Wednesday, December 31, 2008

Finished making the BOM for the entire fast GVT system. speced out enough frame components for a fighter jet sized aircraft.

Wrote some of the Mirage Systems report.

Tuesday, December 30, 2008

Finished BOM for PCBs. Got prices for all components and checked with paul about what kind of capacitor the big one was. It was Panasonic 250V 10uF polyester film capacitor. He said that we could use a Tantilum capacitor instead, it would be smaller and cheaper. He specked one out; part # 478-1841-ND.

Checked what the longest pipe length would be that would yield a natural frequency of >10Hz, when a 2lb mass is located at the middle.
For pinned pinned BC, the longest could be 125".
For clamped clamped BC, the longest could be ~186".

Talked over tube length issues with Bryce. Concluded that we should just order the 2" OD tube. I ordered it from Tube Service. They only have 12' sections rather than 20' sections which could be a problem. They do have 6063-T6 in 20' sections but 6063 has lower ultimate shear stress.

Assigned part numbers to all the parts/drawings I created for the Fast GVT.

Monday, December 29, 2008

Talked to Brian Plasky from Mirage Systems. He said that no errors occurred during the two flights. Despite this, he said to go ahead and write up a report that discussed the vibration environment and what we (CSA) are worried about as far as vibration levels go. Also, he said it would be good to recommend a vibration mount or a different mounting orientation.

Worked on Fast GVT interface box. Measured and finalized dimensions for the laser display mounting plate and accel connector mounting plate. Made drawings for both parts.
Created BOM for PCB.

Monday, December 22, 2008

Found out today that the data from some seismic accels I calibrated was erroneous. The problem was that I used a reference accel that was not good down to the low frequencies that the seismic accels were good to. Thus, the ref accel rolled off and the seismic accels did not, causing an increase in the FRF at low frequencies. "THIS SHOULD HAVE BEEN A RED FLAG"!! Make sure it is in the future!!!!!! I needed to either use an accel that was rated to low freqs or use a coupler with a very low frequency high pass filter.

Also, I found out that an excel spreadsheet I wrote to calculate the natural frequency of a tube or pipe was incorrect. The problem is that E, the elastic modulus, is in lbf/in2, while the specific weight, rho, was in lbm/in3. I needed to convert from lbm to lbf in order for the units to work out. Once I did, I got the correct answer. ALWAYS MAKE SURE UNITS CHECK OUT!!!! I didn't do this the first time so I didnt catch this mistake until now!!!!!!!!!!

Tuesday, December 9, 2008

Worked a lot with Solid Works for the Fast GVT. For awhile I was having problems creating drawings from parts. I found out that this was because I had saved the drawing template in "edit sheet format" mode. I changed the drawing template to be in "edit sheet" mode and it was much easier to create the drawing.

Started to use CosmosWorks to redesign a flexture for a proposal.