27 September 2016

Pitot-static-AOA system routed in airframe

First, the diagram of what's needed for my panel design.

It turns out that the wire clips under the seats are not large enough to house the wiring to the wings and the pitot-AOA lines, in the case of the left wing.  So I had to drill through some of the seat ribs to route those lines.

I marked the route I wanted then used the pneumatic angle drill to start the holes with a #40 bit, then upsizing to a #30.

Then I used my electric hand drill with a right angle drill attachment and 1/4" drive unibit set to upsize each hole to their final 3/8" size so that a SB-374-4 snap bushing could fit.

The final routing for the left pitot (green) and AOA (blue) lines from the rear bulkhead to the wing root is shown below.

The air lines are from Coilhose Pneumatics NC0440, 11/64" I.D., 1/4" OD, 0.04 wall thickness.  I originally purchased these for my Dynon heated pitot/AOA from Avery Tools back on 22-Aug-13 under the SafeAir1 name, however it is now available for much cheaper from MSC Direct and other sources.

Also, the push-to-connect fittings are from MettleAir.  These are much less expensive than the SafeAir1 branded fittings available elsewhere.  I found the MettleAir fittings on Amazon.  They incorporate an NBR o-ring and stainless lock claws.  Each image below links to Amazon.

https://www.amazon.com/gp/product/B00S51JG4C/ https://www.amazon.com/gp/product/B00S51IHYM https://www.amazon.com/gp/product/B00S51LAVY https://www.amazon.com/gp/product/B00S511SAM

My TruTrak ADI2 requires a pitot connection.  Per my diagram above, it uses the right pitot so that it is independent of the EFIS' left pitot.  Below is that connection.  TruTrak specifies that the static connection remain unconnected in unpressurized aircraft.  So the other port on the block remains unused.

The GRT AHRS gets left pitot, AOA and static connections.  If you look closely, my lines come in at a slight angle to each port.  I was originally concerned about that.  However there are no apparent leaks even when shaking the lines.

The Winter 7 FMS 523 ASI and Winter 4 FGH 50 ALT both get static whilst the former additionally gets right pitot.  These instruments were added to provide an independent and non-electric means of airspeed and altitude indications.  The ASI, using the right pitot, provides a redundant indication should the left pitot get blocked.  You'll notice I didn't use red tubing into the winter ALT after the elbow.  For whatever reason, the barb on the pitot port was not beveled, so I just couldn't get the red tube on.  Yet the white tube was more malleable and accommodating to its fitment.

Here are images showing the tee'ing of the lines as they come up from the tunnel.  Left pitot and AOA tees (left), static tee (center) and right pitot tee (right).

The system appears to hold air for at least 5 minutes in all lines.  I will test it more formally later.

A later post will outline the tribulations of my wiring endeavor, some of the details of which are rather prominent in the images on this post.

06 September 2016

Finish: Tricycle Landing Gear and Wheel Fairings.

I probably did about 10% of the work on these.  My RV-9A friend did the vast majority for me whilst I contorted about through the airframe pushing around wires.  Below is the final result.

Now, how to make that happen...

The gear leg fairings halves are fitted to each other, sanding and cutting where necessary to get them aligned and to accommodate the gear leg (right main wheel fairing on left, nose fairing on right).

I cut out the hole for the main gear leg.

Then I attached the U-00002 Wheel Fairing Brackets following match drilling into the fairings proper.

My friend went about further alignment and subsequent sanding, cutting and fitting.

Eventually the fit is acceptable.

Next, the plans call for adding flox mixture around the Wheel Fairing Brackets to fill the space between the main gear fairing's curved surface and that of the flat surface around the brackets.  It also provides for additional stability. Thankfully, no one will see this ugly mess but me.

Next come the gear leg and intersection fairings which my friend completed.

Apparently, other Van's models have the builder bond the U-01411-L/R Lower Intersection Fairing to the wheel fairing and then cut the intersection fairing so that the entire assembly comes on and off together.  The plans do not instruct -14 builders to do the same.  I liked the notion of fewer screws and parts to manage, so I chose to follow the previous models' approach.  My friend did this work.

I cut the gear leg hole far too long on one of the gear fairings.  It was simple enough to re-bond the part in place.  You can also see how the intersection fairing was attached by my friend.

And finally, the fairings are nearly completed.  The addition of some tinnerman washers and perhaps a little more sanding are in order.

Many thanks to my friend for busting through the vast majority of these fairings over about 1.5 weeks.