Missouri S&T AESS UAV Team

Sig Kadet Senior before the crash.

On August 29th we were performing some long range testing with the UAV (Sig Kadet Senior) and everything appeared to be going smoothly.  It was navigating beautifully and maintaining altitude and airspeed very well.  When slowly the link quality started to decrease, it then lost the communication link, but not without the notification that it was “landing now.”  It ended up landing in a tree, which did not bode well for the UAV.
It turns out that the failsafes had been programmed incorrectly so instead of “flying home” it immediately tried to “Land Now” since the trigger time was set to 0 seconds instead of a couple minutes.  This was a rather unfortunate fact, and could have easily been avoided.  The decision then had to be made of whether or not to rebuild, with only 18 days left until we left for Australia.  If we were to rebuild we also had to decide whether or not to stick with the Sig Kadet, which was quickly ruled out due to the fact that the stock wing could not handle our payload.  So instead we selected an ARF Senior Telemaster, which had a much stronger stock wing and more spacious fuselage, this also meant that we needed to upgrade to a larger 1.20 O.S. Four-Stroke engine.

Remains of the Sig Kadet Senior

We scrambled to order the parts and to get the Telemaster together.  Fortunately all of the electronics survived the crash and we were able to get the Telemaster flying within a week.  Leaving a little more than a week to test the new airframe and UAV configuration.

The new Senior Telemaster UAV

Then to add even more to the drama, during early testing with the Telemaster, it was getting late and visibility was quickly diminishing so we decided to bring it in to land.  As the pilot came in for the approach, the airplane was much further out than expected and it dropped below the horizon and control was lost.  We feared for the worst, we expect the airplane to be in thousands of pieces, with no time for us to rebuild once again.  We quickly hopped in the car and tried to find it.  As we drove to the adjacent field we found the Telemaster sitting in the grass as pictured below (the wing was attached when we arrived, but was removed to inspect the internal damage):

Senior Telemaster after minor crash

This was probably the best crash we could have hopped for, one broken wheel hub, bent landing gear, and a few broken bulkheads inside the fuselage.  The repairs were quickly performed later that evening and we were back to testing within a day.

Note: This post has been backdated to reflect the order of actual events.

Sorry about the lack of updates, there are many new updates coming shortly so bear with us.  The first update being that we completed the new wing and completed the first flight with the new wing and it performed very well even in windy conditions.  Unfortunately there are no pictures of the actual flight but here are some pictures of the new wing on the airplane.  This new wing is significantly stronger allowing us to carry our large payload, it also has less drag allowing us to fly at greater speeds.

Although you can’t see from this picture the entire trailing edge consists of the control surfaces for the flaps and the ailerons, we plan on using the flaps during landing to allow us to land slower at slower speeds.

We have also been working on the onboard computer for the airplane, below are some pictures of it and the new enclosure that we had rapid prototyped out of polycarbonate on campus.  The onboard computer is a single-board-computer (SBC) with a 1.8GHz Pentium M processor, 1GB of RAM, and 4GB of flash running Ubuntu Linux.  This computer will handle all of the image acquisition and some or all of the image processing.

Since we have the UAV in flying condition again we will be slowly integrating the all of the electronics into the actual airframe and there should be more frequent updates now that we will be back in the testing/development phase.

We began construction of the new wing on Friday (January 25th) after all the ribs were waterjet. The new wing is build out of plywood and balsa and hardwood rib caps. So far it seems to be significantly stronger than our previous wing. Building a wing from scratch can be a rather tedious and time consuming process, in the last two days we have put in 20+ hours building the wing, and it’s now nearing completion. The control surfaces are the last major component left to build. Below are some pictures of the wing (for more pictures visit our flickr).

The left wing panel.

The complete three panel wing.

By having a three panel wing, transportation is greatly simplified.