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Old Aug 09, 2012, 06:06 PM
jshelton is offline
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Jim in Santee
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United States, CA, Santee
Joined Oct 2001
194 Posts
First flights of my Culex

Been flying my Culex for a few weeks now and wanted to share my experiences. This is the plane from Esprit Model. Culex

Specs: 77" wingspan, 520sq in, 22oz AUW, 6.1 oz/sq ft.

Hyperion GS-2213-14/1337
Jeti Spin 33 ESC
Hyperion 2S 1100mAh 45C Lipo
13x6.5 prop w/BB Turbo spinner 30mm
Hitec Optima 6 receiver, Hitec Aurora 9 radio
(2) Hitec HS-45HB servos (elevator, rudder)
(2) Hitec HS-56HB servos (ailerons)

Building: Although it's an ARF, it took much longer than expected due to design oversights and a badly designed/constructed firewall. The firewall was molded in but it was flush-mounted leaving no recess for motor screws, which would leave a large gap between the fuse and spinner. I then discovered that one side of the firewall was about 1/16" thick but the other side was about 3/16", causing a grossly tilted spinner - and this wasn't a thrust offset but simply a construction defect. After trying to recess the motor screws, use spacers, etc., I got fed up and cut out the nose with my Dremel and installed my own firewall with proper recess!

The elevator servo mount under the elevator seemed weak, so I laminated 1/64" plywood on both sides. The handlaunch-style fin clearly wasn't designed to be landed on so I created a wire skid that I taped to the boom and fin bottom.

The wing mount allows the wing to swivel a little so I used double-sided tape to stick down the rear portion of the wing mount - suitable approach only if you leave the wing on most of the time like I do.

Flying: The CG is at 73mm which provides very good thermal performance but also good handling. It climbs almost vertical, getting to 500ft in about 20 seconds. The MH32 airfoil really shines, providing great penetration, even at the light 6.1 oz/sq ft wing loading. During my first couple of flights, I wasn't pleased with the thermal performance but the realized I was flying too slow. You don't need to fly fast but you do want to avoid mushing along. Just a little extra speed and the plane really come alive. The Culex handles well with some aileron differential and aileron-rudder mixing but to really maximize performance, you'll need an active left stick, often kicking in lots of rudder when you're working those small low-level thermals.

I'm having a blast with my Culex, often getting flights of 45 minutes or longer on the small 2 cell. I've had several times where I worked a tight thermal at about 20ft all the way up to several hundred feet. This is the first glider I've ever done that with! I like that it will handle winds of 15mph but is still light enough to work the weakest thermal.

BTW - I tried a dive test and it didn't take much to make the wing flutter so don't do that! I implimented the butterfly function and had to use it many times to get out of boomer thermals - I highly recommend doing the same!

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Old Feb 04, 2013, 04:00 PM
DownUnderPilot is online now
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2012 NZ Speedcup - 231 MPH
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New Zealand, Tasman, Richmond
Joined Mar 2006
2,391 Posts
Nice review, they look really good for the price. Most cheaper 2M sailplanes seem to have a couple of issues. I'm considering one as I want something to do exactly what you have shown it can do - i.e. catch low lift.
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