Saturday, 19 November 2011

High Altitude Glider

The prospect of dropping a self-guided (UAV) glider from a high altitude balloon is intriguing. Adam Melton has been dreaming of this. I don't have any information on the status of that project. Art Vanden Berg appears to have had several launches and a lot of success over the years 2001 to 2003. In one launch the balloon ascended to 11,000 where the team decided to cut the glider free. It landed gently just 65m from the launch site. Wonderful results. This is surely very pioneering stuff. And it looks like a Mk II is planned. Or did 'life' take over and the project get canned?

Reading about these efforts reveals how deeply impressive and challenging the  engineering involved can be. Who else is doing this around the world? Is anyone attempting this in the UK?

If you know anything about these projects, or others involved in similar activities, please add comments below or write to hialt at fairdene dot demon dot co dot uk

Sunday, 23 October 2011

APEX ALPHA flies into Poland

This is my blog of my experience and photographs having had the privilege, once again, to join the APEX HAB team and CUSF for a HAB launch from the Churchill College site, Cambridge. The team had travelled up overnight. I arrived mid morning.

The flight of "APEX ALPHA" in all its amazing details will become available from the website of the APEX team at Sutton Grammar. Here I just give a few details. The prediction that the balloon would land in the North Sea proved to be very wrong. The last recorded position (unless someone knows otherwise) received from the balloon was:

Time: 2011-10-22 23:41:10
Position: 52.054183,19.82842
Altitude: 36304 m Rate: 0.0 m/s
Max. Altitude: 36645 m
Temperature: -52.31C
Battery (V): 3.4
External Temperature (C): -57.69
Receivers: OZ1SKY

It did not beat the height record, but may have broken other records. Much to everyone's amazement, it traveled from Cambridge, over the North Sea, into Holland, then Germany and then Poland! Despite an internal temperature of -52C, the batteries were still working (reasonably) well. Despite the efforts of radio enthusiasts all over Europe, the team lost contact with the balloon as it headed East across Poland. The team were unable to hail radio tracking help in Poland or Russia.

Below is one of the last screen shots from the tracking systems and an image from the Twitter stream during the final hours of the flight.  It is possible, but unlikely, that the payload will be recovered on the ground.

The APEX ALPHA Operations Centre

The launch of APEX ALPHA was overseen by the CUSF (Cambridge Spaceflight) group who have pioneered HAB in the UK by developing software and servers for HAB tracking and prediction. CU Spaceflight is a student-run Cambridge University society founded with the aim of achieving cheap access to space. The A-level students from Sutton Grammar therefore enjoy access to engineering students at Cambridge. However, it must be stressed that the APEX projects are the sole achievement of the boys at Sutton Grammar who started the project, off their own back, several years ago. Launches are now attended by teachers at the school, including physics teacher Jamie Costello who provides moral support and guidance when required.

In the pictures below you will a large numeric read out. The boys built this hardware, and programmed it on their computers to read out the current altitude readings from the balloon. This was a small, but fun, part of the proceedings. All hardware design, software programming, radio techniques, planning and logistics for APEX ALPHA were developed by the boys.

Outside the Operations Room (4th floor of Cambridge University Engineering Dept) was a balcony. Here, the CUSF team had rigged up a a Yagi antenna which could move under motor control to automatically point towards the strongest direction of signal. (Sorry, no pics). I used the same balcony to test my humble equipment. Great news: I received and decoded some packets for the first time. But not reliably. Still problems to sort out.

APEX ALPHA in the air

No way back now. APEX ALPHA takes to the air. Payload is working perfectly. The team have made predictions as to where it will end up .... in the North Sea. Yes, this is a height record, they don't care whether they get it back. But as things turn out, the flight is going to be far more exciting than they could possibly have imagined.

The launch of APEX ALPHA

The launch of APEX ALPHA was a little fraught due to ground wind. The team had to de-camp to another part of the field because the balloon was being buffeted and any slight scratch on the surface would cause a weakness which would cause the balloon to burst before it reached the target altitude of 42km. Yes, you read that right. Forty two kilometers.

As the launch progressed, the long line between the balloon and the payload under tension caused the balloon to sink close to the ground. The technique to get airborne requires a 2nd line on which the balloon gently rises under its own lift. A team member holds the payload until the point of launch, and then runs after the balloon to ensure that it gets height before the payload is released. This ensures that the balloon does not drag the payload on the ground, or into nearby buildings or trees.

Helium and Latex Balloon

Sutton Grammar bring their own supply of Helium to the site (quite an expensive operation) and purchase their own balloons. APEX ALPHA was a height record attempt. For this, you want a large balloon, not filled with Helium but just enough for lift, and a light payload. The team are adept at the required calculations.

As I arrived on site, the boys were doing the final preparation and testing of the payload. For details of the payload design visit the APEX ALPHA site. Everyone at the site was receiving packets. What was surprising was that the team  a few miles away on the 4th floor of the Cambridge Engineering Dept were also receiving packets. This was probably because they were high up, but their equipment was much better as I was later to find out when I joined them.

PARS HAB Tracking Equipment

PARS has built home-made Yagi and other types of antenna for tracking at 433MHz. We picked up a radio receiver off eBay, a Yaesu FT-790R. Works like a dream. Wish I could say that about the netbook we used to run FL-DIGI decoding software. The audio input appears to have a certain amount of noise, making packet decoding difficult. Ben Oxley of the APEX team helped me to diagnose these problems. Still not adequately resolved.

APEX ALPHA Launch Preparation

I arrived late at the Churchill College launch site due to road closures on the M11. But I was in time for the launch. This was the second time the APEX team from Sutton Grammar had been kind enough to allow me along for the ride. I must move beyond being a "HAB Groupie" and do one of these myself.