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Apr 28, 2019, 08:15 AM
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Extra 330. bash and crash indoor 3d using 8mm EPP


After seeing a multiplex 330 indoor model at my local indoor flying club flying well, I decided to have a go and make a version out of 8mm EPP .. 8mm foam being better suited for our halls hard environment.. seriously a lot tougher..

The multiplex version is produced in 6mm EPP from a better quality foam, with a cost of about 55 for the kit.. A very good model but expensive for me.. DIY is cheaper..

My available EPP foam comes from RobotBirds, in the U.K. its either cut to 4-5mm or 7-8mm.... usually coming at the 8mm thickness.. The thinner material doesn't last long enough, at our bash and crash sessions it tears too easily and gets badly chopped up in any mid air mixup.. the 8mm takes the hits much better, and 8mm models last considerably longer..

My first job was to gather some pictures as a reference to the shape... Then using my favourite Sketchup drawing program I can trace the outline shapes needed to produce a close enough model
Last edited by davereap; Apr 30, 2019 at 02:20 AM.
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Apr 28, 2019, 08:16 AM
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Using sketchup I copy the outlines. At the same time the shapes get made more basic..
Tags and holes are removed , and any fancy shapes which help aligning parts are removed..
Along with servo holes..
The rudder here has been modified so as to not rub the floor when taking off..
this didn't affect its good knife edge in flight and flat turns are nice and easy.
Last edited by davereap; Apr 28, 2019 at 10:41 AM.
Apr 28, 2019, 08:17 AM
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Having copied the basic outlines I made scaled the model to the size I wanted..
An easy job in sketchup..
I removed faces and produced some .pdf files of parts that cant be easily measured and cut .
These PDF files were then put through the scaleandtile program to produce a gridded version, this helps when gluing the pages of the plan together
Note the wings are a measure and cut job..
Last edited by davereap; Apr 28, 2019 at 08:48 AM.
Apr 28, 2019, 08:17 AM
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Cut out all the horizontal parts, remove the ailerons and tail surfaces, cut hinge points with a top chamfer ..
Assemble the horizontal surfaces, fuzz, wings, tailplane , refitting the control surfaces..
I used UHU por for butt joining all the parts.. and uhu por to make the hinge joints..
When its dry, cut side to side on the fixed part of the wing and fit in a 5x1mm CF flat spar..
More strengthening is added using flat CF on the tailplane front and on the control surfaces , ailerons , elevator , rudder
When that's dry we can fit the vertical lower fuzz.. and the 1mm CF bracing
Last edited by davereap; Apr 28, 2019 at 10:05 AM.
Apr 28, 2019, 08:35 AM
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Butt join the lower vertical fuzz using UHU por , Make sure its on straight and square as you add a fillet of cool melt adhesive along the joints..
NOTE.... align from the rear end for later fitting the rudder, the nose can be trimmed easier at the finish if needed..
Add the 1" triangles for a nose block..
Fit the 1mm rod bracing, note the tail plane fixed front needs some of the bracing....
and add wheels (optional)..
Last edited by davereap; Apr 28, 2019 at 09:37 AM.
Apr 28, 2019, 08:48 AM
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Add the top fuzz vertical.. again align first from the rear , make sure its straight and square as you fillet the joints..
Add the nose triangles..
fit the rudder..
Last edited by davereap; Apr 28, 2019 at 10:05 AM.
Apr 28, 2019, 09:19 AM
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Fit the gear, keeping it all forward helps to get a good COG..
pushrods are 1mm CF for the rudder and elevator, they are supported using parts of cable ties drilled then spread along the fuzz..
The elevator rod is on the top of the fuzz so it pulls "up"
The rudder is bellow and pulls "right"..
Last edited by davereap; Apr 28, 2019 at 10:11 AM.
Apr 28, 2019, 09:51 AM
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Specs...
AUW....216 gms with a 450 2s lipo .. 7.6oz
Gartt 2204-1800 motor withh an 8x4 gws type prop.
450 2s nanotech..or 3s for outside.
4x tgy1440a servos
10-12A ESC..
6ch orange RX..

Using the horizontal area total 379"sq... 2.632sqft.. 2.888ozsqft.. It flies nice and slow on low power settings

Hover is fine ..knife edge fine.. rolls fast.. loops fine..
Bash and crash resistance is good..
Its a good model for my harsh hall..
Last edited by davereap; Apr 28, 2019 at 10:31 AM.
Apr 28, 2019, 10:04 AM
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here is its maiden flight, after an initial short flight for trimming..
.
extra 330 8mm maiden flight 25 04 2019 (8 min 21 sec)
Last edited by davereap; Apr 28, 2019 at 11:20 AM.
Apr 28, 2019, 10:32 AM
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Its good, it just needs a better pilot
Last edited by davereap; Apr 28, 2019 at 11:22 AM.
May 06, 2019, 08:47 PM
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Looks pretty good and flies well too!
May 11, 2019, 05:11 AM
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latest videos
.
extra 330 2s indoors 2 (3 min 15 sec)

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extra 330 2s indoors (5 min 39 sec)
May 11, 2019, 05:14 AM
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This is a very neutral flying 3D model... It flies much like the multiplex 330sc it was based on, its just a bit heavier using 8mm EPP so it is a lot more crash resistant but slightly less floaty
Last edited by davereap; May 14, 2019 at 06:50 AM.
May 14, 2019, 12:53 PM
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What is that you are using for the pushrod guides?


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