Repairing a foam 2.1m .60 size Cessna 150- lost an argument with power lines.

[Frank v B]

Am repairing a (huge) foam E-Flite Cessna 150 for a club member.

The damage summary
- one half of the elevators were ripped off the hinges
- a tear in the center section of the wing.  The foam pulled off the buried carbon rods
- the flap was ripped off the hinges (port wing)
- leading edge of the port wing was severely damaged.  It pulled open and off the buried carbon rods.
- the nose gear was lost.  Have to fashion a new one from a ski...unless someone finds it in the beans.

Will take it in sections.

Frank

[Frank v B]

Hinge  repair:

I use a special hinge glue.  It behaves like a runny yellow carpenter's glue.  It stays flexible, does not affect foam and is strong.

Used it on the elevator and flap.  Am doing one side at a time and letting it harden.

[Frank v B]

Center section repair. 
Used 3 mixes of 5 minute epoxy and toothpicks to glue everything together.

F.

[Frank v B]

Outer wing leading edge.  Badly damaged.

Used 3 mixes of 5 minute epoxy and toothpicks.

F.

[GuyOReilly]

There is a porcupine that will fall in love with one of your repair job one day...

[Frank v B]

Guy, re: "There is a porcupine that will fall in love with one of your repair job one day..."

The wing with the toothpicks may even make it as a centrefold in PlayQuil magazine for Porcupines.

F.

[Frank v B]

Hah! 

F.

[Frank v B]

- glued the elevator hinges in place
- glued the flap hinges in place
- glued in the missing leading edge
- glued in a section of the top.  Note: lesson from the foam P-51 repair- I glassed the inside of the piece to add strength.  The 5 minute epoxy has yellowed.  The wax paper on top is visible in the photo.

F.

[Frank v B]

Filling the holes in the foam wing.

Decisions
- plug the missing foam with random foam, then sand, then filler to fill the dips before glassing.
- want to cover the repaired area in fibreglass
- paint the repaired white to match the rest of the wing.

How to fill holes in a foam surface:
step 1- pick out some expanded foam.  I got it from a box that used to contain a glass light fixture.
step 2- Cut the patch larger than the hole. Photo 41
step 3- hold the patch on the wing so it covers the hole.  Use an X-Acto knife (#11 blade, the pointy one) to scribe the perimeter of the patch. 
step 4- Cut the wing hole as marked to it matches the shape of the patch. Photo 44
step 5- Glue the patch in place with 5 minute epoxy.  Just let it stick above the wing's surface. Photo 45.
step 6- when the glue is dry- sand it flat.

[Frank v B]

Patch sanded, one coat of filler (spackling), and sanded again.
Looks good!

F.

[Frank v B]

Repairing a large section on the top of the wing.

The first test patch worked well.  Now trying a larger patch.

Photo 1 (77)- rough cut a foam patch a little bit larger than the area to be repaired.
Photo 2 (78)- lay the patch over the hole and cut around it with an X-Acto knife.  test fit it.
Photo 3 (79)- The patch pinned in place while the glue dries.

F.

[Frank v B]

Repairing the hole in the bottom of the wing.
The repair of the top of the wing worked well.  same process.

Photo 80- cut a patch a bit larger than the damaged area.
Photo 82- use the patch to cut damaged wing.
Photo 83- patch glued in place.  Pins hold it in place until the glue dries.  The cuts/gaps will be filled.

F.

[Frank v B]

wing: - filler applied to the foam patches on the top (photo 93) and bottom of the wing (photo 94).  When dry tomorrow, I will sand it and apply more filler.  Probably needs 3-4 coats.

main landing gear -glue the landing gear plate in place again.  Photo 95
                                    - glue the cracked wheel pant together. Photo 96. When dry, will add a strip of fibreglass on the inside of the cracks.

rear fuse- the fuse opened up from the nose gear to the tail.  Glued the seam back together. Photo 97
note: glued the back part together first because it fit perfectly (top of photo).  Once dry, I will glue the front part (below the vent hole) because this part of the fuse needs to be tweeked.  It is bent.

F.

[Frank v B]

Back to work:

Problem,
- the gear Mandeep found was badly damaged. The wheel pants were fine. Photo 81  shows the two holes in the middle that had the screws break through them.  82 shows the damage to the old housing.
- I had committed to a new approach and solidly glued the new anchors in place the day before he found it.
- the rudder servo was mush.  Gears stripped.  The power wires ripped the nose gear and pushrod out of the plane.

Compromise approach:
- used the LG leg and wheel pants from the damaged landing gear.
- kept the nose wheel anchor assembly as glued in place.
- it requires a tiller arm just below the fuse.    Invoking the 50:50 rule*.  See photo 84.
- replaced the rudder servo.  Am considering a new separate servo for the nose wheel and connecting it via a Y harness.  Safer.

F.

* if you cannot see it at 50 feet and 50 mph don't waste your time on it.

[Frank v B]

More stuff:
1) Rudder servo was toast.  Gears were stripped. - removed it and will buy a new one tomorrow.
2) Added the nose wheel steering servo next to the rudder servo because it will use an external tiller (red tube visible in photos).  Glued it on hardwood beams in the middle of the fuse.
3) Close the wound- This foam was missing.  Used 5 pieces of foam to close it.  Will sand it flush after the glue has hardened.  Will then patch it with fibreglass.

Frank