Converting a trike gear RCM Funster to a trail dragger

Started by Frank v B, November 24, 2018, 09:55:05 PM

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Frank v B

Got an assignment to convert this to a tail dragger.  The customer supplied a landing gear from another plane.

Approach:  I do not believe in small LG plates.  They have to span at least two (full) formers.  The landing gear plate recovered from the old landing gear would never last.
This is a large plane (72" span) for a 45-60 engine.  This plane is a great flyer, is a low winger , has flaps and a lifting tail.  It has a nose-down approach on landing because the lifting stabilizer raises the tail.

Frank
"Never trade luck for skill"

Frank v B

Step 1- cut the bottom of the fuse off.  This cuts through the triangle stock.  It leaves some in the fuselage and some on the hatch.
Step 2- cut a piece of plywood to the rough dimensions so it stretches from the firewall back to the former at the leading edge of the wing.  Note the slots cut at the edge so it will tuck in below the balsa lip I left on the back end for strength.
Step 3- fit the ply plate into the area.  It fits snugly front to back.  I cut it wide of the fuselage so it can be trimmed properly and follow the fuse contours.

Note: used 1/4" plywood for the landing gear mount.

Frank
"Never trade luck for skill"

Frank v B

#2
Next problem:

The front end is so light that the remaining tri stock at the corners broke just test fitting a piece of wood. See photo of flimsy front end.  It's only 3/32 balsa.   Time to double down. >:(

1) Put in a balsa spreader bar to keep the sides together and add more gluing beef.
2) doubled the plywood where the landing gear attaches.

Just added the photo of the old small landing gear plate and the new one.  My money is on the new one.  The blind nuts (T nuts) were re-used in the new plate.


Frank
"Never trade luck for skill"

Frank v B

- Glued the plywood plate in place
- attached the landing gear
- shortened the bottom "hatch" so it starts at the front end of the landing gear and cut off the tri-stock to allow for the thickness of the plywood plate
- added carbon tow (black strips) across two sections to act as fastener and strengthener.  Put waxed paper on top and will let it cure overnight.

Next steps- add fibreglass over the joints between the fuse sides and plywood plate (over top of carbon tow)

Frank
"Never trade luck for skill"

Frank v B

This may look similar to the last picture with the carbon strips.  This photo was taken after fibreglass was added around the corner between the landing gear plate and the fuse side.  Two strips about 2" wide were added so 1" was on the fuse and 1" was on the plate.

The two corners were covered in waxed paper.  You can see the weave of the cloth under the waxed paper.  Let dry overnight.

Two steps to go
- add the old balsa bottom plate
- cover the repaired area.


Frank

"Never trade luck for skill"

bweaver

Re:
"Two steps to go
- add the old balsa bottom plate
- cover the repaired area."


Shouldn't that be "three steps to go"?  Wouldn't a tail wheel or tail skid be the topping on the cake?  Or, is it literally going to be a 'tail dragger'.  Oh, but then, where's the tail? I haven't seen it yet.   :-\

Frank v B

Bruce,

Maybe some main wheels too?  Picky, picky. :D
After the two steps the "building" is over.  Then the "final assembly" begins.
Many small victories.

Frank
"Never trade luck for skill"

Frank v B

#7
Now to keep Bruce happy- adding the tail wheel.

Simple- screw in the tail wheel assembly and finished... right!.... not.  The base was balsa- 3/32 at that, with tri-stock under it.  It had about the structural strength of cold butter.

- Cut out the balsa bottom
- made a 3/32 plywood insert and epoxied it in place.
- added carbon strips to act as straps
- added waxed paper on top to make it smooth.
- Let dry overnight.

I will then add fibreglass cloth to strengthen the rear end.

Frank
"Never trade luck for skill"

Frank v B

Ta-da!

tail covered and tail wheel done.
"Never trade luck for skill"

piker

Very nice!  Is the conversion done now?  Do we get to see an overall shot before you return it to the customer?

Robert

Frank v B

Just have to add axles to the main landing gear.  The customer phoned last Friday and wants me to install an E-Flite 60.  Have to pick it up and install it.

I do not have the wings because all the work was done on the fuselage alone.  Will take a full fuse photo.

Frank
"Never trade luck for skill"

Frank v B

Done and delivered to John's Hobbies on Saturday, Dec 15.

Phew.

Frank
"Never trade luck for skill"

piker


Frank v B

no beauty shot.  I did not have the wing.  Sorry!

Frank
"Never trade luck for skill"