Mad Dog Thread
08-15-2009, 12:48 PM
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Mad Dog Thread
At my last contest in Wichita my "Dawg Gone It" met its maker. This thread covers the replacement model, Mad Dog, also a Matney Model short kit.
Keven makes these and they contain the following materials:
1) Cores
2) Plans
3) Landing gear
4) Fiberglass fuselage
When you order the kit also get some "Skin It" epoxy and glass cloth (2 and 3/4 ounce weights).
Some of the common construction materials are also shown.
Keven makes these and they contain the following materials:
1) Cores
2) Plans
3) Landing gear
4) Fiberglass fuselage
When you order the kit also get some "Skin It" epoxy and glass cloth (2 and 3/4 ounce weights).
Some of the common construction materials are also shown.
08-15-2009, 12:58 PM
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RE: Mad Dog Thread
There continues to be discussion about ways to sheet a wing. Here is how I am now (8/15/09) doing it.
Begin by joining the wing halves together to make one large section. Do the same for shucks.
The last time I bought wood it was 10" wide sheets of light balsa from National Balsa. It takes 2 sheets.
Join the sheets with masking tape (back side) leaving a 1/4" gap.
Spray some 3M 77 contact glue on the 3/4" wide pieces of carbon fiber and tack them in place.
Add a 5" wide piece of 2 ounce fiberglass cloth at the masking tape fold. Tack it in place.
Lay a piece of 3/4 ounce fiberglass cloth over everything.
Begin by joining the wing halves together to make one large section. Do the same for shucks.
The last time I bought wood it was 10" wide sheets of light balsa from National Balsa. It takes 2 sheets.
Join the sheets with masking tape (back side) leaving a 1/4" gap.
Spray some 3M 77 contact glue on the 3/4" wide pieces of carbon fiber and tack them in place.
Add a 5" wide piece of 2 ounce fiberglass cloth at the masking tape fold. Tack it in place.
Lay a piece of 3/4 ounce fiberglass cloth over everything.
08-15-2009, 01:06 PM
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RE: Mad Dog Thread
The vacuum bag is set up next. I used a piece of 4 mil tarp but commercial versions should also work fine.
The bag should be wide enough to cover the shucks and a little left over.
A piece of rope goes across the back of the shucks and some paper towels will be located on the top.
Latex caulking (the cheap stuff) will be used to seal the bag.
The bag should be wide enough to cover the shucks and a little left over.
A piece of rope goes across the back of the shucks and some paper towels will be located on the top.
Latex caulking (the cheap stuff) will be used to seal the bag.
08-15-2009, 01:10 PM
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RE: Mad Dog Thread
I mixed about 1 ounce of Skin It epoxy for each wing half (right or left side).
After mixing it is drizzled on the skin and spread out with a squeegee.
Mix some more for the other side and complete the same way.
After mixing it is drizzled on the skin and spread out with a squeegee.
Mix some more for the other side and complete the same way.
08-15-2009, 01:13 PM
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RE: Mad Dog Thread
The cores were then placed between the skins and placed in the shucks.
Try to line up the cores approximately the same as they were cut.
Pin the assembly together and tape as needed. Remove the pins.
Try to line up the cores approximately the same as they were cut.
Pin the assembly together and tape as needed. Remove the pins.
08-15-2009, 01:16 PM
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RE: Mad Dog Thread
Place the assembly on the tarp and apply some caulking around the outside edge.
Fold the tarp over the assembly and seal the edges.
Apply a small amount of weight on top and turn on the vacuum pump.
Check alignment and adjust as needed. Allow to dry until tomorrow.
Post 1-6 (3 hours)
Fold the tarp over the assembly and seal the edges.
Apply a small amount of weight on top and turn on the vacuum pump.
Check alignment and adjust as needed. Allow to dry until tomorrow.
Post 1-6 (3 hours)
08-15-2009, 09:55 PM
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RE: Mad Dog Thread
The temperature was hot and therefore it only took a few hours for the Skin-It to dry.
The parts were removed from the bag and the leading and trailing edge was trimmed with a razor saw.
Follow up with a sanding block.
The wing weighs about 10 ounces at this point.
Post 8 (1/2 hour)
The parts were removed from the bag and the leading and trailing edge was trimmed with a razor saw.
Follow up with a sanding block.
The wing weighs about 10 ounces at this point.
Post 8 (1/2 hour)
08-17-2009, 08:53 PM
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RE: Mad Dog Thread
I cut some wing tips out of contest balsa.
The 1/4" thick balsa stick was glued to the leading edge with epoxy. The tips were also glued on.
Masking tape works great to hold parts in place until dry.
Shaping will be done tomorrow.
Post 9 (1/2 hour)
The 1/4" thick balsa stick was glued to the leading edge with epoxy. The tips were also glued on.
Masking tape works great to hold parts in place until dry.
Shaping will be done tomorrow.
Post 9 (1/2 hour)
08-18-2009, 09:30 PM
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RE: Mad Dog Thread
Mark a line down the leading edge to give a frame of reference.
Rough out the leading edge with a sharp knife.
Follow with razor plane and sandpaper.
Rough out the leading edge with a sharp knife.
Follow with razor plane and sandpaper.
08-18-2009, 09:38 PM
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RE: Mad Dog Thread
Shape the trailing edge with a sanding block.
Bring the edge down to the 2 ounce fiberglass cloth.
The wing weighs about 12.8 ounces with the heavy duty aileron linkage.
Expect several more ounces for fiberglass cloth and covering.
Posts 10-12 (1.5 hours)
Bring the edge down to the 2 ounce fiberglass cloth.
The wing weighs about 12.8 ounces with the heavy duty aileron linkage.
Expect several more ounces for fiberglass cloth and covering.
Posts 10-12 (1.5 hours)
08-22-2009, 01:47 PM
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RE: Mad Dog Thread
I used some pieces of 3/4 diameter dowel to reinforce the wing bolt holes.
After identifying were the holes are located, use a hole saw to drill.
After identifying were the holes are located, use a hole saw to drill.
08-22-2009, 01:52 PM
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RE: Mad Dog Thread
This model will be equipped with gapless hinges.
These were cut from a piece of taffeta (tightly woven fabric) and were about 1 1/4" wide.
Spray some 3M 77 on the back side of the fabric and tack it in place on top of the hinge line.
These were cut from a piece of taffeta (tightly woven fabric) and were about 1 1/4" wide.
Spray some 3M 77 on the back side of the fabric and tack it in place on top of the hinge line.
08-22-2009, 01:56 PM
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RE: Mad Dog Thread
Three layers of 2 ounce fiberglass cloth were tacked in place using 3M 77. The widths were 9", 6", and 4".
Two 3" wide pieces of fiberglass cloth were applied to the top and bottom of the wing tips (also 3M 77).
Two 3" wide pieces of fiberglass cloth were applied to the top and bottom of the wing tips (also 3M 77).
08-22-2009, 02:00 PM
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RE: Mad Dog Thread
At this point you need to decide if the model will be covered with film or not.
If you plan to cover it with film then apply the Skin-It epoxy to the fiberglass and taffeta and put in the vacuum bag until dry.
A film covered model will be lighter, very near the 3 3/4 pound minimum weight.
My painted models weigh close to 4 pounds ready to fly.
If you plan to cover it with film then apply the Skin-It epoxy to the fiberglass and taffeta and put in the vacuum bag until dry.
A film covered model will be lighter, very near the 3 3/4 pound minimum weight.
My painted models weigh close to 4 pounds ready to fly.
08-22-2009, 02:06 PM
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RE: Mad Dog Thread
Apply some 3/4 ounce fiberglass cloth over the wing and prepare to spread on the Skin-It epoxy.
I mixed about 0.8 ounces of resin, 0.2 ounces of hardener, and about 0.1 ounces of 91% rubbing alcohol in a dixie cup.
This was spread on the top of the wing with a squeegee.
The wing was turned over and the same procedure was followed for the bottom.
I mixed about 0.8 ounces of resin, 0.2 ounces of hardener, and about 0.1 ounces of 91% rubbing alcohol in a dixie cup.
This was spread on the top of the wing with a squeegee.
The wing was turned over and the same procedure was followed for the bottom.
08-22-2009, 02:11 PM
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RE: Mad Dog Thread
The wing was then placed between layers of peel ply (tightly woven polyester fabric) and placed in the vacuum bag.
A piece of rope is located at the edge and a layer of paper towel is on top.
The edges of the bag are sealed with latex caulking.
Fold the edge of the vacuum bag (4 mill plastic tarp) over and smash the latex caulking together for a seal.
Turn on the vacuum pump to remove the air.
Before completely flat insure there are minimal wrinkles on the vacuum bag.
Allow the wing to dry until tomorrow.
Post 13-19 (5 hours)
A piece of rope is located at the edge and a layer of paper towel is on top.
The edges of the bag are sealed with latex caulking.
Fold the edge of the vacuum bag (4 mill plastic tarp) over and smash the latex caulking together for a seal.
Turn on the vacuum pump to remove the air.
Before completely flat insure there are minimal wrinkles on the vacuum bag.
Allow the wing to dry until tomorrow.
Post 13-19 (5 hours)
08-27-2009, 09:10 PM
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RE: Mad Dog Thread
Use a Dremel tool and cut off disk to cut a wide slot at the hinge line.
Grind an area on the aileron for the aileron horn wire.
Use a razor saw to cut the aileron ends.
Use the razor saw to go down to the taffeta hinge but don't go through.
Fold the aileron over and widen the slot about 3/32" with a sanding block.
Use the Dremel and drill bit to make a 1/4" deep slot behind the aileron. This provides room for the aileron rod.
Grind an area on the aileron for the aileron horn wire.
Use a razor saw to cut the aileron ends.
Use the razor saw to go down to the taffeta hinge but don't go through.
Fold the aileron over and widen the slot about 3/32" with a sanding block.
Use the Dremel and drill bit to make a 1/4" deep slot behind the aileron. This provides room for the aileron rod.
08-27-2009, 09:16 PM
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RE: Mad Dog Thread
Apply a couple drops of oil on the edges of the nylon tube.
Slide the aileron rods in place.
Make some balsa dams to hold in the glue while it is drying.
Mix about 1/4 ounce of Skin-It and micro-balloons to make a thick mix.
Dab it in place and insure parts are in there proper spot and let dry.
Posts 20-24 (1.5 hours)
Slide the aileron rods in place.
Make some balsa dams to hold in the glue while it is drying.
Mix about 1/4 ounce of Skin-It and micro-balloons to make a thick mix.
Dab it in place and insure parts are in there proper spot and let dry.
Posts 20-24 (1.5 hours)
08-28-2009, 07:25 PM
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RE: Mad Dog Thread
After the Skin-It dries it sands very easily.
I used a Dremel tool to level off the surface and a sanding block was used to smooth it up.
Post 25 (15 minutes)
I used a Dremel tool to level off the surface and a sanding block was used to smooth it up.
Post 25 (15 minutes)