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Jan 15, 2017, 06:29 PM
springer's Avatar

Adventures in lifting bodies - Burnelli UB14

Some time ago, I was trolling the net looking for interesting planes to build and came across Vincent Burnelli's attempts in the 30's to sell a lifting body airliner to the airline industry. He only built a couple himself, and they didn't gain any traction with airline execs, so are now a dust mote in aviation history, but nonetheless really interesting planes! I was able to get a couple of pieces of Readiboard that had been processed without paper from Adams at my last trip there, and wanted to try a build with it, so this is it! The plane is 29.5" span, weighs 7.28oz with an 850mah 2s lipo. The wing and fuse top surfaces are a single piece of foam, which made the build interesting. The wing is built up with a conventional airfoil (of unknown spec - lots of this build was TLAR - more on that later) with a main spar of two 1/8" square basswood strips separated by foam. 4 ribs in each wing half. Bottom surface is regular DTF. The resulting structure is really strong and stiff, surviving several cartwheels and other indignities. I hadn't figured out how to organize the innards, when building the center section, so just used several partial formers to support the skins. Gear was added after the airframe was assembled requiring three holes to be cut and patched.

I TLAR'ed the CG and placed the battery right at the spar, finished the gear assembly and took her out on a calm morning for maiden. She was hard to handle to say the least. You can see in the first video (actually the second flight) that she bobbed and weaved all over the sky. But I did get to see what was happening, and figured at first that I needed more up trim (actually recentering the elevator) as I had to hold the elevator about half up all through the first flight. Also raised the ailerons for a bit of reflex or at least less camber. Second flight was better as seen in video, but she was very unstable, and response to inputs was erratic. So, it slowly dawned on me that perhaps my CG was wrong and aft. Inside and found the Adamone calculator and found that with a 15% static margin CG should be at 1.9" from center section LE instead of the nearly 3" I had it at! D'oh! Moved the Lipo to the front compartment in nose and got CG to around 2.5". That's all I figured I could do without adding weight which I didn't want to do. The next flight was much better, Plane grooving around nice as can be, but.... I noticed the spira l(that you see in the first video) and in passing wondered if the recycled hxt500 had developed a dead spot, but didn't change it. The sweet flight ended in another death spiral right into a wood pallet! Picked up the pieces and glued it all back together for another flight today, replacing the hxt500 with a hxt900. The second video shows how it handles now. She's become a sweet flyer, a bit sensitive to wind gusts, but other wise good and nicely acrobatic (acrobatic commercial plane???)

As soon as I started the build, and thought of what I could do with it (retractable gear, steerable tail wheel, etc.) I thought I should have done a larger build, so I think I'll do one about twice size in the future. Time will tell....

(1 min 28 sec)

second flight still with aft CG

(0 min 52 sec)

CG moved forward
Last edited by springer; Jan 15, 2017 at 06:44 PM.
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Jan 15, 2017, 07:07 PM
Registered User
Interesting build.
Burnellis have caught the attentions a few builders over the years.

Wondering what the significance(difference?) betwixt Factory Adams Redi board made sans paper skins and 1$ store Adams Redi board with paper removed
Except for the effort of removing the paper?
Same spongy foam I presume ?
Jan 15, 2017, 10:50 PM
springer's Avatar
Yup, same spongy foam, but more of a skin so a little tougher and less dentable. Was interesting to try though.
Jul 20, 2017, 07:52 PM
pro vjb
the1pope's Avatar
Nice flyer. Nice work. Good luck on the larger build.

Check out the restoration of Burnelli's last plane, the CBY-3 Loadmaster, at New England Air Museum. They say it's getting close to getting its paint. The paint scheme is on this page...
Jul 21, 2017, 08:13 AM
Retired CAD guy
birdofplay's Avatar
Similar but different
Jul 21, 2017, 08:35 AM
springer's Avatar
Larry, thanks for the good words! And thanks for the link to the NE air museum. That place would be a dream to visit! In addition to good pics and info on the Burnelli, i found a great shot of their SeaBee showing the gear and strut mounting. I am almost done with a larger 42" version of that plane and am pondering installing functional landing gear.

On the Burnelli, i crashed it really well (ripped both motor pods off) and decided to retire it and focus on a larger version. I think the two power trains in a small plane make for too high wing loading for my flying skills. A 200% expansion should be better. Unfortunately i have let several other planes slip ahead on the build list, so it will have to stay in my head a while longer.

From your blog page, it looks like you have several"interesting" planes. How about posting them in your blog? I will check out the link to your Burnelli site too.
Oct 24, 2017, 02:01 PM
pro vjb
the1pope's Avatar
Here's some exciting news for those who believe (or don't) that Burnelli's Lifting Fuselage was, and is, superior to the tube and wing.

The first, serious study done on the Lifting Fuselage Configuration (LFC) almost 80 years was done by Reist and Zingg, University of Toronto, 2016. Their findings show the LFC has double the "fuel burn reduction" of the BWB/HWB compared to the tube and wing design. Testing to continue.

Reader's digest version...

Full paper...
Oct 24, 2017, 03:25 PM
springer's Avatar
I looked at the short version and saw some really interesting things to model! Was an interesting analysis.

After trashing my readiboard version, I set it all aside and started on a larger MPF size version (like 48" span or larger). But, then I got interested in several other planes, and the sketchup file languishes on my laptop. The little version was just too fast and fragile. It flew ok, kinda fun, but with the gear was heavy wing loading for that small a plane. I figure if I do a much larger version, the gear weight as a percentage of total weight will be less, so lower wing loading. Also, I can fit retracts and clean up the bottom while still able to ROW> Build season's coming, so I'll eventually get to it!
Dec 05, 2018, 03:08 PM
pro vjb
the1pope's Avatar
One more update for the Burnelli CBY-3 at the New England Air Museum. Paint is going on. They say it'll be about 18 months before they unveil her. 2020 will be the 75th anniversary of her first flight.
Dec 05, 2018, 04:36 PM
springer's Avatar
They'll be done with the original before my revisit of the design!

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