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Sep 05, 2007, 06:41 PM
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FlynAZ's Avatar
Build Log

PurFoamance - Extra Full Fuse EPP

PurFoamance Extra
Recently I built a larger version of Soundmanís Silent Mite ( I modified his plans using EPP block and was very impressed by his skinning method. This build is also a combination of tips and tricks Iíve learned from all of the other great contributors on this site.

So I decided to build an Extra using similar technique for the skin. Remember beauty is only skin deep, but ugly is to the bone. Under the skin my plane is bone ugly.

Iíve also built the balsa kits and BluCore and got pretty discouraged when they hit the ground. So I wanted one that would take a hit. That meant using EPP foam as the building material. EPP sheet foam by itself seems to need extra support. So I am using block EPP foam from packing or shipping boxes for the front fuse. It should be fairly simple to find a good supply for most people. This is only the second full fuse EPP plane Iíve attempted but I already see how this could be employed for almost any build. The hardest part was trying to find the EPP block foam that exceeded 22 inches for this plane.

The plans are from an Extra 300 I downloaded. I then modified the plans to fit my needs. Once I got the plan figured out I just used TilePrint to enlarge it to my desired dimensions. I used BluCore for the wings and tail feathers and EPP for everything else.

Wing Span: 43 inches
Length: 32 inches
Weight: 23 oz. (minus battery)
Motor: EFlite Power 10
Batt: TP 2070
Prop: 11 X 5.5
Last edited by FlynAZ; Sep 05, 2007 at 07:10 PM.
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Sep 05, 2007, 07:03 PM
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Building Supplies

Building Supplies:
EPP Packing Foam
EPP 6mm Sheet foam
EPP 9mm Sheet foam
EPP 3mm Sheet foam
2 sheets BluCor fastened at edge
.5mm X 6mm CF strip
3mm CF rod
Welders Glue
15 min. epoxy
Ĺ X Ĺ Basswood (landing gear support)
Plywood for motor mount and landing gear support
Retractable exacto blade knife
Sharp No. 11 exacto blade
Sep 05, 2007, 07:08 PM
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FlynAZ's Avatar

Salvage the EPP foam ....

Buy a new computer from Dell - they use EPP to pack their computers. When it arrives throw away the box and computer but hang on to the packing material.

I had to learn a new skill set here: cutting through 3 inch EPP with a retractable blade, AND keeping the cuts even and straight.

Here is the Before and After pix.
Sep 06, 2007, 12:06 AM
brian94066's Avatar

that really looked like the Extreme flight Extra

maybe this is the cheap way to get it (except the computer part ^_^)
Sep 06, 2007, 05:32 AM
Time for another motto!
Sorry, but that packaging foam is not EPP, it's EPE. The sticker saying LDPE (low density poly ethylene) gives it away. It is still a usefull material for making monoblocks out of, but it is to floppy to be used for much else.
Sep 06, 2007, 05:40 AM
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lol epp expensive i nthe uk
Sep 06, 2007, 12:37 PM
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FlynAZ's Avatar
Originally Posted by brian94066

that really looked like the Extreme flight Extra

maybe this is the cheap way to get it (except the computer part ^_^)

Thanks Brian, actually I wanted it to look like my old seagull 300 extra. I think I came close except for the cockpit - I used a 2 liter Coke bottle. This came out a bit lighter than the balsa model.
Sep 06, 2007, 03:34 PM
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Kyle D.'s Avatar
It looks awesome! Great job.
Sep 06, 2007, 10:03 PM
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trashbug's Avatar
Nice Job! You can honestly say this is a computer aided design, CAD airplane
Sep 06, 2007, 10:48 PM
brian94066's Avatar
Originally Posted by FlynAZ
Thanks Brian, actually I wanted it to look like my old seagull 300 extra. I think I came close except for the cockpit - I used a 2 liter Coke bottle. This came out a bit lighter than the balsa model.
so i guess this is better at pricision, slow fly stuff?

like super slow alternating roll figure 8's ^_^
Sep 12, 2007, 05:09 PM
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FlynAZ's Avatar

PurFoamance modified plans and build guide...

Here are the build guide and plans I modified. The ailerons are a bit bigger (left side) and the wings leading edge is actually straight. Just use the top fuse profile, wing and tail. Also use the basic shape of the 'E' 'F' and 'G' bulkheads and add one more bulkhead between F and G.

I tried to color coordinate the different pieces on the profile plan.

Everything else is 'Build as you go'
Last edited by FlynAZ; Sep 13, 2007 at 05:28 PM.
Sep 12, 2007, 05:37 PM
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Starting the build

Cut out the bottom section of the foam block halves to accommodate all the electronics.
Also cut in the slots for the firewall and landing gear plywood pieces. Leave approximately 1 inch foam for the sides.

Cut a 6mm piece of EPP foam to the profile shape of the fuse. It gets re-enforced with .5 X 6mm CF flat stock witch I epoxy in place. A piece of BluCore completes the tail section of the fuse. Use epoxy instead of Welders glue to join the BluCore and EPP fuse together.

The keel gets sandwiched between the two main fuse blocks and glued with Welders glue.

Use ĎTí nuts on the motor mount where the motor will be screwed/mounted to. Both the motor mount and landing gear parts are fitted and glued in to the foam block. The EPP keel piece is cut flush at the firewall. The CF will butt up against the firewall.
Sep 12, 2007, 05:56 PM
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FlynAZ's Avatar

Do The Blu

Cut out all the BluCore parts. Re-enforce the tail and elevator with CF rod or bamboo skewers. Mark a line 2 inches from the leading edge on the inside of the wing. Then cut two strips of BluCore 1 inch wide and 2 inches shorter than the wing length. Cut two more strips 3/8 inch wide and the same length as the 1 inch pieces.

Sandwich the 3mm CF wing re-enforcement and the 3/8 pieces between the 1 inch blucore strips and tack glue together. Once the strip is dry glue it along the 2 inch line you made on the inside of the wing. The piece is actually placed at the 1 Ė 2 inch distance of the leading edge.
Sep 12, 2007, 09:55 PM
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almost to the paint

Glue and clamp the trailing edges (1/2 inch) of the wing together. I always use epoxy for this. Once the glue is dry, sand the trailing edge so itís smooth and even. Put end caps on the wing and sand and bevel them to your liking.

I like using the floppy drive material for my hinges. I just cut strips of the floppy material (about ľ inch wide and 1 inch long) then cut horizontal slits in the leading edges of the control surfaces with my exacto blade. I then make matching slits in the wing and tail surfaces. Next I bevel the control surfaces where they will meet the wing and tail. Use a straight edge about ľ inch back from the leading edge of the control surface and hold your exacto blade at an angle to cut a bevel through the middle of the foam. Flip it over and do it again. If done correctly both sides will have a nice bevel with the hinge slot in the middle of the foam. Apply some epoxy onto both sides of Ĺ a hinge and side it into a slot and work it back and forth to spread/coat the epoxy thoroughly inside the slit on each of the control surfaces and let dry. Do not put the hinges on the trailing edge of the wing yet. Just the ailerons rudder and elevator should have the hinges glued. For excess glue at the slits use a tooth pick to spread it out along the foam. This should add some strength to the foam hinge area.

Next cut out the two skin pieces. Cut the wing and tail slots exactly on both pieces. This should help when you start gluing the skin on.

Cut out and fit the wing onto the fuse (but donít glue in place yet). Cut the slot for the elevator and check the wing and elevator for true level (trim as required).
Sep 12, 2007, 10:06 PM
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Paint it

Now you can paint all your parts before final assembly. I always use Krylon H2O latex spray paint and find it easier to paint all the parts and then assemble them. If you are using tape for hinges, it also seems to stick to the painted foam better.

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