Design Report: 4th/20
(Highest U.S. Team)
No Flight Score
The 2015-2016 year brought a few new challenges for AMAT. The SAE Aero Design competition had a few new rule changes that the team had to take into account to design the most efficient U.A.V. design possible. Notable changes were the ability to drop multiple payloads and that we had to demonstrate our plane’s capabilities with a video in order to fly at competition. Accepting the challenge, AMAT designed Taranis! Named after the Celtic god of thunder, Taranis was sure to be a worthy plane. Taranis is light and strong.
Taranis is powered by 0.46 in3 displacement, O.S. engine. Made heavily from composite sandwich materials, Taranis weighed in at about 13 lbs and was designed to carry 15 lbs of static weight, plus two 2.25 lb payloads. AMAT wanted to minimize fuselage drag and the only size limitation was component and payload storage. The solution was to use dense sand as our static weight and stuff it into our 3, 3/4in wing spars. This allowed for a trimmed down fuselage. It was a tight fit, but we were able to fit all components.
AMAT is in love with carbon fiber! The wings of Taranis are foam core with carbon fiber lay-up applied. The fuselage was a composite sandwich with 1/8in Balsa wood core. The empennage boom is a carbon fiber rod! The Empennage itself is the only primary structure that is not a majority of composites. A beautiful balsa skeletal structure lies beneath the opaque exterior monocote. Taranis is rocking Aggie blue and gold!
The wheels were 3D printed again this year with fairing shrouds surrounding the rear landing gear for reduced drag.
The year started off slow; AMAT was expecting major rule changes that allowed time to handle some logistics. The AMAT work space was moved out of the EFL and into 1236 Bainer due to EFL renovations the previous summer. Safety policy and respirator clearance took time away from the design process.
Eventually, AMAT was able to begin refining wing manufacturing. Originally a tapered wing, manufacturing complications and concerns over tip stall led the wing back to a straight wing. Each half wing was split into halves in order to cut out wing spar holes. Glued together and then put through the lay-up process, Taranis wings took a long time to get right. Thin surfaces and strong vacuum pressure rendered many wings useless. Nevertheless, strong dedication and work from all AMAT members pulled through to complete the wings.
A dynamic engine test strand was made to get data on engine performance. This stand stuck our engine in the bed of a truck, hooked a load cell to a computer and recorded data while the truck was driving up to 30 mph.
AMAT was hit with some obstacles early on. Registration in the fall was sold out in record time this year. The East competition sold out in 6 minutes and the West in 15 minutes! AMAT was put on the wait list; position 27. AMAT had a decision to make: what to do. We decided to continue onward as planned with hopes that we would make it off of the wait list. We met the report deadline without much time to spare. With a month left before competition, during spring break, we got the news. AMAT was going to competition!
Revitalized, we had 3 weeks to finish the plane, test fly it, and make logistical arrangements for competition. The next 2 weeks were a strong finish for everyone. Everyone was putting in long days, everyday, working hard to finish the Taranis. Carbon fiber lay-ups were done every day. We took over all the Dremels we could find and were trimming components. Finally, all the pieces were finished and epoxied in. It was time to make the first flight attempt of Taranis.
The first attempt did not go so well. The plane veered immediately off the runway and into the grass. The entire landing gear system was sheared off by the grass and had to be remade. There was also a concern that the empennage/fuselage joiner was not structurally strong enough to counteract the moment force from the empennage. This led the empennage to drop too much for comfort. The joiner was also reworked and epoxied in place, which corrected the issues.
AMAT’s second attempt took place the day after Picnic Day, which is an impressive feat. It was a mitigated success. Taranis successfully lifted off the ground smoothly and made a drop! It dropped!… past a field of wild weeds, beyond a barbed-wire fence and in a cattle range….. and the payload burst. After the payload drop, Taranis experienced an engine cut-out and total loss of power. This loss of power foreshadowed future propulsion difficulties. Thanks to the fine skills of our pilot, Taranis had a gentle landing in the weeds, just short of the runway. Only the empennage/fuselage joiner required repair. The redesigned landing gear survived completely intact. Not discouraged, we were happy at the proof of concept of Taranis. Our next test flight occurred just 2 days later.
AMAT’s third attempt was a total success! The newly repaired Taranis went straight down the runway and smoothly took off up into the air. Our pilot performed a fly-over and dropped the payload neatly next to the runway. After one more circuit, Taranis “gently” touched down on the runway and everyone breathed a collective sigh of relief. Just two days before leaving for competition, we had the video proof required to pass the technical inspection.
All that was left was to integrate the electronics and get ready to head down to sunny Van Nuys, CA in the L.A. area. We had plans to have a tour at Jet Propulsion Labs (JPL) in Pasadena, CA. Unfortunately, last minute changes canceled these plans. Special thanks to previous AMAT member and Captain, Nohtal Partansky currently working for JPL, for agreeing to give us a tour.
We were lucky to stay at one of our member’s home for the trip. The Langberg family were kind hosts to AMAT. The first evening there, the Captains were sorting out the presentation and necessary items to turn in once at competition the next morning. Meanwhile, members spent the night double checking that the configuration and acquisition system were working properly. Unfortunately, the transmitter for the electronics (very important) fried and was no longer usable. We searched online and futilely searched brick & mortar stores for anything that can replace our transmitter. Once again, an AMAT member saved the day. Amit Harel has family close by that we were able to pick up thanks to Amazon’s next day shipping. AMAT passed the tech inspection smoothly and prepared for the presentation.
Presentations went well. The panel asked insightful questions and the Captains did their best to thoughtfully answer them. The time limit was 10 minutes and AMAT was 10 seconds over that time and incurred a 2.5 point penalty. This placed AMAT in 8th place and without the point penalty, AMAT would have placed 3rd. The point distributions were that close! Some considered it a 3rd place win.
The next two days were flight rounds that were full of issues. Hardware and software problems have plagued AMAT at every competition. An unwritten rule is that the ground station must link up to the plane after it is on the runway. It was tested to work fine right next to it, but not a few hundred feet away. After replacing the fried transmitter, the longer range antenna was not installed and AMAT timed out on the first flight attempt. We did not have a working tachometer, therefore tuning the engine was an issue. We did our best to tune it by ear, but it wasn’t enough. While tuning the engine before our second flight attempt, our radio transmitter malfunctioned. The throttle signal was corrupted and the kill switch would not turn the engine off. After some head scratching, the trasnmitter was reset. The throttle was now working fine, and the team prepared for our next flight attempt. When it was our turn, the engine started, the data acquisition system connected, and the plane was released. AMAT silently willed the plane to lift off as it barreled down the runway. Unfortunately, force of will isn’t strong enough to overcome gravity. Lift is still required. Taranis sped down the full length of the runway and then off of the runway. On inspection, it was found that the control surface inputs had been inverted by the transmitter reset. Instead of sending a nose up command, our pilot was inadvertently sending a nose down. This prevented the wings from obtaining the angle of attack required for sufficient lift. Without a rotation, Taranis just couldn’t take off. Flights concluded for the day after two rounds for the advanced class, so AMAT was left waiting for their next opportunity to fly the following morning. On the third attempt, all systems worked well; we got off the ground and were flying. Taranis experienced a decrease in engine power. Trying to save the airplane from destruction, our pilot flew out of bounds and the round was disqualified. As we tried to land Taranis, the engine cut off for good and Taranis dove for the Earth. The crash left the electronic components unharmed, but the fuselage was destroyed. The wing spars snapped cleanly in half. The fuselage was designed to be light, and broke in the best way possible. Unfortunately, AMAT left the spare fuselage in Davis. The next 4 hours were spent patching up the fuselage with spare balsa and copious amounts of epoxy. It passed the re-tech inspection and was green for flight. The next attempt was doomed from the start. During the rush to reconstruct the fuselage, components were not placed in their original positions. As a result, the fuel tank was positioned above the engine and consequently flooded the engine. The engine never started and AMAT ran out of time for the last flight attempt in the entire competition.
Teams from Poland have been dominating the competition, and did so again this year. It was a tough competition, but AMAT held its own in the international competition. Despite other teams receiving flight scores, AMAT still came in a respectable 6/20.
Everyone had a great time at competition and we returned to Davis and had a debrief of the year. Most importantly, the team voted for the new season’s Captains.
Congratulations to Keyur Makwana, Rina Onishi, and Bruno Matsui as the new Captains for 2016-2017.
Kel De La Trinidad ( Fuselage/Integration & Structures)
Kevin Saddi (Empennage)
Christopher Stevens (Aerodynamics)
Bryce Fong (Wings)
Rina Onishi (Stability & Control)
Bruno Matsui (Engine/Pilot)
Keyur Makwana (Electronics)
Wyatt Dike (Drop Mechanism)
Mengsu Yang (Landing Gear)
Tim Cuatt (Virtual Simulation)
Lily Gibbons (Logistics)
Francisco De La Cruz