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Transonic truss the solution for regional aircraft?

Posted: Wed May 13, 2020 2:24 pm
by VenturiEffect
A question for the engineers in the forum. Is there anything other than the same engine availability issues preventing the technology being developed for the Boeing SUGAR and NASA TTBW being applied to a sub 76-seat frame? Could this tech bypass the immediate need for a new power plant with positive efficiency gains brought by the wing design?

Many sources but I find this study on potential performance enhancers to be compelling: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20200002388.pdf

Re: Transonic truss the solution for regional aircraft?

Posted: Thu May 14, 2020 11:45 pm
by jetmatt777
Link isn't working for me

Re: Transonic truss the solution for regional aircraft?

Posted: Fri May 15, 2020 11:52 am
by VenturiEffect
jetmatt777 wrote:
Link isn't working for me


I have been a reader for several years and haven’t successfully figured out how to post links appropriately. An alternate method would be to visit ntrs.nasa.gov and search “Transonic Truss-Braced Wing”. The linked study is the 8th result, but all of the studies are valuable for the question. Boeing has also published on its TTBW concept for a 737-size aircraft. My question really revolves around using efficiency gains (once engineering issues like flutter and higher wave turbulence are solved) from the more efficient wing can reduce the need for larger, heavier, high-bypass engines that seem to be one of the major design constraints in regional aircraft design.

Re: Transonic truss the solution for regional aircraft?

Posted: Fri May 15, 2020 3:42 pm
by kalvado
Boeing did show that as one of the future concepts. But there are a lot more concepts than flying planes.. My understanding, maybe not so educated:
-A very clean-sheet design, meaning tens billions and probably 10 years of work.
-A truss-wing joint will be a very delicate point, paper you linked doesn't even touch that.
-high wing may work reasonably for smaller RJ (jetways are overrated anyway)), but would that require T tail with its cans of worms? How would rotation work? Or we're talking engines up there and maintenance requiring lots of machinery - with limited access due to truss in the way?
-how much engine upgradeability such design has? Engines have the potential to develop.

Overall, I suspect this would be a much bigger endeavor than, say, composite barrel body of 787

Re: Transonic truss the solution for regional aircraft?

Posted: Fri May 15, 2020 8:36 pm
by CowAnon
(I'm no aeronautical engineer, but I'll add my thoughts anyway.)

PICTURE: Boeing unveils trussed wing capable of jet speeds (FlightGlobal, 9 January 2019)

    Boeing achieved the improvement by tweaking the truss and the wing sweep. It has estimated such wings can reduce an aircraft’s fuel burn by 8-10% compared to aircraft with conventional cantilevered wings.

    The company on 8 January released details of the design and a computer image of a narrowbody aircraft with the wing.

    But, Harrison says aircraft of any size could carry such a wing. The technology is intended to be ready for operation in the 2030-2035 timeframe.

You were asking about sub-76 seat aircraft. If you're thinking of scope compliance as well, there's also the 86,000-pound weight limit. I don't know how the weight of a regular wing actually compares to an equivalent higher-span truss-based wing, but the TBW looks heavier. In addition, the truss-based wing would seem more beneficial for medium and long range aircraft, which spend a greater proportion of flight time in cruise than regional aircraft do.

Re: Transonic truss the solution for regional aircraft?

Posted: Fri May 15, 2020 9:25 pm
by GalaxyFlyer
Way too much money invested in design, bills, test and certification for 76 seat market. You’re talking $6 billion, at least, and there’s no way to amortize the NRC over at most a 1500 plane production and possibly half that, if it weighs more than 86,000#.

Re: Transonic truss the solution for regional aircraft?

Posted: Sat May 16, 2020 1:13 am
by VenturiEffect
GalaxyFlyer wrote:
Way too much money invested in design, bills, test and certification for 76 seat market. You’re talking $6 billion, at least, and there’s no way to amortize the NRC over at most a 1500 plane production and possibly half that, if it weighs more than 86,000#.


I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific. What I am proposing is that new technology be leveraged (likely on the back of a military or 150-200 seat program) to rejuvenate a segment of the industry that is ripe for innovation. This conversation traditionally centers around power plants, which do push the boundary of efficiency, but by nature grow in size and weight which leaves RJ’s out in the cold. This could be an opportunity to push efficiency in a different direction. The market opportunity has been demonstrated on this forum countless times, it just requires the right aircraft.

Re: Transonic truss the solution for regional aircraft?

Posted: Sat May 16, 2020 1:18 am
by GalaxyFlyer
But, development and certification cost can’t be ignored and there’s precious little transferable. The A220 has about $5 billion in non-recurring costs, new design but most of it well proven technology, nothing earth shattering. If you sell a 1000 frames, you have to recover $5 million per delivery to break even plus the build cost. That’s what it costs to develop a new plane and there’s no escaping that fact.

Re: Transonic truss the solution for regional aircraft?

Posted: Sat May 16, 2020 1:36 am
by VenturiEffect
GalaxyFlyer wrote:
But, development and certification cost can’t be ignored and there’s precious little transferable. The A220 has about $5 billion in non-recurring costs, new design but most of it well proven technology, nothing earth shattering. If you sell a 1000 frames, you have to recover $5 million per delivery to break even plus the build cost. That’s what it costs to develop a new plane and there’s no escaping that fact.


Completely valid and supremely important point. I just haven't seen evidence that the costs have been modeled to a point that we should declare RJ’s dead as some have. A design created to make up for the efficiency hits of new power sources (of which there are many. I for one am not sure we will ever see anything but Jet A) could potentially make up the 15-20% deficiency of last-gen engines. To your point, engine/ weight efficiency gains are a cheaper way forward but we appear to have hit a wall in RJ design as evidenced by the e275.

Re: Transonic truss the solution for regional aircraft?

Posted: Sat May 16, 2020 9:39 pm
by CowAnon
Yes, financing will be a huge problem, and the 150-180 seat airplane market should be targeted before the sub-76-seat market. Though it's unlikely, it's not impossible that a developing/developed country starts throwing money into aircraft development. Same thing with billionaires, though currently the ones who are interested in flight are putting their efforts more into spaceships than aircraft.

If you are looking for something more efficient than the usual forms of aircraft but aren't tied specifically to the truss-braced wing, there are blended wing body and flying wing concepts that can do a lot better than the TBW's 8-10% fuel burn reduction. Considering the terrible prospects for clean sheet aircraft in the short/medium term, shouldn't the OEMs be more aggressive in their designs? With plans for new aircraft pushed farther out into the future, the technologies will have more time to mature.

For example, the Dzyne Ascent 1000, a 112-seat BWB, claims to use 43% less fuel per nautical mile seat (see page 12) than the CS100 (Airbus A220-100).

There's also the EKIP "Tarielka", a thick flying wing design that relies on a complex boundary-layer control system. The designers claim that its L3-1 version can transport 160 passengers up to 4,000 kilometers with a takeoff weight of 45 tons (about 99,000 pounds). If you limited the number of passengers to 76 and didn't replace the average flyer's weight with fuel or cargo, the takeoff weight would drop to below the 86,000-pound scope clause limit. With the EKIP L3-1, you could target the capacity sweet spots occupied by the (over-ranged in some people's view) A320 and B737-8, while also being usable by the US regional airlines. The EKIP has a long history going back to the late 1970s; the Soviet Union, European Community, and US Navy all were involved with the EKIP at various points, and Russia once proposed equipping the United Nations with EKIPs as a global firefighting fleet, since the EKIP has water takeoff/landing capability.

Re: Transonic truss the solution for regional aircraft?

Posted: Sun May 17, 2020 2:11 am
by VenturiEffect
CowAnon wrote:
Yes, financing will be a huge problem, and the 150-180 seat airplane market should be targeted before the sub-76-seat market. Though it's unlikely, it's not impossible that a developing/developed country starts throwing money into aircraft development. Same thing with billionaires, though currently the ones who are interested in flight are putting their efforts more into spaceships than aircraft.

If you are looking for something more efficient than the usual forms of aircraft but aren't tied specifically to the truss-braced wing, there are blended wing body and flying wing concepts that can do a lot better than the TBW's 8-10% fuel burn reduction. Considering the terrible prospects for clean sheet aircraft in the short/medium term, shouldn't the OEMs be more aggressive in their designs? With plans for new aircraft pushed farther out into the future, the technologies will have more time to mature.

For example, the Dzyne Ascent 1000, a 112-seat BWB, claims to use 43% less fuel per nautical mile seat (see page 12) than the CS100 (Airbus A220-100).

There's also the EKIP "Tarielka", a thick flying wing design that relies on a complex boundary-layer control system. The designers claim that its L3-1 version can transport 160 passengers up to 4,000 kilometers with a takeoff weight of 45 tons (about 99,000 pounds). If you limited the number of passengers to 76 and didn't replace the average flyer's weight with fuel or cargo, the takeoff weight would drop to below the 86,000-pound scope clause limit. With the EKIP L3-1, you could target the capacity sweet spots occupied by the (over-ranged in some people's view) A320 and B737-8, while also being usable by the US regional airlines. The EKIP has a long history going back to the late 1970s; the Soviet Union, European Community, and US Navy all were involved with the EKIP at various points, and Russia once proposed equipping the United Nations with EKIPs as a global firefighting fleet, since the EKIP has water takeoff/landing capability.


Their boundary layer diversion method is interesting, this is the first I am coming across it. I perhaps wrongly assumed that the near-term viability of BWB was less than a TBW concept but I am looking forward to reading this study more closely. Perhaps at regional and small narrow body scales, the distance from the centerline in turns is less of a design issue.

Re: Transonic truss the solution for regional aircraft?

Posted: Sun May 17, 2020 11:14 pm
by Dmoney
VenturiEffect wrote:
GalaxyFlyer wrote:
Way too much money invested in design, bills, test and certification for 76 seat market. You’re talking $6 billion, at least, and there’s no way to amortize the NRC over at most a 1500 plane production and possibly half that, if it weighs more than 86,000#.


I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific. What I am proposing is that new technology be leveraged (likely on the back of a military or 150-200 seat program) to rejuvenate a segment of the industry that is ripe for innovation. This conversation traditionally centers around power plants, which do push the boundary of efficiency, but by nature grow in size and weight which leaves RJ’s out in the cold. This could be an opportunity to push efficiency in a different direction. The market opportunity has been demonstrated on this forum countless times, it just requires the right aircraft.



No. The purpose of companies is to earn a return for shareholders. It's not profitable to develop a new plane. That's the reality of it whether you like it or not.

Re: Transonic truss the solution for regional aircraft?

Posted: Mon May 18, 2020 12:45 am
by mxaxai
VenturiEffect wrote:
I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific.

The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand. Even more so when you're applying untested, novel technology. I love the technological aspects, but the business reality is that the standard narrowbodies will drive technological progress.

The issue becomes even more complicated when you consider that airlines nowadays prefer a "one-size-fits-all" aircraft. The LCC's business model relies on that and even legacies are shifting towards simplified fleets. So while certain technologies could create excellent regional aircraft, airlines don't like aircraft that can only be used on one mission. Your truss aircraft will need to excel on short < 1h hops, but it will also have to compete against A320s and 737s on 2-3 h flights. For example, Embraer could de-rate their E2-175 to fit the US scope clauses. But they don't. Why? It would reduce range so much that it loses its flexibility, and can no longer compete against the "abuse" of non-optimised larger aircraft on regional flights.

Re: Transonic truss the solution for regional aircraft?

Posted: Mon May 18, 2020 2:17 pm
by VenturiEffect
mxaxai wrote:
VenturiEffect wrote:
I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific.

The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand. Even more so when you're applying untested, novel technology. I love the technological aspects, but the business reality is that the standard narrowbodies will drive technological progress.

The issue becomes even more complicated when you consider that airlines nowadays prefer a "one-size-fits-all" aircraft. The LCC's business model relies on that and even legacies are shifting towards simplified fleets. So while certain technologies could create excellent regional aircraft, airlines don't like aircraft that can only be used on one mission. Your truss aircraft will need to excel on short < 1h hops, but it will also have to compete against A320s and 737s on 2-3 h flights. For example, Embraer could de-rate their E2-175 to fit the US scope clauses. But they don't. Why? It would reduce range so much that it loses its flexibility, and can no longer compete against the "abuse" of non-optimised larger aircraft on regional flights.



I appreciate the perspective. The realities of aircraft development aren’t lost on me, but we aren’t battling the laws of physics here. Financing is malleable, for example, UPS/FedEx financed the SkyCourier, which under conventional logic never should have existed based on costs. I am of the opinion that a booming economy actually demands regional aircraft, due to the need for frequency and reasonable inter-connectivity. Obviously something like this will take a back seat for the next 5 years minimum due to COVID, but perhaps we could be looking at a SkyCourier situation for the next RJ. That, or a new entrant who isn’t constrained by the same (mostly BS) development costs will come in and do what Tesla did to legacy automakers.

Re: Transonic truss the solution for regional aircraft?

Posted: Mon May 18, 2020 3:13 pm
by GalaxyFlyer
VenturiEffect wrote:
mxaxai wrote:
VenturiEffect wrote:
I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific.

The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand. Even more so when you're applying untested, novel technology. I love the technological aspects, but the business reality is that the standard narrowbodies will drive technological progress.

The issue becomes even more complicated when you consider that airlines nowadays prefer a "one-size-fits-all" aircraft. The LCC's business model relies on that and even legacies are shifting towards simplified fleets. So while certain technologies could create excellent regional aircraft, airlines don't like aircraft that can only be used on one mission. Your truss aircraft will need to excel on short < 1h hops, but it will also have to compete against A320s and 737s on 2-3 h flights. For example, Embraer could de-rate their E2-175 to fit the US scope clauses. But they don't. Why? It would reduce range so much that it loses its flexibility, and can no longer compete against the "abuse" of non-optimised larger aircraft on regional flights.



I appreciate the perspective. The realities of aircraft development aren’t lost on me, but we aren’t battling the laws of physics here. Financing is malleable, for example, UPS/FedEx financed the SkyCourier, which under conventional logic never should have existed based on costs. I am of the opinion that a booming economy actually demands regional aircraft, due to the need for frequency and reasonable inter-connectivity. Obviously something like this will take a back seat for the next 5 years minimum due to COVID, but perhaps we could be looking at a SkyCourier situation for the next RJ. That, or a new entrant who isn’t constrained by the same (mostly BS) development costs will come in and do what Tesla did to legacy automakers.


The Sky Courier is vastly simpler to design and certify than a Part 25 airliner. Tesla-like entrant still has to meet certification standards which is the cost of entry. Using proven technology, a new RJ is at least a $6 billion dollar development program. If you doubt the hurdles, review Vern Raeburn’s experience with the bizjet for the millions aka Eclipse

Re: Transonic truss the solution for regional aircraft?

Posted: Mon May 18, 2020 4:17 pm
by mxaxai
VenturiEffect wrote:
Financing is malleable, for example, UPS/FedEx financed the SkyCourier, which under conventional logic never should have existed based on costs.

The SkyCourier is a 19-seat aircraft, so can be certified under Part 23. Same applies to the Tecnam 2012P, although the regulations are even more relaxed for 9-seat aircraft so is easier to certify than the SkyCourier. But anything over 19 seats falls under Part 25.

The SkyCourier is an interesting example, though. It uses a new (albeit not very innovative) airframe and adds a derivative of a proven engine, thereby reducing development cost and risk. The DHC-6-400 is exactly the opposite, it uses the old DHC-6 fuselage and wing but adds a new engine and modern avionics. So if a trussed wing alone - with a reasonably efficient conventional fuselage and the in-service support of an existing OEM - can improve efficiency enough that you don't require a brand new engine, then you might reduce development risk and cost to the point that a bank will provide financing. Alternatively, you would have to time it so that your aircraft is the first to utilise a leap in engine technology; that's what the CSeries tried but delays of both engines and aircraft made it lose the time advantage.

What could work is to apply the technology to a low-cost aircraft first, like a business jet, and then upscale it to a regional jet. Or you can find someone willing to lose a lot of money, like the government, to pay for the development and then transfer the technology to a commercially viable aircraft.

Re: Transonic truss the solution for regional aircraft?

Posted: Wed May 20, 2020 4:28 pm
by Sokes
mxaxai wrote:
The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand.

Good info. Sounds as if one should invest in Embraer.

Re: Transonic truss the solution for regional aircraft?

Posted: Wed May 20, 2020 5:03 pm
by GalaxyFlyer
Sokes wrote:
mxaxai wrote:
The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand.

Good info. Sounds as if one should invest in Embraer.


There’s some bad investment advice right there.

Re: Transonic truss the solution for regional aircraft?

Posted: Wed May 20, 2020 5:21 pm
by mxaxai
Sokes wrote:
Good info. Sounds as if one should invest in Embraer.
Off topic, but investing into aviation is almost never a good idea.

Re: Transonic truss the solution for regional aircraft?

Posted: Wed May 20, 2020 6:03 pm
by Sokes
mxaxai wrote:
Sokes wrote:
Good info. Sounds as if one should invest in Embraer.
Off topic, but investing into aviation is almost never a good idea.

Agreed.

Re: Transonic truss the solution for regional aircraft?

Posted: Wed May 20, 2020 11:28 pm
by Starlionblue
mxaxai wrote:
VenturiEffect wrote:
I came to this forum to learn, but the question of a new RJ design always ends with “it’s too expensive, it will cost XX”. I find that extremely unsatisfactory and nonspecific.

The problem is that aircraft development and certification costs are (almost) independent from aircraft size. Simply because the systems are the same, the manufacturing technology is the same, the certification requirements are the same. The Mitsubishi MRJ is already at over $ 9 billion, the CSeries / A220 is in the same ballpark. The A350, on the other hand, cost "only" $ 15 billion. But Airbus can ask 4x the list price for the A350 compared to the A220. So smaller aircraft need to sell a lot more.

Problem is, only the standard narrowbodies are in such demand; even the successful E-jets and the CSeries sell a magnitude less than the A320 & 737 (~2,000 vs. ~20,000). You can easily see how clean-sheet RJ's have become extremely difficult to finance, considering high development cost + low sales price + high(er) CASM + limited demand. Even more so when you're applying untested, novel technology. I love the technological aspects, but the business reality is that the standard narrowbodies will drive technological progress.

The issue becomes even more complicated when you consider that airlines nowadays prefer a "one-size-fits-all" aircraft. The LCC's business model relies on that and even legacies are shifting towards simplified fleets. So while certain technologies could create excellent regional aircraft, airlines don't like aircraft that can only be used on one mission. Your truss aircraft will need to excel on short < 1h hops, but it will also have to compete against A320s and 737s on 2-3 h flights. For example, Embraer could de-rate their E2-175 to fit the US scope clauses. But they don't. Why? It would reduce range so much that it loses its flexibility, and can no longer compete against the "abuse" of non-optimised larger aircraft on regional flights.


While I agree that A320 and 737 sell more than A220 and E Jet, the sales comparison of "~2,000 vs. ~20,000" needs more context. The 737 has been in production for over 50 years and the A320 since the for almost 40. In comparison, the E Jets have been in production for less than 20 years and the C Series for less than a decade. Comparing sales since 2010 might be more accurate.

Re: Transonic truss the solution for regional aircraft?

Posted: Fri Jun 19, 2020 3:23 am
by CowAnon
NASA may actually build a flight demonstrator for the truss-based wing:

https://www.flightglobal.com/airframers ... 61.article

Re: Transonic truss the solution for regional aircraft?

Posted: Thu Jun 25, 2020 3:22 am
by strfyr51
VenturiEffect wrote:
A question for the engineers in the forum. Is there anything other than the same engine availability issues preventing the technology being developed for the Boeing SUGAR and NASA TTBW being applied to a sub 76-seat frame? Could this tech bypass the immediate need for a new power plant with positive efficiency gains brought by the wing design?

Many sources but I find this study on potential performance enhancers to be compelling: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20200002388.pdf

actually? No, NASA Ames had a few airplanes that had truss braced wings that they flew in tests that never saw commercial service. They were just strange looking airplanes. one was a STOL airplane I had never seen before or since. But my last time at Moffett Field was in 1980.