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Oct 06, 2008, 01:56 PM
damn you tree!
roballoba's Avatar
Thread OP
Build Log

Presenting.... For-Macchi GW-72 (GWS Formosa built as Macchi MC-72 racer)

This has long been my favorite float plane. It's red, it's Italian, it floats, it has contra-rotating propellers, and it holds a world record for fastest float plane.

The Macchi-Castoldi MC-72

I have been wanting to build this forever....
and here it is!

The GWS Formosa was the ideal candidate for this build and it worked great!
Powered by a Vision Hobbies contra-rotating motor tested at about 350 watts, my Macchi should fly nicely.


Last edited by roballoba; Oct 06, 2008 at 02:36 PM. Reason: Build log
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Oct 06, 2008, 03:07 PM
Registered User
cool. I like the floats and wheel combo. Nice build!
Oct 06, 2008, 03:17 PM
damn you tree!
roballoba's Avatar
Thread OP

motor install

Motor from Vision hobbies....

motors installed on bent aluminum stock.

Fuse hogged out to allow for dual esc's, battery, and CF tubing.

Carbon fiber rods entire length of fuse - both sides.

Plywood battery tray attached to CF tubes.
Oct 06, 2008, 04:00 PM
damn you tree!
roballoba's Avatar
Thread OP

Beginning to take shape...

All the lines are straightening out and we are starting to have something other than a formosa.

I filled in the dents with light weight filler then covered the entire plane with .5 oz fiberglass cloth and waterbased poly-urethane. Next came the paint. H2O spray paint (doesn't eat foam) and acrylics brushed on for details.

The floats for GWS planes tend to rip from the plane rather quickly when flying on or off ground, so I used welding rod to form the bracing. This is AMAZINGLY strong!!!! The wire is attached by wrapping thread around the place where the two wire join and the soaking in CA glue. The Fairings will be made from blue fan fold foam as well.
Last edited by roballoba; Oct 06, 2008 at 04:06 PM. Reason: floats details...
Oct 06, 2008, 04:15 PM
Midnight Maniac
planekiller's Avatar
WOW! Nice work!
Oct 06, 2008, 04:16 PM
damn you tree!
roballoba's Avatar
Thread OP

finishing up the For-Macchi

Paint goes a long way for details and it's starting to look like the real thing....

The windshield was bent from plastic I saved from the recycle bin. Try making one from paper first, then transfer your shape to the plastic - it's easier.

Although I have salt water in front of my house, I am not close to a fresh water lake to fly from. I have wasted too many pieces of electronics to fly off the lagoon again.... So, I attached wheels! The largest GWS wheels were mounted with rods through tubes through the floats and secured with wheel collars... (makes sense?)
Oct 06, 2008, 04:34 PM
damn you tree!
roballoba's Avatar
Thread OP

power setup

I planned to run a 2100mah 3s lipo, but I just got the new Thunder Power 2600 prolite. it fits just as well!

The props go in opposite directions, and there are supposed to be tricky efficiency balancing dynamics involved because the rear prop does not have to work as hard as the front one...
here's what I ended up with...

Front APC 9x6p
Rear APC 8x8

tests ran about 350 watts combined and about 17 amps each tested individually (while running together)

ESC's are 30 amp Suppos, and a separate BEC was added for constant power to the radio.
Oct 06, 2008, 04:47 PM
damn you tree!
roballoba's Avatar
Thread OP


980ish grams without battery
1160ish grams with prolite 3s2600
Oct 06, 2008, 05:14 PM
that's sooooooo coooool

I want one of those where did you get the twin motor?
Last edited by BladeRex; Oct 06, 2008 at 05:28 PM.
Oct 06, 2008, 05:37 PM

Bet it was hard keeping it on the ground during those taxi sessions.

Can't wait to see her in the air, R. She's got really nice lines.
Oct 06, 2008, 06:14 PM
Registered User

Macchi maiden

So when is the maiden. Call me when you plan. Hell I'll take the day off to see that. May have to finish off my H-1 and have a race
Oct 06, 2008, 06:34 PM
Got the Fever
ppatron's Avatar

Nice one

Wow! Great job Rob! She looks mighty perty! Let me know when you will maiden that baby.

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