The glider's flight computer is successfully working in the garage! Woo hoo!

1st photo - XCsoar software has been loaded, showing a map and terrain data for New Mexico. (Airspace boundaries I'll add tomorrow.) No GPS data at the moment.

2nd photo - FLARM powered up, green status light...so it's got a GPS fix. Now to configure the glide computer to receive the FLARM data...GPS position as well as info on nearby aircraft. This is a debugging screen that shows I'm getting a meaningful data stream.

3rd photo - now the map is properly located because we have a GPS fix.

4th photo - Even with antennae casually draped over the fuselage, I'm getting ADS-B data of airliners miles away!

I also tested the three pneumatic inputs to the glide computer: pitot, static, total energy. They all cause the glide computer to respond in the correct manner.

Aircraft and glider transponder codes - FAA gotcha.

I have not yet received my glider registration from the FAA (any day now, lol!), but they have assigned a transponder code for the N-number I have reserved. (see first screenshot)

To configure my avionics, I need to load this transponder code into the device.

FLARM wants it as a 24-bit hexadecimal value. (Each hexadecimal value is 4 bits in binary...so it's going to be a six-character code...but my code is not six characters.)

Hmmmm, that number the FAA gave me just doesn't seem correct.

I then called up a known, long-registered aircraft to compare their transponder code. (2nd screenshot)

Surprise! The transponder code I was given was in octal, but not labeled as such. OK, convert to hexadecimal and now everything makes sense.

Onward!

Successful first power-up of the glider's FLARM module. (Boring video)

Current draw is nominal. The status light shows the unit going through self-test (steady amber), then blinking red/green to write to the USB drive on the instrument panel.

https://www.youtube.com/watch?v=0VkrUG3OrPc

More boring stuff after lunch: upload configuration file (aircraft ID, etc.) and latest firmware.

Where can I fit a GPS antenna in the glider?

This antenna will feed position information to the transponder.

1st photo shows the antenna and its connecting coax cable. (The piece of wood is the same diameter as the narrower fitting on the cable. It serves as a probe tool as I thread the cable through bulkhead walls and cable clips.)

2nd photo - behind the instrument panel it's crowded, and I still have other antennae (FLARM) to install later. I need to use the full length of the cable and put this GPS antenna behind the landing gear box.

3rd photo - I have ground the cable fitting even narrower. Every little bit helps. I have to enlarge one bulkhead hole, but everything else can remain unchanged.

4th photo - snaking and threading the cable from aft forward.

This GPS antenna will sit under the turtle deck (not shown). That part is fiberglass...radio transparent.

Glider flight controls!

This is only part of the entire system. It is one of the more complex parts. This portion of the system changes camber of the wing flaperons. Please read the alt-text for more details.

One important part of this subsystem is the use of a push-pull cable, which is rather different from the cables you typically find on bicycles. (See the first comment to this post for a photo of the push-pull cable.)

I will post other videos that show other portions of the mechanical flight controls.

The single seat glider I am building is a far cry from a Boeing 787, but there are still some commonalities. I have switches of various types that control different aspects of the glider's operation.

This video shows three switches on my instrument panel. The master switch is entirely unguarded, and a casual bump or incorrect movement can flip the switch. The next two switches have different types of guards. The second switch requires you to pull back on the switch to get over a mechanical bar that prevents accidental flipping. The third switch is entirely covered with a bright red guard that must be first lifted before you can access the switch. Now that I think of it, I may want to add some sort of guard to the (first) master switch because it turns on and off all electrical systems.

Before I install my 'shark fin' external antennae for the transponder and FLARM systems, I am taking time to improve their aerodynamics.

In both photos the leading edge is on the left, trailing edge on the right. The leading edge is ok for aerodynamics, but not the trailing edge. It should taper down gradually to almost nothing. (Blunt in the front, pointy in the back.) I added low density filler to the trailing edge, and I'm gradually sanding and shaping.

This is a tiny reduction in drag, but I've chosen to make this small refinement. Call it pride of ownership.

I will also reshape the antenna base somewhat to reduce interference drag a tiny amount. (I will add a fillet.)

https://en.wikipedia.org/wiki/Parasitic_drag#Form_drag

https://en.wikipedia.org/wiki/Aircraft_fairing

"Fillets smooth the airflow at the junction between two components...."

https://en.wikipedia.org/wiki/Transponder_(aeronautics)

https://en.wikipedia.org/wiki/FLARM

Just ordered my first part from Vans for my rv-9a! This little piece of 0.050" x 0.5" x 20" 4130 bar stock. Why do I need this? I am much shorter than the previous owner. For comfort, I want to move the rudder pedals forward a bit. I'm going to do that by making new, adjustable rudder links (the parts connecting the rudder cables to the rudder pedals).

I'm not making this into a project plane, but there are some upgrades I want to make over time.

Can I measure how fast the oleo strut on my glider loses pressure?

Science! Empirical data! Quantitative data!

Now that the strut is pressurized, the retaining cable is under tension.

If I pluck the cable, it has a fundamental frequency. OK, download a free piano tuner app to measure the frequency. Make a spreadsheet so that I can record the data...daily measurements over a week or two.

Assembling, filling, and pressurizing the glider's oleo strut.

[The first comment to this post will contain more photos and text.]

https://en.wikipedia.org/wiki/Oleo_strut

1st photo - my hand holds the lower portion of the oleo strut. This is a hollow cylinder with the bottom forming a hermetic 'cup'. (The upper portion of the strut will make it a completely hermetic chamber.)

2nd photo - A double O-ring (four-lobed cross section, similar to a four-leaf clover) is on the bottom of the alu plug. Not seen, on the top of the alu plug is another double O-ring.

3rd photo - How do you fill the oil into the strut after assembling the parts? I don't have pro gear, so it's an assemblage of tubing and a funnel that feed the inlet valve. Stubbornly, the oil refused to bubble and flow into the strut...so I manually extended and retracted the strut a few times to suck oil in and bubble air out.

Strut travel is 3.25 inches.

Assembling parts of the glider flight control linkages in tight places.

1st photo - if only every job were this simple! Room to get both hands in, visibility, room to turn wrenches, etc. That's more the exception than the rule.

2nd photo - looking into the landing gear box through a hole that's large enough for one arm/hand. At the far end, where the bulkhead walls and fuselage converge into a tight corner...and where there are plenty of parts already installed...I need to connect another push-pull tube. I can only get one hand in there, there is barely enough room to insert the bolt, I'm working only by feel, and I also need to start the nut and tighten it.

What to do?

3rd - bolt the rod end outside the landing gear box, insert through a hole, then spin the rod end into its threaded socket.

4th - there is only room for a half wrench to tighten the jamb nut.

Whew!

How fast does brake fluid dissolve certain tubing?

I have read that DOT 3 brake fluid will dissolve vinyl tubing, so I won't use it in my brake system.

But how fast does vinyl tubing dissolve in DOT 3? A couple days ago I put a piece of vinyl tubing in brake fluid. I also put a piece of Tygon tubing in fluid...as a control/comparison.

So far the vinyl has not turned into a pile of goo. Perhaps it's gotten a bit softer, but only a bit.

I'll run this experiment a bit longer, but not as long as the famous Pitch Drop Experiment:
https://en.wikipedia.org/wiki/Pitch_drop_experiment

Ultralight glider ... with a jet engine?!

Homebuilt in Greece.

https://www.youtube.com/watch?v=NQio8kpH6zQ

https://www.youtube.com/watch?v=ouUnPcKKdp0

https://www.weglide.org/flight/613353

https://www.facebook.com/people/Neutrino-Ultralight-Glider/61555164861463/

Crater lake from 10,000 feet!

I bought a plane. An RV-9A. I'm really excited to have this. Flew it home today with the seller/former owner. Did a few touch and goes at KEUG before he disembarked for his return flight. Then I soloed to my home airport. Very long day today. I'm so tired right now.

I'm really looking forward to all of the flying I'll get to do this summer. But first, I need to do a bunch of pattern work.

I'm still working on my Cozy, don't worry. No plans to stop working on that.

My elevators on the horizontal stabilizer (my black-gloved hand is touching them) need mass balance to minimize flutter at high speed.

My rudder, also in 1st photo, has the mass balance built into it. There is not enough room to do that for the elevators.

Where to put the mass balance?

The oval hole at the bottom of the vertical fin is an access/inspection point. It goes there.

Note: when the mass balance is 'far away' from the control surface, the control system linking the two should have as little slop (backlash, hysteresis) as possible.
https://en.wikipedia.org/wiki/Backlash_(engineering)
https://en.wikipedia.org/wiki/Hysteresis

The counterweight is lead shot in thickened epoxy. (I won't melt and cast molten lead!)

The density of lead shot?
https://en.wikipedia.org/wiki/Sphere_packing

Read alt-text for more info.

Info on mass balancing, and a view of my rudder with its integral chunk of lead:
https://universeodon.com/@KrajciTom/114484536950179218

What size mylar strip do I need to cover the various control surface gaps?

This is the elevator, full down position. I need a 30mm wide mylar strip to cover it.

The mylar strip will be cut to length and taped in place.

The rudder and flaperons may need different width mylar strips.

All of this drag reduction should boost my cruising speed by 0.01 knots.

The glider fuselage has been wet sanded.

It's time to for final buffing.

I did some experimenting this morning to get a feel for process and especially process control.

I had two different polishing pads. Would they give different finish quality?

Would a grid of black Sharpie help me keep track of buffing progress?

(Don't worry about the Sharpie. It doesn't stain the polyurethane paint. I can wipe it away with a solvent like acetone.)

Either polishing pad gives similar results, and buffing until the Sharpie grid is gone appears to be a workable control technique.

Water beading on the buffed surface is another indication of progress.

On areas with complex, and especially concave curvature, I'll buff by hand.

I'm not trying to do a fantastic job on the fuselage, but I'll gain experience before I do the critical stuff: the wings.

Yesterday evening was my EAA Chapter's build night for our Zenith kit. Some of us went about drilling the final holes for the wing ribs and riveting them while the other members were in the process of preparing the rear spar for the wing. While we were working a very heavy rain storm hit (just in time to soak the grass runway that just dried out).