ViperDog Build Thread
 

The UPS man was good to me today! [8D]

He brought a ViperDog kit to replace my Mad Dog. It met it's end at the CAPS race.


The kit comes with a fiberglass fuselage, foam wing cores, and aluminum landing gear.

If you want a ViperDog just order a Mad Dog kit and add comments in the notes to send a ViperDog instead.

RE: ViperDog Build Thread
 

The nice thing about the ViperDog is that the fuselage fits the Viper (Great Planes) wing and tail.

I prefer to build my own so that will be done here in the thread.

RE: ViperDog Build Thread
 

Kevin (Matney's Models) molds a lightweight fuselage that is also very strong.

The nose and other areas are reinforced with carbon fiber and Kevlar.

It weighs a scant 7.4 ounces.

RE: ViperDog Build Thread
 

Kevin has listened to modelers and made a couple improvements to the original Mad Dog fuselage.

1) The tail is widened to allow internal control horns.

2) The nose fits the square back-plate mounts.

3) The landing gear block is reinforced with both carbon fiber and Kevlar.


This model should fill the bill for someone that broke an original Viper fuselage or for someone that wants to build a new model.

RE: ViperDog Build Thread
 

Hey where is the rest of the build???? You wet our appetite and then leave us hanging???





Just kidding Scott, I always enjoy your build threads!!!

RE: ViperDog Build Thread
 

Hey Scott where did you go????

RE: ViperDog Build Thread
 

Hopefully I will begin construction this weekend. I've been working extra hours and haven't felt like building when I got home.

RE: ViperDog Build Thread
 

yeah, that working for a living sucks..

RE: ViperDog Build Thread
 

I used three pieces of 4" x 1/16" x 48" balsa to make each wing skin.

Just trim parts to fit and tape.

Each skin was later trimmed to about 10 1/2" wide. This leaves a little overhang on both sides of the wing shucks.

Both skins were joined with a piece of masking tape. You leave about 1/8" of gap between the skins to allow for folding.

RE: ViperDog Build Thread
 

Cut a 6" x 48" piece of 2 ounce fiberglass cloth.

Tear off a 3/4" x 48" section of carbon fiber.

Lightly spray a small amount of 3M 77 adhesive to the sheeting.

Tack on the 2 ounce cloth at the wing fold (like a book).

Tack on the carbon fiber on the bottom sheeting.

RE: ViperDog Build Thread
 

Spray some 3M 77 to the shucks and then attach waxed paper.

RE: ViperDog Build Thread
 

Use a razor saw to cut a slot for the carbon fiber vertical spar.

It is a piece of 1/2" x 36" x 0.021" carbon fiber.

Mix a small amount of wing skin epoxy and dab it in place using a disposable brush.

Push the carbon fiber spar in place and dab a little more epoxy as needed.

RE: ViperDog Build Thread
 

Some 3/4 ounce fiberglass cloth is laid on the sheeting prior to applying the finishing epoxy.

Mix about 1 ounce of finishing epoxy for each side. About a cap full of 91% alcohol is added to each cup to thin out the epoxy.

The contents are immediately drizzled on the wing panels and then squeegeed out until the epoxy covers.

RE: ViperDog Build Thread
 

The sheeting and wing cores are placed between the shucks.

Adjust parts to fit and then temporarily pin the parts together.

Tape the parts together, insuring parts are straight, and then remove the pins.

I used vacuum bags made from 4 mil thick pieces of plastic tarp. Commercial vacuum bags also work fine.

The edges were sealed with inexpensive latex caulking.

A picture of my Vacuum Pump is also shown. It was made from a refrigerator compressor, a few pieces of PVC, and uses a vacuum switch to shut off. It turns off at about 6" of vacuum.

RE: ViperDog Build Thread
 

The core was removed from the vacuum bag.

Check to insure that the wing core remained true in the shucks. Adjust if needed.

Trim the leading and trailing edges flush with the shucks.

Use a sanding block to true up the edges.

RE: ViperDog Build Thread
 

There were a few dings on one piece of sheeting.

These were fixed by applying a small amount of water to the dings.
A dings absorbs the water and return to the original shape.

RE: ViperDog Build Thread
 

A piece of 1/4" x 3/8" x 48" balsa stick was glued on with epoxy.

Masking tape holds parts in place until the glue dries.

RE: ViperDog Build Thread
 

Draw a reference line down the center of the balsa leading edge.

I used a knife, razor plane, and sand paper to shape the leading edge.

RE: ViperDog Build Thread
 

The trailing edge was shaped with a sanding block.

The wing sheeting was later sanded until it was smooth.

RE: ViperDog Build Thread
 

The wing was sheeted with medium weight wood and came out at 11.1 ounces.

Using light or contest wood will drop the weight a couple ounces.

RE: ViperDog Build Thread
 

Thanks are Looking great!!! Keep up the Good Work!!!!

RE: ViperDog Build Thread
 

I spent a few minutes sanding the seam smooth using a sanding block.

A 3/4" hole is drilled in the front of the fuselage to provide access to the back of the firewall (for blind nut installation).

RE: ViperDog Build Thread
 

The location of the wing mounting bolt holes were identified for the fuselage and wing.

RE: ViperDog Build Thread
 

A 3/4" hole saw was used to drill the holes.

RE: ViperDog Build Thread
 

Pieces of electrical tape seal up holes prior to gluing.

Some 30 minute epoxy was used to glue the dowels in place.

RE: ViperDog Build Thread
 

Contest grade lightweight wood is used for the wing tips.

I've pinned the tips in place and am tracing the outline for later trimming with a scroll saw.

RE: ViperDog Build Thread
 

Looking good Scott!

RE: ViperDog Build Thread
 

The wing tips were roughed out using a scroll saw.

They were attached with 5-minute epoxy.

RE: ViperDog Build Thread
 

Slots were made for inserting 1/64" plywood.

The plywood is glued in place using thin CA.

RE: ViperDog Build Thread
 

The tips were roughed out with a sharp knife and a sanding block.

RE: ViperDog Build Thread
 

A piece of peal ply (nylon fabric) is cut to cover the wing.

RE: ViperDog Build Thread
 

Ailerons are marked off on the top sheeting.

A piece of satin is used for the hinge.

Apply a thin layer of Skin It with a squeegee and then apply the fabric.

RE: ViperDog Build Thread
 

A layer of 3/4 ounce fiberglass cloth is laid on first.

The center sections are reinforced with additional layers of 2 ounce cloth.

There are three layers on the bottom - 9" wide, 6" wide, and 3" wide.

The top has a 6" wide piece and a 3" wide piece.

I prefer to apply the wider pieces first. Later apply the more narrow pieces.

RE: ViperDog Build Thread
 

Mix two portions of Skin It epoxy. Each should be about 1.25 ounces.

Immediately pore the epoxy on a side and squeegee it out. Do the other the same way.

After the epoxy is smooth, slide the wing in the peal ply.

This is later placed in a homemade vacuum bag made from 4 mil plastic and sealed with latex caulking.

A piece of rope is on the far side of the wing.

Close the bag and turn on the pump. Mine shuts off about 6" of vacuum.

Allow to dry overnight.

RE: ViperDog Build Thread
 

After removing the wing from the bag you must trim the trailing edge.

RE: ViperDog Build Thread
 

Lightly sand with 220 grit paper on a sanding block.

RE: ViperDog Build Thread
 

The fabric used as the hinge adds a small amount of thickness.

I used some Spackle to level the area.

After dry you can sand as needed.

RE: ViperDog Build Thread
 

I marked out the ailerons on the bottom of the wing.

I cut about a 3/32" slot for the bottom gap.

RE: ViperDog Build Thread
 

Use a heavy duty set of aileron torque rods for this model.

Bend as needed to fit.

Sand the surface of the nylon tube to provide a surface for gluing.

Apply a drop of oil inside the tubes prior to gluing.

RE: ViperDog Build Thread
 

I mixed some Skin It and micro balloons for the adhesive.

Let this dry and later sand flush with the surface of the wing.