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Old Oct 25, 2010, 01:47 PM
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Build Log
first scratch-build! :D

Crafted from finest 3/8th inch blue foam, a sheet of 6mm depron, and with the aid of a little carbon here and there; this li'l beastie boasts a wingspan of 24 inches, and a total length of 18 inches including prop and rudder. Power comes courtesy of a 22g 2350kv brushless outrunner on a 10amp esc, turning a GWS HD7035 on an 800mah 2s1p li-poly. Radio is a cheapo 2.4ghz 4-channel setup with built-in elevon mixing. The servos are whatever I had lying around in the 9g range.

I decided to name this one "eXDee" due to it being an experimental design.

Maidened this afternoon! Performance is great. She won't do the unlimited vertical thing, but she'll climb out at 60 degrees without a problem. I must've been up a good 15 minutes total. Motor, Battery and ESC stone-cold.

I had a second outing with eXDee this evening, but had to land after about 10 minutes due to failing light. I'm definitely getting a couple more of these li-pos.
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Old Oct 28, 2010, 11:31 PM
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cool, congrats!!

keep building
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Old Oct 29, 2010, 10:07 AM
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^^

Thanks.

Just waiting for the wind to drop so I can try eXDee with a slightly pitchier, slightly stiffer prop. Will update this when the results are in.

Also, just curious, but can anyone recommend plans for a backyard / carpark flyer I could build from 3mm / 6mm depron, that would suit a 5g 2000kv outrunner? I acquired this and a 300mah 2s lipo a couple of weeks ago, but I'm yet to see any plans that small. According to the datasheet, it'll pull 75g with a GWS 5030 on 2s, but would release its magic smoke on 3s.
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Old Oct 29, 2010, 04:17 PM
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Melbourne, FL
Joined Sep 2010
677 Posts
Clean build! You sound like you know your stuff, I'm impressed this is your first. Congrats!

Quote:
Originally Posted by ClippedWings78 View Post
Also, just curious, but can anyone recommend plans for a backyard / carpark flyer I could build from 3mm / 6mm depron, that would suit a 5g 2000kv outrunner?
I'm a huge fan of the Nutball, it really is a fun RET design. I fly my 14-inch 3mm depron nutball in the driveway, street and backyard. It rolls, turns on a dime, would prop-hang if I had enough power... overall I'm smitten by this curious little design. If I'm going to be flying rudder/elevator, its gotta be my nutball.

14-inch Nutball, 3mm Depron RC Airplane (1 min 52 sec)
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Old Oct 30, 2010, 10:33 AM
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Further Testing

Just took eXDee up with an APC-E 7x5. She seemed to have a lot more 'go' with that prop over the shallower and more flexible GWS type, though when I felt the motor, it was perhaps lukewarm. I guess I could try a 7x4, if I can find one that'll fit on a propsaver.

One problem I came across was the design's wind-sensitivity. I'm not sure if it's just the massive wing surface, the (lack of) airfoil, the profile design, the mid-wing configuration or just me being a noob, but eXDee became uncontrollable when the wind picked up to more than a gentle breeze. My guess is that wind-sensitivity is the trade-off for having a semi-sedate easy-build wing. This thing was flying so slow during the first test in flat-calm, that my EPS Mister Mulligan etrainer would have kept up with it.

Jefte: I have to ask. How did you accomplish the tip-dihedral in 3mm depron? I see the NutBall's creator uses a soldering iron and a straight-edge on the larger versions, but that would be a touch fiddly with thin-sheet depron, would it not?
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Old Nov 01, 2010, 02:39 PM
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Melbourne, FL
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Quote:
Originally Posted by ClippedWings78 View Post
One problem I came across was the design's wind-sensitivity. I'm not sure if it's just the massive wing surface, the (lack of) airfoil, the profile design, the mid-wing configuration or just me being a noob, but eXDee became uncontrollable when the wind picked up to more than a gentle breeze.

Jefte: I have to ask. How did you accomplish the tip-dihedral in 3mm depron? I see the NutBall's creator uses a soldering iron and a straight-edge on the larger versions, but that would be a touch fiddly with thin-sheet depron, would it not?
If you look at the Nutball, it has massive amounts of wing surface. I doubt too much wing surface is the issue. Does it feel pitchy in the breeze? Perhaps it needs more length, nose to tail? Hopefully someone with more knowledge chimes in.

Regarding the dihedral, just find a nice hard edge and bend. Just don't go too fast or you risk cracking. I completely eyeballed the wing-tip angle, too.

On the nutball in the video I pre-cut into the depron to make it easier to bend. But on subsequent nutballs I have created with friends, we have found just bending it without scoring the seam creates better, more rigid tips that don't have to be flexed back into place every few flights.
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Old Nov 01, 2010, 07:39 PM
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Many people will slice the depron part way thru on the back side. Bend in place to the proper angle and fill in the created slot with hot glue. This two piece scraps jig has lasted me for years... http://www.rcgroups.com/forums/showp...postcount=4095
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Old Nov 01, 2010, 08:45 PM
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:o so THAT's how

Thanks guys.

Been wondering how that was done for a while now.

Well I found that in the last "unscheduled landing" that my elevon horns had dislodged, so I decided that whilst I fixed those, I would adjust their angle, as they were set too far back before and I lost a lot of downward throw on both elevons. This should hopefully allow me to trim out eXDee's nose-up tendency on WOT.

I don't really -know- if it helps with penetration or not, but I've applied some shiny black tape to the LEs. I figured it might help.

I've been looking at other scratch-built foamies, watching the flying videos etc. I know eXDee flies rather slower than most wings, doesn't have anywhere near the sharp handling of most either, but for me, the satisfaction is in the fact that it's -my- plane, I built it, and it -flies- (Just have to work on my landings now. eXDee will probably end up being made from PU glue, with traces of blue foam )

I'm hoping for another chance to fly eXDee this week. I'm still yet to see how she flies on this prop in flat-calm, and I have the new horns/throws to check out.
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