Category Archives: Maiden

Maidened My Freewing Rebel EDF Today

My wife bought me the Freewing Rebel EDF for Christmas this past year. I have been slowly building up the courage to get her into the air and finally took the plunge today. I had two great flights despite all my nerves and shaking hands – thank god for expo!

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She’s definitely faster than anything else I’ve flown, but really stable and well behaved. Take-offs were uneventful, except she feels a bit sluggish until it picks up speed, and needs a bit more take-off roll than any of my prop planes. In the air, she was very predictable and responsive on low rates. I didn’t do anything fancy, but never felt like I was out of control, and at full throttle, she was tearing up the sky! With half flaps, landings are a breeze, really no harder than my old T-28. I did not try full flaps. Flight times are a bit short, I am getting about 3-1/2 to 4 minutes with a 3000 mAh 4S battery, with ending capacity at about 20%.

This was my first Freewing plane, and overall, I am very impressed with the quality. I did end up fussing with the elevator a bit. The stock setup had two pushrods, one for each elevator side inserted into a single hole in the servo arm. While I am sure that this would work fine, I was having a hard time getting both sides of the elevator to travel identically and could only het about 10mm total travel (vs the 16mm recommended).

To address this, I made up a new custom pushrod set by silver soldering two wires together and replacing the clevis links with Du-BRO micro links . I also slightly trimmed the foam ahead of the servo to provide clearance for the pushrods. Most of the control surfaces on this plane use low friction nylon hinges, but the elevator is a standard foam hinge, and felt a bit stiff. So, for peace of mind, I replaced the stock servo with Hitec metal gear servo. Finally, I used a slightly longer servo arm to get a bit more travel. All together, these small changes got the elevator travel up to the full 16mm, aligned, and moving smoothly.

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The battery compartment is a very tight fit. The receiver and wires fit, just barely, behind the battery cavity. I needed to trim a small amount of foam from the front in order to fit the pack without mashing the battery wires.

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With the 3000 mAh battery, the plane needed about 1-1/2 oz of weight in the nose to balance. Before gluing on the nose cone, I cut a small hole in the nose, then mixed some lead shot into a bit of 30 minute epoxy and “pouring” it into the hole.

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The only other fussing required was getting the aileron throws set properly. The right aileron had about 3-4mm more travel than the left. Since there are no empty spots on the 6 channel receiver, there is no choice but to join the servos on a “Y” connector. There is no way to trim one servo separately from the other. I’m not sure if the problem is with the servo, or (more likely) with the position of the control horns relative to the hinge line, but to fix the issue, I simply moved the right aileron pushrod to the outer hole on the control horn, and left the left in the middle hole. Travel is now aligned to within 1-2mm.

I probably am fussing a bit more than needed, but fussing is what I do!

I also got in a bunch of flights with my trusty ParkZone F4F today. This continues to be my no-fuss, no-muss plane. Like their tagline says “Just Fly”.

On the other end of the spectrum is my E-flite Hurricane. This is my “repair after every flight” plane. I had one fairly good flight with her today, but landed a bit hard and pulled the right landing gear mount out of the foam (again). No damage to the foam and, in truth, this is working the way it is supposed to (easier to glue the mount back into the foam than it is to repair a broken wing!).

New Project – FT Viggen

It’s been a while since I last posted. Summer has been busy but I have found time to get out flying when I can. Like last summer, I got sidetracked with a scratch-build foamy EDF. This time I, went with an established design and put together an FT Viggen. I didn’t bother with documenting the build process at all since there is a great build video on the Flite Test site, and I just followed it along step by step.My only deviation from the FT build was to add a 1×2 mm carbon fiber wing spar. I re-used the fan and all of the electronics from my original (failed) Fan Trainer project, and I must say that I am pretty happy with end results.

I really enjoyed the build process. I transferred the downloaded plans onto the Dollar Tree foam boards by taping the plans down to the board, then pushing a pin through the plans at each corner, or intersection point. I then used a pencil and a straight edge to lightly “connect the dots”. Working with hot glue and foam may not be quite a s rewarding as a full on balsa build, but it fast, cheap, and surprisingly strong. Overall, I can’t argue with the results.

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I maidened it a few weeks back, and I must say that I was quite impressed with how stable she was. The guys at Flite Test did a great job with the design! Just a gentle underhand toss with the throttle at about 75% and she flew away and got right on step. She is very sensitive to aileron input and I kept looking for rudder while (i.e.; I’d move the rudder stick, but of course, since there is no moveable rudder so nothing would happen – duh). I may try to add a rudder (or just build another with one).

I did run into one problem and learned a good lesson about battery charging. In particular, that I learned that I need to be mindful of the power supply power/current capacity when charging.

I am using a 4s 3700 mAh batteries (slightly larger than the recommendation of 3300 mAh, but what I had available already). The last time I used these batteries was in my original Hanger 9 Alpha Trainer a few years back. Since then, I bought a new battery charger that allow supports much higher charging rates. While field charging the batteries using my Duracell Powerpack, the charger died about half way through the cycle. At first I was quite certain that my charger had crapped out (I have a Hyperion 1420i charger and they have a reputation for early failure). Fortunately, when I got home, I discovered that the 12V cigarette lighter pulg-to-banana plug adapter that I was using had a blown its 10 amp fuse (I didn’t even know it had a fuse!).

A little math shows the problem:

  1. Battery Voltage (3.7 per cell empty, but  4+ volts per cell charged):  4 x 4v = 16v
  2. Out power to battery:  16 x 7.4 = 118.4 watts
  3. Input current required at 12v (assuming 100% charger efficiency):  118.4 / 12 = 9.9 amp

Knowing that the charger is not 100% efficient, it is pretty easy to see why the 10 am fuse blew. Overall, a cheap lesson. But, given the reputation of the Hyperion 1420i (now discontinued), I may want to think about picking up a new charger before next year’s flying season.

Fan Trainer Fiasco

One of my projects from last summer was an attempt at a foamy scratch building with a Fan Trainer EDF built from Dollar Tree foam board. I patterned it after the 150% scaled up version of the plans found in this build thread: http://www.rcgroups.com/forums/showthread.php?t=426281.

This was my first attempt at both EDF and at building with foam. The building process went well and I kind of enjoyed working with foam.

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The total investment in foam was about $5 (including scrap and re-work). I powered it with a Detrum 70mm Fan combo from HobbyPartz.com which includes the fan, motor, ESC, and servos for under $50. All in, with batteries, and a 4 channel receiver, total investment was under $100.

Unfortunately, it did not survive its maiden flight. The wings were simply not stiff enough and fluttered badly. Apply enough power to keep the plane flying, and the wings flapped like a hummingbird. Back off the power, and there was virtually no control. I ended up lawn-darting and disintegrating everything from the wings forward (sorry, no picture of the damage).

Oh well, nothing ventured nothing gained. The electronics and fan escaped unscathed, so the total loss was under $10 (and a little bit of pride). I have a few ideas for how to use the fan and other bits from this attempt in a new creation!

Stella Flys!!!

I successfully maidened Stella today! Wow, she is a great flier. A few clicks of up and few clicks of right aileron trim and she was rock solid in the air.

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Definitely a bit more responsive than what I am used to, but once I got my nerves under control, I was able to bore some clean holes through the sky with confidence. I got three solid flights in with no problems – needless to say, all flights were at low rates with a a fair amount of expo dialed in. I kept it simple, just trying to get confidence and get a feel for the plane, but I can tell she will be a favorite flyer.

I was a  bit nervous about weight (all in with batteries, she is a touch over 18 oz about 2 oz over target weigh), but she seems to fly just fine. She literally leaps off the ground and slows down to a craw for landing. I always find landing on grass a bit tough with these small planes, I did nose over on two out of three flights, but at very low speed with no damage detectable.

Two very non-flying related issues did pop up though. One was the inevitable wrinkling of the darker colored Solite in the sun. Nothing major and most of it tightened up once I got her home, but a little tweaking with the trim iron to tighten up a few spots will probably be in order. The second was the prop from the other plane I was flying today poked a small hole in the turtle deck covering during the car ride home. Easy enough to patch, but hanger rash on a new plane is always a bummer.