Lid trusses

Getting closer.

Three trusses (all identical length and construction) are now fabricated and pinned in.  It's wonderfully stiff.  They all need a corresponding pin block support welded into the upper rail before I can drive (it would rattle like crazy currently), but the stiffness is noticeable.  It also only takes a few seconds to de-pin and remove / pin and install.  I like it.

 

Creating the lid trusses started with a 1in bar, which was hand-milled down to 0.9in to fit inside the 1/20in wall thickness.  I started with the band-saw and then tried to use an end mill on the drill-press.  It was functional, but scary, and I don't recommend doing this.

After getting 0.9in thickness, I lopped off 1in long sections that become a welding plug.

It did not take much work to weld the plug into the end and match-drill a through-hole.  A few minutes with the sanding and filing tools cleaned up the welds.

The first plug was easy enough.  I have three trusses (and three wing support cross-members) that all need both ends plugged.

After a while, the trusses were ready for fitting.  I put just one end first and figured out my spacing so that each of the three lid trusses was identical length, and thus are all interchangeable.  It was 90-5/8in between holes, if anyone cares.

After drilling both ends of the truss and making sure the holes in the rails were all set for the same spacing, the trusses are all installed.  I still need to weld in a 1in cube backer block.  The hitch-pin keepers will bump against the backer block nicely so they do not rattle.  

Trailer to do's are now:

• build three lid trusses
• weld in six backer blocks for the lid trusses
• finish weld the upper rail to the vertical supports
• epoxy-coat seal the ply decking
• figure out how Goat parts sit in the trailer
  
• take all of Goat for its first trip around the neighborhood 

Optional trailer to-do's:

• install and wire running lights on the sides
• add reflective tape on the sides
• figure out front/side/back walls 
• create a rear door that can be quick-pinned in place
  

For the first-flight:

• backyard final assembly and thorough pre-flight check, including weight & balance
• re-weld the tow hitch release (I'm now doubtful it had good penetration) 
  
• buy tow rope, weak-links, and end rings
  
• buy/borrow radios (1x airborne, 1x car)
  
• find a place to fly
• travel
• fly

After the first-flight:

• add leather patch to wing tips where will rub the ground
• install leather patch guides for elevator control lines
• paint trim color
• install wing root kiss seal
• build a wing tip dolly
• build a wing wheel
• jury strut fairings
  
• main strut fairings (after flying to figure out the right angles)
• emergency parachute
  
• real variometer (LXNav with a TEK probe is my intention, if it is sensitive at low speed...)
• dogue chute

First hitch pins

I finally took a weekend off of work and got a little done on the trailer.  It isn't much, but the trailer finally now has removable pins for the rear spreader bar.  I welded in a small gusset plate and then match-drilled holes to install a removable hitch pin.  Only very gross tack welds are in place so far.  All finish welding is going to be for another day.

I narrowed down how to finish off the structure.  The "lid" will be three 8 foot trusses of 1/16th inch wall, 1 inch square tube.  The ends will have solid aluminum inserts for supporting the hitch pin, and the trailer rails will have a 1 inch block welded in and drilled for the hitch pin also.  With these three trusses c-clamped onto the frame, it's finally stiff enough in torsion.  Once these truss pieces are in place (and several broken welds are repaired), I'll take another test drive around the neighborhood and hopefully make a small road trip.

Sealing the plywood floor with epoxy is waiting for warmer weather to arrive.  Once the sealing is completed, those pieces will be bolted to the frame for good.

Last, I also figured out how to create cross supports to hold up the second wing.  Pictures of this will come out later.  Getting the two wing panels tied down into the trailer and out for a drive will be a momentous occasion.

My goal is to fly this summer.

Trailer to do's are now:

• paint axle assembly with some enamel paint
• repair left tail-light wiring
  
• buy more Argon gas
  
• finish weld the vertical elements
• finish weld the upper rail
  
• epoxy-coat seal the ply decking
• quick-pin the rear "door"
  
• dream up a top lid
• build lid trusses
  
• figure out how Goat parts sit in the trailer
  
• take all of Goat for its first trip around the neighborhood 

Optional trailer to-do's:

• install and wire running lights on the sides
• add reflective tape on the sides
• figure out front/side/back walls 
• create a rear door that can be quick-pinned in place
  

For the first-flight:

• backyard final assembly and thorough pre-flight check, including weight & balance
• re-weld the tow hitch release (I'm now doubtful it had good penetration) 
  
• buy tow rope, weak-links, and end rings
  
• buy/borrow radios (1x airborne, 1x car)
  
• find a place to fly
• travel
• fly

After the first-flight:

• add leather patch to wing tips where will rub the ground
• install leather patch guides for elevator control lines
• paint trim color
• install wing root kiss seal
• build a wing tip dolly
• build a wing wheel
• jury strut fairings
  
• main strut fairings (after flying to figure out the right angles)
• emergency parachute
  
• real variometer (LXNav with a TEK probe is my intention, if it is sensitive at low speed...)
• dogue chute

Lots of finish welding

It was freezing outside today, which made for a fine day to be outdoors.

I have moments of success and times of failure.  The most success came from switching in a new tungsten, cleaning the welding rod with alcohol, cleaning the welding surfaces, and turning up the argon to about 20 SCFM.  I ran 180A, 120Hz, and 30% cleaning, 0.8s pre-flow, and 4.5s post-flow.  I have a CK17 air-cooled torch running 3/32" rod.  Green tungsten is not super happy running at 180A.  Amazon delivered some blue tungsten literally as I finished up today.

Today started with trimming the four new 3x1.5x0.18 structural c-channel using the same methods as a few years ago.  This part went quickly.

After welding the accessible top pieces, I flipped the trailer on its side to access the bottom.  This gave way better access.

Seeing the bottom also showed that many of the original welds had cracked down their center.  I we-welded these and tried to get good penetration.

It was still challenging to weld the thick webs.  I haven't figured out what does work consistently, but I can sure find what doesn't.  Best I can figure for this awful weld was insufficient argon flow rate and a dirty tungsten tip.  I ground off all of this grossness.

After putting in a newly ground tungsten, and increasing the argon flow rate, it seemed to run better. I wish all welds were this easy.

 

After a full day, all of the frame pieces are welded.  The upper rail still needs work and so too the inside of the frame.  But it is getting stiffer.  It is definitely also getting heavier.  Maybe I'll take a drive around the neighborhood tomorrow.

More welding again

I installed one cross-member and now clearly the next open bay flexes.

Adding floorboards for 24-inch on center will add some weight, but will add more structure.  Another $200 of aluminum is on order.  I've spent a considerable fraction of the cost of building Goat on the trailer to carry it.  I've heard planes are 1/3rd for the airframe, 1/3rd for the engine, and 1/3rd for the avionics.  Since Goat doesn't really have an engine, maybe that third is for the trailer.

Anyhow, the extra cross-member in the front let me add a few support welds to transfer loads from the hitch into the frame.  Welding in these corners is challenging, as it takes full 200A to get enough heat into the thick c-channels to melt either side.  These are gross welds, but I am happy to have them.

In other locations, I repaired the broken welds and tried to get in more heat to have better penetration depth.  I'm sure it isn't enough for the long-term, and it'll be wonderful to weld along the inside as well (how?), but more is better.

That's all for today.  Just a quiet Saturday afternoon clearing my head of work for a bit.

Boxing is the trick

I finally finished painting the mega axle with two coats of black enamel paint, which included painting inside the cross axle square tube.  Painting inside a tube was an old trick using a sponge and a coat-hanger.  It was messy, but functional.  Now the axle is fully painted and bolted onto the trailer frame.

Moving on to torsion.  I've been disappointed at the low torsional stiffness.  Adding the side-walls was very helpful, but I can stand on the back corner of the frame and see everything flex, including the walls.  I see the main beams twist slightly  One idea was to add more parallel frames beneath the floor (which also doubles up support for the plywood floor).  The last good idea was to add a top lid of trusses.

Some previous experimentation clamping spare angle across the top seemed plausible, but didn't give enough improvement.  Today, I clamped three eight-foot 2x4's as trusses across the open top.  Those were instant magic for increasing the torsional rigidity.  I can literally stand on the back corner and the front of the frame stays stiff.  Amazing.  This finally puts a finger on the right next step.

I took a drive around the neighborhood with the three 2x4's clamped across the top (this was the first real drive with the torsion axles too).  Driving was better, though the long unsupported upper rail on the front was quite wobbly.  After stopping to inspect, one of my original frame welds had broken, which let the vertical strut start to flex.  That's fixable.  It also suggests that adding more cross-frames may help more than I realize, since not having just one weld made such a difference.  Lastly, it also means I really must weld all of the inner joints rather than just the upper flange.  For another day...

Also of note, TIG welding thick aluminum had been getting more frustrating.  At 180A, the tungsten tip was melting (green) or exploding into nodules (blue), which meant re-sharpening the tungsten literally every weld.  After watching several tutorials from the excellent Pacific Arc Tig Welding channel on Youtube, it appeared my AC balance of 30% was too much cleaning action for an air-cooled 3/32" tungsten.  My Weldpro only goes down to 30% balance, so decreasing further was not an option.  After watching several more tutorials, today I finally tried the second idea of increasing the AC frequency.  Going from 60Hz to 120Hz did seem to make a difference, and I was able to weld longer without melting the tungsten tip nearly as much.  Hopefully I can keep experimenting with this trick during finish welding.

Before driving around the neighborhood, I repaired the broken wires on the left tail light.  The road literally ground a hole the plastic, so this LED light is probably fine for a bit, but will die a slow death from corrosion.

Oh!  I'm pretty sure I found a field for a first flight.  Blackstone Army Airfield (KBKT) is uncontrolled on the weekends and has a 5,000ft x 300ft dead runway that is perfect for both driving on and doing a takeoff and landing.  Most airfields are not cool driving a car on their beautifully manicured grass runways (for good reason), or the paved runway is active for general aviation traffic.  According to the airport owner, so long as I have an air-band radio, I should be good to do the maiden flight there.  He has had other ultralights fly from the field, so there is even precedent.  Hopefully this ends the search saga.  It is a three-hour drive to get there, and will be even slower when towing a trailer I do not yet trust to go around the neighborhood.  One day at a time.  At least this is non-zero progress!

Trailer to do's are now:

• paint axle assembly with some enamel paint
• repair left tail-light wiring
  
• buy more Argon gas
  
• finish weld the vertical elements
• epoxy-coat seal the ply decking
• install and wire running lights on the sides
• add reflective tape on the sides
• create a rear door that can be quick-pinned in place
• figure out front/side/back walls
  
• dream up a top lid
• figure out how Goat parts sit in the trailer
  
• take all of Goat for its first trip around the neighborhood 
• be comfortable driving six hours at highway speeds
  

For the first-flight:

• backyard final assembly and thorough pre-flight check, including weight & balance
• re-weld the tow hitch release (I'm now doubtful it had good penetration) 
  
• buy tow rope, weak-links, and end rings
  
• buy/borrow radios (1x airborne, 1x car)
  
• find a place to fly
• travel
• fly

After the first-flight:

• add leather patch to wing tips where will rub the ground
• install leather patch guides for elevator control lines
• paint trim color
• install wing root kiss seal
• build a wing tip dolly
• build a wing wheel
• jury strut fairings
  
• main strut fairings (after flying to figure out the right angles)
• emergency parachute
  
• real variometer (LXNav with a TEK probe is my intention, if it is sensitive at low speed...)
• drogue chute

Painted axle

Just chipping away at an easy task on an unexpected weekend day off, I put a coat of paint on the new axle.  The steel had some light surface rust already starting to grow, so it was time to add protection.

I simply brushed on Rustoleum black semi-gloss enamel paint.  The axle went from looking reasonable to looking awesome.  Paint makes such a difference visually, and I really hope that it protects the metal beneath (expect three coats, and inside the open square tube also).

Trailer to do's are now:

• paint axle assembly with some enamel paint
• repair left tail-light wiring
  
• buy more Argon gas
  
• finish weld the vertical elements
• epoxy-coat seal the ply decking
• install and wire running lights on the sides
• add reflective tape on the sides
• create a rear door that can be quick-pinned in place
• figure out front/side/back walls
  
• dream up a top lid
• figure out how Goat parts sit in the trailer
  
• take all of Goat for its first trip around the neighborhood

For the first-flight:

• backyard final assembly and thorough pre-flight check, including weight & balance
• re-weld the tow hitch release (I'm now doubtful it had good penetration) 
  
• buy tow rope, weak-links, and end rings
  
• buy/borrow radios (1x airborne, 1x car)
  
• find a place to fly
• travel
• fly

After the first-flight:

• add leather patch to wing tips where will rub the ground
• install leather patch guides for elevator control lines
• paint trim color
• install wing root kiss seal
• build a wing tip dolly
• build a wing wheel
• jury strut fairings
  
• main strut fairings (after flying to figure out the right angles)
• emergency parachute
  
• real variometer (LXNav with a TEK probe is my intention, if it is sensitive at low speed...)
• dogue chute

Mega-axle!

The torsion axles are not going anywhere ever again.  The frame is going to bend before this axle dies.

Welding steel is so much more enjoyable than aluminum.  It took about three hours to work my way around all the open edges, but it wasn't that bad.  The arc is more stable and it seems like this is the way welding should be.  I must be doing something wrong with the aluminum setup.

The axle assembly is bolted back to the frame now.

I thought about going for a short drive around the neighborhood, but I've done this before.  One of the aluminum truss members has broken tack welds from yesterday's crash.  Without the ~200b of plywood being bolted back on, the trailer will ride light and bounce around.  I'll save the drive for another day.

Next up is liquid wet stuff.  Enamel paint for the axle.  Epoxy-coat for the plywood decking.  It'll be a few days in the garage, so I might not get to this for a while.

There are some repairs to do from the broken axle event last night.  The left trailer light rode on the asphalt and destroyed the wires and scraped away some plastic.  Ironically, I have a spare left light assembly if this one not repairable.  Some of the metal frame also scraped away and needs inspection.  It never ends.

Trailer to do's are now:

• weld axle assembly
• drill holes in axle assembly
• mount axle assembly
• paint axle assembly with some enamel paint
• repair left tail-light wiring
  
• figure out how Goat parts sit in the trailer
  
• take all of Goat for its first trip around the neighborhood
• buy more Argon gas
  
• finish weld the vertical elements
• add reflective tape on the sides
• install and wire running lights on the sides
• epoxy-coat seal the ply decking
  
• create a rear door that can be quick-pinned in place
• figure out front/side/back walls
  
• dream up a top lid

For the first-flight:

• backyard final assembly and thorough pre-flight check, including weight & balance
• re-weld the tow hitch release (I'm now doubtful it had good penetration) 
  
• buy tow rope, weak-links, and end rings
  
• buy/borrow radios (1x airborne, 1x car)
  
• find a place to fly
• travel
• fly

After the first-flight:

• add leather patch to wing tips where will rub the ground
• install leather patch guides for elevator control lines
• paint trim color
• install wing root kiss seal
• build a wing tip dolly
• build a wing wheel
• jury strut fairings
  
• main strut fairings (after flying to figure out the right angles)
• emergency parachute
  
• real variometer (LXNav with a TEK probe is my intention, if it is sensitive at low speed...)
• dogue chute