Monday, February 24, 2014

ADAHRS Tailcone Tray

A while back I designed a tray to install the Dynon ADAHRS units in the tailcone.

For those of you who don't know these are little boxes that tell the airplane it's speed, altitude, rate of climb, angle of attack, pitch, roll, yaw, etc. They are very sensitive devices that cannot be installed near any magnetic material...more importantly any moving magnetic (ferrous) material. The control rod bolts installed in the lower portion of the tail could cause errors in the readings if installed too close and these are very important readings. The ADAHRS units must also be installed straight and level in relation to the aircraft. A small 1 degree difference is all that is allowed between it and the airplane. Think of these boxes as my airplanes sensing center that tells the brain (EFIS) what's going on. I am installing two of the units one is a backup to the other. The two units constantly cross check each other for full redundancy in the system. If one goes down I flag will pop up on my control screen.

I designed the tray to install in the top of the tailcone hanging from the upper stringers. The tray was made from scrap 6061-T6 aluminum and channel. All the rivets are solid aluminum #3 button head rivets. I used my iPhone's inclinometer to install the tray at the same plane as the door frame longerons which are the straight and level flight reference point on the RV-10. The tray after installation measured in the same plane as the longerons on all axes.

Date and Time
Mon 17th -7.75hrs- Worked on canopy sanding, built and primed the ADAHRS tray.

This is the 3D model I made to design the tray.

I ran an analysis on my design and it easily passes a 10g crash load.

Here are a few pictures of the actual tray. It will be installed with 4 rivets on each side into the upper stringers.

I have a few full size prints to help people make the parts if they want to. You should be able to click the links below and it will download my PDF file from my Google Drive. If you print the PDF on an 11x17 paper it will be full size. Check the measurements on the drawing after you printed to verify it's a true 1:1 scale. These should be all you need along with my pictures above to do the install. Also, a helpful note, after I printed the plate drawing full scale I just spray mounted it to my aluminum sheet and then just cut and match drilled to the printed lines....worked really well.

Link to Bottom Plate Drawing

Link to Side Plate Drawing

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