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Old Oct 13, 2007, 02:03 PM
Engineer for Christ
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Amherst, VA
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Mini-HowTo
Build the Demon pylon racer

The Demon Pylon racer is a very high performance plane. It flies well on a 3S lipo with motors ranging from a 360 class (55 watts) up to a 450 class (280 Watts). For brushless systems a good match is a 6-8" prop with a motor kv between 1500kv and 2400kv. A 1000kv motor works well with an 8x8 prop.

The kit can be assembled in about 2-4 hours plus the time it takes to install electronics.

First cut out all of your parts.

Note: when cutting the balsa, a good metal straight edge is useful to keep straighter lines when cutting.

-Alex
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Old Oct 13, 2007, 02:11 PM
Engineer for Christ
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Fuselage assembly

First assemble the fuselage. Gluing the fuselage can be done with gorilla glue/white glue mix (5:1 ratio) or Super 77 spray adhesive. I used spray adhesive.

For 77:

Spray 3 medium coats about 8" away from both surfaces. Wait about a minute or until the glue is tacky and mate the balsa with the foam. Repeat for the other side. Be sure the balsa lines up! If it isn't even and level, your wings and tail will be crooked.

For gorilla:

Mix the glue in a small cup. Place a very thin layer on the balsa wood and lay it on the foam with some weights (10 lbs works) Tape the balsa corners to keep it from shifting while the glue expands. Repeat for other side.

Plain white glue works too but isn't as strong. I'd guess epoxy would work as well.

Once the glue sets up. Trim off the excess foam with a knife or hot wire.

Edit: It can be beneficial to add a 1/8" piece of balsa to run along the bottom of the model as a floor in the event the foam gets thin when melting out chambers. This can be secured with regular CA or gorilla glue. My model doesn't have this, but it might make things easier for some modelers. It also will add some durability.
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Old Oct 13, 2007, 02:22 PM
Engineer for Christ
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Amherst, VA
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Assembling the tail

The tail can be mounted using epoxy, gorilla glue, or even regular CA. I used a combination of Gorilla on the foam, and the ran CA around the balsa edges.

The odd looking semi triangular piece is for the lower rudder support. It is unneeded if there will be no movable rudder. If using rudder, make a slit in the bottom of the plane and glue the part in with Gorilla or epoxy.

Edit: Some people have asked me what the two little rectangular pieces are for. Look closely at the tail picture and you'll see they are on either side supporting the tail.
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Old Oct 13, 2007, 02:30 PM
Engineer for Christ
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Amherst, VA
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Assembling the wing

The wing is 6.75" in the middle and 6.25" at the tips. Be sure to glue the wider parts and not the 6.25" sides or you will have a reversed taper. Again, epoxy or a 5:1 gorilla glue/white glue mix works well. I used a soldering iron to cut a channel for a carbon spar in the bottom of the wing. I would highly recommend doing this.

Once the wing is assembled, use sandpaper (220 grit or so) and smooth any rough edges or cut lines.

Cover the wing with monokote or Tyvek homewrap when done. To cover with homewrap, coat the wing and the homewrap with 3 coats super 77 spray adhesive. Let set for a minute or two so the glue gets tacky and then press on. I would do the bottom first and the cut a slit in the center of the remaining wrap, coat the wing and wrap and then place over the top of the wing.

Edit: For those who don't have covering or an iron (or are terrible at it like me) you can use white construction paper with spray adhesive, or even just packaging tape. The wing doesn't need to be covered, but it will add strength and durability if it is.
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Old Oct 13, 2007, 02:35 PM
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Mounting the wing

The kit has a small piece of balsa (1.5"x6") that goes over the rear of the wing to hold it down if making a removable wing. I then used a 2-1/2" Nylon bolt run through the wing and the fuselage and secured with a nut. I also put small rails on the wing to keep it from shifting.

If not making the wing removable, just glue it in.
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Old Oct 13, 2007, 02:37 PM
Engineer for Christ
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Amherst, VA
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control surface

Sand a 45 degree radius on the rudder, elevator and ailerons and secure them with tape. I, of course, used Tyvek tape.

The ailerons supplied are 1.5" by 8". They should be installed 1.5" away from the edge of the wing.

WARNING: if you don't like your plane extremely reactive you might consider cutting them down to 1.5"x6" or 1"x8" or even as small as 1"x6" is plenty for most pilots. The ailerons supplied will spin the plane 3 revolutions per second!
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Old Oct 13, 2007, 02:41 PM
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Installing electronics

To install the servos, I melted chambers in the foam wing and fuselage with a screwdriver I heated with a hobby torch. I them secured them in place with double sided tape and then over the top with Tyvek tape.

I used the heated screwdriver technique to melt the battery chamber as well. My battery chamber is directly in front of the wing and fits a 1000-1500 3S Lipo.

Center of gravity on this should be 1.75"-2" from the leading edge of the wing. Beginning flyers will want this to be a bit nose heavy and should make the COG at 1.5" from the leading edge.

I leave fitting the motor up to the modeler. A stick mount can be made by hollowing out the fuselage and installing a 3/8x3/8" basswood spar with Gorilla glue. I opted to drill out a small piece of aluminum and tape it to the fuselage.

Edit: For those people who may not have access to the necessary parts, I can make a motor mount for your motor. I also have specilized hot wire tools to melt out the chambers for most batteries and servos. I would recommend mounting the battery flat rather than on it's side or the foam might become too thin beneath the battery.

Additionally, if using a battery heavier than a 3S 1000 Lipo, you'll probably want to mount your elevator and rudder servos as far back in the plane as possible to get the COG in the correct place.
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Old Apr 13, 2008, 01:38 PM
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As a side note, this is the frist and only plane that has ever stripped one of my HXT900's in flight. It was a very windy day so that might have something to do with it, but I'm keeping my eye on the aileron servos (I might have to go with something beefier).

I have an AUW with a 1320 3S ThunderPower of 15oz. I did include an extra sheet of balsa under the battery compartment (for structural rigidity) and I should have put my elevator and rudder servos farther back. It did require some lead in the tail to get the CG right.
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