Tonight's Topic Archive
ElCheapo Combat Foamy build - Presented by Mike Reinhart
I first saw this
Combat Foamy plane flying at the Dome All-Night Funfly and had to build one!
It uses 6mm Depron foam, and despite it's strange boxy shape, makes an excellent
"dome" plane that flies extremely well.
If you would like a precut foam parts kit, Dan Malone will sell you one for only $15. (see
parts list at end)
Since this is a combat plane, I chose to use the cheapest and lightest
weight electronic components I could find.
If you elect to fly it outdoors, the winds need to be very low (less than 7mph).
It's final weight including battery is only 9 oz. with wing loading of 3.2 oz. per sq/ft.
Cruise power draw measured out to be only 2 amps with 9 amps at full power which can pull it straight up.
My paint scheme and C.G. / servo location.
C.G. is 5-5/8" measured from the rear face of motor mount.
I mounted the servos close to the c.g. line to keep in balance. Notice
how the
servo case just touches and is mounted aft of the c.g. line.
I used a hot glue gun and then wire tied them down.
BOTTOM
Stripes are a must for this plane. It is easier to paint them before glue
up. Use foam safe paint such as the new H2O spray paint
available at Ace hardware, Cumberland & Lawrence.
Also add a couple of triangle pieces of foam to the bottom rail just behind the
engine block to shore it up for landings.
GLUE-UP THE MAIN SECTION FIRST LIKE THIS.
(I suggest you use the new
Fast Cure/White Gorilla Glue)
Use some heavy weights to press in and hold bottom together with dual rubber bands and pins
to hold top until glue is dry.
ELECTRONIC COMPONENTS INSTALL WITH VELCRO.
>>> 7-2009 UPDATE: SEE PARTS LIST FOR UPDATED BATTERY AND PROP <<<
Notice how antennas are mounted away from any metal or other wires.
Also notice how prop is mounted with excess shaft length cut off.
HINGES
Install 3 CA hinges in each 45deg. beveled elevon using
foam safe CA.
RADIO
Since this only has two servos, you'll need a transmitter capable of "delta
wing" or "elevon" programming.
My settings:
Aileron: 50% low rates with 70% expo and 125% high rates with 72% Expo.
Elevator 50% low rates with 70% expo and 125% high rates with 93% Expo.
LINE UP THE PUSHRODS AND EPOXY INTO CARBON FIBER RODS.
I used small hollow carbon fiber rod (11" long) with small sections of steel
"Z"
bend rods (2" long) epoxied into each end.
Notice how the horn is mounted so linkage holes are on the hinge line.
Align your servo arms up, elevons flat and epoxy in place, no need for clevises.
I clipped
popsicle sticks using clothespins to the elevons to keep
them flat while epoxy was drying.
SERVOS ARE HOT GLUED IN PLACE AND THEN WIRE-TIED THRU BOTTOM FOR ADDED SECURITY.
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Here is the ElCheapo Combat Foamy parts list:
Airframe
A precut Depron foam kit $15 + $7 shipping (CNC machine cut, well worth the
price) includes main spar c.f. tube,
servo pads & motor mount.
Obtain it from Dan Malone (812)490-0016
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The following parts can be obtained from HobbyCity.com
with my discount:
Motor
TP2408-21 $7.95
TowerPro Brushless Outrunner Motor 2408-21
Servos (need two)
HXT900 $3.65
HXT900 9g / 1.6kg / .12sec Micro Servo
ESC
TP_w12A $11.95
TowerPro 9g w12A Brushless Speed Controller
Foamy Horns
07-00303x10 $0.97
Pin Horns L22xW19xH.9 (10sets)
Prop ( pac of 6 )
GWS-prop-EP-8040
$4.05
GWS EP Propeller (DD-8040 203x102mm)
JST Style Battery Connector (pac of 10)
AM-9017A
$1.99
Female JST battery pigtail 12cm length
Battery
ZIPPY Flightmax 800mAh 3S1P 20C $9.32
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... if you have any questions, don't hesitate to ask. Have fun building &
flying!!!