Towing test

Georg writes

While all the others are writing on the Documentation for the critical design review which has to be finished tomorrow I am trying to keep you up to

Mario & Mikko running facing the Parachute in the pickup

date on what happened during the last couple of days.

And the most important thing was probably the towing test. On Wednesday last week more or less the whole team gathered to do a drag test at Tierp Airfield a bit north of Uppsala. The goal of this test was to investigate the deployment of the parachutes and to find a working folding technique.

Gustav is adjusting the RIG

In order to be able to do the test we all had a busy Monday, Mario and Gustav built a rig to mount the FFU onto the car and I had to produce something to attach it in different angles. Unfortunately the mounting device from bent aluminium wasn’t as stable as I expected it to be.

However, after some starting problems with broken swivels and opening problems a couple of runs worked out quite well, the chute deployed when it was mounted with the attacking wind. The two tested folding techniques seem to work equally good and parachutes seem to work fine.

There is already another towing test being planned in order to refine the results a bit, I hope this time the attachment will work a bit better…

SQUID army

Frame and top cover

There is something happening down in the basement, but what is really going on in the workshop?

Well, as the drag test is coming up it would be cool to have two fully functional prototypes in order to prepare one while the other on is being tested. So I started to produce another prototype and be sure, there are more coming.

However, as the prototypes need to have a functioning cover they will get a top frame and a cover according to a design from Mario.

More SQUID prototypes

Unfortunately the manufacturing of the frame doesn’t seem to be as easy as everyone thought. At first cutting the inner part out just using a jigsaw felt right, but cutting aluminium with a jigsaw is no fun.  So I am back to milling again. I just hope this works out without any incidents this time.

The mockup of the FFU is coming together

Soon we will be starting to do tests on the parachute deployment. Therefore the production of mockups of the FFU have begun. George, the team’s new member, is working like crazy down in the workshops to manufacture the models. Great job George!!

Our parachutes that we ordered also arrived a while ago. The parts are starting to come together, at leas a bit 😛 We chose a cross-chute type due to its favorable characteristics such as stability and less drifting with wind than a regular umbrella shaped one.

Before we do the actual test the parachute folding has to be tested and developed. This has proven to be a quite intriguing task due to that we actually have no idea of how to fold it correctly into the FFU. But one thing at least can be concluded, it seems to at least be possible to fit it into the compartments that we have 😛

The test day is set for the towing test. On May 19:th we will head to the airfield in Tierp to conduct the towing test on the parachute deployment. For now we will work hard to plan for this event because we really need to get as much data and results from this day as possible.

We all look forward to this and hopefully it will go well 😀

Cutter test

To improve the cutter design for ejecting the parachute, Gustav and David suggested a new design some time ago. The design has since then been discussed together with some of the members of the LAPLander team and a decision to test the performance of such a cutter where taken. The design of the new cutter is quite simple and consists of a pipe made of ceramics with good heat propagating properties. The pipe is then threaded and a cantal wire is twisted around it. The result is that the cutter works as an owen and melts the rope which is guided through the pipe. The test showed that the cutter performs quite well even in this early stage even if there are a number of improvements that needs to be added to the design.

The new cutter with an enthusiastic David behind it

The art of making streamers

Jacob writes

After two presentations at Bergtorpsskolan in Täby and two more at Naturvetargymnasiet in Södertälje the school visit part of our outreach plan is done for the time being. All work is now focused on the tasks that need to be finished for the Critical Design Review in the beginning of June!

One such task is choosing the proper streamer for the landing system.

In order to minimize the risk of the parachute getting entangled with the free-flying-unit (the ejected part of the experiment), it needs to be pulled out and away from it. We hope to be able to do this with a simple streamer, which is kind of like a long ribbon of cloth or plastic.

Streamers are commonly used on model rockets in place of parachutes, but we haven’t found any good info on them being used for anything bigger. This means we have to do some testing! What we’re mostly interested in is how the drag from the streamers varies with speed, the weight of the material, and the dimensions of the streamer itself.

This weekend I have a great opportunity to test just this my holding them out on a stick from a car, but first I need something to test! During lunch today I headed to a hobby store which just happened to have some streamers for model rockets at hand… including some big 7*70 inch ones!

The model rocket streamers are very light while the info we’ve found on the subject says that a heavier streamer might provide a lot more drag. However, thanks to the LAPLander team we have a lot of thick, heat- and tear-proof airbag cloth lying around at the lab, so I immediately got to work cutting out more streamers of various dimensions from that.

It’s going to be fun sitting in the back seat of a convertable testing all these during the weekend, I’ll write up a post about how it went next week!

Oh, and here’s a pic from one of the presentations we held at Bergtorpsskolan. It’s been great fun and the students have been really interested, and haven’t been afraid of asking us tricky questions! Hopefully we can go out and do this again after summer.

David and a group of students at Bergtorpsskolan