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FeiJi's blog
Posted by FeiJi | Jun 05, 2014 @ 07:22 PM | 1,646 Views
I was flying my P51 when one of the landing gear fell off into the woods never to be found. So bent a bike spoke , added a spoked wheel and now have a beautiful replacement. Actually have two right wheels now.
Posted by FeiJi | Apr 21, 2014 @ 03:38 AM | 1,743 Views
Just flew 16 minutes and 45 seconds on an 1800mah battery in my 40 inch epp wing. Not even a new battery. That is with 2 ounces of steel ballast. Also passed 60 hours total air time. Not much time to show for 3 years of flying but I have lots of video and it has been memorable. Happy Easter (day after).
Posted by FeiJi | Mar 29, 2014 @ 08:28 PM | 2,229 Views
Got my 40" BoneYard 5 finless epp wing out today and ran 4 batteries through it. Great fun. Got 10 to 12 minute flights on each 1800 mah lipo in 10 mph wind. Flying about 50% throttle most of the time but pretty much unlimited loops and rolls, just used altitude to do them. This wing is pretty interesting to fly as it flies straight when at speed but waggles like a kite when you do a hammerhead or slow turn up wind. I kind of like that because it remains controllable but has a touch of unpredictability at times - something most fliers don't like but it keeps this wing interesting to fly. I suppose I could put fins on it but then I would get bored with it.
Wing is about 400sqin, AUW 695 grams, (24.5 ounces), 1800kv motor, 1800mah lipo, 40amp esc, 7*5 prop. I did get a 15.5 minute flight one time on a new battery.
It has a couple ounce metal plate in the nose that I could get rid of with a 2200mah lipo and then I might get some real airtime. But Im too cheap to buy them.

Going to get my Ugly Plank out next and take the wing extensions off it cause I like the way it rolls with shorter wings. Plan to build a new Ugly Plank soon.
Posted by FeiJi | Dec 24, 2013 @ 09:27 PM | 2,173 Views
My first little trainer had only a single axis of movement, I guess yaw. So I decided to add another axis so now it has pitch movement. It isn't totally realistic as the higher it gets, the less power it takes to fly so you have to back off the throttle or it will just peg the lever to the stop. It really needs a way to control the counterweight so that the weight on the rear of the lever decreases a bit as the motor side of the lever rises. But that is too much work for me. It is kind of fun now in that it takes a really light touch and you have to jockey both sticks to get it to fly level.
The only improvement I think I will make is to put the motor on a little gimbal so that the prop and motor stay level.
RC Flight Trainer II - Two Axis Movement (2 min 51 sec)

Posted by FeiJi | Nov 22, 2013 @ 01:47 AM | 2,236 Views
I found that adding large diameter rods to the leading edge makes a significant difference in flying behavior, more stable, seemingly faster and definitely stronger. Also added a little cover for the electronics as I will be landing in the snow for a while now.
Posted by FeiJi | Nov 20, 2013 @ 03:31 AM | 2,501 Views
Here are a couple of more flights with my open close canard wing. Both resulted in hard landings but I did transition from open wing to close wing and flew around a bit. Also figured out why I am hard landing. When I play with the pot on my radio to open the wing back up I accidentally shut the throttle off. Oh, well, it works and when I get better weather I will learn to fly it more smoothly. This wing is pretty fast as only doing 60% throttle with 1800kv motor and a fat 7*5 prop. Imagine it will really scram with a 2600kv. Not bad for a flat plate. Added a couple of fishing pole supports to leading edges which added another ounce and thought it would hurt performance but I think it flies faster and smoother than when the body was flexing without them.
Swing Wing Flight 2 (3 min 44 sec)

Posted by FeiJi | Nov 16, 2013 @ 12:35 AM | 3,590 Views
I have been working on this delta with a movable forewing or canard. I have had successful flights with it rotated out and rotated in but only one time did I rotate it out and in during flight successfully. The final rotate in led to spiral into ground. I think I have figured out what leads to the spiral when I rotate the wing in and when I rebuild the wing will try out my theories. The cg shifts a little bit after rotation but easily corrected with a little bit of elevon up or down. With wing out it is a little high alpha and with wing in a little low alfpha.

The video shows take-off with wing out, then I did rotate it in successfully but it is impossible to see in the video,then rotated it out again then when I rotated it in the second time it led to death spiral.

Plane does land softer with canard out and comes in pretty hot when it is rotated in.

My final flight yesterday ended up in tree and I had to buy a fishing pole to get it down.

My thinking about the transition behavior is this: when I slowly transition the wing in or out with the radio pot, it seems to work ok but if I use a radio switch to transition - it leads to some serious flight instability. So will use my radio pot to gradually transition the wing when I get it flying again. Also, perhaps if I go a little high alpha before transitioning the wing in, perhaps that will prevent the spiral in. Also, noted in the video that I throttled back during transition - maybe some problem there.

Anyway, kind of interesting. Will post another video when I get it sorted out which may be a while since we are getting lots of snow now.
Swing Wing Canard Foam Delta (1 min 9 sec)

Posted by FeiJi | Nov 01, 2013 @ 08:13 AM | 2,407 Views
Just doing some flying around. Finally resolved why takeoffs and slow flying would stall. I had rounded the leading edge of the forward half of the wing with wooden dowls but left the rear halfs flat - this is a 9mm epp flatplate. On takeoff the delta would roll left then right terribly until I got some speed up. So I rounded the rear half leading edges with dowls and problem went away. Now this is a really fun and easy to fly flatplate.
Also I cut the elevons down in an attempt to solve the problem but it wasn't due to too large elevons and now wish I hadn't cut them down.
I plan to make a slightly larger X45 like this but with an airfoil.

X45 EPP Scratchbuilt Delta Wing flight (3 min 29 sec)

Posted by FeiJi | Oct 19, 2013 @ 10:49 PM | 4,706 Views
AUW 22.9 ounces, Wing Area 511 square inches. WCL 3.4 and is pretty much a glider.


Ugly Plank (3 min 2 sec)

Posted by FeiJi | Oct 15, 2013 @ 07:47 PM | 2,943 Views
Decided to build another x45 type delta. Laminated 9mm epp foam flat plate with a few barbecue spits to reinforce - very stiff wing. Using a small brushed motor because I accidentally ordered a few brushed ESCs. AUW 270grams with 500 3s lipo. Wingspan is 680 mm. WCL is about 3.4 so hopefully the little motor will push it around a bit. Later I will install 2208 2600kv motor and see how fast I can go. Just have to install control rods- ran out of spokes. Took about two hours to build

Update Oct 18: little brushed motor barely pushed it around. So have mounted 1800kv motor w 7x5 prop. AUW 320grams 284 sq inches, WCL 4.3, 1100mah 3s lipo. Waiting for football field to clear from soldier trainees to fly.

Flew it, a little fast and difficult to launch as wings are warped down a bit.
Have reshaped wings so will see if it curse stall on slow landing.
Update Oct 27: Still twitchy especially on takeoff. These elevons are huge so trimmed some off and will move to lower hole on servo arm. Fun to fly though but this is my last flat plate - something just seems different about flying a real airfoil and the flatplate just doesnt seem like an airfoil.
Posted by FeiJi | Oct 11, 2013 @ 04:25 AM | 3,183 Views
Added these plug in wing extensions to my 1 meter plank to make it 1.5 meters. They plug inside the ends of the 1 meter wing and then are held on by tape. Feel very sturdy and little flex. Haven't tried flying yet. Made from 9 mm epp, then laminated then added couple barbeque spit spars. Each extension weights 50 grams.
Wanted to get more soaring time but still be able to fly 1 meter wing aerobatically without them. Also will allow me to test out different wing tips
AUW is 640 grams now with little 2208 1800kv motor - should still fly.
Update Oct 12: It flies. I was afraid it would be too heavy for the motor but in fact I had to back off the throttle to keep it under control. Tons of lift and in poor conditions, in the lee of a building, on a tennis court and in gusty wind. It also still banks sharply, I was afraid the now inboard elevons wouldn't work so well but they do. Just wanted to know if it would lift off. Sunday is supposed to be fair weather.
Update Oct 13: Took it out today and floated it around way up high to take some video of the school. Real floater and can be flown very slow.
Update Oct 18: Trimmed extensions a little to be more aerodynamic. Wing area = 511 sq. in., AUW 22.2 ounces for WCL 3.3. It really qualifies as a glider.
Posted by FeiJi | Oct 01, 2013 @ 07:48 PM | 3,158 Views
Replaced tail with a bit bigger and more aerodynamic one. Rolls are a bit better after I fiddled with elevons. Flew this morning for 10.5 minutes on 1100 mah battery. Just floating around with the birds at about 30% throttle. This wing is my favorite to fly now as it is so bird like. The only real weak point is my motor mount. Just a bit of plywood hotglued to epp. Tends to break on landing because the prop is still windmilling. I have some prop savers ordered but still need to build stronger mount. New Hobbit installment is due in Dec - looking forward to it.

Added piece to top of fuselage and it is stronger and looks better I think.
Added tail piece so have a few more square centimeters of wing area.

Am going to build a new plank similar to this one but use rectangular fuselage construction, thicker wing and bring top wing section all the way to the trailing edge so will be smoother airfoil without any trimming necessary. Also thought about building some wing tip extensions that plug into the end of the current wing tips to get some more soaring capability.

Update: I messed up putting a flat surface on the top of the fuselage that slopes up to the top of the wing - it is acting as a control surface and making the plane fly strangely and seemingly with more drag. Will take it back off and mount two panels at 90% angle to each other and see if that works.

Update Oct 5: rounded the flat panel on the fuselage and flew 3 flights. One was for 12 minutes on an 1100mah lipo. Flies beautifully now. Absolute joy to fly this wing.
The hollow wings are open at the ends so need to tape them up but they make a cool sound when they are open. The diagonal stripe on the tail makes it easier to see orientation of wing when it is far away.

EPP Foam Ugly Plank Wing (3 min 50 sec)

Posted by FeiJi | Sep 28, 2013 @ 04:31 AM | 3,126 Views
First flight of my 9mm laminated EPP foam plank. Great carves (banks I guess), nice loops, not very good rolls (that could just be me though).. Great fun to fly. Seems pretty stall proof. Have to make a better motor mount though.
Going to make a better tail.
Sound on video breaks up a bit - I am using a cheap usb mic adapter and the driver doesn't play well with my video editing software.

Update: found out it rolls to right great but not left. Right elevon doesn't have as much throw as left so increased it a bit. Will see how it goes now.
Fixed the problem, not enough up elevon. Rolls great - fast and axial.
Ugly Plank Maiden (2 min 35 sec)

Posted by FeiJi | Sep 27, 2013 @ 03:31 AM | 2,889 Views
1 meter 9mm epp laminated foam. Wing has fiberglass fishing pole spars and is unbendable. AUW with lipo is 520 grams. Could have saved another ounce if I skipped the spars which I really didn't need. 1800kv motor with 1100mah lipo. This one is a half pound lighter than my first plank which flies really well. Will maiden in day or two. Wing is really ugly as I trimmed with knife but didn't have any sandpaper. Wing held on to fuselage with couple of zip ties. About 5 hours to build.
Did I mention that it is ugly.
Posted by FeiJi | Sep 17, 2013 @ 04:56 PM | 3,057 Views
I pulled out my Plank wing, replaced 1800kv motor with 2217 2700kv motor and 1100mah battery with 1800mah. Flew right out of my hand, very fast and smooth then started doing loops and rolls, went into death spiral and boom. Surprisingly, the wings just separated from the fuse, the motor shaft got pushed back a bit and the casing of the rx came apart but it all fits back together. Couldn't find prop or prop adapter. Crashed not far from an automobile so am thinking I need to test this out on the island where there is nothing to hit. Wow, flying it felt so smooth and effortless - and it looks cool in the air. I thought as I was walking to pick up the pieces that there wouldn't be anything left but epp just bounces. Have to rebuild this one.

Figured out why I spiraled in, left screw out of servo arm and right elevon jammed all the way up when I was slamming it around. - so my theory goes. Bent motor shaft a bit, motor probably wont last long as I will fly it anyway. Don't have any straight shafts.

Took about an hour to get plank back together. Ready to fly tomorrow.
Posted by FeiJi | Sep 05, 2013 @ 06:01 PM | 3,269 Views
My one trick pony solution.
RC Foam WIng with Elevating Motor Mount (0 min 57 sec)


Since my first flights I have had a few more and now takeoff is smoother and when I transition the motor mount to normal position and add down elevons it goes nicely into level flight. If I transition the mount without down elevon the plane will nose up and harrier until I add down elevon. The original flights were tail heavy so added more nose weight. Landings are a breeze as the wing is pretty stall proof.
Posted by FeiJi | Aug 06, 2013 @ 08:08 AM | 3,974 Views
Here is a short video of my epp finless wing prop clawing its way into the wind.
The takeoff was abysmal. The final pass is what I guess drag sounds like.
Update: I woke up this morning and just realized what is probably making the whirring noise as the wing passes downwind: I have an exposed carbon spar holding the back of the wing together - except that it is broken on one end and free to vibrate, and the wing is hollow to boot so it is probably acting like a stringed instrument. Maybe.
That might be an interesting sound effect to pursue. Like throwing a guitar out of a 20 story window.

40 inch EPP Wing in the Wind (1 min 23 sec)

Posted by FeiJi | Jul 08, 2013 @ 06:34 PM | 3,327 Views
Here is a little trainer I made for someone who has never touched a transmitter. Kind of fun.
Scratchbuilt RC Flight Trainer for Copter or Airplane (10 min 40 sec)

Posted by FeiJi | Jul 05, 2013 @ 05:20 PM | 3,128 Views
Flew at 5:00am with slight breeze - 1800mah 3s lipo and got 15.5 minute flight on my 40" scratchbuilt epp wing. Guess that is my limit as my arm is sore from holding the radio and just tired of looking up that long but happy - longest flight to date.

From 12 sheets of epp foam I now have a fast wing, a putzing about aerobatic delta wing, a 40" wing, a P51, a couple of "normal flying" 30 inch wings, a forward swept wing, a plank wing, and a few failure wings.

Sitting at about 44 hours total air time now for about two years flying. 6 more hours and I could qualify for my private pilot certificate.
Posted by FeiJi | Jun 22, 2013 @ 08:09 AM | 3,182 Views
Finally got my 40" wing flying well. A pretty good glider at around 5 WCL. Got 12 minute flight in a little wind on 1800mah 3s lipo, 1800kv motor and 7*5 prop. Moves pretty fast full throttle and floats around on 30%. Want to try 2700kv motor next.
Boneyard #5. Laminated 9mm epp foam. Had to move motor forward and still has 2 ounces of weight in nose. Should just move up to 2200mah battery.
Shouldn't have made the weird prop cutouts though, should have rounded them. Put a fiber rod to tie back ends together.