HobbyKing.com New Products Flash Sale
Reply
Thread Tools
Old Oct 29, 2006, 11:40 PM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Build Log
"SOARBIRD", a hawk-like slow flyer / thermal glider, Bluecor & EPP

SOARBIRD is a 61" wingspan slowflyer / thermal cruiser built in a stylized soaring hawk shape. It should look a lot like a hawk or eagle from below when it's riding thermals above. (I've wanted to do one something like this for a long time!) There are already a few other bird-like designs of varying complexity; what I wanted to do was to come up with a design that would be relatively easy to build, without complex airfoil shaping or any hot-wire cutting.

SOARBIRD borrows it's basic wing geometry from the 'air surfer' design. It uses elevon controls, and due to the wing geometry / dynamics, it should not need any rudder / vertical stabilizer, so the silhouette should look quite hawk-like. Functionally, you could think of it as a dressed up flying wing in most ways. The horizontal stabilizer (tail) need not be servo driven, but will be able to be adjusted for trim if & as appropriate; it's primarily there for the bird silhouette, as viewed from below.

This one is light weight, with a light wing loading; it's being designed for slow flying & thermaling on light wind days (since I do not have access to an indoor flying facility)... so it will be out soaring with the local eagles & hawks.

It will use a CD-ROM motor and a folding prop on the nose. (This design is intended as a mellow cruiser, not a speed ship.)

It builds out from one sheet of BlueCor, one block of black EPP foam 2-3/8"x4"x20" for the body, 1 tubular 1/8" x 48" C.F. spar, and 4 pieces of 3/32" diameter bamboo (from a matchstick window blind) as the main structural members ... K.I.S.S. is the design principle. The wing is a Bluecor single surface undercambered style- quick to build.

Attached are a couple of photos of the airframe, ready for painting & close to ready for gear installation; there are some details of wing mounting and motor mounting to be finalized yet. I'll post further progress reports and photos as this bird shapes up, and report on the flight performance when it gets through the flight tests & final setup tweaking / optimization.

VIKING
viking60 is offline Find More Posts by viking60
Last edited by viking60; Oct 29, 2006 at 11:49 PM.
Reply With Quote
Sign up now
to remove ads between posts
Old Oct 30, 2006, 02:46 AM
Registered User
kimhey's Avatar
nøtterøy, NORWAY
Joined Mar 2006
1,171 Posts
Hmm.. Interesting build. Looking forward to more pics and flightreports.

Kim
kimhey is offline Find More Posts by kimhey
Reply With Quote
Old Oct 30, 2006, 05:32 AM
gpw
“There’s no place like Foam”
gpw's Avatar
United States, LA, New Orleans
Joined Jul 2002
24,126 Posts
NICE !!! Might need a touch more dihedral ... (from Big Horten experience)
gpw is online now Find More Posts by gpw
Reply With Quote
Old Oct 30, 2006, 08:03 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
GPW,

thanks for the input; I'm starting off using a fair amount of reflex at the trailing ends of the swept-back wings, which should offer some fairly good stability. I have yet to do the final heat tempering that will set this reflex in place.

I cut out two sets of 61" span wings while I was laying this SOARBIRD out directly on the Bluecor, so I can always try variations on the second. (There's lots more black EPP around too, so I'll be able to possibly play with body variations later.) Plans will be drawn up later; I have only rough notes & sketches for now.

This flying wing is built flat on the building surface after the undercamber is formed in each wing half.

The balsa dowels get glued to the leading edges before the two halves are glued together at the center joint. I then fit / sand the center joint for a close fit, then 'woodpecker' the Bluecor joint faces so that the 5 minute epoxy I use can penetrate deeper into the Bluecor structure. (I'm a fan of five minute epoxy for certain jobs, & this is one of them.)

Once the epoxy has set, I turn over the wing and lay in the one-piece Carbon Fiber spar tube; it runs span-wise, crossing 1-1/2" in front of the center area of the trailing edge. It's glued into a pressed groove with foam-safe CyA, then overlaid with Scotch "Extreme" cross-filament tape.
(The wing is flat in this area, allowing for use of the one piece spar; an angled joiner at the center would be needed if a builder decided to install a spar in another location.)

[The K.I.S.S. principle is implemented in this build, with a bit of T.L.A.R. thrown in now & then to keep it simple & fun! The test flights & final setup adjustments will be the final word on obtaining the desired flight performance envelope.]

I also formed / warped another piece of the bamboo rod (from the matchstick blind) as a cross-brace on the underside just back from the wing's front center; it's inset into the foam, glued in place with the foam safe CyA.

The 'feather- edged' elevons are tape hinged in place.

This wing is close to ready for a base coat of paint; I may do the first one in basic black (Krylon H2O) for the contrast against the sky, just to get it in the air quickly, and save the fancier art work for a later edition after I'm past the 'proof of concept' stage.

More later!

VIKING
viking60 is offline Find More Posts by viking60
Last edited by viking60; Oct 30, 2006 at 08:12 AM.
Reply With Quote
Old Oct 30, 2006, 10:12 AM
Just chillin @ 403 MPH
Jantar2A's Avatar
Boulder Colorado
Joined Nov 2005
5,208 Posts
It looks cool Bruce
Hope it soars well,,use lots of differential with the no virtical fin,,,,hummmmm,,makes me think of a wingeron or wing tiperon controll for roll axis,,lol there I go complicating things again,,lol,,,But some of the things I like about your models is the simplicity/quick build/low cost & great flight & durability and of course the most important part high level of fun flying them,,,,,,,,,,,,,,,,,,,,,,Nick
Jantar2A is offline Find More Posts by Jantar2A
Reply With Quote
Old Oct 30, 2006, 10:58 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Nick,

Yes, excellent consideration; I'd planned to implement heavy aileron differential on this wing- probably start with about 20% down compared to the up travel, with lots of up travel available. I may try implementing the differential totally within the elevon control horn geometry, rather than relying on the computer radio's programmability. This would allow other builders to fly this SOARBIRD on a very basic three channel radio system (as long as they have the Elevon mixing capability.)

I'll do photos & the setup details when I install the specially shaped control horns and set the servos in the wing tips; this will be simple to implement.

SOARBIRD #1 will use a pair of inexpensive BlueBird BM306 6.5 gram servos- plenty of control authority for this light weight slow flyer. I'll fly a CORONA RD620 receiver.


More Later!

VIKING
viking60 is offline Find More Posts by viking60
Reply With Quote
Old Oct 30, 2006, 08:01 PM
Just chillin @ 403 MPH
Jantar2A's Avatar
Boulder Colorado
Joined Nov 2005
5,208 Posts
Sounds great,,can't wait to see the paint job,,,I would have to find some airbrush artist as I'm not 1 myself,,,,,,,,Nick
Jantar2A is offline Find More Posts by Jantar2A
Reply With Quote
Old Oct 30, 2006, 08:24 PM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
Quote:
Originally Posted by gpw
NICE !!! Might need a touch more dihedral ... (from Big Horten experience)
Hawks have dihedral too! Cool concept - no vert stabilizers may be an issue.
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Oct 31, 2006, 05:20 AM
Registered User
Silverthorne, Colorado
Joined Jan 2004
33 Posts
Bruce,
How about curling in some winglets at the outter edge? That will make it look very real.-- I'm currently in the Florida Keys. No snow here... 89 degrees. Home this Saturday.
teamteke is offline Find More Posts by teamteke
Reply With Quote
Old Oct 31, 2006, 05:27 AM
gpw
“There’s no place like Foam”
gpw's Avatar
United States, LA, New Orleans
Joined Jul 2002
24,126 Posts
On all our "pure" flying wings the secret is sweepback , washout , and dihedral ... all three seem to be necessary for Finless stability ...
gpw is online now Find More Posts by gpw
Reply With Quote
Old Oct 31, 2006, 08:37 AM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Dr. Tyler MacCready's influences on WindRider & AirSurfer

Friends,

This wing layout is loosly based on Dr. Tyler MacCready's work and his 'Walk Along Glider', as inplemented in the Air Surfer and Wind Rider glider designs. There's another thread started back in October of 2002 on the "Air Surfer's Big Brother" that further demonstrates the viability of a wing of this planform; it was started by SPFD-E-FLYER.

http://www.rcgroups.com/forums/showthread.php?t=65870

You can buy a three-pack of the WindRider 'Walk-Along Gliders" from this web site, play with them, and go from there in scaling them to any desired size, and implementing your own adaptation if you are inclined:

http://www.windrider.com.hk/products/product.cfm?id=8

(WindRider also produces the BEE, one of the top competitive 48" slope combat flying wings being flown by the Colorado slope combat flyers these days; it's not listed on the site above, however, which only features the "toys".)

The deep sweep in the wings, placing the wing tips well behind, along with the substantial reflex of those wing tips MAY allow this design to fly without adding any vertical stabizers.... That's one of my initial concepts that I'm investigating in building this prototype. (Reshaping the bird tail from a flat surface to some form of a Vee could also add a bit of stability without loosing the look, if needed.... lots of unexplored options at this point.)

If you were designing for a different performance envelope, - say, for a fully aerobatic flying wing, or a faster flying wing- then you'd likely do a lot of things quite differently. I'm working on a rather large lightweight slowflyer / thermal glider that looks sorta like a soaring hawk when in the air.... and trying to keep the construction fairly simple & inexpensive in the process.

GPW, thanks again for the input; you've brought up the very important aspect that adding dihedral will add greater stability... I'd first been inclined to try the flat-built wing because it would be simpler to add the one-piece spar to give the wing the needed strength... but I'm now inclined to build in some dihedral and deal with the spar joiners at the center joint as necessary. The added stability gained will be a "good trade", and having some hands-off cruise capability is well worth building into a light thermal soaring bird.

Flying back down out of those "BOOMER THERMALS" that we often encounter up here in the mountains will require more structural strength in the spar system than might be needed for a light indoor flyer; I'll be working on implementing that, too. On the 61" span, I'm already inclined to go to building in a leading edge tubular C.F. spar with a solid center joiner to gain the added strength as well as warp resistance there. The 3/32" bamboo just will not give that at this scale. (On this large of a Bluecor wing, setting and *keeping* the alignment will likely be an ongoing issue...)

TeamTeke, thanks for the thoughts! Once I get the first one flying, I'll look to further posible modifications to make it look even more bird-like. Since you have a fair supply of BlueCor tucked away in your hangar, you could always do your own version of a soaring bird!

Jantar2A,

Tiperons are always a possibility- they have been implemented by others in the past. For starters & proof-of-concept on this light bird, I decided to start off simpler. You can always add the enhancements once the basic wing planform is optimized for light wind soaring. So many possible variants, so little building time...

Since I have other work to also do, I may not be able to get this one in the air as quickly as I'd like to. I'll continue to photograph the build progress, & post it here as appropriate.
viking60 is offline Find More Posts by viking60
Last edited by viking60; Oct 31, 2006 at 09:35 AM.
Reply With Quote
Old Oct 31, 2006, 01:35 PM
Master of 1 point landing
Naperville, IL
Joined Jul 2005
2,841 Posts
Quote:
Originally Posted by viking60
Friends,

This wing layout is loosly based on Dr. Tyler MacCready's . . .
this is a really interesting project, please keep us updated. You know controlling by wing warping would be very cool too!
ImaBiggles is offline Find More Posts by ImaBiggles
Reply With Quote
Old Oct 31, 2006, 03:31 PM
High Altitude Flyer
viking60's Avatar
Fairplay, South Park, CO
Joined Sep 2005
1,608 Posts
Power option and folding props

Friends,

Here's a couple of photos of the CD-ROM motor and Folding prop I'm presently planning to use. The motor is a GoBrushless GBv1.0 kit motor, wound with 21 wraps of 26 gauge wire; WYE termination will be used. I'll fly it on a 2S LiPoly.

The folding prop with the red spinner was bought from BPHobbies; it's set up with 8x6 blades. (The hitch in using this inexpensive folding prop set is that the motor shaft adaptors available are either 2.3mm or 3.2mm, while the shafts for GBv motors are 3.0mm.... I'll have a friend with a mini lathe drill out the collet to 3mm for me... I've butchered too many of them trying to do it without a lathe! The good news is the reasonable price- under $10.00

The Multiplex Easy Glider prop can optionally be modified, and blade lengths trimmed from the stock (9.5"x6.5"?) for use. (I did this for my Wild Wing.) (Sold for $8.50 to $10)

DYMOND Modelsports sells fancy aluminum spinners with 3mm collets for use with the Freudenthaller blades, too, so about any set of blades could be used on a kit brushless motor. (About $15.00 for the spinner set)

More Later....

VIKING
viking60 is offline Find More Posts by viking60
Reply With Quote
Old Nov 01, 2006, 06:19 AM
gpw
“There’s no place like Foam”
gpw's Avatar
United States, LA, New Orleans
Joined Jul 2002
24,126 Posts
Viking ... Know it's gonna' be Super !!!!! : ... our experiences are based on the Air Surfer and positively HUGE Air Surfer that SPFD made and flew ... which led to the 60"Big Horten experiments ... all had no vertical fins and flew GREAT (Really slow floaters) very stable , and flyable (Ask the Whorley Bros. ) Made on the Bendfoam Jig ... required very little power and I eventually powered the BH with a j250 with a C gear.. and got long , long flights ... 45 min +... My elevons required about 25 degrees UP(reflex neutral )) to fly right ... I KNOW yours will be a Great Flyer , with a unique look too!!!!!! ... but watch those birds...either they'll leave or attack ... !!!! We routinely get chased by even the smallest birds when we get too close to the nest ... Momma' Thing !!!!
gpw is online now Find More Posts by gpw
Reply With Quote
Reply


Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion Need slow flyer 3 channel EPP plane Flyboy03051 Micro Ready-to-Fly 0 Sep 14, 2006 07:38 PM
Recommendations for an EPP electric thermal glider Peter Young Foamies (Kits) 3 Oct 17, 2004 04:02 PM
Needed: Plans for bluecor SLOW flyer crashsiegel Scratchbuilt Indoor and Micro Models 5 Oct 07, 2003 06:59 PM
Slow Stick in Glider Configuration? Slope flyer? Zymurgy Parkflyers 1 Aug 11, 2003 06:22 AM
Slow Flyer wing on a glider? tenover Parkflyers 0 Oct 09, 2001 10:54 PM