ThunderStruck X-2 Speed Profile

Balloon Flight with ThunderStruckCalculating ThunderStruck X-2 Speed

Recently we spoke about the spreadsheet that we have created to calculate the speed to be achieved by the ThunderStruck X-2 craft. We took into account a range of figures and that gave us some big design changed to ensure that we could meet the Mach 1.5 speed that we wanted for the experiments on board. Those changes took into account the drag of the vehicle, the angle of the nose cone, the size of the fuselage, gravity at altitude, air density and more. For the sake of the initial calculations we did not bother with the drag of hitting Mach 1 as we believed the air density to be so thin that it would not stop us achieving the speed that we needed.

I am pleased to say that team member Todd Hampson has now incorporated the transonic factors and ongoing supersonic factors into the spreadsheet and I am pleased to say that we were right. There is very little variation in our calculated speed if dropped from 45km altitude. Lower altitudes certainly had issues, but not if dropped from 40km and above. Although we are aiming for 45km using hydrogen, it is possible conditions like potential grass fires my limit us to Hydrogen

The addition factors that we have added to the spreadsheet are:

  • Base Drag
  • Area Rule
  • Transonic Wave Drag
  • Supersonic Wave Drag
  • Friction Drag

Remember that this spreadsheet is designed to measure an aircraft in a vertical dive into the ground. You can see it slow with thick air to very low speeds. None the less we intend to transition to horizontal flight at below 10km altitude, to the remainder of the graph becomes meaningless at that point.

One of the outputs of the spreadsheet is a set of figures. Below are the figures for 45km altitude release and below that for 40km altitude release. Both heights break Mach 1 sea level equivalent.

 45km stats

Above: Figures showing the results of a 45km release.

Below:  Figures showing the results of a 40km release.

40km stats

Mach 1 at Sea Level and Mach 1 at Altitude

Simply put, altitude does not really change the speed of sound. Temperature does. It is the biggest factor. Because the speed of sound is lower at altitude where the temperature can be as low as -60C, many people feel as if we are cheating if we only break Mach 1 at the altitude that we are traversing. They want to see the speed of sound broken as if we were doing it at sea level. We have provided those calculations here. The chart automatically compensates for the increased effects of the speed of sound at a given altitude by assuming a standard set of temperatures at those altitudes. These vary by time of year and region. We will publish the set of tables that we have used for this in a future post for reference.

For our purposes, the figures used will be accurate enough for the calculations. Why do we know this? Because they do not vary much at the altitudes that we are breaking the sound barrier. The coldest air in our flight will be in the jet stream and is well below 20km altitude.

We intend to give others on-line access to our spreadsheet in the near future, when we are assured all the bugs are ironed out. At this time the spreadsheet looks stable and accurate.

Below is our Velocity Profile showing Max speed in Mach figures. Remember the speed of sound changes with altitude and this is adjusting the Mach figures for the air temperature at each altitude point. The bump near the 15km is the point where the craft decelerates going through the speed of sound. Given its proximity to the ground and the density of air, it is very possible that we will hear a sonic “boom” from this event.

 45km Velocity Profile

The graph below is the Acceleration Profile in Gee Force. The bump at 15km is showing the additional drag going through the sound barrier to subsonic speeds. there is a similar bump centred at 39.5km, but the air is so thin, it is extremely attenuated and not visible and thus it has little effect.

45km Acceleration Profile

Below is a graph showing the Velocity vs Time for the first 125 seconds. After this time, the aircraft will level out.

45km velocity vs time - 125 seconds
From the top graph – Velocity Profile – if Thunderstruck X-2 continued its dive to the ground, it would hit at Mach 0.27 or 320kph . This is a lot slower than the Mach 1.5 it achieved at 39.5km. Lets hope that the landing will be a lot smoother!

Trimming ThunderStruck for Speed

X2 shadow Trimming ThunderStruck Needs Extreme Knowledge

by Robert Brand

This post is very technical. I will try and make it a little easier to understand. I will not go into very deep into the various aspects that slow the craft, nor will I get into every aspect, just the major aspects that will cause us issues.

Designing a supersonic aircraft needs knowledge of supersonic aspects of airflow and pressure/shock waves. In a previous post we looked at the basic limiting factors and those important to getting us past Mach 1. This post will look at other factors that will cause us to make small changes to ThunderStruck to ensure we reach the maximum speed possible and get as close to Mach 1.5 as possible. We previously discussed the following:

  • Varying gravity due to altitude
  • The angle of the nose cone
  • The width of the fuselage
  • Altitude
  • Vehicle mass
  • Wing and Vehicle Drag Coefficient
  • Reference Area of the object in the direction of motion

In this post we will now look at other aspects of the design that will slow the crafts acceleration during its flight:

  • Base Drag
  • Area Rule
  • Transonic Wave Drag
  • Supersonic Wave Drag
  • Friction Drag

These factors take into account compressible air flows and incompressible air flows. Look them up, but simply Transonic and supersonic flows are compressible, subsonic flows are incompressible.  They are reflected in the items above.

If you would like to look at the Maths for these issues, there is a great document from Sydney University that can be viewed on the link below:

http://web.aeromech.usyd.edu.au/AERO2705/Resources/Research/Drag_Coefficient_Prediction.pdf

Base Drag

My knowledge here comes from rockets – same as the document. A flat based rocket does not have Base drag when it is firing its engines as the air flow does not have a pressure problem when compared to having a flat rear end! Below is a snapshot of the pressure differentials at the rear of the craft. There are more and bigger pressures not shown here, but you can clearly see the problem. as a rocket flies horizontally with its engines ignited, there is no void. The moment the engine ceases ignition, these pressure waves appear – Base Drag.

X2 Base Drag Pressure snapshot

Looks like a tapered fuselage at the rear of the craft is super important to acceleration towards the ground and again as the craft decelerates due to the thickening air density. It will need to taper from half way along the main wing part to the rear and go from 300mm to 50mm– enough for a parachute to be deployed – about 50mm. Whether we add a tapered cap, taking the final taper to a point for even less drag is not important at this stage. It will look better without the cap in drawings.

This important diagram from the linked document. This shows the flight of a rocket accelerating to Mach 1.6 (Dashed blue line) and then decelerating to to low speed (the solid black line). All the various drag issues are in this typical diagram. Base drag however is the difference between the two. There is no base drag during the rocket burn and then there is base drag once the engine ceases ignition.Drag issues in Transonic and Supersonic Flight

By gently tapering the fuselage to a point, we avoid disruption the boundary layer and any turbulence. For the X2 ThunderStruck flight the fall and acceleration will also look like the deceleration. Base drag will almost be eliminated.

Area Rule

We have spoken about this in an earlier post. That is keeping the cross-sectional area of the craft constant – so thinner where there is space (area) allocated to the wings. Area ruling will be somewhat addressed by the taper to the rear as discussed above in Base Drag. It is a fairly small effect unless you were spending significant time near the speed of sound. The X-2 ThunderStruck craft will spend 15 seconds between Mach 0.9 and Mach 1.2. I believe that it will be small and this is where the area rule has the biggest effect – but still small. There will be no additional change for area rule.

Transonic and Supersonic Wave Drag

The taper of the rear of the craft will minimise Wave Drag – both Transonic and Supersonic. Some playing with Wing Design may change the Wave Drag, but we will ignore it at this stage. I am not looking to play with the design unless there is a strong case. In the diagram above the Transonic Wave Drag begins at about Mach 0.9 and Mach 1.2 and Supersonic Wave Drag continues upward from that point.

Friction Drag

Friction drag occurs at low speeds with laminar flow being disrupted and the airflow becomes turbulent. We will have stalled at that stage and thus this is of no interest since we have an aircraft. We should have landed! This is ignored.

Trimming the Design

We have determined that we need to do two things. Stop the leading part of the winglets from protruding in front of where it joins the wing and to taper the fuselage. We will provide a picture of the new design shortly. Here is a render of the current X2 design without the new modifications:

X2 - Clouds2

The X2 ThunderStruck craft will have minimal impact regarding its maximum speed. I will reveal the new graphs shortly showing the speed at any given altitude point. As the air is extremely thin at our launch altitude, the increase in drag above 35km from the items above will not likely to be affect our top speed much as previously calculated, but may increase the deceleration slightly. That is the max G force as we slow. I will publish the updated results soon.

Finally a scan of the pressure waves from front to back on the X2 craft before we trim the craft:

X2 Pressure_Cut_Raised

45km Free Fall Spreadsheet

ThunderStruck Phase 1 Version 2Fine Tuning ThunderStruck’s 45km Free Fall

By Robert Brand and Todd Hampson

This post will examine a drop from 45km. Todd has done an amazing job on this interactive Excel spreadsheet. We can change a few variable and see the change effects. It has done an amazing job in letting us see what changes produce the greatest “bang for the buck”.

The first thing was changing the diameter of the craft creates a great difference in drag. We have decided that we need to make the fuselage 300mm in diameter (down from 600) as it have a huge effect on when the craft stops accelerating. It adds Mach 0.3 to the top speed. from a 45km drop. We also noticed that if we get the craft the right dimensions  and mass, the need to get the balloon to 45km is reduced. We can still break the sound barrier with a release from 40km altitude. At 45km we get a top speed of Mach 1.54 and at 40km we get Mach 1.36. This is also with a mass of 15kg rather than 10kg as we previously had though would be sufficient. We do not want to release much lower as things change rapidly with the thicker air.

Thunderstruck Drop Test Simulator

Thunderstruck Drop Test Simulator

Above is the top part of Todd’s spreadsheet, the coloured cells to the left allow different inputs and the cells on the right are the snap summary. The model that we have made only just got us over Mach 1 with little to spare. Changing the diameter and elongating the nose (a smaller 1/2 vertex angle of the cone) made a huge difference and making the mass 15km means a huge leeway. As mentioned on TV recently, we are aiming for Mach 1.5 and now we have the maths to prove that we can reach that speed. One interesting aspect of the reaching Mach 1.5 is that the deceleration by the thickening atmosphere is about 1.3G. Barely more than standing on the ground. It is a really gentle load and it is mainly on the nose cone of the craft. The wing and tail assembly will keep the craft oriented in the denser air and we will rely on the ballast in the front of the craft to keep it nose down.  The ballast is likely to be antifreeze and we can shift it or eject it for a more stable and slower level flight.

We hope to have the fully interactive spreadsheet available on the site for those interested, but until then let’s have a snapshot of the curves that count. That is a free fall from 45km.
Thunderstruck Drop Test Simulator Max Speed

At sea level, mach 1 is about 340m/s. I say “about” because air pressure has little to do with the speed of sound. It is mainly air temperature. From the graph we should reach 530m/s and that is Mach 1.56.

Before we streamlined the craft to punch through the thickening atmosphere, the wider bodied version of ThunderStruck slowed down really fast and took some stronger G force on the nose (mainly). The version 2 craft slows almost at the same rate that it accelerates. This gives a very gentle change as can be seen below.

Thunderstruck Drop Test Simulator Deceleration

From the graph above it is clear that at 45km, as the speed increases, the air resistance has a greater effect. At that height air density is about 0.025 10-1 kg/m3 compared to air density at sea level which is about 12.25 10-1 kg/m3 (plus or minus about 5%).

This means that our air density at 45km as a percentage of air density at sea level is about 0.284% that of sea level and it increases as we go lower. The effects also increase with ThunderStruck’s speed as the drag has a greater effect with both speed and increasing density.

With the calculated drag of the craft, we find that all acceleration stops at 26 km and as we fall into denser atmosphere, we begin to slow. The graph above is calculated in metres per second per second (known as m/s/s or m/s2) and that can be directly converted in to G force. Since 1 g = 9.80665 m/s2 a simple rule of thumb conversion to remember is 10m/s/s = 1G.

Now for many the next part of this may be hard to grasp, but at free fall at 45km we have what is loosely termed 0G where, if we were in a craft also falling at the same rate, we would float inside the craft. Once we reach terminal velocity at 26km altitude ( I will ignore the lag in deceleration here), we have 1G acting on the craft. If we were inside that craft we could walk around the interior and feel the same as on the earth’s surface (again small variations in gravity, etc excluded). A skydiver that has reached terminal velocity has the air flow stabilising his speed and that air flow has a force of 1G on his body. G force real is only noticeable when there is change – ie a change in direction or acceleration or deceleration.

The “vomit comet” aircraft that simulates zero G does so by moving steadily in a straight line while accelerating towards the ground at 9.8m/s2.  If they just dipped the nose and began that arc, but stopped accelerating towards the ground we would all feel an initial 0Gs but then would be back on the floor when the rate of change returned to zero and we would be back at 1G. So, with ThunderStruck, it is the rate of change that determines G force and at 26km altitude, the G force is 1G on the overall craft, but since the greatest drag is caused by the nose, the 1G force is felt here. Other parts of the craft would be happy to continue accelerating! So at 26km, the structural form of the craft must allow the nose to hold the craft by the nose vertically – good to know, but it does not stop there.

The craft continues to slow and decelerate with the denser air and we have to slow way more. That now takes us into the realm of more than 1G. In fact at 17km we experience the greatest rate of deceleration or change and that is an additional 1.25G for a total of 2.25G on the nose of the vertical craft.  That is the base amount of structural integrity we will need in the nose assembly. If the craft weighs 15kg, then the nose assembly has to support 33.75 and then an amount that we required to ensure it is strong enough. My design had better look to supporting 50kg on the nose when the craft is stood vertically at least.

It seems that what you gain, you have to give back. The higher the speed and the longer the period in low Gs, then the the higher the Gs or the longer in negative Gs you need to complete the flight back to a complete vertical stop. I have not analyses the areas on either side of the 0m/s/s on the chart above, but I would not be surprised if they where equal. As we say here – swings and roundabouts. What you gain on the swings, you will lose on the roundabouts.

Mathematics is a wonderful tool for designers. From a few simple facts in a spreadsheet, we have calculated the speed at all points in the flight (vertical dive perspective) and also the internal forces on the craft at many points. ie the winglet tips will be a point of high drag so they will need to handle more than 1G vertically. The same with other leading edges and that also goes for surfaces affected by shock waves. All of which can be determined by design and software. You don’t have to be a maths genius, but you do need to know maths enough to ensure that you can use them in day to day work. Unless you visualise what is happening, you will have an unhealthy reliance on software for everything you do. That often denies the genius of innovation. It is also why a novice can invent something a seasoned engineer fails to see.

By manipulating the graph by fine tuning the inputs we found that our craft accelerated longer or you could say “the rate of deceleration was slower” by:

  • Making the nose cone pointier
  • Making the fuselage (and the nose cone) a a smaller diameter
  • Increasing the weight of the vehicle

In fact with the new design we have found that we can still break the sound barrier at a starting altitude of 40km. that is our plan B if the weather or winds in the atmosphere go against us. ie, we can launch early if the winds are taking our balloon out of range of our communications systems.

So what does our new design look like?

This is an early look as there are a few bits at the rear that still need adjusting.
ThunderStruck Phase 1 Version 2

We also took the opportunity to correct a few other aspects of the craft:

  • Bigger wing Area with a larger area ahead of the main wing
  • Longer spikes on the winglets (the winglets are not as high due to the smaller fuselage). This is to move the supersonic shock waves away from the control surfaces on the rear of the wing.
  • Twin rudders trailing the craft (there are some wing tabs in the drawing that need to be removed.
  • A tapered tail to stop high drag behind  the craft (we also need to remove some wing tags in the model above.
  • Tapered rudders on the bottom to stop it hitting the ground on landing (not shown)
  • Tapered rudders on the top for symmetry to ensure that it has little differential in forces on the craft to make it pull out of the dive.
Bruce Boler and Jason Brand with ThunderStruck Phase One 1/6 Model

Bruce Boler and Jason Brand with ThunderStruck Phase One 1/6 Model

So there you have the new design based on maths and simulations on a home computer. It seems that building a supersonic aircraft is child’s play as Jason (12) is jointly working on this design. This morning I asked him what G force is at work on a skydiver at terminal velocity and he confidently answered “1G”. Good one grasshopper. He then went on to clearly say that g force was related to change in acceleration (relating to a skydiver). I love it when he talks maths. He needs to know as he will be the remote control pilot for this Mach 1.5 aircraft.

Calculating Maximum Speed in Free Fall

100km accelerationFree Fall Speeds

by Robert Brand and Todd Hampson

Oddly enough, there is very little information on the web for calculating the maximum speed that a craft will fall from a specific height. It is a complex calculation requiring knowledge of the shape of a craft, the size of the craft, the amount of gravitational attraction at each height, the thickness of the atmosphere and the mass of the vehicle.

Todd Hampson has done some great work in getting the information together although he has not found a simple formula for calculating atmospheric density. He has temprarily used look-up tables and that has caused some rather “jerky” graphs. He will work on embedding a formula into the equations and removing the problematic look-up tables. None the less, this is a story of our travels and thus our problems too. Eventually it will be our triumphs too, but a bumpy chart is not a major worry to me, especially as we already know the solution. Now for the fun stuff.

Calculations, Calculations and More Calculations

Getting something “just right” the first time is near impossible and this is no different. Lots of complex data and no simple formula for air density, simply because it is not linear and non anything else. Tomorrow we will add the formula into the data and smooth out the bumps.

Today let us look at the graph that is all important, but first let’s look at an version of ThunderStruck falling from 100km. We will need to do this for Phase 2 with a different craft, but let’s look at the maths.

Todd says:
– For mass of the vehicle I used 10kg.
– For the Area of the object in direction of motion (vertically downwards I am assuming for the high speed part of the fall) I calculated the cross sectional area of the cone ie: a circle using the diameter of 600mm as per the current drawings.
– For the Drag Co-efficinet there was a URL on the VUId page that pointed to an aerospace.org page discussing different drag co-coefficients. For a 3D cone the Cd is calculated using a formula that needs a half-vertex angle. From your drawings (cone depth 450mm, cone diameter 600mm) half-vertex angle is 33.7 degrees.

100km release; max speed

max speed for an aircraft released from 100km – from a sounding rocket apogee of 100km

In the graph above, the first part of the flight was a little more difficult than I thought as lots of things are changing as it falls ie: gravity, air density, drag etc but I’ve got there now.

The first model I have done is the 100km drop test. I need to clean up the data below 18000m but the show is well and truly over by then anyway, but I will get it right so the graph is correct (I need to be more accurate with the air density below 18km).

This says a lot. Thanks Todd. This shows that tourist flights to space at just over 100km altitude at apogee will reach a top speed of Mach 3 on their return – that is about 1,050m/s. Then without any further intervention, they will slow to a fall of about 50m/s near the ground. This shows that the Virgin Galactic trick of feathering the craft is all about stability and not speed. There is nothing that will prevent the craft from reaching this speed since there is not enough air to interfere with the acceleration. The “chunky” graph below shows that clearly. Please assume that the peaks to the left in the deceleration part of the graph are correct.

Acceleration from 100km fall and then deceleration

Acceleration from 100km fall and then deceleration

Free Fall Speeds

From the above, you can see the acceleration is flat and continuous until the craft reaches an altitude of 60km and the acceleration starts to slow. It crosses the zero point of a stable speed at about 47km and then begins to decelerate quite rapidly until it reaches 33km altitude. At this point the deceleration slows down and at 20km altitude the deceleration is slowing in the thick air. You may notice that the maximum deceleration is 38m/s/s and since we accelerate at nearly 10m/s/s when we jump from a platform, simply put every 10m/s/s equates (rule of thumb) to 1G. This means that any craft headed straight down will experience a maximum G force of about 4G. Nothing too harsh. Slowing from orbit is very different and we will eventually cover this in future posts about re-entry.

The first thing to notice is that we will never reach Mach 3 from a release at around 45km. We will achieve over Mach 1. There are a few things that we will need to play with to reach the desired Mach 1.5 and we will cover that in a future post as we look at the graph for a drop from 45km and another from 35km.

Unveiling Phase 1 ThunderStruck Design

ThunderStruck Design and 1-2 size measurementsTransonic Test Design

In the first phase testing of our ThunderStruck spacecraft, we want to go fast so that we can test some “drag” experiments. As such, the airframe proposed looks nothing like what our spacecraft design will probably resemble. After all we wish to slow down returning from space, not speed up.

Below are the design shapes and dimensions for a 1/2 size model of our flight aircraft. Why 1/2 scale? Simply, a full scale mockup would be too big to fit into my car!

After looking at the figures our modeller has recommended that we actually use a 1/3 size model as the 1/2 scale model is too big to fit his lathe! We will talk about the design in another post. I just wanted interested people to have a look at the craft ASAP.

The final craft may have a supersonic spike that will double as a VHF antenna, but it will not need a spike. The wheels will have brakes to stop them spinning during flight. There is a lot to do yet, but we are enjoying the challenges. Note that we may tweak the design further plus I have not included the canards for subsonic flight. They will deploy slowly as we slow the craft. They will not deploy until the craft is subsonic.

ThunderStruck Design and 1-2 size measurements

Above are the dimensions for a 1/2 size ThunderStruck airframe.

 

Press Release 2

Jason's CAD picture of ThunderStruck above the earth

Jason’s CAD picture of ThunderStruck above the earth

Thursday 10th Nov 2014

Release Date: IMMEDIATE

Press Release: A New Australian Spacecraft Begins Concept Testing

Sydney, NSW, Australia.

Project ThunderStruck is the brainchild of Australian aerospace entrepreneur Robert Brand. The craft, code-named ThunderStruck is a small winged spacecraft able to re-enter the atmosphere from orbit and land on a runway with a small payload. In fact it is being designed around the premise of being the smallest craft to be stable enough to re-enter and land safely.

The first test is negotiating the transonic phase (the speed of sound) scheduled for April 2015 and it is expected to reach a top speed of over 2,000kph or approaching Mach 2.

The concept testing will be in three phases:

  • Transonic Testing (April 2015)
  • Sounding rocket to space and land (Dec 2016)
  • De-orbiting and landing (5-6 years away)

This is not a rocket and needs to be launched to space aboard a commercial rocket. The craft will be capable of  maneuvering in earth orbit and de-orbiting. It will need an ion engine to go further about the solar system and could service the asteroid miners providing taxi services for returning samples back to earth.

Depending on the outcome of tests and limitations of weight vs size, the payload should be somewhere between 10 to 50kgs. The craft is not expected to be reused if it has been in orbit as the cost of refurbishment of a craft twill likely exceed the cost of a new craft. A craft that has been sent to space on a sounding rocket will not need a heat shield and may be reused.

Project ThunderStruck has support from many aerospace companies and sponsorship will be announced shortly.

The transonic phase will conducted by remote control and it will be a global news event as it will break many world and Australian records. As it will break the sound barrier, sonic booms will be heard. It will need to be launched over a remote area of Australia for the first test and it will have live TV coverage of the event. Cameras on the balloon will show the ThunderStruck aircraft drop on its dive to break the sound barrier. Cameras in the front of the aircraft will display the cockpit view and overlay instruments on the video allowing the pilot on the ground to fly the craft. Missile grade GPS will record and relay the speed of the craft to the ground.

Australia built their own orbital craft back in 1967 and launched it on a spare rocket left over from US testing at Woomera. There has not been a substantial spacecraft built in Australia since that time. There have been cubesats and other small amateur radio craft, but this is a huge departure from just placing small payloads in orbit. This will be the first craft that will be capable maneuvering and the first to have long range capability. There are almost no winged re-entry craft capable of de-orbiting. There is one US military spacecraft and another NASA sponsored craft being built. ThunderStruck is looking to service small payloads and will not compete with other craft.

A mission control centre will be created in Sydney and a backup in another site outside of Australia. The craft will be sold as a service and not a device. It will provide significant employment in the aerospace sector and support companies. At this time most aerospace graduates leave Australia due to poor employment prospects.

Website: http://projectthunderstruck.org

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Contact:   Robert Brand – contact@projectthunderstruck   Australia: 0448881101     Int’l:+61 448881101 – leave a message if not answered.

Photos of Robert Brand on the Project ThunderStruck webpage are available for publication as is the logo and the CAD images of the aircraft.

Robert Brand: Leading Australian space entrepreneur, Senior Adviser for Team Stellar, ex-OTC staff member, amateur radio operator, Public Speaker on Innovation, Social Media and Space with a focus on Australian Space. Proud father of three amazing kids.

Worked on Apollo 11 equipment at 17 years old, supported Apollo missions, Voyager missions, Shuttle missions and ESA’s Giotto mission to Halleys Comet. Several times he was stationed at the Parkes Radio Telescope.

With his son Jason he has launched 21 high altitude balloon mission and recovered all 21 – two of them were in Croatia. He has designed a mechanism to turn a weather balloon into a zero pressure balloon during flight. Many of the balloon flight have been commercial flights for customers.

Balloon Flight with ThunderStruck

Press Release 1

Jason recovering Payload Cameras gets his photo snapped

Jason recovering Payload Cameras gets his photo snapped. Robert Brand top right

Press Release 1 – 12 year old to Break the Sound Barrier

Thursday 9th Oct 2014

Release Date: IMMEDIATE

12 year old to Break the Sound Barrier

Sydney, NSW, Australia.

Jason Brand, 12 years old has commenced work on building a Remote Control Glider expected to reach Mach 1.5. He has worked with his father, well-known Space Entrepreneur, Robert Brand, on High Altitude Balloon launches since he was 9 years old. Coupled with his love of flying remote-controlled aircraft, Project ThunderStruck was born. Jason will use a massive high altitude balloon to take his glider to over 40km altitude (>25 miles) often called “the edge of space” and release it. The glider will dive through the extremely thin atmosphere and into the record books. It will be controlled from the ground via video and radio links and reach an expected top speed of around Mach 1.5 (1,800kph or 1,120mph).

Jason thought of the idea when his father was talking about a winged re-entry vehicle project that he has commenced. He was discussing the testing required at different stages of the flight and Jason realised that he could actually fly the tests for the transonic phase – the area around the breaking of the sound barrier.

Jason has been immersed in flying for many years. Since he and his father launched their first balloon when he was 9 years old. He was so inspired that he studied and passed his test to become a radio amateur operator (HAM) on his first attempt, again at age 9. 19 balloon launches later, they have maintained an unheard of 100% success in recovering their payloads. Jason flies radio controlled model aircraft, is a cadet in the Australian Air League (Riverwood Squadron) and is determined to solo at age 15. He has also be designing radio systems for long distance control and video. He will “see” from the cockpit camera via a video link and the instrumentation will be overlaid on the video. He will wear goggles and guide the aircraft through the dive, the leveling off at about 80,000 feet (24km / 15 miles) altitude. He will then fly the craft in for a landing.

Special tracking and GPS equipment will be required to verify the speed of the craft for the record books. Most GPS does not work above 60,000 ft and only special GPS systems will work near or above the speed of sound, like those used in missiles. Similarly the aircraft will carry a radar transponder that will advise other aircraft of the ThunderStruck aircraft diving at Mach 1.5. Even military aircraft do not get much over 80,000 ft and controlled airspace is below 60,000 ft. This will probably be the highest balloon and definitely the highest aircraft in the world that day.

This has never been done before and let alone by a 12 year old. It showcases STEM education (Science, Technology, Engineering and Maths) and the fabulous things that happen students are brought up to understand that most limits are there to be broken. Our motto is “New Heights and Breaking Barriers” and those include the Sound Barrier (1,233kph / 766 mph). Soon we will start our funding campaign as it will cost nearly $100,000 to make this a reality and we are looking for global support for such a spectacular event. On the day the event will be captured by cameras on the balloon, the aircraft and from the ground. These will be both live and also recorded. A live broadcast will be available on the Internet for the event scheduled for April 2015.

Website: http://projectthunderstruck.org

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Contact:   Robert Brand – homepc@rbrand.com   Australia:  02 9789 2773    Int’l: +61 2 9789 2773

Photos of Jason and Robert Brand on the Project ThunderStruck webpage are available for publication as is the logo and the CAD images of the aircraft.  http://projectthunderstruck.org/media/

Jason Brand (12 y/o), creator, designer, builder and flier of ThunderStruck

  • HAM radio operator since he was 9 years old
  • First balloon launch and recovery at 9 years old
  • Member of the Australian Air League – Hornets Squadron, Riverwood, Sydney – Cadet
  • Flying Radio Controlled aircraft since 2013
  • Launched, tracked and recovered 19 High Altitude balloons and recovered 100% (all 19)
  • Attends Sydney Secondary College, Balmain Campus – Y7 in 2014
  • Is the Student Representative for Team Stellar – a Google Lunar X-Prize team headed for the moon.

 

Robert Brand: Leading Australian space entrepreneur, Senior Adviser for Team Stellar, ex-OTC staff member, amateur radio operator, Public Speaker on Innovation, Social Media and Space with a focus on Australian Space. Proud father of three amazing kids.

Worked on Apollo 11 equipment at 17 years old, supported Apollo missions, Voyager missions, Shuttle missions and ESA’s Giotto mission to Halleys Comet. Several times he was stationed at the Parkes Radio Telescope.

With his son Jason he has launched 19 high altitude balloon mission and recovered all 19 – two of them were in Croatia. He has designed a mechanism to turn a weather balloon into a zero pressure balloon during flight. Many of the balloon flight have been commercial flights for customers.

End Press Release.

Stability

Creating Stability Between Supersonic Dive and Subsonic Level Flight

Here is the problem. During the supersonic dive, the weight is ideally forward to ensure that, as an airflow is felt by the aircraft, the drag of the tail keeps the craft oriented in vertical dive. That is assisted bythe drag across the aircraft and a low centre of gravity near the nose. During level flight below supersonic speeds the centre of gravity must be further back and ideally between the wings.

Jet fighter design has all sorts of tricks to alter the centre of gravity (or appear to) to make he changes needed. This can be as simple as changing wing shape or even extend more wing during lower speed flight. Some aircraft even have had swung wings. It is hard to control the major variations between the lift and drag that changes dramatically between subsonic and supersonic flight. None the less they do not need the dramatic changes in the centre of gravity that we are engineering.

ThunderStruck will be essential a poor flier as we are, at this stage, proposing symmetrical wings. The problem is that nothing is perfect and even the subtle differences between the wings can give on more lift than the other and create spin. Because of Bernoulli’s law, you might have supersonic flow on the wings, nose, or any other curvature way before you reach Mach 1. Battling with supersonic airflow below mach 1 is difficult and de-stabilising. We will be experimenting with dropping light airframes with a camera at the nose. Before we reach controlled airspace, we will deploy our parachute and have a reserve one for safety. We will watch carefully to see the effects on stability.

The diagram below is one solution to moving the mass required for stable flight in both modes. The pump must be fast and the liquid must stay “thin” and not become viscus. We will need baffles to slow the sloshing around during the changeover. These divide the tanks into chambers with some small holes joining the chambers to allow them to fill.

Centre of gravity adjustment transitioning from dive to level flight

There are other solutions such as screw thread that will shift the battery and electronics forwards or backwards. Since the flight is short the transition only needs to be one way, the design is thus simplified. I am not a fan of shifting the battery and electronics around. It will take a large movement to have the desired effect and it could cause wired t break if they get caught on something. I personally favour pumping the fluid from forward to back as shown above. Moving it down during horizontal flight creates even more stability by creating dihedral effect between the wings on an otherwise symmetrical aircraft.

Dihedral in aircraft is the inclination of an aircraft’s wing from the horizontal, especially upwards away from the fuselage. in this case it is the centre of gravity that I am measuring it against and this indicates that the weight is below the wings and the aircraft will be easier to fly.

Below is another thought on using systems, but this time we vent the fluid without the need for a pump.

gravity does the work for us and we remove the liquid away from any potential problems within the aircraft. Making it lighter will also make it more controllable once out of the dive.

gravity does the work for us and we remove the liquid away from any potential problems within the aircraft. Making it lighter will also make it more controllable once out of the dive.

Whatever system we chose, we will be writing it up here. we need to fly the craft and we also have access to a wind tunnel for subsonic tests.

Breaking Mach 1, but by How Much?

A Zero Pressure Balloon fill_2610Hitting the Mach.

by Robert Brand

The aim of Project ThunderStruck is hitting Mach 1 and a bit more for good measure. Basically breaking the sound barrier. We may reach Mach 1.5, but that will be very much related to the height we reach with the balloon and few other factors. Project ThunderStruck is about Breaking Mach 1 – anything faster is a bonus.

ThunderStruck will rise to 40Km or more for its record attempt. It will need to use a Zero Pressure Balloon capable of reaching 40Km plus carrying a payload in the region of 20Kg including cameras and electronics on the Balloon.

Thanks to http://hypertextbook.com/facts/JianHuang.shtml for the information below regarding Joe Kittinger’s Record Jump in 1960:

Captain Kittinger’s 1960 report in National Geographic said that he was in free fall from 102,800 (31.333Km) to 96,000 feet (29.26Km) and then experienced no noticeable change in acceleration for an additional 6,000 feet (1.83Km) despite having deployed his stabilization chute.

The article then goes on the mention that he achieved 9/10ths the speed of sound and continued to suggest (with maths) that he would have broken the speed of sound with an additional 1,300 m (4,200 feet) of free fall.

If we assume an average acceleration of 9.70 m/s2, it is a simple matter to determine the altitude at which a skydiver starting at 40 km would break the sound barrier.

 maths to calculate altitude at which the sound barrier is broken

That’s an altitude of about 116,000 feet or 35.36Km. So how fast might we go starting at 40km altitude?

maths to calculate the max speed from altitude

Sorry if the equations are difficult to see – that is the quality from the website.

This is nearly 200 m/s faster than the local speed of sound. At the incredible speeds we’re dealing with, air resistance can not be ignored. A maximum of Mach 1.3 seems very reasonable for a human in a pressure suit compared to the prediction of Mach 1.6.

Given that the altitude of the glider release will be 40Km or more, then a top speed of near Mach 1.5 is possible. If we go higher, then we go faster.

Why is ThunderStruck an Aircraft?

Why is it considered an aircraft if it is in free fall with little to no drag? Simply because it is designed to use the little airflow to stabilise itself. Like and aircraft at lower heights uses its control surfaces for stable flight, ThunderStruck does the same. As you might remember from the jumps in the past by Joe Kittinger and Felix Baumgartner, they had serious trouble controlling spin. ThunderStruck will use the exceedingly thin air to control the spin and other forces acting on the craft during its record breaking dive.

After the dive and breaking the sound barrier, ThunderStruck will pull out of the dive under the control of RC pilot Jason Brand (12 years old) and level off, washing off excess speed. It will then fly to the ground under manual control to land just like any other aircraft.

This piece on Felix Baumgartner from Wikipedia:

203px-Felix_Baumgartner_2013Felix Baumgartner; born 20 April 1969, is an Austrian skydiver, daredevil and BASE jumper. He set the world record for skydiving an estimated 39 kilometres (24 mi), reaching an estimated speed of 1,357.64 km/h (843.6 mph), or Mach 1.25, on 14 October 2012, and became the first person to break the sound barrier without vehicular power on his descent.

Baumgartner’s most recent project was Red Bull Stratos, in which he jumped to Earth from a helium balloon in the stratosphere on 14 October 2012. As part of this project, he set the altitude record for a manned balloon flight,[8] parachute jump from the highest altitude, and greatest free fall velocity

The launch was originally scheduled for 9 October 2012, but was aborted due to adverse weather conditions. Launch was rescheduled and the mission instead took place on 14 October 2012 when Baumgartner landed in eastern New Mexico after jumping from a world record 38,969.3 metres (127,852 feet and falling a record distance of 36,402.6 metres. On the basis of updated data, Baumgartner also set the record for the highest manned balloon flight (at the same height) and fastest speed of free fall at 1,357.64 km/h (843.6 mph), making him the first human to break the sound barrier outside a vehicle.

This piece on the Speed of Sound from Wikipedia:

The speed of sound is the distance traveled per unit of time by a sound wave propagating through an elastic medium. In dry air at 20 °C (68 °F), the speed of sound is 342 metres per second (1,122 ft/s). This is 1,233 kilometres per hour (666 kn; 766 mph), or about a kilometer in three seconds or a mile in five seconds.

The Speed of Sound changes with altitude, but surprisingly this is not due to density or pressure, but with temperature!

 Altitude vs temperature pressure densityDensity and pressure decrease smoothly with altitude, but temperature (red) does not. The speed of sound (blue) depends only on the complicated temperature variation at altitude and can be calculated from it, since isolated density and pressure effects on sound speed cancel each other. Speed of sound increases with height in two regions of the stratosphere and thermosphere, due to heating effects in these regions.

You can click of the image  (left) to enlarge the image and see it with a white background! For the purposes of this flight, we will be using the speed of sound at sea level.

Will there be a Sonic Boom?

Yes, but it will not likely to be heard. In fact there will be two. One as it breaks the sound barrier and goes supersonic and one again as it slows to subsonic. Givent he size of the craft and the distance and thin atmosphere, it is unlikely to be heard from the ground.