Test fitting wings in the trailer

I needed a weekend away from work.  It was chilly and windy outside, but the clouds gave way to sunny skies.  Perfect weather for tackling some trailer tasks, toward a maiden flight this summer.

First up was bolting the third epoxied plywood to the frame.  This task was more painful than it should have been.  I had to remove the middle 4x4ft section and plane it down to allow the aft 4x8ft piece to bolt down.  I also had to chase several bolt holes with larger drill bits to get everything to bolt together.  I suspect the trailer changed shape slightly when welding in the second row of floor c-channel floorboards.  This would be a different project if the design was known from the beginning...

After working floors, I turned attention to the wing support mounts.  These could be made many different ways, but I had some leftover 1x1x1/16in square tube, so designed a small support (these are knee-knockers, so small is good).

After cutting six of these supports and clamping them in place, it was time for a test fit of the wings.  I've split the trailer height approximately in half, but needed to see that the wings would fit acceptably before welding anything in place.  With the struts still on and the ailerons not folding cleanly against the wing upper surface, it is a tight fit.

The struts, aileron linkage, and cabane all fold very nicely against the bottom of the wing.  However, the wing does not rest on them very well when laid flat.  The trailer-ride is going to be very bouncy and transfer a lot of loads into the wing structure, so they need to be well-supported.  For the next fit-check, I'll remove everything from the bottom of the wing and see if that is better supported.

After removing the wings, I tack-welded the supports in place (no more Argon again).  Joining these 1/8in and 1/16in pieces was fairly straightforward, and these welds look reasonable.  Perhaps my machine setup is just not powerful enough for welding 1/4in thick material of the frame.

Another random chore was to move the axle closer to the trailer center of gravity, since the addition of plywood floors changed the weight distribution dramatically.  Tongue weight was close to 100lbs.  With a helper, I unbolted the axle structure, slid it forward to a new pivot point, and drilled new mounting holes.  Tongue weight is probably 30-40lb now, which is reasonably close to 5-10% of the approximate 450lb trailer weight.

While drilling new holes for the axles, I did have access and opportunity to re-index the axles to a shallower angle, but did not take this opportunity.  I'd like to see how the trailer rides at its new heavier weight.  In the picture below, it's just one bolt to remove.

Trailer to do's are now:

• move the axle forward to re-balance
• index the axles to 12deg at 1G (skipping for now)
• figure out how Goat parts sit in the trailer
  
• weld in the wing support tabs
• drill for the wing support hitch-pins
• take another drive around the neighborhood
  
• finish weld the upper rail to the vertical supports
• take Goat for its first trip around the neighborhood
• create a rear door that can be quick-pinned in place
• UV paint on the ply decking 
  

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

Last of the messy epoxy (part 3)

After buying more epoxy from West Marine (boy, a gallon has gotten expensive), I finished the last 4x8ft plywood deck second side epoxy coating.  Temperatures did cool down today, so the heat gun came in handy again.

It is premature, but I bolted the first two deck plywood pieces to the trailer.  The UV protection paint is at least a week away.  I'm ready to have this project done.  It looks good though.  The plywood is heavy too, so plopping 200lb of weight on the axles will be interesting.  I did not adjust the axle angles today.

I did clamp in all three wing supports.  They're going to work.  It'll be interesting to see how the wing panels both sit in there.

Here is a close-up of the intersection joint.  It'll take cutting at some weird angles to make this work and look reasonable.  Welding a short cutoff 1" square tube to the vertical is my plan, so the same hitch pins work here also.  These will be awful shin knockers.

The list is slowly getting shorter.

Floor:

• 4x4 epoxy bottom
• 4x4 epoxy top
• 4x8 epoxy #1 bottom
• 4x8 epoxy #1 top
• 4x8 epoxy #2 bottom
• 4x8 epoxy #2 top
• 4x4 bolted
• 4x8 bolted #1
• 4x8 bolted #2

 Trailer to do's are now:

• seal the ply decking (see above)
• UV paint on the ply decking
  
• index the axles to 12deg at 1G
• take another drive around the neighborhood
  
• finish weld the upper rail to the vertical supports
• 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

 

Smell of epoxy fumes (part 2)

It was a nice early spring Saturday, with highs in the mid 60's, sunny, and very windy (Sunday is a high of 40F).  

I did two rounds of epoxying today, completing three of the remaining four faces. Even with the relatively warmer temperatures, using the heat gun to lower the viscosity of the mixed resin was critical to thin it out enough to spread with a chip-brush.  This process would not have worked without the heat gun.  Here are three visible plywood faces all curing (just one face to go!).  That fresh new quart of West Systems resin and pint of hardener is now empty, if anyone is keeping count.

We'll see if I can make a West Marine run tomorrow morning and clear off the sixth and last face needing sealing.  I need to use a q-tip to seal inside the drilled holes before bolting the panels to the trailer frame.  The frame also needs to be inspected again to see if any more welds broke on the last drive.

I designed and 3D printed a small helper part to get the foam noodle onto the cross-beam.  This is the start of the mounting system for the second wing in the trailer bed.  The foam noodle (aka pipe insulation) is a tight fit over a 1" x 1" aluminum square tube.  I'll need to wrap something (cloth tape?) around the ends of the foam to keep the split from opening up, but the foam is firm and will support the wing nicely. 

 

 

This view shows two of the three planned supports.  I can easily make it five supports if that many are needed.  The final number will likely depend more on how the wing panel is strapped down.  Yes, the ends on the right will be trimmed to length once the mounting system is designed.  I'm hoping to use more hitch pins for quick installation and removal.

I did have a thought about the rough ride last weekend while doing some research.  According to the Flexiride technical library, the adjustable axle should be set to ~12deg down at 1G (sitting with the static load).  Since I do not have the whole 925lb of the rated load on the axles, they do not deflect at all.  It will be a good test to index the axles so they sit at ~12deg from horizontal and then do the neighborhood drive again.  The new geometry will be more compliant to bumps since the lever arm is longer.  The dead load is still too light for the torsional spring constant, so the ride will be bouncy, put perhaps less violent than last weekend's drive.  We'll find out.

Floor:

• 4x4 epoxy bottom
• 4x4 epoxy top
• 4x8 epoxy #1 bottom
• 4x8 epoxy #1 top
• 4x8 epoxy #2 bottom
• 4x8 epoxy #2 top
• 4x4 UV paint 
• 4x8 UV paint #1
• 4x8 UV paint #2
• 4x4 bolted
• 4x8 bolted #1
• 4x8 bolted #2

 Trailer to do's are now:

• seal the ply decking (see above)
• index the axles to 12deg at 1G
• take another drive around the neighborhood
  
• finish weld the upper rail to the vertical supports
• 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