Thread Tools
Dec 14, 2018, 08:47 PM
treefinder
springer's Avatar
Thread OP
Discussion

Continuing adventures in blended wings


Now that it's indoor season here in the northern hemisphere, I am back searching for the best plane to fly in our church gym (besides the Nutball, of course). The plane in the pics and video is the latest attempt at slow speed and maneuverability. It actually does pretty well in the single basketball court size gym. Was a bit fast, but after playing with it outside (where there are no walls to intimidate me) I think I can slow it down. The design a combination of the earlier blended wings based on the Manta kit I saw online and a swept arcing wing that began with my grandson sketching it as a "space plane" that he wanted me to build. We did build it and it flew really well (especially considering he was only 11 at the time - good basic idea with a little grandpa help). That morphed into the wing of the OSCanard 47 that has been my fave flyer for the last month or so. And now, into the wing for this blended wing version. The two manta look alikes flew ok, but not great indoors. I suppose it was mainly due to the short rudder, a side effect of the height I raised the tail surfaces, which also limited the dihedral. In any case, All that muddled in the necktop computer and out came this design. Wing span is 31.5", Wing is KFM2, all MPF. Hextronik 19 gm motor, at 1700Kv (i think) with a 7x3.5 gws type prop. I used a 2s 350mah lipo, because that's all that will fit in the fwd battery compartment, but that still gives 5-6 minute flights.

(2 min 8 sec)
Last edited by springer; Dec 14, 2018 at 09:02 PM.
Sign up now
to remove ads between posts
Dec 14, 2018, 08:54 PM
treefinder
springer's Avatar
Thread OP
I am finding I really like the scimitar-like wing planforms. They seem to provide really stable yet maneuverable flight. The KFM2 foil helps stiffen the long tips (though they are still flexible and perhaps fragile, though I have cartwheeled the plane once with no problems) and with added thickness softens the response. It's not twitchy at all. Whether it helps glide or not I don't know, but I do like the way the plane handles.

In response to the issues with rudder authority (lack of) in previous blended wings, I made the rudder (and tail offset up) 2" by 2.5". With high rates (100% throw) she turns nicely and with authority as you can see in the video. Plenty of elevator as well for good loops.

Fun little plane, need to put some color on her!
Dec 14, 2018, 08:54 PM
Registered User
The key to slow flight bis low wing loading. And for plasnes with not as nlow wing nloading as u like good rudder control and hasrrier abilitys.

I have an EPP 3d plasne. It's not that big but I need tl juggle all 4 controls. Keepikng enough throttle for control and helping them tsail down to get it slow enough.....


Leadfathers pizzabox flyer is gold if you build light.
Dec 14, 2018, 08:58 PM
treefinder
springer's Avatar
Thread OP
Yeah, low wing loading is best! The servos are 4gm i think (recycled from another plane), the small lipo helps as well. No reinforcements in the wing or structure yet, so all these help keep weight down. Plus, I suppose that everything counts toward wing area, even the planform of the "uprights".
Dec 14, 2018, 09:22 PM
Build straight - Fly twisty
Whiskers's Avatar
Well, I can say something nice about that.
Looks wild, flies great. You have to be happy with that combo.
Dec 14, 2018, 09:47 PM
treefinder
springer's Avatar
Thread OP
aww, thanks!
Dec 15, 2018, 06:56 AM
gpw
gpw
ďThereís no place like FoamĒ
gpw's Avatar
Those are so COOL !!! Love the Manta ...
Latest blog entry: Lost plans
Dec 15, 2018, 08:04 AM
Vertical approach specialist
potshot's Avatar
Quote:
Originally Posted by gpw
Those are so COOL !!! Love the Manta ...
Me too! I did a fair amount of searching to see if any plans were available, came up empty. I'd love to build a very light weight version for indoor flying in a gym. Springer, did you build the Manta you showed here?
Dec 15, 2018, 09:33 AM
treefinder
springer's Avatar
Thread OP
Yes, that is my rendition. I don't think I did plans, just guessed at proportions. I will check the hard drive to see. If not, I will trace the wing shape for you. The one shown was the first and flew best. The second was larger with a fuse more like the BW31. It suffered from sluggish response at low indoor speeds. I will take a pic of all three together to show relative sizes.
Dec 15, 2018, 04:29 PM
skumgummi dave
Mike :

The BW31 is another winner. Very cool! Love slow fliers. They are good for old guys like me.

Dave-
Last edited by foamdave; Dec 15, 2018 at 04:56 PM.
Dec 15, 2018, 06:47 PM
I Look, Listen, and Learn
Timbo383's Avatar
Me likey, where are the plans?
Dec 15, 2018, 10:21 PM
treefinder
springer's Avatar
Thread OP
Ahhhhhh, the plans. . . Well, I did do the main wing template, but all the little bits were just done free hand . Was gonna reverse engineer today, but family Christmas craft day took precedence. Perhaps tomorrow.
Dec 15, 2018, 10:39 PM
Build straight - Fly twisty
Whiskers's Avatar
No plans! Yea! Freedom through planlessness...
Dec 16, 2018, 01:29 AM
skumgummi dave
Thanks Mike. Family always comes first. Merry Christmas to you and yours.

Dave-
Dec 16, 2018, 08:42 PM
treefinder
springer's Avatar
Thread OP

pics and templates


A bit quieter today, so got to finish the sketchup file of all the parts. The first thing I found was that the wing is actually 32" span, not 31.5, so I guess it will be a BW32 instead of a BW31! Single sheet and tiled to letter size sheet PDFs are attached below. I didn't take any pix of the build, but since i haven't added color yet, it should be pretty easy to see how the parts go together from the attached pics.

In the template files, I show only one wing step and fuse side, but you'll need two of each of course.

Dihedral hinged at the fuse width (1.125") flat under fuse. I helped the dihedral while the glue set with some support at wing tips. (about 2"/side), but it is essentially set by the fuse height at 2.25".

The servos I used are 4gm, 3/8" wide, 7/8" long, so holes and wood screw mount spaced accordingly. I made the wood pieces about 1/16" long and embedded them in the foam when I glued it all up. There is a 1 1/8 x 3/4 piece of foam under the servo tray at aft end to set height. There is also another 3/4 piece aft of the aft former/ back wall of gear pocket that the aft fuse top glues to; it's hidden in all pics.

The fwd fuse pieces are two layers of foam laminated and glued to fuse sides to form the fuse "box" . I glued a ply motor mount to the fwd one.

The battery pocket is small, and I found that my typical 850mah 2s lipos won't fit (too wide for width or height of the pocket). I use a 350mah 2s pack and get about 5 minutes at puttering around speeds. In order to get room for the larger lipo, the RX could be moved to aft fuse behind servos, and fuse made another 1/8" wider. If one was flying mostly outdoors these mods would be a good idea, but if flying indoors, the smaller lipo goes with the small servos and motor well and gives good indoor performance.

CG is 4" aft of motor mount at centerline.
Last edited by springer; Dec 18, 2018 at 01:11 PM.


Quick Reply
Message:

Thread Tools

Similar Threads
Category Thread Thread Starter Forum Replies Last Post
Discussion need help for a 4000mm wing span giant Scale EDF blended wing body desing mohsenfjs RC Airliners (Commercial, Cargo, Troop Carrier) 5 Apr 23, 2018 09:45 PM
Help! Wing fillets/ blending in SolidWorks Altocirrus CAD/CAM 15 Nov 11, 2011 11:11 AM
Discussion Continuing adventures of Patrick Kennedy aerogel Life, The Universe, and Politics 45 May 10, 2006 01:57 PM
The continuing adventures of the Mini Max Vonbaron Parkflyers 7 Dec 22, 2001 07:24 AM