Multiplex DG 300 Quarter scale glider- assembly and conversion to electric.

[Frank v B]

This is big.  Over 12' wingspan (3.75 meters).... a respectful 2" less span than Ben's power glider.  He owns the category!

- length: Fibreglass fuselage is 5'10" long!
- span: Wings are 145" span- pre-built but not covered.
- weight is 9.5 to 10.0 pounds

Challenges - no instructions!  Will search the internet.
          - the nose comes to a point and so does the cockpit cover.  Will have to McGyver it once the motor is in place.
          - the clear canopy is missing.  Will have to fake it like the Flamingo.  Can always call Guy and ask him how to fake a glider cockpit. 

Motor- based on the weight, calculations show a Power 32 on 5 cells should get it off the ground.  Just happen to have one.

Wish me luck.  Gonna need it.

Frank

ps: "what possessed me?"

[GuyOReilly]

That is a massive glider.
I may have an old plexiglass canopy (or Mylar or some such) that may fit with some creative cutting and forming.

[Frank v B]

Locating the motor and firewall.

Picked a folding prop/spinner combo from my collection.  Picked the one in the bag at the top.  A 12x8. Photo 58

1) - cut off a piece of the point so I could figure out the shape of the nose relative to the spinner diameter
2) - held the spinner up to the fuselage and cut it where the diameters were equal.  Cut number 2. The two cut-off pieces in photo 60
3) - assembled the motor/spinner and marked the fuse where the firewall should be.  Cut slots in the fuse flange. Photo 61
4) - shaped a scrap piece of 3/32 balsa to get the shape of the interior of the fuse and transferred it to plywood.  Dremel-sanded it until it fit.  Note, the top part of the firewall has not been shaped yet. Photo 64
5) - dropped the cockpit on top to start to figure out my options. Photo 65

Stay tuned.

Frank

[Frank v B]

OOPS!

Problem: The white spinner no longer works.  Installed the firewall.  When I tried to install the motor, the X-mount would stick out everywhere.  It would only fit one way and it put the motor lower in the fuselage.  When I installed the spinner it stuck out below the fuse.  No good. See photo 81

Solution: use a smaller spinner and glue one of the cut pieces back onto the nose to lengthen it and taper it towards the spinner.  Clamped and added some fibreglass cloth over the joint on the inside. Photo 79.

The new spinner fits a lot better.  Still have to do some trimming. Photo 80

Note: there is a fair amount of down thrust that increased the spinner problem.  In my experience a glider gets incredible lift when it speeds up with a motor.  On the Electro UHU power glider (72" span) I put the motor at 0/0 thrust angle.  When powering up to get to altitude I would have to give a lot of "down" elevator or the plane would loop on neutral elevator.


Frank

[Frank v B]

Faking the nose cone and canopy.

Nose cone
- built from the firewall forward.  Made out of pieces of balsa stacked inside and out to follow the contours of the canopy and hug the motor.  The pieces were glued together, then sanded to shape.
- attached by two pins on the sides and two magnets on top of the firewall.
- once roughed to contour I painted it white just to see what it would look like.

[Frank v B]

Canopy.
The clear bubble canopy was missing in the kit.  Decided to pull a Guy and make the front half solid so it is easier to find clear plastic to make it fit.  The original canopy was 21" long.  Would need a Magnum of Soda water to get a bottle big enough.

- making the front of the canopy solid.  From the instrument panel forward has been covered with balsa.  It will be sanded to shape and then covered in sheet balsa and Monokote.

Note: the pieces are never cut to shape.  It is easier to trim with sandpaper when all the pieces are in place.  It also allows some mid-course corrections.

Frank

[Frank v B]

Cockpit structure a la Guy

- sanded the forward cockpit structure.  Looks like the Bloom & Voss 141 cockpit.  See photo.  Aunt Heidi's solarium used as a cockpit.
- decided to cover the sides with 1/16" balsa and leave the top open. Then cover the whole thing with white Monokote to mimic the scale one.  So tempted to use black as contrast but stopped myself.

Photos show the sanded structure and the 1/16" sides in place.

Note: the last photo shows what happens to balsa in 5 minutes when just wetting one side (outside of the desired curve).  Did 2 passes under the hot water tap and then mixed the epoxy, got the pins and clamps ready.

Next step- cover with white Monokote.

Frank

[Frank v B]

Done!! Good enough for the 50/50 rule.

Cockpit done.  Now have to fish around for a clear canopy.  The clear canopy has to be 10" long by 6" wide.  A lot easier to find than the original 21" long by 6" wide.

F.

[Frank v B]

Houston, we have a problem!

The canopy has to be 10" long and 6" wide.  Decided to build it out a plastic from a soda bottle because the neck area has a curve. 
Bought two clear 2 litre plastic bottles to build a canopy.  One to try, mess up and one to build the proper one.
The Compliments House brand uses the most useful bottle.  The label ridge is on the bottom.  Photo 46

By the time I cut off the spout and the bottom below the label ridge it was too small. Photo 49

Decided to connect two bottles so needed a way to join them.  Decided to build a bow out of thin wood strips at the joint so they are easy to curve round the balsa form.  Will use about 5-6 strips and laminate them with epoxy so the plastic can be joined with screws.  Glue makes such a mess. Photos 72,73,74,75.

Frank

ps: installed the rudder and elevator servos.  No Andy, I did not write the job descriptions beside the servos. I know how to spell.  Photo 76

[Frank v B]

Making the bow to join the two sections from the plastic bottles.

- Mixed 15 minute epoxy and thinned it with about 30% rubbing alcohol.
- Took 5 strips and coated all 5 both sides
- clamped them to one edge of the frame template and clamped them around the frame.
- letting it cure overnight.

When dry, I will cut the balsa away and Dremel it smooth until all the balsa is gone.

Frank

[Frank v B]

Added the bow to the canopy so it could cure in the correct position.  When cured I will sand it and paint it white to make it disappear.

F.

[GuyOReilly]

Nice lamination work @Frank v B .
Personally, I like the dark wood colour.
Guy

[Frank v B]

Added the rudder.

The rudder had to be installed but only when the elevator linkage was properly installed.  It comes out of the top of the fin ahead of the rudder.  The rubber band on top of the fin holds the elevator linkage in place so I don't accidentally glue it permanently shut.  This plane has a "T" tail.  Also, the rudder had to be covered in white Monokote before installation.

The whole rudder assembly had to be installed into the back of the fin which is part of the moulded fuselage.

The green tape is to squeeze the fin together to trap the plywood rudder stock inside while the glue cures.

The fuse is now essentially finished. This fuse is BIG.  From the tip of the spinner to the tip of the rudder is
5 1/2 feet!.  Bigger than the wingspan on 90% of my planes.

Will build the DG 300 wings once the Polestar is flying.

Frank

[Frank v B]

Guy, re: liking the wood colour.
 
Will see what it looks like tomorrow when the glue has cured. 
Your wish may come true. (less work!)

Frank

[Frank v B]

That Worked!!

Used the two clear soda bottles to make up the canopy.  The joint is in the middle of the mahogany bow.

Note the curve at the top (left) of the canopy.  It is shaped by the neck of the bottle.


love it!

frank

ps: still have to paint the wood at the edge of the canopy and properly trim the canopy edges.  Just glad it worked.