FeiJi's blog - RC Groups
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Posted by FeiJi | Jul 03, 2018 @ 01:09 AM | 3,271 Views
Couple more photos of my delta wing. Learned a couple of lessons. Bottom is perfectly flat so next time might use symmetrical shape. See how this one flies. Might use some sort of software to design ribs but that is too work intensive for me. Probably use a single center fuse rather than two.

Strapping tape ironed on seems t adhere to epp ok, if not then will use hinges for elevons.
Made motor mount from couple layers of 3mm plywood. Want to be able to dismount motor mount easily. Plastic motor mount will be bolted to plywood.
Elevons are very rigid. Used a carbon rod and laminated them.
Not too much more work to do now.
Posted by FeiJi | Jul 01, 2018 @ 02:04 AM | 1,037 Views
Bought a few sheets of 5mm EPP foam and using one to build a delta wing with ribs and spars. I just like the idea of a wing having a frame of some kind. This is totally a design it as I go and it already has characteristics of that kind of build: adhoc structure, crooked cuts, dimples on the skin. But it should have a lot of lift and be very light.
I am using carbon fishing pole sections for the internal frame and 8mm epp foam for the ribs.
I plan on powering it with a 2206 - 1500kv motor tractor style.
It should light up nicely with leds inside.
It will have chord of about 53 cm and wingspan of 85cm.
Weight so far is 175 grams.
Should weigh about 12 to 14 ounces with 450in sq of wing area and WCL of 2.2 or so.

Working on elevons next. Will double the 5mm foam, add a carbon rod and laminate them. Heavy but since the motor is in the nose it doesn't matter.

Update: elevons done, tail cut - needs to be laminated. Then install servos, then figure out a motor mount, then install electrics, then final foam pieces, then fly. Unfortunately I have to go to Beijing for a couple of weeks so this project is on hold.
Posted by FeiJi | Jun 04, 2018 @ 07:51 AM | 1,369 Views
This craft seems a little unstable in flight. Bobbing up and down in pitch. Even the pilots seem to be fighting the sticks a bit.

Richard Branson Welcomes VSS Unity Home from Second Supersonic Flight (2 min 43 sec)

Posted by FeiJi | May 15, 2018 @ 01:10 AM | 2,251 Views
Didn't see anyone posting this from Flitetest and you shouldn't miss it. Pretty cool.

CHAIRPLANE! We made an IKEA chair fly! (9 min 34 sec)

Posted by FeiJi | Apr 01, 2018 @ 11:36 PM | 1,726 Views
Still figuring this stuff out. Got to flying field at 5:00am and forgot one of the led batteries so had to fly with only one wing lit up. Still learning the app and flew couple flights thinking I was photographing when in fact I wasn't.
Need to point camera up a little more next time, too much black space at the bottom (or I could just fly lower).
Some kind of frequency thing going on with the camera, or app, that puts little black lines in the light trails. Don't know what is going on there. Might try a different app next time.
Going to order some different colored LEDs someday. Also may use a multiplexor thingy so I can switch the lights flashing sequences and stuff.
This plane (Lighting epp wing) is great for flying at night because it is so smooth and predictable. Don't think I could do that with the little wing that I have. Might buy a Crackwing and light it up as it looks very controllable. Always something new to do and learn with this hobby.
Posted by FeiJi | Mar 30, 2018 @ 07:53 PM | 1,694 Views
Flew my Lighting EPP Plank at 4:00 this morning trying to get some long exposure photos. Everything that could go wrong - did. Started off flying and my controls were inverted so crashed the plane. Then flew and got one photo but broke one of the LED leads. Then flew and took another couple of shots at different F stop level and the motor quit working - broken lead. But at least my handy dandy DIY tripod phone mount worked beautifully.
Phone mount is just an angle bracket of aluminum to which I clip my phone with an oversized clothes clip.
Long Exposure app is free app on Google Play.
First photo: f/5.6, other two at f/4
Posted by FeiJi | Feb 09, 2018 @ 06:28 PM | 3,313 Views
Here is an interesting article that says 20 degree rotor angle tilt can improve pitching movement in wind.
https://www.sciencedaily.com/release...0209100730.htm
Posted by FeiJi | Feb 07, 2018 @ 04:28 PM | 3,313 Views
Here is an interesting article showing how shark scales generate lift and perhaps this could be used in designing wing skins to generate more lift.
It would be an interesting project to 3d print a cross section mold of these vortex generators and use that to mold a foam flying wing to see how well it performs.

https://www.rdmag.com/news/2018/02/u...-wind-turbines
Posted by FeiJi | Feb 06, 2018 @ 05:53 PM | 2,236 Views
Incredible historic success.
Posted by FeiJi | Dec 18, 2017 @ 12:03 AM | 12,518 Views
Cool looking plane, hope it happens.
Posted by FeiJi | Dec 14, 2017 @ 05:29 PM | 2,986 Views
I wasn't paying attention - I guess as of December 12th, we need to register again if we fly anything over .55 pounds. If I come back to US then will have to just fly under 249 grams.
Posted by FeiJi | Dec 09, 2017 @ 04:07 AM | 2,507 Views
I can't fly 3D yet but this is a good plane to learn on without hurting anyone.

3D EPP Sumo Clone (2 min 19 sec)

Posted by FeiJi | Nov 18, 2017 @ 10:52 PM | 2,789 Views
Update: did maiden flight this morning, wow, cool. I am hooked. Flies a long time on 800mah 2s or 500mah 3s lipo. Weight with 43 gram battery is 218 grams.

I haven't done any flying or building in a long while and have never really done any 3d flying so bought this EPP kit for 15 dollars here in China that has the foam kit and hardware, I think I have everything else. It will use 2 5gram servos and one 9g. I have a couple 800mah 2S batteries but may have to buy some 3s for this one. I guess this is a Sumo clone huh?
I put the foam together with some hot glue. Will leave off the decals to save some weight.
Here is the link and couple of videos (in Chinese), the flying one is pretty entertaining.
https://item.taobao.com/item.htm?spm...cket=12#detail

I have finished adding the hardware and servos and just lacking a motor and prop now. Don't have the 1500kv motor and 8-inch prop so might just fly it as a regular airplane with at 2200kv and 6-inch prop until the suggested motor comes.
Posted by FeiJi | Aug 09, 2017 @ 11:09 PM | 3,338 Views
Here is an interesting article on how drones of the future will be powered by gas/electric generators for hours of flight rather than minutes.

https://www.rdmag.com/news/2017/08/h...ater-distances
Posted by FeiJi | Jul 04, 2017 @ 08:16 PM | 4,368 Views
Interesting article about owl wings leading edge serrations and other characteristics that make for a quieter flight.

https://www.sciencedaily.com/release...0704093621.htm
Posted by FeiJi | May 27, 2017 @ 09:37 PM | 5,203 Views
Formerly I had just taped some green LEDs onto my wing and that worked ok but you could hear the increased drag as the plane flew by and it cut down on flight time so I decided to cut some forward facing slots and insert the LED strings into the BOTTOM of the wing. Here are a couple of photos. I cut the slot, then push the wing apart and insert the string into the slot and then used a little hot glue in few places and just spread it over the slot to give it a little more strength. The LED string is flush with the wing so no increased drag.
I have done both wings and ironed on some bi-directional tape over a few areas. Hope the tape sticks.
Currently am using two small 1s lipos to power the 3 volt strings but plan on buying some 12 volt strings for the future so can just run them off the main lipo.
This should be loads better than taping on the wing. Here is an awesome writeup by CrashTestHobby.com about how to do it.
http://www.crashtesthobby.com/night-...ed-lights.html

Also an acrylic painting I did of one of my students.

Update: flew last night on football field and flies great. No drag and very visible. Unfortunately one led battery was dead so flew with only one wing visible but still easy to fly. Now can fly with or without lights and no difference in fight characteristics.
Posted by FeiJi | May 13, 2017 @ 08:16 PM | 5,300 Views
Put couple of LED one meter strings on my wing. Wow, very bright at night and dawn (totally ruins night sight). Much better than EL wire. My LED strings were 3 volt which posed a problem as I had to power them separately from my ESC battery but I had two small 1s lipos that are light and power the strings just fine. I tried using the 6 volts off the receiver but it almost killed my ESC - drew too many amps. I suppose 6 volt LEDs might work but could still draw too many amps. Other alternative is to use 12 volt LEDS and use ESC battery - probably the lightest solution and better if having more than 2 meters of LEDs.

I put the leds face down on the EPP so that they light up the wing more. Need to tape down the wires I guess for less drag. Very little weight added to the wing.

I bought my LED one meter strings (3528) for 11 rmb each (about 2 bucks) which is a whole lot cheaper than US prices that I have seen. Was worth the try. Guess I will keep them on the wing for a while and do some dawn flights since I go out running on the football field at that time anyway before the students start arriving for their runs.

Have a strange problem in that when I solder connectors to the strings and plug in the battery, only the green lights work. The red and yellow just blink on briefly and then go out. Guess the plug causes a touch too much resistance for the current my batteries are supplying (450mah). Not s
ure how I will get around this problem except with larger current batteries. Would be nice to have some other colors on the wing.

Lighting Wing with LEDs (7 min 50 sec)

Posted by FeiJi | May 02, 2017 @ 07:42 AM | 5,813 Views
Mounted my Canon 350HS Elph on my baseball cap. Much better at taking night video than my micro camera.

Lighting Dawn Flite May (4 min 18 sec)


Here is longer version of dawn flight.
Lighting Dawn Flite May 2 (8 min 47 sec)
...Continue Reading
Posted by FeiJi | Apr 30, 2017 @ 08:31 PM | 6,049 Views
A snippet of an early morning flight. Camera barely picks up the el wire lighting on the wing. Need to try leds. Will also mount my Canon Elph on my hat and try that first.
Lighting Night Flight (1 min 19 sec)