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Old Apr 24, 2006, 02:32 AM
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Gallery
Folland Gnat (70mm) by Robbe

Folland Gnat by Robbe ...

Kontronic Fun 480-33, Kontronic Smile esc, Schuebeler DS-30 carbon fan and PQ 4S 3100 Lipo. ca. 36 oz and 490 Watts ... about 105 mph level. More details here and here.

Robbe Gnat video :

Early EDFs - Robbe Gnat (2 min 48 sec)


www.schuebeler-jets.de
www.kontronic.com

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Old Jan 19, 2007, 03:55 PM
EDF Jet Jam 2015, May 28-31st
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United States, KY, Crestview Hills
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Herb,
I don't ever remember seeing the Costa Mesa field look that green...must be early spring time.
Bob
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Old Jan 21, 2007, 06:47 AM
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Hi Bob, mid-april I guess from the date in the thread ... I wish it was that green all year long - but then you can't have everything
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Old Sep 14, 2007, 07:02 AM
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Hey,

I've got a Gnat too. Yours looks very nice, including the seams where the wing meets up with the fuselage. How did you do that? My wings seem to be a bit high i.e. there's an edge of approx. 2 mm.. ? I was thinking about removing the wing that I already epoxied to the fuselage or just sand those edges away from the wing and filling the fuselage a bit up.

Also, how did you get that nice finish? The surface looks very smooth.

Thanks.
Dave
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Old Oct 28, 2007, 03:45 PM
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I filled the foam joints with lightweight water based spackle, and then covered the whole plane in silkspan. See the link posted above, there's a few pictures there that might answer your question ...

On the silkspan I then applied some water-based varnish, most likely minwax polycrylic which is a water based acrylic. Other acrylics will work too provided they don't melt the foam. Polyurethane varnishes look very nice but are way too heavy, avoid those.

Laminating epoxy is too hard and heavy for the Gnat. You can use fiberglass cloth, but then you have to fill the weave which adds weight.

JePe ( www.jepe.org) now has some very nice pages on how to finish foam.

The final coat is water based tamiya acrylics thinned with alcohol and applied with an airbrush.

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Old Nov 30, 2009, 09:06 PM
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Quote:
Originally Posted by Pat Mattes View Post
Hi Herb,

I wondered if you could help me. A friend went to a swap meet and called me to say there was a "pink jet" I might be interested in. He bought it for 20 bucks, and when he came back into town I find it's a Robbe Gnat!

Lots of things are missing, and I can figure out most everything, but I was hoping I could get a hold of some instructions for it. Mostly just interested in how they set up the linkages. Without knowing what was SUPPOSED to be it looks like they tried to run all 4 control surfaces with 2 servos. I can convert to 3-4 servos, but I'd be really interested in seeing how the original setup was. Can ya help? thanks!

Pat

It's a great flying airframe, so take good care of it No, I don't have the instructions.

Yes the original linkages were quite odd, two servos to run four surfaces. One servo would run both ailerons, and the other would run the elevators. A lot of mechanical adjustments, as well as tubes/rods running across the duct. The advantage back then was saving the weight of two extra servos.

I find the "modern" setup using four micro servos much simpler !

I use one servo for each aileron, with eg. a y connector. An then two servos buried in the left and right back fuselage for the two elevators. Plus possibly a reversing y harness to get one servo to rotate the opposite way. Or a suitable radio mixing, with long servo wires.

If you look at the threads I mention you will see plenty of pictures. If you need me to post some more, tell me which.

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Old Mar 19, 2013, 01:40 PM
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Here's the finished product :

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Old Mar 19, 2013, 01:46 PM
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I had another Gnat before (ca 1999), and that one flew with a Kyosho fan, Graupner 480BB race motor and 8 Nicds ... too heavy for that flimsy foam - and I didn't know what I was doing either back then

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Old Mar 19, 2013, 01:49 PM
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Some pictures of the original :

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