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

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.

GPS and Supersonic Speeds

NovAtel OEM615Most GPS and Supersonic Speeds Don’t Mix

As if the cost of the zero pressure balloons is not enough, we have a real burden in using a GPS system that works at supersonic speeds and also one that worked above 60,000 feet. Yes, we want to do both so a standard GPS system will not work.

So Why the Limits?

It is not such a big issue these days as technology has moved on, but 10 to 15 years ago, this was a major deterrent to anyone wanting to use them in a missile. Unfortunately today, that is less of a deterrent as most people could easily source someone capable of updating the GPS firmware. None the less it is still a better and safer path to pay the manufacturer for a GPS system that has the limits removed. There are many manufacturers that can provide the product and some are harder to work through than others. This is often the result of a country’s regulations regarding export licenses. For instance, buying from Canada is simpler than buying from the US. It still takes a couple of weeks, but the opportunity to get a limited version for testing will allow us to swap out the limited version for the unlimited version prior to flight. As the system that we wish to use is available in Australia from a local distributor, it is very likely that we will buy from a company called NovAtel. Their product is the Receivers OEM615, although they have more expensive products that would do much more for us.

What are the Limits on Regular GPS Engines?

This from Wikipedia: CoCom is an acronym for Coordinating Committee for Multilateral Export Controls. CoCom was established by Western bloc powers in the first five years after the end of World War II, during the Cold War, to put an arms embargo on COMECON countries. CoCom ceased to function on March 31, 1994, and the then-current control list of embargoed goods was retained by the member nations until the successor, the Wassenaar Arrangement, was established.

In GPS technology, the phrasing “COCOM Limits” is also used to refer to a limit placed to GPS tracking devices that should disable tracking when the device realizes itself to be moving faster than 1,000 knots (1,900 km/h; 1,200 mph) at an altitude higher than 60,000 feet (18,000 m). This was intended to avoid the use of GPS in intercontinental ballistic missile-like applications. Some manufacturers apply this limit when both speed and altitude limits are reached, while other manufacturers disable tracking when only a single limit is reached. In the latter case, this causes some devices to refuse to operate in very high altitude balloons.

Can we get a Single Limited GPS Engine?

It is hard, but it is not impossible. If it was not for the manufacturers implementing an “or” function instead of an “and” function we could possibly manage to use a unit that would measure our speed and display GPS co-ordinates at over 60,000 feet (18km provided that our speed was under 1,900kph / 1,200mph). This is difficult as we may go over that speed limit. At that point the GPS output is usually nulled.  We need data at all times and do not want a blackout on our data. It will also let us say that we broke the sound barrier, but not by exactly how much. Thus we want a a fully unlimited module for the flight.

Other Factors

Ideally we would like to store our flight measurements. We will have telemetry and can store everything that is down-linked, but there is a risk in doing that. If we use a more expensive unit, then we can have “on-board ” storage. This is mission critical if the telemetry link malfunctions. The aircraft will still fly itself to the runway on auto navigation and we can try again if we have the gas and a second balloon.

Another issue is the rate of poling of the GPS data. We need more than once a second or we could miss our top speed by hundreds of kilometers and hour. This means simply poling of maybe 20 times a second. This rate is easily supported by our telemetry so we will get an instant top speed on the ground before it lands. Something that a basic unit will not be configured to do.

Specifications for the NovAtel Unit.

This is not the one that records, nor is it the top of the vibration resistant unit, but it is very well placed to do the job, after all, we can record the data on other equipment before it is sent to the telemetry system. The cost of the export License is probably $5K and the cost of the unit will be another $5K making a grand total of $10K. The Export License checks your usage of the device and makes sure that you are not a group building a missile for nefarious reasons.

The following from NovAtel’s documentation:

The dual-frequency OEM615 offers future ready, precise positioning for space constrained applications. Backward compatible with NovAtel’s popular OEMV-1 form factor, the OEM615 provides the most efficient way to bring powerful Global Navigation Satellite System (GNSS) capable products to market quickly.

Features

  • Increased satellite availability with GLONASS tracking
  • L1, L2, L2C, B1 and E1 signal tracking
  • GLIDE smoothing algorithm
  • RT-2®, ALIGN and RAIM firmware options
  • SPAN® INS functionality

Benefits

  • Proven NovAtel technology
  • Easy to integrate
  • Low power consumption
  • API reduces hardware requirements and system complexity

Attributes

System Type

Board

General Info

Length (mm)

71.00
Width/Diameter (mm)

46.00
Height (mm)

11.00
Weight (g)

24.00
Typical Power Consumption (W)

1.00

Constellation

GPS
GLONASS
Galileo
BeiDou

Tracking

Max Num of Frequency

Dual
SBAS
QZSS

Number of Com Ports

CAN Bus  2
LVTTL  3
USB Device  1

Performance

Accuracy (RMS)
Single Point L1 1.5m
Single Point L1/L2 1.2m
SBAS 0.6m
DGPS 0.4m
NovAtel CORRECT™
RT-2® 1 cm + 1 ppm

Designed with Performance and the Future In Mind

The OEM615 tracks all current and upcoming GNSS constellations and satellite signals including GPS, GLONASS, Galileo, BeiDou and QZSS. It features configurable channels to optimize satellite availability in any condition, no matter how challenging. The OEM615 is software upgradable to track future signals as they become available. Maximizing satellite availability and optimizing GNSS signal usage now, and in the future, ensures consistent, high performance GNSS positioning.

– See more at: http://www.novatel.com/products/gnss-receivers/oem-receiver-boards/oem6-receivers/oem615/#sthash.caG8JrgA.dpuf

Dimensions 46 × 71 × 11 mm
Weight <24 g
Power
Input voltage +3.3 VDC ±5%
Power Consumption11
GPS L1/L2 <1.0 W
GPS/GLONASS L1/L2 1.1 W
all on 1.2 W
Antenna LNA Power
Input voltage 6 VDC-12 VDC
Output voltage 5.0 VDC
Max output current 100 mA

NovAtel OEM615COMMUNICATION PORTS
3 LVTTL up to 921,600 bps
2 CAN Bus12 1 Mbps
1 USB 12 Mbps
Pulse Per Second (PPS) output
ENVIRONMENTAL
Temperature
Operating -40°C to +85°C
Storage -55°C to +95°C
Humidity 95% non-condensing
Vibration
Random MIL-STD 810G
(Cat 24, 7.7 g RMS)
Sinusoidal IEC 60068-2-6
Bump ISO 9022-31-06 (25 g)
Shock MIL-STD-810G (40 g)
Survival (75 g)

Aerodynamics of Supersonic Craft

Supersonic Glider-spacecraftSupersonic Shock Waves

by Robert Brand

Phase 1 Test Craft

As you all know by now, Jason, my 12 year old son, will attempt to break the sound barrier mid year – he will be 13 by then. This is the first test of a high drag system that should limit our airspeed at supersonic speeds. It is the Phase 1 testing that we talk about in our documents. We need to go fast for this experiment, but returning from space we need to slow down. Our transonic tests will be with a very different looking craft than our future spacecraft.

To the right, you will see where Jason’s design started. As you may have noticed, the ThunderStruck’s current design looks nothing like the image to the right. At each stage he has had to modify the craft to achieve the goals of going supersonic and get up to around 2,000kph ThunderStruck Design and 1-2 size measurementswith full stability. Only then will we deploy the experiment and hopefully slow the craft dramatically. As you are aware, it now looks more like the craft to the left. These are massive differences and we will explore the choices he made in another post. Right now we are looking at how we get rid of the major shock waves and also how our Phase 2 test aircraft may look. The main differences in the 2 craft are:

  • No supersonic Spike
  • No central tail
  • Winglets above and below with a ganged rudder
  • Delta wings that have two angles of protrusion from the fuselage
  • Elevators and ailerons are at the rear of the wing
  • The wing extends to the rear of the craft

Phase 2 Test Craft

In Phase 2 the craft that we design will need to travel straight up into space on a sounding rocket. We will separate from the rocket and continue our climb (momentum) to apogee (top of the flight) and then fall back to earth. Apogee may be as high as 200km. The air is so thin that we can conduct what we call weightlessness experiments for several minutes. Once the air starts to create drag, the experiments will end as the craft will slow. At this time we do not want the craft to accelerate further, but it will. Unless we feather the wings(like Virgin Galactic’s Spaceship 2) or create massive drag in some other way (our Phase 1 experiment) we will go too fast for our craft’s well-being. We need to go slow as possible. We do not want to have to slow with unusual braking as this may de-stabilise the small craft.

Hyabusa reentry sequencWe could use a capsule, an ablative heat shield and a parachute like JAXA’s Hyabusa, but we are creating a winged vehicle, although the capsule will always be another option. I guess the cat’s is out of the bag. We will have a couple of configurations possible with capsule or winged reentry as an option. The ThundrStruck craft will be a modular design in the style and electronics. The picture to the right is the landing sequence for JAXA’s Hyabusa that landed in the centre of Australia. It is not complicated, but you do have to know what you are doing and the downside is that it lands where ever the winds take the parachute.

I want to fix that problem for those customers that need a precision landing or effectively or a smooth landing. I would love to be able to direct the returning spacecraft to a point on the map that allows us to land it without having to recover it from an unknown place in the desert.

Supersonic Aircraft SpikeThe picture at the top of page is where we started. I expect that the spike will not be on the spacecraft and it is also now unlikely to be on the transonic test vehicle, but it is important to understand why we see them on supersonic craft. Sometimes a very long sharp nose can also produce the desired effect.

The picture at right is a NASA test vehicle with a spike. There are many supersonic aircraft that either have a spike of a very sharp nose well ahead of the wings. Why? We discuss this after the following paragraph.

Returning from space the spike would be a liability in the heat of reentry. It will also not be an asset in slowing down a craft. We only need to have the spike as an option to help lower the Resistance to breaking the sound barrier for our tests. At the time of posting, Jason has gotten rid of the spike and opted for wings tucked back behind the shock wave.

In our tests we will use gravity to accelerate the test craft to way past the speed of sound, but shock waves (pressure waves) would slow us down and limit our top speed. We would probably still break the sound barrier dropping the craft from around 40km altitude, but the quicker we transit the sound barrier the higher our top speed and the better the results from our experiment.

So What Does the Spike Do?

supersonic shockwaves in a windtunnelAs I said a sharp nose is the same as a spike and the image to the left shows the effect of the nose/spike as it moves the shock wave to a point well ahead of the main body of the craft and away from the wings. A sharp point is a very low area of shock and in the image you can see the shock waves from the wings as very low level compared to the shock from the tiny front of the aircraft. So long as the wings are tucked in behind the initial shock wave than the drag is lowered considerably. The reason that it was so hard to break the sound barrier was simple. The craft used had their wings in the high drag area caused by shock waves.

Now I may have been a bit simplistic here, but none the less, the spike is important to supersonic flight. Since we are wanting to slow down in Phase 2 tests returning from space via a sounding rocket, we can actually round the nose of the returning spacecraft and still get the supersonic shock to clear the wings

So Why Didn’t the Shuttle Need a Spike?

WPointy nose and shockwaves at mach 6.ell it did need to slow down and so you might think that a blunt nose is a good thing to create drag, but that is not the reason. Wouldn’t a sharp nose be good for takeoff, spike or no spike? Well, in some ways, yes, but the shuttle had wings that were very wide and a spike could not be placed that far forward. The resulting shock waves on takeoff and especially re-entry would be a bit problem as they would hit the wings.

Re-entry would be the biggest problem. The shock wave from a sharp nose would hit the wings and further heat the air. You would be adding thousands of degrees to the heat that it is already being generated on the leading edge of the wing – not a good idea! See the image above right. This would be a poor design for such a craft. The image shows a pointy nose model in a mach 6 airstream. You can see the shock waves hitting the wings midway along their leading edge.

So What Happens with a Blunt Nose?

The image to the right says it all. The blunt nose acts as a ram and pushes the shock wave way to the sides. This misses the wings by a long way – and the tail of course. The blunt nose does add to drag so that is another benefit to slowing down, but a minor one. It is the additional heat caused by the shock wave over the wings during re-entry  that had to be eliminated

What Else Protected the Shuttle from Shock?

Ever consider the orange main fuel tank? Where was the shuttle positioned relative to its nose. It had a point, but was really broad.

What effect did that have during launch at high speeds. The shock wave that resulted missed the shuttle entirely. It is important that the top of this tank was far enough forward to protect the shuttle. The whole design and shape of the combined modules on the launch vehicle was super critical and not just a random bunch of sizes. Minimizing shock waves means being able to both protect the vehicle and increase the payload as you have less drag.

In other words, if the main tank had needed less fuel and had been smaller, then it would still have needed to be as high to push the shock waves aside.

Each and every part of an aircraft that changes its size or sticks out causes shock. You must account for it or suffer the consequences.

The image at right clearly shows the shock wave of the jet disturbing the water. You do not have to be traveling at supersonic speeds to produce shock waves, but the faster you go, the more power is lost and the stronger the shock wave.

Aircraft Design Changes

ThunderStruck mk2ThunderStruck Design on the “Fly”

We now have 2 major changes to the ThunderStruck aircraft. The first is shown in the image to the right. Winglets. The second is a square-ish cross-section to the fuselage rather than a round fuselage – this is under consideration to aid in landing the craft.

The image to the right still shows the aircraft with a round fuselage, but it is obvious that we will miss out on some lifting ability from the body at landing by making the fuselage round. A flat surface on the underside if the craft will provide more lift at the right angle of attack.

winglet_effect_Winglets

The image right is from Wikipedia:

Line drawing of wingtip vortices behind a conventional wingtip (on the left) and a blended winglet (on the right).

This is important as it reduced the vortices behind aircraft that cause so many dangerous incidents at airports when aircraft get too close to each other. It also reduced drag and thus efficiency in aircraft.

The ThunderStruck craft will certainly use the winglets to reduce drag by reducing vorticies, but this will have no impact at supersonic speeds because we will be using symmetrical wing. Normal wings have a flat bottom and a rising leading edge and a trailing edge on the top surface.  This makes the air flow faster over the top compared to the steady flow over the bottom. This reduces the pressure on the top pushing the wings up. This would be nice for the cruising stage after the dive, but bad for holding the craft in a supersonic dive. Any air flow over any asymmetrical surfaces may produce drag or lift that could pull the craft out of a supersonic dive early. The effects could be catastrophic.

Many high altitude model aircraft dropped from high altitude balloons (usually illegally) follow a roller coaster ride due to the thin air and lift in the wings. We don’t want that so the wings will be symmetrical – no lift. We do not need them for the supersonic dive. What we also need is symmetry in the aircraft at any cross-section, vertical or horizontal. The closer to total symmetry, the more likely that ThunderStruck will reach speeds of near 2,000kph. So if we have winglets, they need to extend top and bottom.

So Why the Winglets?

Simply we need wheels. The winglets hide the wheels and any need to lower wheels for landing. We may use a retractable wheel for the front, but not the rear wheels.

The Winglets will also house twin rudders, making a dedicated rear stabiliser (top and bottom) unnecessary. The rear cross-section looks like the picture below:

ThunderStruck Cross-section

Lifting Body (at Landing).

In the cross-section above the flat surface of the lifting body is obvious. This will only be important when landing as the craft assumes a significant nose down attitude during the gliding phase. Since we have no lift from the wings, the craft needs strong elevators to redirect the airflow at the rear of the aircraft to keep control. We will stay aloft by having speed due to a high angle of attack (nose down). Large elevators will keep the aircraft flying at this high angle of attack. It will be a poor glider – but so was the space shuttle – for different reasons – more to do with the delta wing configuration. A round fuselage cross-section would not aid the lift of the craft at landing. A square fuselage will increase the drag as the surface area is greater, but it will help fly the craft at lower speed when landing. It will have little effect during the glide phase. We may add canards to the front of the craft to increase the lift at the front during low speed flight, but they will pop out after we go subsonic. Delta wing craft work well at supersonic speeds, but are poor performers at low speeds. In the picture at the top of screen, the craft does not have a supersonic spike. We will need this for the Transonic tests, but not for return from a sounding rocket or re-entry from orbit.

Below is a closer look at the Winglets. We have yet to show the square cross-section in an image, since this is still under test. It is felt that the flat surface will help drive a higher pressure under the craft (between the ground and the craft) allowing it to land at a slower speed. This is a form of “ground effect” making the need for a long runway important to drop off speed until the effect lessens and the aircraft eases to the runway. Tests may find little difference in the landing speed and thus we may revert to a cylindrical fuselage. Time for some wind tunnel testing.

ThunderStruck mk2 closeup

 

What is Project ThunderStruck?

ThunderStruck verticalProject ThunderStruck set to Break Barriers

by Robert Brand

This project is two projects in one. The total aim of ThunderStruck is to build as small a space craft as possible that will handle reentry, remain stable and land softly. The “softly” is important as commercially there are payloads that may need to be conducted in a “weightless” environment and then be brought down without too much jarring. A parachute landing will not be suitable. My son who is very aerospace savvy was keen to be involved in some way and Project ThunderStruck was born. We will help do the low altitude testing – when I say low, i mean from 40Km altitude (25 miles)

Imagine a time when a 12 year student could design and build a supersonic glider 2.5m / 8ft long, attach it to a huge helium or hydrogen balloon and take it to the edge of space, release it, fly it into a dive back to earth that will reach Mach 1.5 / 1,800kph / 1,120mph and land it. Well that time is now and the student is Jason Brand from Sydney Secondary College / Balmain Campus. He is in year 7 and has already broken plenty of records with his hobbies. Breaking the sound barrier will be another cool record.

New Science, New Data, New Opportunities

Apart from the glitz of the big event in 6 months (a 12-year-old breaking the sound barrier) there is a lot of science being done. In fact the event side of this project will be funded by sponsors and the crowd funding will be for the additional science outlined below.

There is a commercial opportunity to design and create a winged re-entry vehicle specifically for delicate payloads and experiments that last for more than 4 minutes in a weightless environment (tourist sounding flights to space). These are experiments and payloads that would find a parachute landing too harsh. There is a final output of the work and that is a spacecraft for experiments or even a payload taxi service back to earth. The most important aspect of this work is determining the smallest size of a winged spacecraft that can remain stable during re-entry. There are three stages of the physical testing:

  • Transonic – Project ThunderStruck in 6 months time
  • Reentry from space (delivered on a sounding rocket – no orbit); 2-3 years away.
  • Re-entry from orbit; 6 years away

There are two science components to the upcoming testing over the next 6 months:

  • Stability of a small aircraft at mach 1.5 / 1,800kph / 1,120mph and lower speeds for landing
  • testing a new type of surface for high-speed flight. (not a heat shield)

Since Jason has experience and a fantastic track record in High Altitude Balloon flights and flying remote control aircraft, he wanted to look after that first phase of the project. The transonic Phase. Transonic flight is the flight around the area of breaking the sound barrier. All sorts of problems occur near the sound barrier. When we drop the aircraft from 40Km altitude, first we have to get through the sound barrier as the drag increases significantly, but once through the barrier, the drag essentially reduces until your speed increases further. The real testing then commences as our tests will be about slowing, not increasing speed. We will be measuring the behaviour of the craft and airflow over the surfaces.

Project ThunderStruck has Commenced Flying Tests

Just in case you are concerned that this is all talk and no action, we started test flights in Sept 2014. The results are simply amazing and we will use them to refine our project.

The event will take 6 to 9 months to complete and the testing is the most important aspect of this project. It is new territory for us and almost the entire world. There is still fresh science to be done and innovative ways to use new materials and designs. Recently we learned a lot when a non-aerodynamic payload (space chicken from Clintons Toyota) reached speeds of 400kph / 250mph with its parachute deployed. This is because the air is pretty thin up at 33.33Km or 1/3 the way to space. Our payload took several measurements during the fall.

Rankins Springs Free Fall UpLift-19The space chicken was a simple test and we are now happy that we can easily fly at speeds of Mach 1.5 in the very thin air high up in the stratosphere. Left is a picture of the chicken falling back to earth at 400kph. Even the parachute could not slow the payload in the thin air. It slowed down as it reached 28Kms altitude and the air got a bit thicker.

We have started fund raising as we need help to cover the costs of the science parts of the project. Once we know what we have, we can decide on the extent of the program. We need $20,000 or more just for science and we have turned to crowd funding for that.

We have some “Perks” as part of crowd funding that I hope you will love. Some of our payloads will go supersonic before the big event, but they will not be aircraft. We might even donate one of our supersonic payloads to a generous contributor.

STEM – Project ThunderStruck set to Inspire Kids Worldwide.

Fighter jets break the sound barrier every day, but this radio controlled aircraft has no engine, weighs 9Kg (20lbs), is 2.5m (8 ft) long. So the pilot must be a really experience Top Gun to fly this plane at 1,800kph (1,120mph)? Well, no. His name is Jason Brand and he is 12 years old.

This is probably one of the most important demonstrations of STEM education that you can support. This is beyond the ability of almost every adult on the planet, yet a 12 year old student is set to inspire kids around the world with a daring project that is pure STEM – Science Technology Engineering Mathematics. It will make the seemingly impossible the domain of the young if they choose to break down the barriers imposed by themselves or others. Not only that, there is real science going on here.

Your Assistance is Essential

Your crowd funding help now is essential. It gets us started immediately. Flying balloons to the edge of space for testing is an expensive exercise and we have a 7 hour drive each way to get into areas of low air traffic away from the major aircraft trunk routes. We also have to buy a lot of radio systems to allow remote control from the ground when the glider is up to 100kms distance.

You can click on one of the 2 crowd funding links at the top right of the page. Even $1 will help unlock new discoveries and bed down older science.

Who is Jason Brand?

He is a 12 y/o student from Sydney Secondary College, Balmain Campus in Sydney, Australia.

He carried out his first High Altitude Balloon (HAB) project at age 9 and was so inspired that he sat for his amateur radio license at 9 years old. Since then he has launched a total of 19 HAB flights and recovered all 19. Some flights were in Croatia where mountains, swamps and landmines are risks not seen in Australia. He is also the Student Representative for Team Stellar – A Google Lunar X-Prize team attempting to get a rover onto the moon.

J20130414 Jason Brand on the Fuzzy Logic Science Showason appears on Radio and TV regularly and the picture right shows him talking about HAB flights on Canberra’s Fuzzy Logic Science Show in 2013. He is also a member of the Australian Air League, Riverwood Squadron. He plans to solo on his 15th birthday.

His father Robert Brand is an innovator in creating low cost solutions for spaceflight. He speaks regularly at international conferences, is a regular guest lecturer on aerospace at Sydney University, writes about aerospace and takes a very “hands on” approach to space. He supports Jason’s project fully.

How will ThunderStruck work?

The same way that the first pilots broke the sound barrier: in a steep dive. The problem is that since there is no engine and the biggest issue is air resistance, Jason will launch the aircraft from over 40km altitude or nearly half way to space! He will get it there on a high altitude balloon. The air is very thin at that altitude and the craft should accelerate past the speed of sound before it is thick enough to slow it down. A tiny fraction of one percent of the air at sea level. During the dive, the craft will accelerate to well over Mach 1 and way less than Mach 2 and will need to be controllable by its normal control surfaces to pass as an aircraft. As the air thickens at low altitudes, the craft will slow and with the application of air brakes will slow and then be levelel off for normal flight to the ground.

The Technology

We will have a camera in the nose of the aircraft and it will transmit TV images to the pilot on the ground. Jason will be either in a darkened room with a monitor or wearing goggles allowing him to see the view from the on-board camera. This provides what is known as First-person Point of View (FPV). The aircrafts instruments will be overlaid on the video signal. This is known as “On Screen Display” or OSD. Below is a view typical of what will be seen by Jason as he lands the craft.

osdThe video signal must travel over 100kms to be assured of the craft being in the radius of the equipments limits. Similarly we must send commands to the control surfaces of the radio controlled aircraft. Again this must work at a distance of over 100kms. The craft has ailerons, elevators and rudder as well as air-breaks and other systems that need controlling. We will use a 10 channel system to ensure that we have full control of every aspect of the craft and a “binding” system will ensure that only we can fly the aircraft.

We will have to buy 2 x $5,000 GPS unit capable of sampling at what is essentially the speed of a missile. These are highly restricted items, but essential. The unit will record to an SD card and send back telemetry every second. It is essential to know the speed during the flight rather than waiting until after the event. After all Jason needs to knowthe speed to be able to fly the aircraft. We will also need 2 x radar responders to allow other aircraft and air traffic controllers to know where our craft is and our balloon is at any time.

The Big Event

We can expect global TV News coverage of the event and many records to be broken. The day will start by filling a large Zero Pressure Balloon like the one pictured below.

OLYMPUS DIGITAL CAMERAThe balloon will carry the aircraft to over 40km where it will be released and go into a steep dive and break the sound barrier. As the air thickens, the speed will slow and the craft will be pulled out of the dive and leveled off to drop speed. The aircraft will eventually land and data and video records will be recovered. We will already know the top speed, but there is nothing like solid data rather than radio telemetry that may miss the odd data packet. Both the balloon and the aircraft will be transmitting live video.

There will be opportunities to attend, but it is likely to be in a rather remote part of the state (NSW, Australia) or a nearby state. The flight will be broadcast over the Internet and the opportunity to track and follow the flight will be available to all. The chance to be involved is high and the science and inspiration will be out of this world. Project ThunderStruck is set to thrill.

Visit our sister site wotzup.com for more space and balloon stories

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

————————-

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

————————-

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.

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.