The Burnelli configuration has long fascinated me, for no obvious reason. Recently I came to try and be objective about it, and was surprised at the figures, and the potential of that type, or a contemporary equivalent, as a short haul commuter. Discounting its STOL capacities, the DHC6 Twin Otter, now in production again by company Viking, sees use as a commuter airliner, yet with the same engine power the UB-14 beats it at all points: 3800 kgs payload vs 2500 (including fuel), 330 km/h cruise speed vs. 278. (all data from en.wikipedia.org, slightly rounded here and there). Replace the radial engines with PT6’s or so and the payload will be even greater.
Even a comparison with the B1900 doesn’t do that bad: with comparable max gross, the UB14 is 500 kgs lighter – again, with turboprops it would be even lighter. Its cruise speed of 330 km/h is meagre, compared to the B1900’s 518 km/h, but the Burnelli makes do with 1500 HP where the Beech uses 2500, the difference in fuel burn must be more relevant than the speed difference, on short distances. Admittedly, the B1900 is pressurised, which puts it in a higher category really. But for short haul, does commercial traffic want to climb above FL080? Perhaps, for better fuel economy, and/or for a smoother ride?
Would there be a business case for a turboprop powered UB-14 derivative, today?
Would there be a business case for a turboprop powered UB-14 derivative, today?
I am a strong believer in Darwinism and that includes technical solutions as well. If the lifting fusealge concept would have offered large advantages over the “conventional” layout (at least in relatively slow flying aeroplanes), then by now the majority of aeroplanes would look like this Burnelli thing. Burnelli was not the first and/or only designer who went this way, if you do a google picture seach for “lifting fuselage aircraft” you will find a variety of projects, many of which predate Burnelli’s by a decade. Maybe one day the basic layout will come back as “blended wing body” aircraft, but these are designed for high subsonic Mach numbers where aerodynamics works differently.
Regarding a re-introduced UB-14 with turboprops: The most difficult to beat competitor in the segment of non-pressurised 19-seat commuters/utility aircraft might actually be the Do 228. It can do everything a Twotter can do but faster and with less fuel. You won’t beat this kind of performance with a taildragger that has a 1,5 metre thick wing.
Good points, Max, but allow me to use your own Darwinism argument against you (which isn’t really nice, admittedly) :
If the Do-228 were really that superior, why isn’t it omnipresent? Is it even in production, today? The Twin Otter is! But that must be by merit of its STOL capacities. My own interpretation is that there is not (or was not, up till now) a sufficient market demand for a non-stol small capacity short hauler. Perhaps the Do-228 could be relaunched now?
The Burnelli concept suffered a major setback for purely political reasons during WW2 – could it be it was simply forgotten ever since? I’ll agree it seems hard to believe, yet the figures are there. If the concept has inherent disadvantages, I am curious to learn about them.
If the Do-228 were really that superior, why isn’t it omnipresent?
Because it serves a very small niche market only. The 19-seat commuters have disappeared all together when low-cost airline travel was invented. There is no way an aeroplane doing scheduled services with less than one hundred seats can be operated profitably (and almost no way to operate one above 100 seats profitably either…) which means that even the feeder airlines now have to use the ATR 72, Dash 8, Embraer 170, CRJs or similar aircraft which have well above 50 seats.
Which leaves only a few specialised markets for the 19 seaters. Like flying mountaineers to Mt. Everest base camp (AFAIK only the Twotter and the 228 fly to Lukla), flying surgical teams to remote bush strips in Africa and South-East Asia, flying 2 tons of express cargo to places far off the commercial routes. World wide demand in this sector calls for a few hundred aircraft only and on the smaller end of the business there is strong competition from things like the Cessna Caravan.
Is it even in production, today?
Yes, demand was such that RUAG (who after the collapse of Fairchild acquired the project) has restarted the production of the Do228 (as Do 228 NG).
Strong arguments, WN, you managed to convince me. Still I’ll keep up that anything the Do-228 can do, the UB-14 could do better, in a contemporary version. But I’ll agree the market is too small, it would be impossible to sell a sufficient number to make up for the cost of designing and certifying a virtually new design.
And yes, there is much less commercial opportunity for very small airliners than there was 30 or 40 years ago; at least in countries where people can afford to travel at all. Still I’d set the limit at 60 seats rather than at 100, but that is only a remark on the sideline.
Still I’ll keep up that anything the Do-228 can do, the UB-14 could do better…
One thing that immediately comes to mind is “generate drag” 
If I, as an aerospace engineer, would be tasked to design something with the maximum drag from the minimum number of components, something like this UB-14 will materialise on the drawing board… Aerodynamic understanding has progressed a lot over the last 70 years. The only advantage of the UB-14 over modern designs is that you can fill that big wing with Helium and then it will float away all by itself without even needing engine power.
I found a good article in Air&Space magazine (Smithsonian Institution) regarding Burnelli’s aircraft.
A key point against them (drag…) is explained in a little more detail:
“According to standard aerodynamic theory, the “extra lift” provided by a Burnelli fuselage is, under most conditions, beside the point. A Boeing 767 cruising at 41,000 feet doesn’t need extra lift from the fuselage. Its wing easily provides all the lift necessary to balance its weight. (In engineering terms, the aircraft cruises at well below the wing’s maximum lift coefficient.) The designer’s task is to get that lift with the least drag. It happens that a high-aspect-ratio wing (long and skinny) has inherently less induced drag than a low-aspect-ratio lifting surface (short and fat, like a Burnelli fuselage). In cruising flight, the less the fuselage lifts, the lower the inducted drag.
Conventional wisdom also dictates that a Burnelli jetliner would suffer drag penalties because of its larger frontal area, larger wetted area (the area over which air flows), and the discontinuity between the lifting fuselage and the wings. NASA aerodynamicist Jerry Hefner comments: “I would think the induced drag would be horrendous. And your skin friction drag is going to go up because of the larger wetted area.” An engineer from a major aerospace firm who asked to remain anonymous (to avoid angry letters from Goodlin) estimates the drag penalty of a Burnelli-style jet transport at about 20 percent more than that of an airplane like a 767. That may be a reasonable compromise for a bulky cargo carrier like the Husky, but not for a passenger jet"
The whole article is here:
http://www.airspacemag.com/history-of-flight/the-burnelli-controversy-15233082/?all
Jan,
I was reading your interest in Burnelli’s work. I’ve been working on up-to-date and future lifting fuselage designs since 2006. I’m very passionate about it. Some people think it was or is only a slow design but old NACA testing, several current fighter designs as well as experts say otherwise.
Here’s a little of my work http://www.burnelliaircraft.com/wp/blog . I built and flew the RC, pictured in front of me, in 2008. It flew very well and I pretty much didn’t have a clue what I was doing. The day of its maiden flight there were a lot of questions like, “How did you get the center of gravity and the center of lift?” My answer was I didn’t know, what’s that? An old RC flyer helped me out with “LARTM,” Looks About Right To Me.
I’m sticking with that design approach on my newest, a 4 foot, 4 ducted fan, supercritical body/wing design. It’s a work in progress. I hope to have it flying by September. This full sized plane design will take off at 100 mph or less and cruise at or above any of today’s airliners’ speeds. An aviation expert, who’s specialized in Circulation Control for over 40 years, told me he could make my design (500 passenger) take off, fully loaded, at 65 mph and cruise very close to Mach 1 with little drag penalty.
Even though I have no background in aviation design or RC modeling, I’ve collected a pretty good support group of people who DO know what they’re doing. One is the project manager of the FA/18 Hornet at Northrop Grumman. He’s encouraged me throughout my journey since 2006.
Another is the Lead Scientist on the Sub-sonic Fixed Wing Project at NASA, Langley. We connected in 2010 and he’s been very encouraging, as well as keeping me posted on the newest composite testing. He says the latest composite, tested this spring, could certainly produce my plane design and safely hold an atmosphere, somewhat useful when trying to create a people friendly airliner. He was also involved in the NASA/Boeing X-48, blended wing project.
There are several others at different universities that have shown interest in what I’m trying to do and have had positive comments and suggestions. One professor at the University of Texas, Austin in 2008 wanted to get my RC into a student program the next year and into their wind tunnel. Sadly, he was forced into retirement in early 2009 and the 30 plus year old wind tunnel was dismantled. So close! He’d taught for 44 years and loved what he did. The university wanted some new blood I guess.
There is one Burnelli that survives at the New England Air Museum, the CBY-3. The lead in the restoration is Harry Newman. He’s doing a great job. I’m told they are already halfway through the restoration, in barely 2 years. Harry has thanked me for a few contributions I’ve made. I stumbled upon a detailed picture of the color scheme he wanted to use for the finish. He’s also agreed to let me and another man, who wants to put wheels on the ground within 10 years, go through many boxes of files that came with the plane. Exciting stuff! Now if we can just get our schedules to match so we can meet there. Check out the CBY-3 restoration… https://www.neam.org/index.php?option=com_content&view=article&id=1421 .
The main complaint of Burnelli’s designs by armchair aerodynamisists refers to excessive induced drag. In the article in Air & Space they imply that Burnelli’s designs were draggy, slow flying behemoths that couldn’t get out of their own way. Some of the comments by aviation specialists were, “It must have horrendous drag” just off the top of his head. In reality, every Burnelli design in every iteration out performed every other similar sized and powered design of the time. The numbers were made clear in NACA testing on the UB-14 and later testing on the CBY-3. The CBY-3 could carry 1200 pounds more than the (original) DC-3 and carry it faster and just as far.
To see the reason for the misunderstanding of induced drag on this design please read this… http://www.meridian-int-res.com/Aeronautics/Burnelli.htm . Also, a Sr. Aeronautical Engineer Rick Wood at NASA wrote this about Burnelli’s design in 2001… http://www.meridian-int-res.com/Aeronautics/Burnelli_AIAA.pdf The word he used to compare Burnelli’s last design before his death in 1964, the GB-888A, to a NASA, X-43B, hypersonic design is STRIKING!
Part of the reason the lifting fuselage has gone nowhere, besides in military fighters, is from all the bad mouthing by people who have not studied his designs in any detail. Some of them are very passionate about proving its worthlessness. For what reason I cannot understand. They should do their own testing to show the errors of NACA, NASA and the military.
Hope I haven’t bored you with all this. You might be able to tell, I’m quite passionate about Burnelli’s designs. I’m trying to get his work recognized and back into universities to be studied. If I make money along the way, OK, but this has never been my goal. The military has already gone there with the F-14, F-15, F-22, all lifting fuselage bodies as well as NASA’s X-43 and X-51 hypersonic projects.
I just want you to know that there are people who have studied Burnelli’s work in detail and have concluded the design is superior in many ways to the tube and wing. The reasons his designs went nowhere are many but the reasons to continue his work are even more numerous. Please share this with anyone you know who finds these things interesting. Your initial gut feeling was right. Burnelli’s designs are worth pursuing. I’m workin’ on it.
The military has already gone there with the F-14, F-15, F-22, all lifting fuselage bodies…
With all due respect, but those three are not really “lifting fuselage bodies”. In each of them, 80% of the lift – or even more – is generated by the wings just as with every other conventional aircraft. The wide shape of their fuselage is dictated by the distance between their twin engines (so that a hit into one engine will not take out the other one as well). Other than true lifting fuselage bodies, they do not even carry all their payload (weapons and ordnance) inside the fuselage but under their wings instead.
as well as NASA’s X-43 and X-51 hypersonic projects.
Those two are hypersonic reserach vehicles (the X-51 is more a rocket than an aeroplane) not even designed to fly at subsonic speed or land on their own. A completely different breed.
An aviation expert, who’s specialized in Circulation Control for over 40 years, told me he could make my design (500 passenger) take off, fully loaded, at 65 mph and cruise very close to Mach 1 with little drag penalty.
As much as I would love to see something like that materialise I stick with Carl Sagan by quoting his famous skeptic’s principle: “Extraordinary claims require extraordinary evidence”. As long as no credible calculations, wind tunnel results or test flight results are published, I believe nothing.
The main complaint of Burnelli’s designs by armchair aerodynamisists refers to excessive induced drag.
The problem is that these “armchair aerodynamisists” have their armchairs cemented into every aerospace faculty of every university in this world.
But honestly, I hope you can prove us all wrong and revolutionise air travel with safe and fuel efficient designs based on Burnelli’s ideas!
