious lobbying for this site unless a better one exists, so please place your thinking caps on and let me know your thoughts.

Reading

This following link is a bit old, but will fill you in on some useful background. Cape York and Weipa Spaceports never progressed and people felt bunt by the experience.

http://www.spacetoday.org/Rockets/Spaceports/Australia.html

The following link is also very old and the Christmas Island spaceport also never progressed:

http://members.optusnet.com.au/virgothomas/space/spaceport.html#History

Darwin Area and Spaceport Darwin

Point Stephens NT_2

Point Stephens NT General Area

Spaceport Darwin Proposal

Point Stephens NT General AreaSpaceport Darwin – 55Km Drive from Town.

by Robert Brand. It is clear that Australia needs a Space Agency and the Agency needs to help establish an Australian Spaceport. Given that it is only a matter of time I am very interested in Spaceport Darwin!

What is a Spaceport?

The Oxford dictionary simple states: a base from which spacecraft are launched.

These days, with spacecraft returning to earth for reuse and also for winged spacecraft, the definition must also include landing so a modern definition would be: a base from which spacecraft are launched and landed.

Port Stephens in the Northern Territory of Australia, would seem to make an ideal spaceport. I believe that the land is mainly Crown Land on a perpetual lease to the Northern Territory Land Corporation. There are no buildings on the point and the land appears to be available for development. A gravel road is the only way of getting close to the site and it may currently be unpassable during the wet season. The wet season tends to cause major access problems without high dry road access. Luckily the road traverses only high land, but the rain can make this road impossible to travel. If development starts, the road would need to be sealed from Darwin and also new roadways within the complex.

For those wanting to take a better look, it is on Google Earth and it is the land to the south east of Gunn Point NT Australia:

-12.180 Latitude and 131.160 longitude.

The land is 19km north to south and up to 11km east to west at the furthermost points.

Possible Australian Launch pointsWhy Spaceport Darwin?

In the picture to the right, I have outlined (in red) some areas suitable to launch. It would be ideally suited to an equatorial orbit and possibly a polar orbit. It should also be suited to a sounding rocket launch with a forward landing spot. There are few places that a space port should and can be built. There have been several false starts with Great Barrier Reef concerns and major land rights groups forming a huge lobby in Cape York. Inland sites tend to have severe restrictions on large launches because of the risks of launching over land and an population.

Australia does have Woomera, but it is inland and has massive issues for launching anything other than sounding rockets (straight up and down). Launching over water offers a way lower risk and the cost of insurance. Woomera’s costs are very high at the moment. Commercial launch sites are more competitive. The nearest large town is a day’s travel.

Any launch site needs to be capable of growing with the needs of the site and I expect that this proposed site should be able to grow to 4 launch pads for the future. Obviously it will start small, and grow with the need for local space services.

What Makes a Good Spaceport?

What are the important requirements of a Spaceport. This is not a spaceport for space tourism, but it could easily be included. We are looking at a serious launch facility in this proposal. The possibility exists to launch multistage rockets from this site. So as a launch facility, what essentials or important items do we need?:

  • In a country with financial stability.
  • In a country with political stability.
  • In a country with geological stability.
  • In a country with a well educated workforce.
  • Clear path to the east (equatorial orbit).
  • Clear Path to the north or South (polar orbit).
  • A safe distance from any public building or public road (8Km from launch pad).
  • Fresh Water. Lots of it.
  • Short distance to a major town.
  • Road, train, air and port facilities near by.
  • Ability to isolate the area for launches.
  • Construction work force.
  • Operational work force.
  • In town fabrication.
  • Land ahead capability for sounding rocket flights.
  • Close to the equator for equatorial flights.
  • Expansion for future launch pads
  • Private launch facilities / launch pads
  • 5km or longer runway a possibility.
  • Substantial power services.
  • Calm water in the launch area
  • A substantial distance from any airport
  • A substantial distance from town for safety reasons.

There are way more requirements or “should haves” like fuel handling facilities, but the ones above are a great start. Let’s see how Spaceport Darwin shapes up.

Essentially we have a green light on all of the above points. The only issue is the need for road works once the site becomes operational.

There are issues with the northerly launch, with a tight flight path between some islands. There is land only to the south.

Another benefit is the local waters to the east are only about 10m to 15m deep. This is well within normal scuba diving capability (usually 27m depth max for sports diving). Recovery of rocket components that may parachute to the water can easily be recovered.

A large observation area for the general public can be placed on the southern end of the complex Launch days attract many people that want to get close to the launch of a major space vehicle – even a small launch. It is essential to keep people 5Km from any launch. The launch pad should be 8Km away from public property. All of this is a green light for Spaceport Darwin.

There is a small national park to the east only a 10km kilometres away. It is small and only 8km wide. Human access is only by boat. Another small piece of land is crossed by any spacecraft launched to orbit and it is 170Km to the east. Most rockets will be in space or near to space by that time and the land is sparsely populated. This is perfect for a sounding rocket flight with a winged glider returning from space. There is even a sealed runway at Oenpelli Airport. This is 200Km distance from the launch site at 95 degree bearing and within gliding distance for a landing. The rocket would land in Van Diemen Gulf.

Electric power is not far away and fresh water is readily available from underground sources and large tanks can be filled over time before any launch. Water recovery following a launch is also possible.

There is plenty more to look at and assess, but Spaceport Darwin has a lot of positives and with operations cost being 60% or more for a launch, having local staff living in Darwin with a short drive each day is very attractive. Below is the Van Diemens Gulf map. Note most flights are likely to be in space or close to space as they pass over the land to the east. The population density is extremely low.

Space Port Darwin - Van Diemen Gulf NT

Spaceport Darwin Benefits

Spaceport Darwin will:

  • Attract high tech staff to the area
  • Increase local tourism
  • Improve unemployment figures
  • Create innovation in the region
  • Attract foreign companies and investment
  • Improve roads and services
  • Focus attention on the region as a global Space Hub
  • Have a 5km runway in the region for emergencies once fully operational.
  • Be a space tourism launch and landing site.

This discussion will continue over time. Please leave your comments about this site.

– and yes, there are crocodiles!

Fuels for Space Flight

Handling Hypergolic_Fuel_for_MESSENGER spacecraftFuel for Thought.

by Robert Brand. Fools and Fuel. It is the one thing that you can’t avoid and possibly the biggest risk to spaceflight. Fuel.

ThunderStruck will start with the premise that we are going to use the safest fuels and the greenest where ever possible.

Since we are initially talking about booster capability, we are looking at solid fuels and for safety, we will also not use hypergolic fuels as they are very dangerous.

This excerpt from Wikipedia:
https://en.wikipedia.org/wiki/Hypergolic_propellant

A hypergolic propellant combination used in a rocket engine is one whose components spontaneously ignite when they come into contact with each other.

The two propellant components usually consist of a fuel and an oxidizer. Although commonly used hypergolic propellants are difficult to handle because of their extreme toxicity and/or corrosiveness, they can be stored as liquids at room temperature and hypergolic engines are easy to ignite reliably and repeatedly.

In contemporary usage, the terms “hypergol” or “hypergolic propellant” usually mean the most common such propellant combination, dinitrogen tetroxide plus hydrazine and/or its relatives monomethylhydrazine and unsymmetrical dimethylhydrazine

Our booster will have a mass of about 2500Kg to 3,000Kg with fuel and the fuel will be about 2/3rds of the mass.

Below is a list of most common space fuels in use today. Please look up any words that you don’t understand.

We will discuss the Specific Impulse and Density Impulse more in a later post.

Specific Impulse:

Wikipedia:    https://en.wikipedia.org/wiki/Specific_impulse

Specific impulse (usually abbreviated Isp) is a measure of the efficiency of rocket and jet engines. By definition, it is the total impulse (or change in momentum) delivered per unit of propellant consumed and is dimensionally equivalent to the generated thrust divided by the propellant flow rate. If mass (kilogram or slug) is used as the unit of propellant, then specific impulse has units of velocity. If weight (newton or pound) is used instead, then specific impulse has units of time (seconds). Multiplying flow rate by the standard gravity (g0) before dividing it into the thrust, converts specific impulse from the mass basis to the weight basis.

A propulsion system with a higher specific impulse uses the mass of the propellant more efficiently in creating forward thrust, and in the case of a rocket, less propellant needed for a given delta-v, per the Tsiolkovsky rocket equation. In rockets, this means the engine is more efficient at gaining altitude, distance, and velocity. This is because if an engine burns the propellant faster, the rocket has less mass for a longer period of time, which makes better use of the total force times time that was acquired from the propellant. This is much less of a consideration in jet engines that employ wings and outside air for combustion to carry payloads that are much heavier than the propellant.

Density Impulse:

https://www.quora.com/What-is-density-impulse-and-why-do-propellants-with-higher-densities-have-higher-density-impulses

Impulse density is a way of measuring the performance of different propellants regardless of their density. It’s a measure of how much force per time (impulse) you’ll get from a given volume of propellant. Higher density fuels have a higher Impulse Density because Impulse density is basically the propellants Specific Impulse multiplied by it’s density.

As comparison Lox-Butane and Lox-Methane both have a specific impulse of 365s, but the average density of Lox-Butane (at 1000psi) is 890.62kg/m3 while Lox-Methane is 823.34kg/m3. So Lox-Butane’s Impulse Density = 890.62 * 365 = 325076.3Kg-f-s/m3 and Lox-Methane = 300519.1Kg-f-s/m3.

This basically means that per Kg of Lox-Methane you’ll get the same Isp as Lox-Butane, but Lox-Butane can be stored in a smaller tank.

ROCKET PROPELLANT PERFORMANCE
Combustion chamber pressure, Pc = 68 atm (1000 PSI) … Nozzle exit pressure, Pe = 1 atm
Oxidizer Fuel Hypergolic Mixture Ratio Specific Impulse
(s, sea level)
Density Impulse
(kg-s/l, S.L.)
Liquid Oxygen Liquid Hydrogen No 5 381 124
Liquid Methane No 2.77 299 235
Ethanol + 25% water No 1.29 269 264
Kerosene No 2.29 289 294
Hydrazine No 0.74 303 321
MMH No 1.15 300 298
UDMH No 1.38 297 286
50-50 No 1.06 300 300
Liquid Fluorine Liquid Hydrogen Yes 6 400 155
Hydrazine Yes 1.82 338 432
FLOX-70 Kerosene Yes 3.8 320 385
Nitrogen Tetroxide Kerosene No 3.53 267 330
Hydrazine Yes 1.08 286 342
MMH Yes 1.73 280 325
UDMH Yes 2.1 277 316
50-50 Yes 1.59 280 326
Red-Fuming Nitric Acid (14% N2O4) Kerosene No 4.42 256 335
Hydrazine Yes 1.28 276 341
MMH Yes 2.13 269 328
UDMH Yes 2.6 266 321
50-50 Yes 1.94 270 329
Hydrogen Peroxide (85% concentration) Kerosene No 7.84 258 324
Hydrazine Yes 2.15 269 328
Nitrous Oxide HTPB (solid) No 6.48 248 290
Chlorine Pentafluoride Hydrazine Yes 2.12 297 439
Ammonium Perchlorate (solid) Aluminum + HTPB (a) No 2.12 277 474
Aluminum + PBAN (b) No 2.33 277 476

More discussion on fuels in a future post and we will explain our initial choice of booster propellant. The results of an explosion can ruin a flight or kill people. Safety is the big issue. More on that too in a later post.

aptopix india rocket fuel explosion

Greetings Fellow Rocketeers

Did I say that we were Building a RocketDream Chaser spacecraft Graphic on top of a Rocket for Launch?

by Robert Brand. No we haven’t, but here is the buzz – we are developing significant rocket technology.

It was ThunderStruck team member David Galea that headed his email with “Greetings Fellow Rocketeers” and it may stick because ThunderStruck is building rocket technology. We may be building more rockets later but right now we are specifically building a booster for a bigger rocket. A booster that could make it to space all by itself with a ThunderStruck suborbital winged craft as the payload (mounted right on top of the thruster). The rocket will be configured as a sounding rocket – not orbital. The picture (above right) is a similar craft, but a way bigger craft, on top of a bigger rocket. Non the less it will look similar.

Rocket Basics

This will take years to build and it may result in a static test fire in the Australian desert in the next year or two depending on financing. None the less, it will be an amazing opportunity for a small company to gain considerable traction in the rocket building field.

The info here is a basic format that hopefully high school students can understand.

Rocket design commencesRockets and Maths

Mathematics is essential in building space equipment, space craft and navigating in space to mention a tiny bit. Without maths, rockets would explode from over-pressure or fail to get to space because we over-engineered it and it was too heavy to be a work horse.

The image at right is a basic configuration. Solid fuel with an air core and a thrust and nozzle at the bottom. Looks simple, but the maths have to be done first to get an estimation of the pressure we can expect and the strength of the tank and the weight of the tank with different metals. note that as the fuel burns down from the inside towards the metal of the tank, the area burning is greater and the pressure thus increases in a big way. You can change the fuel configuration to burn slower or have less thrust, but that could change simplicity of equation below so we will assume that the fuel is the same for the entire burn. That has been done and we came up with two limits on the mass that we can now work with. The optimum design will be in the middle somewhere.

After putting a rough design on the table with a mass of 2,000Kg fully fueled, we managed to get to space with a big payload and a coasting altitude of 150Km or more. This was with a speed of 1.5Km (or more) per second at the 30 second burn when the fuel is exhausted.

A second design with 3,000Kg mass fully fueled only managed a bit less than 25km altitude. The optimum booster, configured as a sounding rocket lies somewhere in between. The next part of the work is to consider the options. That is:

  • Do we use more thrust and increase the tank and nozzle pressure?
  • We we increase the fuel load and mass?
  • Do we reduce the fuel load and mass?
  • Do we change the fuel and increase the pressure and even the burn time?
  • Do we reduce the mass of the payload (250Kg in this initial desktop design?
  • Do we reduce the mass of the rocket?

These are just a few of the options, but how do we calculate these things – Mathematics of course.

Below are the maths for the heavier second design that only got to under 25Km configures as a rocket. It would have made a poor booster.

NOTE: this is a simple bit of maths for model rockets, but it applies to the bigger ones too. It is not the whole deal, but will give a good estimate for the first pass.

David Galea’s maths for the second configuration performance:

ThunderStruck Rocket Flight Profile – Estimated Calculations

There are three basic equations to find the peak altitude for the rocket

  • Max velocity v, the velocity at burnout = q*[1-exp(-x*t)] / [1+exp(-x*t)] = 916
  • Altitude reached at the end of boost = [-M / (2*k)]*ln([T – M*g – k*v^2] / [T – M*g]) = 13,191.684 m
  • Additional height achieved during coast = [+M / (2*k)]*ln([M*g + k*v^2] / [M*g]) = 11,515.9877 m

Total Height Achieved = 24,707.67 m

All the terms in these equations are explained below on the method for using the equations.

  1. Compute Some Useful Terms
    • Find the mass M of your rocket in kilograms (kg): 2950kg
    • Find the area A of your rocket cross-section in square meters (m^2): 0.342m^2
    • Note that the wind resistance force = 0.5 * rho*Cd*A * v^2, where
      rho is density of air = 1.2 kg/m^3
      Cd is the drag coefficient of your rocket which is around 0.75 for a model rocket shape.
      v is the velocity of the rocket. You don’t calculate this drag force, though, since you don’t know what “v” is yet. What you do need is to lump the wind resistance factors into one coefficient k:
      k = 0.5*rho*Cd*A = 0.5*1.2*0.75*A = 0.1539
    • Find the impulse I and thrust T of the engine for your rocket. I= 3907501 Ns , T= 118841.27 Ns
    • Compute the burn time t for the engine by dividing impulse I by thrust T:
      t = I / T = 3907501 / 118841.27 = 32.88 seconds
    • Note also – the gravitational force is equal to M*g, or the mass of the rocket times the acceleration of gravity (g). The value of g is a constant, equal to 9.8 meters/sec/sec. This force is the same as the weight of the rocket in newtons.
  2. Compute a couple of terms, I call them “q” and “x”
    • q = sqrt([T – M*g] / k) = sqrt([118841.27 – 2950 * 9.8] / 0.1539) = 764.427
    • x = 2*k*q / M = 2 * 0.1539 * 764.427 / 2950 = 0.079759536
  3. Calculate velocity at burnout (max velocity, v), boost phase distance yb, and coast phase distance yc (you will sum these last two for total altitude).
    • v = 764.427*[1-exp(-0.079759536*32.88)] / [1+exp(-0.079759536*32.88)] = 660.916
    • yb = [-2950 / (2*0.1539)]*ln([118841.27 – 2950 *9.8 – 0.1539*660.916^2] / [118841.27 – 2950 *9.8]) = 13191.684
    • yc = [+2950 / (2*0.1539)]*ln([2950 *9.8 + 0.1539*660.916^2] / [2950 *9.8]) = 11515.9877

Rocket SoftwareDavid says: I have double checked my calculations with wolfram alpha (https://www.wolframalpha.com) with the same results.

Well fellow Rocketeers, we will continue to let you know about our big adventure with things that could “go BANG” as we develop our technology.

The Screen shot at right is a basic program that you can get for free or you can buy a more professional version for model rocket hobbyists. None the less it is fine for early desktop modeling.

We will keep you in touch with the professional software that we will eventually choose and use for the serious design phase.

All you students, please get your head down and study maths. We will need to have capable people working in the space sector as Project ThunderStruck becomes an Australian Space staple.

ThunderStruck mk2

Australia’s First Real Spacecraft

ThunderStruck mk2ThunderStruck Spacecraft – a First for Australia

Yes, Australia has built vehicles that have gone into space, but ThunderStruck will not be an orbiting satellite. It will be a vehicle that has propulsion other than that used for orbital watch-keeping. It is being designed to have both an Ion Engine for long distance travel and also a high DeltaV for rendezvous and reentry control.

So what is DeltaV?

Simply: Delta-V, or dV as it’s sometimes abbreviated, is a measure of the total amount of acceleration (or deceleration) your ship can output. Skip down to the next heading if you hate maths!

Mathematically, delta-V takes the form: delta-V = ln(M/Mo)* Isp *go

where delta-V is the change in velocity, ln is the natural logarithm function (look for it on a scientific calculator, or use =LN() in MS Excel), M is the full mass of the rocket stage, Mo is the dry mass of the rocket stage (i.e. what it weighs when all its fuel tanks are empty), go is standard gravity (9.81 m/s2 regardless of what body you’re orbiting/launching from) and Isp is the specific impulse of the engine (a way of measuring the engine’s efficiency). It’s importance, is in determining the total magnitude of the changes the rocket may make to its velocity before it runs out of fuel; in the process it determines where a rocket may go given a certain mission profile. There are three main ways of increasing a rocket’s delta-V:

1) improving propellant mass fraction (i.e. more fuel)
2) increasing specific impulse (by selecting an engine combination that increases this value
3) staging (shedding mass that’s no longer needed, which has the effect of improving the propellant mass fraction)

ThunderStruck’s Range

With an Ion engine, we expect it to be huge, but this spacecraft is designed to re-enter Earth’s atmosphere and land, so we have to slow and return. Basically, however long we took to get there, will also be how long it takes to slow. We will have some ways of beating that equation, but for now, we have to understand that Ion engines have an appallingly low DeltaV. That is why we need strong thrusters for the craft and a radically different system to make the craft more versatile. None the less, ThunderStruck  is being built for orbit but also for round trips to the Moon, Mars and Asteroids. With an upper design payload of around 50Kg, it should be able to handle significant experiments. The most appealing destination for long flights is of course the asteroid belt. ThunderStruck’s main role as a space taxi will be to meet with survey vessels to bring back payloads. The survey vessel will need to be able to rendezvous with ThunderStruck, remove the empty container and load the full container for the trip back to earth.

ThunderStruck is a Space Taxi – but not for people

Most craft are built uniquely for every mission. ThunderStruck is a “space taxi” built to a standard design. it will have a payload that will be able to be opened to space for any science such as collecting particles or other experimentation and be closed again for the return to earth. It is envisaged that a capsule version will be available for high velocity returns to earth and it will use a parachute to land. A further version may be used in a one way trip and not need an ablative shield. This will make it inexpensive to get somewhere and the navigation can be handled by the ThunderStruck team’s mission control.

ThunderStruck and Cruise Mode

I mentioned that there was a way to save time and fuel. Simply that is to launch directly to the direction required by buying a ride on a launch vehicle with a bit of power. The rocket can power us to fly in the right direction with plenty of speed. This either lowers the fuel consumption or the time taken, or a bit of both. None the less getting to your destination with more fuel and in less time is a good start to the flight. Launches like this are not precise. We will spend some time and fuel correcting the trajectory , and with an ion engine, that can take time. None the less in Cruise mode, we will put the bulk of the craft to sleep for periods. This lessens the load on the electronics and can provide more of our solar power to the payload that may in fact be fully operational. In Cruise mode all unnecessary systems will be shut down. They may be woken up for checks on position and direction or orientation to the sun for the solar panels, etc. For such a long flight we will need to use systems like reaction wheels for orientation to ensure that fuel is not used. Solar is renewable. Thunderstruck will need both solar panels for the ion engines and solar power for the spacecraft systems. The ion engine will have its own solar units and Thunderstruck will deploy its own for the flight. these may vary depending on the payload requirements.

Deceleration

About halfway on a flight that has not had boost assistance, we need to turn the spacecraft around and fire the ion engines again to slow the craft. Using the ion engines, this will be the same time taken to accelerate to that speed. It is a slow braking system, but it must be done. If we are using a winged vehicle that is designed for re-entry for Low Earth Orbit (LEO), then we must slow to reach those speed and enter an orbit that will be suitable for a LEO re-entry. If we hit the atmosphere too hard, we could bounce off (like skimming stones on water) and our heat shield and structural integrity would both fail resulting in a breakup of the craft. As stated before a capsule version of the craft may allow us to re-enter at high speeds.

A First For Australia?

Well in fact a first for the entire world. There is nothing to currently service this part of the marketplace. The same winged craft without a massive heat shield could also do significant experiments using a sounding rocket – straight up to over 100Km altitude and back down for a landing.

Heating is insignificant compared to the fiery re-entry that we are accustomed to for orbital re-entry but still a concern that will be addressed. Cold gas thrusters will be all that is needed for flight control until the atmosphere thickens and also a feathering system to keep the spped as slow as possible.

Phase Two Testing from Space

This will occur in about 2 years time and will test the feathering system for a sounding rocket. If nothing else it is likely to be the commencement of building a return vehicle for sounding rocket flights as these can be serviced with different guidance systems and cold gas thrusters – very different from the ThunderStruck spacecraft.

The cold gas thrusters may only be needed before and after the period of “weightlessness” has been used for the experiment. Unlike the tourism spacecraft, sounding rockets are capable of flight higher than 105km and thus a reliable return craft would be a commercial success. It may still have the same shape of the ThunderStruck spacecraft, but have no need for space systems as we know them. It will still break the wound barrier, but be able to land near to the takeoff point. This means full video from space and the entire return flight and that of the payload.

Support for ThunderStruck

The world needs a craft of this capability and Australia needs a healthy space industry. please support ThunderStruck by:

  • Linking to http://ptojctthunderstruck.org
  • helping with fundraising
  • contributing funds
  • talking about ThunderStruck
  • becoming a shareholder in the new company to own the intellectual property.
  • Donate time and resources to assist the project.

Air Pressure, Altitude, Balloons and Rockets

Air Pressure and how it Affects Balloons and Rockets

Weather Balloon Burst

By Robert Brand

Rockets

One of the big issues for rockets flying to space is the air pressure it must climb through. As a rocket climbs it gets faster and has to push more air out of the way. As it goes higher the air thins and you can see from the table below that it is exponential. Have a look at the 1/100th  fraction of one atmosphere below and you will see that the atmosphere is 1% of sea level. The change is not linear. The atmosphere thins to a tiny percentage at twice that height, but at half the height it is 10% of the sea level pressure.

NASA says: The velocity of a rocket during launch is constantly increasing with altitude. Therefore, the dynamic pressure on a rocket during launch is initially zero because the velocity is zero. The dynamic pressure increases because of the increasing velocity to some maximum value, called the maximum dynamic pressure, or Max Q. Then the dynamic pressure decreases because of the decreasing density. The Max Q condition is a design constraint on full scale rockets.

fraction of 1 atmosphere (ATM) average altitude
(m) (ft)
1 0 0
1/2 5,486.3 18,000
1/3 8,375.8 27,480
1/10 16,131.9 52,926
1/100 30,900.9 101,381
1/1000 48,467.2 159,013
1/10000 69,463.6 227,899
1/100000 96,281.6 283,076

The Falcon9 reaches the speed of sound at 1 min 10 sec into its flight and then reaches Max Q just 8 to 13 seconds later depending on speed,and air pressure variables. Unlike airplanes, a rocket’s thrust actually increases with altitude; Falcon 9 generates 1.3 million pounds of thrust at sea level but gets up to 1.5 million pounds of thrust in the vacuum of space. The first stage engines are gradually throttled near the end of first-stage flight to limit launch vehicle acceleration as the rocket’s mass decreases with the burning of fuel.

Want to know more? This is not full of maths, just some fun stuff about Max Q and reaching orbit.

Balloons and Project ThunderStruck

Well for balloons we have a different issue. Balloons have to displace their weight in gas in the atmosphere and that includes displacing enough gas for the weight of the payload too.

Rate of Climb - Fall vs TimeThe climb to maximum altitude for the most part is linear. I discovered this when analysing the stats from my first balloon flight. It was linear until it reached the point that the balloon exploded. If you launch a balloon that does not explode, it will slow its climb and then float. My best guess is that as the climb becomes more difficult due to the air thinning thus and thus the displaced gas is getting closer to the weight of the balloon and payload, but the air resistance is getting less. The size of the balloon is also increasing with height and has to push away a greater volume of air to climb, but the number of air molecules in the increased mass is way less. All up it produces a fairly linear climb. The graph (left) from uplift-1 shows he linear climb and the exponential fall with the parachute deployed. For the parachute, the air gets thicker as it falls and thus slows more as the altitude decreases. Note the initial glitch was caused by a strong thermal just as we let go of the balloon. Once out of the thermal the climb was very linear. It is obvious when the balloon burst.

Altitude and Air PressureAnother view of th same data is shown on the left from UpLift-1′s flight. Note that the rate of climb is linear, but increasing slightly. This would be affected by balloon size and fill amount. The rate of climb may be fast, slow or medium, but that will also change the rate of change of the volume. Not all graphs are the same, but they tend to be similar. Note also that the size of the parachute needs to change with the weight of the payload. The ideal speed for the average payload would be about 5mto 6m per second at the landing altitude, thus landing at Denver, Colorado, USA will require that you make the parachute a little bigger since it is nearly 2Km above sea level and the air is noticeably thinner.

There are good fill charts on the web allowing you to calculate the size of balloon and the amount of Helium or Hydrogen to determine the altitude at which the balloon will explode. More on that another time. The picture at top of page is a weather balloon exploding at altitude.

All up, air pressure can destroy a rocket if its speed is too great and it will destroy a weather balloon if the air pressure gets too low. Both rely on understanding the effects of air pressure, but the dynamics are totally different.

Project ThunderStruck will use weather balloons for testing and they may explode. ThunderStruck‘s record attempt will be using a Zero Pressure Balloon to climb to or beyond 40Km.

Too finish off the post here is a video of a balloon burst. They are spectacular, especially as the balloons grow to a huge diameter and fill the screen of most wide angle GoPros!: