FeiJi's blog View Details
Posted by FeiJi | Sep 22, 2018 @ 01:32 AM | 618 Views
This is a neat article about using acceleration and roll torque sensor readings to make course corrections for better thermal navigation.
https://www.sciencedaily.com/release...0920101605.htm
Posted by FeiJi | Aug 20, 2018 @ 07:03 PM | 1,307 Views
In making my epp plank wing I had inadvertently made a crushable fuselage - shock absorber when I extended the front of the fuselage by putting a smaller diameter rod inside a larger one. When I crashed nose-on the fuselage collapsed and just wrinkled up the epp foam and the motor just popped off, no real damage. Just hot-glued it all back together again.
Wish I had taken photo of fuselage all crunched up. Hopefully it wont happen again. I had just launched my plank but it was responding to a turn so slowly because the tail was loose and bending back and forth.
Posted by FeiJi | Aug 14, 2018 @ 08:00 PM | 1,042 Views
Added little nose wheel to drag out landings a bit. Seems to land nicer than and with less shock than just a skid. Now want to raise the nose wheel to give prop ground clearance to see if delta can take off from the ground. May have to change motor and prop to give it more thrust.
Update: I raised the nosewheel to provide clearance for the prop- did takeoff from the ground. It worked but was so unstable in the air that I clipped the nosewheel on the ground and it broke off. Wish I had videoed it - was funny and cool at the same time. Will glue it back on and try video sometime.

Delta Take Off and Landings With A Nose Wheel (2 min 16 sec)

Posted by FeiJi | Aug 13, 2018 @ 02:23 AM | 1,380 Views
Epp Plank finally flies. It flies fast considering it has a slowfly prop and tiny 2206/1400kv motor. It is heavy, 450 grams and I have to really heave it to get it into the air and then it sort of fights its way up. Way under powered plane but great once it gets going. Unfortunately I had a tiny ESC on it and it was too much at full throttle. Plane doesn't really land, it just kind of falls out of the sky onto the ground. But built Ford tough. Looking forward to getting this one up to speed. It sounds kind of cool because one end of the wing is open. Also replaced crooked control rods with stronger straight ones cause they were bending - that's why it ended up in a tree. Got it down with a 5 meter bamboo pole.
See if you can hear when the ESC gives up the ghost.

EPP Plank Maiden, Fourth Flight and ESC Expires (1 min 9 sec)

Posted by FeiJi | Aug 01, 2018 @ 10:52 PM | 1,197 Views
This is a lot better than the maiden. Smooth takeoff and landings, tight rolls but it just kind of flips over on loops. Very pitch sensitive. Think it is because too much play in the elevons. Elevons are too large too but if I fly it more aggressively then that makes it more fun. Don't like to use expo.

EPP Delta Second Flight (2 min 25 sec)

Posted by FeiJi | Aug 01, 2018 @ 07:15 PM | 1,237 Views
Got this headstrap that can hold my mobile phone which has a great camera. Much better than my micro camera which had such a small field of view that it was difficult to keep the airplane in sight.
Posted by FeiJi | Aug 01, 2018 @ 06:10 AM | 1,540 Views
Pretty much finished building this plane. It ain't pretty but it sure is strong. AUW is about 14 oz and wing area is about 270 sq inches so WCL is about 6. Should fly. Got a tiny motor 2206 1400kv with a slowfly prop but thrust will be about 1:1. Going to be an interesting maiden.
Used some servo arms for the control horns.
Rubber bands holding wing on but may use bolts.
Rubber bands holding hatch on but will use magnets.
If it flies then will try a larger motor and proper prop.
Also would like to build second very flat wing to see how fast it will go.

Raining so much lately just cant get out to fly.
Finally got a proper headgear to hold my cell phone for taking video.
Posted by FeiJi | Jul 30, 2018 @ 07:23 PM | 3,172 Views
You gotta watch this thing take off and land. Incredible.

DRACO - The Most Badass Monster Bush Plane EVER! (20 min 37 sec)

Posted by FeiJi | Jul 30, 2018 @ 12:55 AM | 1,803 Views
Wow, awful maiden - too many problems.
Servos were reversed so nosed into the ground when I thought I should be pitched up. Prop mounted backwards. Servos loose. Bent motor mount on first take off. CG too far back. Windy.
So fixed all those except CG and it flies - but motor angle is down because of motor mount so will redesign motor mount and it should fly fine.

This micro camera is awful - audio out of sync and video got sped up. Ordered a head mount for my mobile phone as I like the video it takes.
Next flight should go much smoother. It does have a lot of lift and the tiny motor still can make it scoot. Put a proper propeller on it and it should really move.

Scratchbuilt Delta Maiden (0 min 58 sec)

Posted by FeiJi | Jul 21, 2018 @ 10:41 PM | 1,828 Views
Started building a plank using 5mm (and a little 9mm) EPP and carbon fiber fishing pole tube sections. Will skin in 5mm foam and then laminate. Won't be pretty but will be strong. Will build wing same way. Love foam and hotglue and just eye balling it.
Posted by FeiJi | Jul 19, 2018 @ 09:13 PM | 1,718 Views
Not quite finished, needs a couple of hatches made but it is functional and ready for maiden which I could do tomorrow but will probably wait to get a headmount for my phone camera to take videos. CG is back about 23 cm and had to use a little ballast to get it to balance. Could use a much heavier motor and/or battery with more thrust - this little motor gives about 1:1 but the lift should be awesome as the AUW is 340 grams. I added some tape covered skids on bottom to protect fragile leading edges and to keep motor mount from digging into ground.

If it flies nice I might try faster prop rather than this slowfly prop, and add a rudder with 5g servo. Also could go with a bigger motor.

Excited to fly it but am thinking about my next project already which will be a scratchbuilt hotliner using same 5mm epp foam and fishing pole tubes and just elevons with only a vertical tail.
Posted by FeiJi | Jul 03, 2018 @ 01:09 AM | 3,818 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 | 1,616 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 | 1,915 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 | 2,781 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 | 2,234 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 | 2,228 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 | 3,960 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 | 3,816 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 | 2,728 Views
Incredible historic success.