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Old Feb 19, 2011, 07:38 PM
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Build Log
Better fpv Video added. New member here, checking in with a 54" flying wing

**Newest: Better Quality video with fpv overlay (fpv shot under wing away from prop this time, using same dv80 mini cam) and much more aerobatics this time. My wonderful wife is great at many things, but we are still working on video technique apparently.. enjoy The dv80 was $16 shipped on ebay and works awesome, but the file format for a 15min video yields a 1gb file!! Had to rip it down with avs editor, which is a great way to sync up an fpv overlay to whatever filesize you need. The hat cam you see me wearing is a 1080p hp cam that somehow never got the plane in the shot, so I'll have to figure that one out, so my overlay is still done with the video taken from my new Motorola Atrix phone, which can do 720p btw.
Also I should reiterate the fact that all this is being done at 70w per lb so I sorta chucked the ol rule o thumb out tha window not to mention most all the 11 minute flight is done at 60% throttle and using only 1700mah total power with a hefty 40oz auw!
3rd vid w fpv overlay (11 min 20 sec)


**video shot from inside car with and fpv picture thumbnail "picture in picture" window. Took a bit of effort to get the time sync right but I think it made for a more interesting video! The second video underneath is better quality and without the fpv inlay. I'm still figuring this video editing stuff out as I go.

More aerobatics, loops, inverted loops, rolls from a dive, and some big nasty stall thing, and a double camera video test, nearly all the sound is from the fpv cam. -- please, pardon my wife, she has a hard time keeping the camera pointed at the plane and following smoothly, she did better this time but I think she's more interested in being comfortable than anything, which is why I thought it'd be best to have her shoot from inside the car (plus was windy and cold.. )

2nd Wing Flight W FPV overlay (11 min 4 sec)


Better quality, same video, without fpv inlay.
2nd wing video (11 min 4 sec)


**Video added of 3rd time flying. This is one stable bird. Winds were 10-11mph, but you couldn't tell it flying. Video complete with minor aerobatics (a few loops and rolls around 5:00 and toward the end) and a very nice ending with a land-in-place.. Please excuse the camera-woman, she is normally only marginally interested in what's going on..



1st Vid Flying Wing Design (12 min 44 sec)




Hi everyone, I am a new guy here, a senior mech engineer undergrad, and I guess I use my spare time for things I shouldnt, like building planes out of foam for weeks on end....

I guess I may do a seperate build thread for each of these and possibly provide plans for them if any interest is shown, but this is honestly just to show off my favorite of the builds I've done. This wing flies like it's on rails and surprised me with how very little reflex it needs for level flight (almost none as far as my eyeball can tell).

Flying Wing design: Scratch built from an idea on a very snowy day after flying the Twist 3d on the clearview simulator, it is floaty, controllable, great at 3d, and has a huge symmetrical wing.. Also inspired by seeing the "swifter slope glider" on youtube as it is very stable flies on rails in high wind and also uses a big rectangular wing.. So the project just morphed into this big wing as my biggest 450 motor would be underpowered for a full fuse plane I think, and the short fuse kept it light and very strong.

Very aerobatic capable, but not much vertical though a higher kv 450 will fix that, a little wind and loops pretty easy, rolls are like any wing should be, pretty axial, pretty predictable, flies fast and stable or slow and stable, but if you build one of these just know that 10mph winds will give you a fit with landings, but makes it fun in the air, just really light with big wing area so wind really tosses it a lot, yet doesnt make it unstable, just carries it, so I think the thick airfoil is working like it should.

Details:
54" ws (wing weight before adding fuse and elevons was 450g on the dot, which I think is pretty light for as stiff as it is with the foam and carbon spars)
21.5" chord
20% guesstimated airfoil - reflex comes from elevons but doesnt need much
rectangular symmetrical design
~5oz./ft^2 wing loading (40oz auw at ~8ft^2 wing area)
alpha 450 890kv motor ($12@Hobbypartz includes shipping)
11x4.7 apc sf prop- perfect match for the power system
Blue Lipo 1800mah 3s ($9 shipped from hobbypartz holds full spec'd capacity)
Exceed Proton 18A esc (got the prog card but didnt need it I guess)
3 Dynam/Detrum 7g servos ($3.60 a pair hobbypartz also)
Flysky fs-ct6b radio (using elevon mixing works flawlessly)
CG @ 20%

Hardware used
Control rods from $1 kites at walmart/dollar tree with heatshrink from radio shack and wire for z bends from hobby lobby (.032")
Bracing rods from $3 walmart 52" delta kite (Barbie one works best)
Landing gear rods from same walmart kite.
Tail skid from $1 kite rod sandwiched b/t double thick v stab
Elevon protector skids from leftover $3 kite rods (they just stick out and down behind the trailing edge and are about 8" long- they also keep the plane from rolling backwards in wind)
Control horns from $1 50pk dental flossers ($tree)
Hot glue (dollar general sells packs of sticks for $1.50, the cheapest I found anywhere by far)
Harbor Freight contact spray adhesive and it didn't eat the foam at all, but very very sticky stuff and stays that way (used for skinning)
Packing tape for sealing the wrapped edges of the clear giftwrap (used a monokote iron to stick it down, then finished sealing with plain $1 packing tape, works very well)


This thing is pretty pitch sensitive yet very stable at the same time, takes off in less than 10ft, flies at under half throttle, and was flying in place in 8mph winds, I could actually gain some altitude and cut throttle to 0% and it would hang midair for a bit, wind was gusting to 11mph and very turbulent today for such a light wing load, but honestly the wind made it more fun I think, all but the landings that is..

Ribs are elmers foamboard due to it's rigidity, but it was also free from the architecture dept dumpster (about 50x rectangles of it 24x6 all identical). I also found about $100 worth of scrapped balsa along with the foam..

The fuse is skinned with dollar tree foam maybe 2 sheets.. The wing spar is 1 40" carbon rod, and the fuse uses one easton arrow shaft sourced for $1 from the local arrow shop.. They have about 100 left at that price... Very light and strong...

The wings are skinned with dollar tree transparent gift wrap, and the skin came out tighter and nicer than many monokote jobs I have seen, the trick is to NOT use too much contact adhesive, and cut it to fit overlapping itself, then I melted the overlapped edges together tacking it with a shrinking iron on med-hi then used packing tape to seal, then shrink with gun, the packing tape will shrink very nicely too on repairs and is almost invisible, surprised me greatly as I fixed a hole from the gun and the tape shrunk drum tight..

Hope you guys like it, it was a very simple build, and I used some fiberglass rods sourced from the $3 walmart kite (52" delta) for the landing gear, and some popsicle sticks for bracing, and some bbq skewers for triangle braces on the lg, and for the rubber band motor mount which survived a nose into the gym floor yesterday with no significant damage at all... Soft gray foam works nicely for battery compartments, my lipos have survived several nosedives due to using it for holding them in place in their compartment. even a lawndart maneuver from about 50ft up..

I am an inexperienced pilot yet this wing was very easy to control after learning to hover the various profile foamy's on clearview and a few hours of flying several different models..

Enjoy the pics, video will be here in a week or so, but I read here all the time and thought I would share what the foam craze here has inspired me to build and I must say it was very satisfying to actually use up 3 batteries and fly for nearly 45 minutes in gusty wind without breaking a single thing on this plane and after a little redesigning the landing gear has very good suspension qualities and was bounced a few times today with no visible damage, which is a big jump for me especially in wind!

The photos don't show the newly added rudder btw, which works very well when airborne..









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Old Feb 19, 2011, 08:02 PM
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larryross's Avatar
Grand Junction, Colorado
Joined Dec 2007
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Cool concept, but I really like your quick change motor mount and your hatch latch... simple, but effective. Good Job.
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Old Feb 19, 2011, 08:28 PM
Just call me crash for short
Quick61's Avatar
United States, OH, The Plains
Joined Jan 2011
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Nice build. i can see where the statement "I guess I use my spare time for things I shouldnt, like building planes out of foam for weeks on end" comes from. mechanical engineer and a craftsman. In my travels, a rare find. (if I had a nickel for every argument I had with an engineer where it turned out that I was correct and they were not.....) I really like the wing construction. What did you cover it with, may I ask?


EDIT:
*** Never mind. It would help if I read the entire post first and not jump to the pretty pictures. :-)
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Old Feb 19, 2011, 09:08 PM
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United States, NY, New York
Joined Dec 2009
487 Posts
nice interesting build u have. One suggestion or question is - u going to use the rubber band to hold the motor mount? that seems a little weak. i do enjoy building something that could fly. Wish u good luck and have fun building this design. keep us posted.
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Old Feb 19, 2011, 10:22 PM
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Joined Feb 2011
108 Posts
It is probably important to note that all my landing gear crossbraces as well as the main axle (fg rod from hobbylobby bat-kite) were all tied with kite string with multiple wrappings, then square-knotted and finally soaked in superglue for a very strong and resilient connection, and I couldnt think of a better way to do it either.... ( used medium ca, sold at dollar tree as "future glue" with brush applicator for $1). The kites come in handy for cheap pushrods, supports, and even landing gear structure.

I used fg rods for all my pushrods from the $1 kite from dollar $ but I found that the $1 kite from walmart has a little better/heavier rods.. Made z--bends with the $0.89 .032 metal wire from hobby lobby and heat shrunk it to the rods end, just after dropping a dot of thin ca into the open heat shrink... The only thing is that once you ca them you aint movin em, BUT if you hot glue them you can adjust the rod length with a lighter later (instead of using your perfectly centered trim switches that look so much better to me in the middle ... Just a tip there...

Well yeah, you missed the covering because I cant seem to just write just a few sentences about anything, and if you knew how long-winded I am in conversations you'd understand..

The motor mount uses only one rubber band per side, and it is folded into 4 sections total, so the tension is pretty high, but it flew very well today and they didnt break after the nosedive into the gym floor during landing gear and taxi tests... Sorry, an engineer with no numbers is not much...

Well, thanks for the compliments and the welcome anyhow, I must give credit to this calculator for flying wings for finding the cg, it was pretty much dead on, even though the glide test would tell you it wants to nose dive, that wasnt the case at all under power or in wind..

http://fwcg.3dzone.dk/?wing_span=116...ow_mac_lines=0

The latch idea just came to me, on the radio compartment I was in a hurry so I just bevel cut the panel door on a rough 45 so it wouldnt just fall through, then taped it back shut, much easier than making 3 latches..

It's hard to see but there is an air intake on the bottom esc compartment cover made from a coke bottle neck, like a hood scoop or a blower intake and I used an ir thermometer to verify about a 25 degree F temp drop when using the air intake ventilation/cooling method over just cutting holes.. The prop wash is perfect for diverting some cooling air for hot components and after my batteries were getting pretty warm today I'm doing the same to the battery door..

I also must say I'm impressed with the flysky ct6b 2.4 radios, @ $32 shipped with rx and unlimited model memory (via laptop) it's an unbeatable value and has worked great on a tiny 500mah 3s lipo, so that proves there's no need for the specialized tx lipo's, as I flew for an hour and the battery was still 11v..

More pics after adding rudder (glad I did mostly for landings and crazy wind!) and pretty heavily revised landing gear, needed lots of triangle bracing and gusseting to be bounce proof, and it took lots of bounces today with no breakage, the trick was tying the tension line across the right section of the fg rods to get the bend right, so the resting points would be very forward of the cg to prevent nose-over on landing or takeoff, and the steep angle of attack resting on the lg makes for a very short takeoff and very slow landings possible too.


Battery cooling idea with forward intake made with coke bottle plastic (just in pencil as of yet)

Newly revised landing gear with tons of spring but not much weight. (skewer x braces make it very stiff in the right places and side to side but still allows lots of spring up and down)
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Old Feb 19, 2011, 11:04 PM
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Here are a few other planes I made just for show and tell...

This was inspired by leadfeather's pbf, but is about 400in^2 and flies really slowly and easily in a regular gym, despite it's porky 16oz weight.



This was sorta my own design with a sorta self modelled kf wing but using packing tape to smooth the steps, and it has a third step on top to create higher lift at slower speeds (good trainer) and the third step also covers up the heavy balsa spar that runs most of the wing length..



Now this plane is unreal how well it has held up to multiple dead stop nosedives, as well as being lawn-darted AFTER smacking a football field light pole!!! It tore the wing rubber bands off with the mounts, then proceeded to plummet straight into the ground driving the alpha 370 motor 2 inches into the dirt, and the fuse flew like a dart with the h and v stabs, and that motor still runs great on the pbf today, and the plane still flies perfect, the wing took very minor damage when smacked into the light pole, I was shocked that it just went right back together and needed one piece of tape on the leading edge of the wing and some foam bent back into shape and that's it beside rebuilding the landing gear, which I have done about 5 times now... Wish I had known about these kite rods then.. The balsa just isn't cuttin it...
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Old Feb 19, 2011, 11:05 PM
Just call me crash for short
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United States, OH, The Plains
Joined Jan 2011
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Yea, I get the whole long winded conversion thing, preaching to the quire here...

I have been designing / building my own bird and have just had some initial success. You being a mechanical engineer and all, maybe we could get together, here, there (http://www.rcgroups.com/forums/showthread.php?t=1389983 my build) or somewhere and see what can be done to lighten up the design? I was shooting for ~10.5oz AUW and ended up with 12.1oz. Mind you that this experimental KF wing looks to be able to lift 2X that weight if not more, I would like to find a way to get it lighter and still have the strength to withstand heavy loads. If at all interested, take a look and let me know what ya think. PM, here,(I'v subscribed to the thread), or on my build thread, no matter, it's shiny. If your not interested and/or don't have the time, no biggie. Nothing ventured, nothing gained. Just threw it out there, no one has to catch.
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Old Feb 20, 2011, 01:20 AM
Foam Av8r
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In Teh Garage (Rossville, GA. USA)
Joined Sep 2008
3,351 Posts
I thought I would ask before some one else does....
got any build plans?
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Old Feb 20, 2011, 01:50 AM
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Joined Feb 2011
108 Posts
Quick I responded on your thread, it's only about 2 pages too.

I can photo the foil drawing for you which was just freehanded, it just wont fit on a scanner and you can scale it. As for the construction steps, let me see what I can produce over the next week or so. This has come together slowly, but was really worth it. My final semester is proving to be tough as expected and time is shrinking like my brain, plus I have superglue all over my fingers too..

After cutting the main shape of the 10 ribs I marked only one, stacked them all together and squared them up with a square, then drug my knife ($1 from dollar tree) across the square edge lining up with the marks on the single outside rib, which made perfectly matched cuts in all ribs at once, try that with balsa!! so anyway I trimmed the notches out of each one individually after getting the cuts perpendicular to the edge all done at once, drilled one hole for the spar on 8 ribs(smaller bit for tight fit) and bam, it built right up really quick using (way too much) hot glue. Cut out the circles from a traced roll of masking tape and very tediously cut them out with a #11 bladed knife for a loss of almost 100g from all the holes! The trailing edge was just too weak to leave it foam and taper down as thin as desired, so I just used balsa, and you can see I changed trailing edge methods after bending the first side like crazy after shrinking. T braced is far stronger...

the landing gear was trial and error, more error than trial, and I started off using 10lb test for the tension lines that held the rods bent for the right skid shape, but one smack on the ground and they all went... Redesigned the whole landing setup and tied on an axle and the wheels are held on snug with some fuel line. After adding the x braces using bamboo skewers, suddenly the landing gear stopped acting like spaghetti and started acting like a landing frame with a suspension! the wheels can bounce over an inch, combined with that thick foam on the wheels, it can bounce pretty good, and it also allows the axle to shift left and right about an inch too with the flexy rods, but not much more movement than that. I am amazed at how well the rods work for the landing gear I might add.

Rudder has good authority when on the gas and will produce some tight circles and help with landing, but I like big surfaces better, BUT this thing yaws automatically using only elevons i guess due to the v stab lining it up or something, which is something a standard fused plane probably doesnt do.

The elevons are flat foam, but the hinge edge is doubled with about a 1/2" doubler, then cut at a 45 or so, and I then wrapped them with clear film, taped the seams and edges, then shrunk them to make a perfect tapered control surface that matches the taper of the wing.

I can almost say i prefer the attitude and characteristics of this wing more than any tailed airframe I have tried to fly whether simulator or otherwise.
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Old Feb 20, 2011, 02:39 PM
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Pics of construction:

Scale photo of ribs, length is right on 24, and you cut off 3" for elevons.. Thickness is right on 2.125", you can barely see the small arrows I chose to designate as the top side of the foil if you look closely..

Side photo of the wing tip shows the cutouts for the spars, one for leading edge, one down the thickest part of the foil (two halves meet in the middle really), one on top offset toward rear, one on bottom directly down center inline with carbon rod for load bearing right down the center of the bottom of the wing, it also forms a compound truss combined with the carbon rod as well as with the skin tension of the film covering. I can hold the wing and shake it violently back and forth flat side against the air and it barely flinches or flexes.

The thin kite rod pushrod on the rudder needed a guide in the center due to flex when pushing, so I cut a piece of elmers foam, then stripped the foam and paper from one end, leaving a flap of paper that would fold over the pushrod, and ca glued it to the other side's paper after wrapping it over the pushrod tightly, and no more flex at all.

you can see the balsa t-brace trailing edge and how the elevons are skinned also.





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Old Feb 20, 2011, 08:51 PM
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Landing gear test video, shows how well the leaf spring design/effect works:

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Old Feb 20, 2011, 08:59 PM
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nice suspension for most rough landings. keep up the good work.
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Old Feb 20, 2011, 09:55 PM
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ive honestly never seen it done this way but leaf springs are awesome for this. I recall it bouncing off the ground so much I needed to hit the throttle again to level it out but I was too late and nosed on the prop, but no damage at all.. It really seems to take impact well and just return the energy into a bounce instead of transferring all the landing energy into the airframe which just ends up breaking stuff if it's a hard hit which is realllly nice.
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Old Feb 22, 2011, 11:18 AM
Just call me crash for short
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United States, OH, The Plains
Joined Jan 2011
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Wheels

Sense you seem to be a fan of the $tree stores, thought I would pass along what I picked up today. While most looking at this pic might see a couple of toy trucks (one dissembled) what I see is 8 relevantly light weight wheels (4 grams ea. that could have a gram or so shaved off of them) and 2 small screws. All for $1.00. Should work out OK for landing gear. Happy flying!
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Old Feb 22, 2011, 11:30 AM
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Haha I wouldve never thought of that. At $1.70 a pair including shipping these super light foam wheels are cheap enough for me, but that vw bug would make a great canopy!

I will say that the toy aisle at walmart can turn up more parts than one may think and they are really competitive with the dollar stores with lots of items due to buying power, and the fg rods from their $3 kite are a gem of a find I will be stocking up on. I can't seem to find fg rods like them anywhere for even close to the price..
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