31 July 2016

Avionics/Panel: Lit up in airframe.

After spending 20+ hours routing wires and connecting them in the airframe, I hooked up the panel to some juice and fired the bad boy up.  Though the EIS, switches and indicators are not yet wired up, the whole shebang still looks like a party.

I have at least 20 hours of wiring remaining before it's done as I need to fashion the wing and tail harnesses and tidy the mess up.



You can read a reverse-chronology of my panel design and construction.  After learning what the cost is to have a panel professionally designed, built and wired, I opted to do the whole thing myself.


Finish: Canopy and Window. Canopy fairing complete.

After some additional work, the canopy fairing is essentially complete.  Go here to read about the entire process of assembling the window.




You can see the wheel fairings in the above picture.  Those are complete and a forthcoming post will outline my experience as I'm waiting to finish the leg and intersection fairings before posting.

28 July 2016

Avionics: LEMO connectors installed.

I see no need for standard headset jacks in my aircraft.  LEMO connectors provide both ship's power for ANR and a single connection point.  Additionally, the connectors lock into the socket (though that also introduces risk of breakage should one accidentally egress the aircraft whilst still donning one's headset).

I slapped together some images to show the pinout of LEMO connectors, shown below.


The PTG.M0.6NL.LC65N LEMO connectors require a 9/16" hole, which is a bit larger than the audio hole provided in the F-01447-L/R baggage floors. It's a tight fit in there for a unibit to upsize the headset hole.  I found a 1/4" drive unibit set on Amazon for the purpose.

 My drill just fit.


Here are the power, audio and mic wires from the airframe ready for connector assembly.  I left these wires nearly 2 feet longer than necessary to provide adequate slack for any later work I might need to perform on them.  This is why you see them outside of the airframe.


I opted to use some small 6-pin Molex connectors so that if the LEMO connector breaks, it can be easily removed and replaced.  These Molex connectors can be found here and here (required pins are also on those pages).


Looking in to those connectors, I configured them with the pinouts outlined below.


Here is the pilot side Molex connector.


The LEMO side Molex connector connected to the airframe wiring for testing. 


The pilot side LEMO installed.  The mic jack hole on each side will remain open and unused.  I'll probably close them off with a nylon washer lest any cookie crumbs fall down them.


A non-LEMO headset plugged in using an adapter.


Avionics: Control column harness.

Assembling the control column harnesses was relatively easy.  A run of a 48" set of wires was encased in 1/8" PET Expandable Braided Sleeving.  The sleeving was important for two reasons:  1) to reduce wear on the wires as the CS-00007 Control Stick Bases move and 2) to make fishing the harness through the absurdly tight space between the F-01451-L/R Tunnel Sides and F-01438-L/R Cover Ribs (shown below).  It was also a great time to make the communications coax.


Below is how I wired my Tosten CS-8 sticks.  Circles indicate wire colors from each pin. The color of the rectangles indicate the color of the wires coming from the sticks.  Though I don't have roll trim installed in the airframe, I accommodated that option in my wiring should I chose to install it later.


The harness and communications coax are ready for installation.  The coax has a BNC on only one end for now.  The BNC for the other end is affixed after the coax is routed. 


My vehicle trim panel removers were used to nudge the cables into the bushings.


Success!

Control Column Bases connector, a Molex 0430201200 using pins 0430310001.  I had to file off the powder coating to get these to fit in.  I'm still fidgeting with how best to fasten the harnesses to the stick bases to accommodate stick movement.


Stick connector, a Molex 0430251200 using pins 0430300001, as wired.


Testing of the stick buttons comfirmed proper wiring as all panel components and the relay deck operated as desired.

02 July 2016

Avionics: AHRS Bracket.

Because I'm using GRT avionics, I am unable to use the AHRS tray provision in the stock wing kit, as the GRT box has a different shape and location requirements.

GRT requirements for AHRS installation:
  1. Should be mounted in the cabin to prevent condensation.
  2. D-sub connector should be pointed aft.
  3. Length of box must be aligned with longitudinal axis of airframe and that box must be level in roll.
  4. Pitch orientation isn't critical, though should match longitudinal axis of airframe.
  5. Alignment between the magnetometer and AHRS should match with 0.5° in all directions. 
  6. Should not be exposed to direct airflow from any source.
  7. Must be mounted on a rigid structure.
These requirements exclude mounting in the wing.  So, my friend suggested I copy the approach he used in his RV-9A, which is to create a welded, rigid shelf mounted against the firewall on the aft side.

Doing some simple trigonometry, we found the correct angle and part lengths to create the below temporary proof-of-concept tray out of 0.125" thick stock.


I then created the parts in my CAD program for precision and had it cut and welded at a local waterjet joint.  It probably cost about $100.


Following priming the tray and the addition of flush-mounted nutplates, the AHRS unit was mounted on the tray and the assembly was then bolted on to the firewall with AN3 bolts.  The angles of the AHRS, the magnetometer (already mounted in the tail) and longitudinal axis of the plane (as referenced by the F-01418A longeron) all agree to the 0.1° precision of my digital level.

Should the unit need to be serviced, I'll have to get on my back and shove myself into the footwell, but it will be easy enough to release the d-sub connector, pitot, static and AOA lines and then unbolt the tray to lower and remove the box.




Don't mind the crazy wires.  I'm not done routing and affixing them.

Update 11-Sep-16:  I added some lightening holes, cut area away from the bottom to match AHRS base's footpring and removed some area from the upper corners.  I foolishly neglect to add (subtract?) those in my CAD design.  I wanted to put a hole on each triangular piece, but I didn't want to risk it.