Sunday, January 17, 2010

Spring Fly Day 1


After all the hard work over winter break, the weather finally cleared just enough for a fly day. We headed to the LMAC Field with the two new composite fuselage DuraPlanes and the Red ARF plane. The weather was a little cold, but the winds were calm.

The first two flights were with the first composite DuraPlane. The plane flew perfectly and required little trim. The aircraft was very stable and predictable on the first flight. On the second flight after shifting the CG some and increasing the throws the plane became more responsive and in no time we were doing rolls and split S maneuvers.

Next we attempted to start the second DuraPlane. But there was a servo issue we were unable to correct at the field, so we moved on to the the ARF plane. The ARF plane was fitted with a flight computer to provide real time data to the ground. The plane flew well and the computer worked. Unfortunately the monokote used to patch the pitot tube lines began to shed during some sharp turns. The aircraft continued to fly, but we choose to bring it down and not push our luck.

The forth and fifth flights were again with the duraplane with again more tweaking to the servos and different prop sizes. Also Jim Burgess (ME-Jun) was given the chance to fly some and did quite well for his first time.

Five flights, five landings, five touch and go, total flight time 35 minutes, and only one monokote patch needed is always a success.

Winter work week summary

The winter break work week was overall a success. Several issues arose with parts being ordered and building the power supply to run the motor in the tunnel but solutions were found and we have moved on.

The week started with the finalization of all aero numbers and then moving the model from XFLR5 to ProE. A few fit checks were done and the model was ready to be printed for construction.

Work first began on the fuselage. Plywood sheeting was laminated with cross sections of the fuse, then cut out and assembled on a base board. Pink foam was used to fill the gaps and then the never ending process of whittling away then sanding and painting the positive molds began. From this the negative fiberglass molds were laid. Further work needs to be done to create the support mold for the negative mold, since scaling up the previous plaster method proved not to work.

In parallel work was being done on the wings, thanks to Jim we now have a full construction model of the wings ready to be sent to the laser cutter. This model was also given to Neil who is now running ANSYS to better determine the wings strength characteristics.

The propulsion group continues to trouble shoot issues with the power, a solution has been found and we now only are waiting for parts. While waiting Aaron was able to setup the Eagle Tree flight computer on the Red ARF plane.

Sunday, January 3, 2010

Aero Progress (Fall 09)

The Aero group started the semester off by first doing a study of previous years DBF aircraft. Collecting specs from every DBF aircraft we could find, trends were developed to get first level numbers on our aircraft.

From there using various book methods and XFLR5 the model was furthered developed. This eventually lead to having the basic numbers for airfoil, chord, span, and with help from the structures group a first weight estimate. With all the basics determined the only part left was the fuselage construction and aircraft layout. For this a full 3D model was developed.
Aero has also been leading the effort to design an MDO code to help optimize our design and future designs.

Propulsion Progress (Fall 09)

The Propulsion group has been busy doing a lot of research into all the options we have for motor, prop, esc, and battery combinations. To verify potential propulsion combinations they have designed and built a thrust rig for the wind tunnel to measure, thrust, rpm, and power consumption while in the tunnel.

We are also plan on using a flight telemetry system to measure air speed, ground speed, altitude and other key flight parameters in real time for flight testing.

Saturday, January 2, 2010

Structures Progress (Fall 09)

The Structure Group has had the interesting position this fall of figuring out how to build the lightest, strongest, and quickly constructed, on a budget aircraft as possible.
Evaluation of previous winning aircraft showed composite fuselages to be key; especially with the high volume needs of the 10 softballs. A fiberglass-balsa composite has been found to be ideal. Since the final aircraft was not designed yet, the group elected to build replacement fuselages for the smaller duraplanes.

After the mold was made, we began laying up different fuselages.

The team uses a non-autoclave, vacuum bagging technique to layup the composites. Thanks to Northrop-Grumman for their gifts to help with our use of non-autoclave composites.