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Old Feb 22, 2013, 06:05 AM
DIY Mania from Taiwan
Taiwan
Joined Aug 2011
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Japaness flying snake

Designed by famous Japaness RC veteran.
he did it in a simple way but seems a lot of fun
like the way he packed up the snake after the flight
not yet to scratchbuild but anyone like to join to build one
FLYING SNAKE 空飛ぶヘビ (4 min 0 sec)

maiden flight succeeded.
cheap and easy,great fun with this multi-segments toy
Sam
http://www.rcgroups.com/forums/showp...5&postcount=93
PICT1922 (1 min 0 sec)

glide test at last second
PICT2100 (1 min 10 sec)

PICT2070 (0 min 59 sec)

here're scratchbuilt info:
snake head:cut from 340mm X 420mm 5mm depron
snake head undercarriage:glued from 2 pieces of 40mm X 420mm 5mm depron
snake head vertical fin:cut from 110mm X 420mm 2mm depron
6 tail segments:cut from 200mm X 420mm 2mm EPP
motor:36gram 1600kv BL
prop:GWS slow prop
ESC: 10A
servos:6 gram micro servos X 3 (elevon/rudder)
Lipo:3S 850mah
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Old Feb 22, 2013, 06:45 AM
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Now hang helium filled waterballoons in strings from the ground for it to catch! Real-life 3d Snake.
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Old Feb 22, 2013, 07:05 AM
TonyS
United States, AR
Joined May 2010
607 Posts
Sam,

Thanks for sharing the video!

The basic dimensions appear to be rather easily estimated; 4 to 4.5 hands wide by 4.5 to 5 hands long for head and 3.5 hands by 4.5 hands for the first two body pieces, slightly narrower for the next three, and the tail piece is tapered--about 3.5 hands wide by 4 long.

Do you think the material is Depron or softer foam, like in Dollar Store poster board? And, what material and shape for connecting the sections?

One of the two big questions for me is how much power to use. This may have to wait until the total weight can be estimated.

The main question for me where would the C of G be located? When we see the break in the tail at the end of the video, it seems the craft becomes nose heavy and he can not keep it from descending. So, as should be obvious to me, the balance point has to take in consideration the weight of the body and tail pieces. Perhaps he balanced at 20-25% of the total length?

I will ponder these questions for a while. I will also work a basic design SketchUp.

TonyS
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Last edited by tonystro; Feb 22, 2013 at 07:07 AM. Reason: to add a question
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Old Feb 22, 2013, 12:11 PM
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DeBary, FL
Joined Nov 2010
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Quote:
Originally Posted by tonystro View Post
Thanks for sharing the video!
Yeah I've seen his ornithopters before, 2 and 4 wing, you should go see the 16 wing. The prevs were too birdlike looking and acting, heavy, and ungainly. These new ones are lighter and *FAR* more flyable.

Quote:
Do you think the material is Depron or softer foam, like in Dollar Store poster board? And, what material and shape for connecting the sections?
I just weighed a piece of posterboard 26g/ft^2. It is about the right weight for that size snake segments.

Buuut 2mm depron is about the same stiffness and I just weighed it at 7.7g so that wraps that up.

The head might be 3mm to take the stress of the motor and surfaces.

Quote:
One of the two big questions for me is how much power to use. This may have to wait until the total weight can be estimated.
[Tapping foot patiently...] Starting at the bottom of the scale look at Park 180 http://www.e-fliterc.com/Products/De...rodID=EFLM1120

The manf pages (all manfs not just eflite) are *horrible* as far as sorting by weight, size, power, anything. No sorts at all. So here's a link to my LHS which does sorts, scroll about halfway down the page to where the motors start. http://www.gravesrc.com/SearchResult...show=30&page=1

Quote:
The main question for me where would the C of G be located? When we see the break in the tail at the end of the video, it seems the craft becomes nose heavy and he can not keep it from descending. So, as should be obvious to me, the balance point has to take in consideration the weight of the body and tail pieces. Perhaps he balanced at 20-25% of the total length?
The CG is flapping in the breeze literally and figuratively. Flight will be all about throttle control. Ever fly a Vapor? It's got very little throttle range with heavy undercamber it climbs like crazy. Well this one is pure flat but it looks like it handles similarly.

The underside views look like a flat flexible strip connecting the segments, maybe CF, to limit twist both laterally and longitudinally otherwise it'd just whip around like a rope. Wow my LHS has -1- piece of 0.007" (0.2mm) x 1" x 24" which is just about right. $7.50 24" is about enough to do one snake. Or is that too thin?

The head segment it looked like he detached maybe a nylon screw. Maybe all the segments have nylon screws, with 2 nuts jammed to allow very free movement but firmly attached.

Or the connection between further segments might be a kind of S-hook which might account for that one scene where a segment separated. That would save weight, but at the risk of unhooking. Maybe that detachment was broken depron or screw fell out.

The depron needs to be reinforced though at the segment joints or it will tear very easily. Maybe a flat nylon washer on the top side, and a 1"-2" long piece of 1mm CF on the LE/TE adjacent to the mounting holes.

Quote:
I will ponder these questions for a while. I will also work a basic design SketchUp.
I'd aim for about 50% larger in size (length and width of everything.) Larger is simply always easier to fly. But it's got to be 'walked' to get most of the snake off the ground first or the tail drags too much. Maye only 25% larger.

(Ignore this paragraph if you like these are just thoughts based on seeing how the snake flies.) I think I'd increase the width by 25% to reduce roll. I've never flown (but want to builld) a Skycart which is basically a pure square pizza box style with wheels. That's a little too far on the square side though compared to the snake. Maybe not 25% maybe 15-20.

I don't see a rudder or a 3rd servo. Is This ailevator style? The only thing I can relate to is Slo-V but that had a rudder. I'm looking at my Futaba standard setups which includes v-tail. That includes/implies rudder, but with essentially v-tail ailevons maybe just ignore rudder.
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Old Feb 22, 2013, 12:52 PM
Registered User
DeBary, FL
Joined Nov 2010
1,780 Posts
Taper

I wonder if the segments should taper a lot more down the length of the segments, instead of 'nearly the same size' all the way back.

The tailmost segments have almost an equal amount of resistance to air, but their effect is in a sense amplified because of the -distance- between the head and tail.

When the segment just behind the head goes off by 10deg, no big deal, I've had wings the flexed more than that. LOL! But when the farthest segment goes off by -90- deg that -drag- is transferred all the way back to the head. If that last segment was 80% -smaller- the drag would be drastically less.

Further, each segment should be tapered not rectangular for a -much- more natural snake look (and maybe even improved smoother aerodynamics as the snake pulls through the air.)

I'm sure that snake flies awesomely in zero wind zero turbulence, at near-zero speed, but that's just not very realistic. It -has- to be capable of 10mph flight or it's just gonna float away and not come back.
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Old Feb 22, 2013, 01:11 PM
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DeBary, FL
Joined Nov 2010
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Linear stability.

One more idea. I was gonna add this to previous post but it's pretty unrelated. If you get tired of reading all this just tell me to shut up. I probably won't but if it makes you feel better you can tell me to.

I wonder if the segments should include a dorsal/ventral/both fin/keel similar to the head segment. Not as large as the head segment but in proportion to the previous taper idea. And ventral fin curved at the LE to discourage hanging up on landing. Yeah it adds 20%-30% to the weight and assembly time. But might drastically improve straight line motion and discourage whipping because it's a 3D shape rather than a 2d flat shape.

The front 1/3 - half of that snake looks like it's flying very nicely, but the last third is an unwanted appendage because it's too far out of control -as- -related- to where the head end with the motor is trying to 'lead' it. Instead of leading it it's just pulling and dragging it around. The tail should behave in a way that it wants to -help- itself be pulled around -neatly-, not thrashing and whipping.

I'm relating this to Slow Stick for which I built a flat bottom KF wing. SS has essentially no fuse, no later cross section -except- for the v-stab/rudder. Going flat through the air was fine. Roll 90 deg and it simply falls down because in that orientation there's no horizontal surface to hold it up.

So I added big flat pieces to the wing, top and bottom, to 'simulate' a fuse, to have something to fly on at 90 deg roll. With that I could knife edge forever.

No the intent is not to KE the snake (though that should be possible, nice clean rolls.) But when the tail end segments get twisted off 90 deg they have nothing to fly on and pull down like a ton of depron.

OK so that's V2.0. Actually since it's a totally open structure they can be added, trimmed, or removed at any time.
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Old Feb 22, 2013, 01:14 PM
Fremont, CA
United States, CA, Fremont
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This is truly a FIRST (no matter what anybody says!).
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Old Feb 22, 2013, 03:08 PM
Redacted per NSA "suggestion"
dedStik's Avatar
United States, VA, Virginia Beach
Joined Feb 2012
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I'd be more inclined to put the head at 6mm and the body segments at 3mm.
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Old Feb 22, 2013, 06:31 PM
Flying Models for 51 Years!
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Georgia, United States
Joined Oct 2002
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Quote:
Originally Posted by djacob7 View Post
This is truly a FIRST (no matter what anybody says!).
I have to agree I've been Flying Model Airplanes for 50 years, never seen anything like this Just them Gliding Snakes in the JUNGLE
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Old Feb 22, 2013, 08:16 PM
Kamikaze Ace
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USA, FL, Lakeland
Joined Jan 2010
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Umm, to me that's just a powered kite.

If you think about it, on a regular old kite you have a tail out back to act as a sorta stabilizer.
The tail follows the kite's head so to say. Really from what I saw it has elevators and a rudder on it's head, so the tail is just going along for the ride.
Pretty slick though.
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Old Feb 22, 2013, 09:07 PM
Out the Window
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United States, FL, Alachua
Joined Jul 2004
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Great looking airplane! I would think the body of the snake would be about the same as pulling a paper tail used in combat. It might have more effect on the airplane (head).

It would be fun to give it a try. Looks cool flying!

Ray
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Old Feb 22, 2013, 09:12 PM
Registered User
Billings, MT
Joined Jun 2010
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With a few minor modifications this could become a flying Chinese Dragon.

Hmm, I may have to watch how this unfolds.
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Old Feb 22, 2013, 09:16 PM
Don't look at me like that....
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United States, AR, McDougal
Joined Aug 2005
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Cool.
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Old Feb 22, 2013, 10:20 PM
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DeBary, FL
Joined Nov 2010
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Quote:
Originally Posted by Glacier Girl View Post
Really from what I saw it has elevators and a rudder on it's head,
I see two servos and I guess it's ele/rudder. But they're both in a bad spot anyway. Any servo that close to the end of a control surface is just screaming 'flutter me! flutter me!' LOL! Just an opinion because been there done that.

Quote:
so the tail is just going along for the ride. Pretty slick though.
It's more than going along. Given relative masses and surface areas it's a MONSTER tail wagging a tiny-tiny dog. It is *not* a typical kite tail in any sense other than it's physically attached to the head.

A better way to describe it might be 'segmented fuse.'
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Old Feb 22, 2013, 10:32 PM
Registered User
NorCal
Joined Dec 2009
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Seems to be a Nutball with a tail. Cool
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