TU Wien Space Team Aim for the Karman line and European Altitude Record

Vienna (TU WIEN) – The Space Team of the Vienna University of Technology wants to know it again: in Nevada (USA) two rockets are launched, which are to reach record-breaking heights.

If everything works out perfectly, the rocket should reach a height of over 100 km – the area where the atmosphere gets thin and space begins. The Space Team of the Vienna University of Technology, an association made up of students from different TU disciplines, will attempt to break records in the Nevada desert with two self-developed two-stage rockets. The previous European record for student teams is 32.3 km.

In the last attempt last year, the goal could not yet be achieved. Now the team tries again. The launch is scheduled between 20.9 and 22.9 – updates are posted on the Space Team’s website.

Much know-how at the Vienna University of Technology

The Space Team has already made a number of remarkable achievements. Various rockets have been successfully launched, a mini-satellite has been built and is still sending data from its orbit, a novel mountain system has been developed, with the probes without parachute unscathed from space to return to Earth.

The technical challenges that needed to be overcome for the record attempt are huge:

For about three and a half seconds, the first stage of the rocket burns. This is then separated from the rest and the upper stage continues for fifteen seconds, until it is then ignited at a height of about twelve kilometers. This is made possible by a sophisticated electronics system, which was developed and built by the Space Team.

“This is a challenging task, and there are countless things to consider such as safety and reliability,” says Project Manager Christoph Fröhlich. “The last time we tried a security mechanism was not wired correctly, this year we will launch the rocket again, and in addition we will try a second improved missile in detail, especially the electronic systems and the upper stage ignition have been revised.”

Both rockets are each just under four meters long and weigh (including fuel) each about 30 kg. In the development, it was important to choose the right materials that could withstand extreme loads – such as special glass fiber reinforced polymers. Due to the strong air resistance, the rocket is extremely hot. At atmospheric pressure at sea level, such a rocket would burn, but as the air pressure and thus also the air resistance decreases, the team hopes to surpass the previous European record for student teams of 32.3 km. Achieving a world record is possible, albeit difficult: a team from the University of Southern California has now reached 100 km. “What height we can ideally achieve is hard to say because the simulations come to quite different results. Ultimately, we will only know when we analyze the sensor data after the flight, “says Christoph Fröhlich.

Video Caption: In September of 2018 the TU Wien Space Team launched the two-staged rocket “The Hound” in Nevada, USA. More information under http://spaceteam.at/2018/10/20/the-ho…

CS: DIY Parachutes Part II

Video Caption: This is a follow up video to our June 29th Spica space capsule ballute and parachute system tests. Here we talk about the data we got from those jumps. If you haven’t seen the first part of this video, you can watch it here: https://www.youtube.com/watch?v=4SQet…

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Why Tolerances are Important

As rocket projects become more complicated and with the advent of cheap and readily available machinery, and machinery services (3D hubs for example) a lot of people are starting to push the limits with what is being made in the garage.

When it comes to rockets you are never going to get it right first time and you will soon find yourself in the iteration process as you improve on your designs. If you are having to remake parts from rough or non-existant drawings you may find yourself in a dilemma with parts not fitting and potentially botching a few.

From a mechanical standpoint, there are a few things you can do to make your life easier, a simple tolerance is one of them.

We must first understand what a tolerance is, in engineering, a tolerance is the limit or variation of a physical dimension. This can be set by yourself on how accurate you want your part or it is sometimes set by the machine used, a bad operator can also play a part but for this write up I will not consider this.
As a general rule the higher the tolerance you put on your part the more it will cost, if I wanted a shaft with a diameter of 20 mm ±0.1 mm (19.9 mm to 20.1 mm) this would be easily achievable on a lathe with no extra tooling. If I was to make this ±0.01 mm (19.99 mm to 20.01 mm) then things start getting harder, the shaft would now require a grinding process to achieve this, meaning more time and man-hours and thus a more expensive part.

Not only is cost a factor, but also the fit of the part, which is what we probably really care about matters. If my 20 mm diameter shaft had to fit inside a hole, a bushing for example, and if there were no tolerances involved then how would I know it would fit every time? It could be oversized, undersized or it could be ok.

Luckily for shafts and holes (or anything concentric like a rocket tube and bulkhead), there is a simple ISO tolerance letter/number designation system to make life easy, shown below.

Fits (Credit: Machinery Handbook 29th Edition)

To go along with this, there is a handy Limits, Fits and Tolerance calculator from Amesweb which makes this ISO system easy to understand.

Let’s look at out 20 mm diameter shaft and the bushing it must go into. From the above chart I’d like a sliding fit, with a basis on the hole (hole limits are maintained but shaft limits can vary), therefore I want a H7/g6 tolerance on the shaft and hole.
Plugging this into the above-mentioned calculator yields the following,

As can be seen, I have a nice tolerance dimension that will always enable a sliding fit, but what are these dimensions?

My bush dimension becomes 20 mm -0 mm on the lower end and 20 mm +0.021 mm on the upper end, while my shaft diameter becomes 20 mm -0.020 mm on the lower end and 20 mm -0.007 mm on the upper end.
This gives me a range that I can make each part too, and as long as each part is within that range I will always have a sliding fit, no matter who or where it is made.

This is a very basic introduction, more specifically relating to cylindrical components and fits. In a future post, I’ll go into a bit more detail into the next steps you can take to ensure your parts are concentric and cylindrical using the Geometric Dimensioning, and Tolerance (GD&T) language as well as covering the three basic types of tolerances you may see on a drawing.

BPS.space on TMRO

Video Caption: Joe Barnard of BPS.space joins us to talk about his work in making model rockets emulate larger, liquid fueled vehicles such as Falcon and Electron. He has created many amazing models and has been working on thrust vector control (TVC) steering of models as well as being able to stage and even land model rockets. This is his story.

If you would like to continue the conversation we have a few great ways to do that: – Comment right here on YouTube. We’ll comment back or even feature it in the show – Create a new post on our community forum at https://community.tmro.tv – Head over to our real-time Discord channel here: https://discord.gg/9NkkFWD

DARE: Parachute Research Group News

As well as designing the recovery systems for the upcoming Stratos IV flight, the team will get a chance to test their systems in the REXUS/BEXUS program, first flight in 2020.

From the REXUS/BEXUS website,

The REXUS/BEXUS programme allows students from universities and higher education colleges across Europe to carry out scientific and technological experiments on research rockets and balloons. Each year, two rockets and two balloons are launched, carrying up to 20 experiments designed and built by student teams.

DARE: Engine Testing and Recent Happenings

The team has also released a newsletter covering what they have been up to recently. Download it here to find out!!

Video Caption: Test 16 of the DHX-400 ‘Nimbus’ hybrid rocket motor for the Stratos IV student built sounding rocket.

Delft Aerospace Rocket Engineering is a student-team of Delft University of Technology and one of the largest and most advanced student rocketry teams in the world.

Follow the journey of Stratos IV to space on our social media!

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November 2018 at FAR

FAR is the Friends of Amateur Rocketry and is an organisation and test facility in the Mojave Desert where experimenters can test and launch their rocket projects.

Video Caption: A few of the larger projects at the FAR Saturday, November 17, 2018