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caoimhin
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 10:10 am

I'm still very skeptical of the economics of this aircraft. It's range seems oriented toward TATL routes, and while I'm sure there are *some* passengers willing to pay the enormous cost of flying on one of these, I question whether it will be enough to support the program--especially if (when) fuel prices increase and the aircraft becomes significantly more expensive to operate.
 
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Faro
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 11:05 am

Who are Aerion? Do they have the money to develop this bird?


Faro
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Alfons
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 12:03 pm

Are there some aerodynamics and physics professionals here?

What can have been the reason to limit the velocity to only 30-40% faster than what's flown today, when building and using an aircraft which clearly has its brand on speed and time saving?

When remembering past documentaries and articles, they said that the issues in the 60ies for going supersonic is that airflow behaviour changes and planes need to be built differently. So why limiting Aerion to only 20-30% above the speed of sound, when it's already built to be able to go much faster? Is the business case maybe around the attempt to build an aircraft which consumes the same fuel/F-class seat ratio like a normal airliner, and try to make it go the fastest while not crossing this line? Which would make the most sense for me from an economical and capital investors point of view. Concorde was an idealism, a dream.

Alfons
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 12:43 pm

Quoting LAX772LR (Reply 12):
I could not find the slightest thing from Airbus (or really any source other than Aerion themselves) that Airbus was really doing much of anything

I think the Airbus "involvement" is overrated. I guess they are keeping a handful of otherwise idle engineers busy, now that no new developments are being designed. If the program goes well, they'll jump in more seriously, and say how they decisively contributed. If it doesn't, they'll silently bail out as if they had never been there.

Quoting aviationaware (Reply 45):
I still don't get why anyone would want to do a Mach 1.2 plane. Terribly inefficient for very little speed gain...

M1.2 is only the boomless cruise. Cruise over ocean is M1.5. There is a big premium to pay once you go over the sound barrier, which doesn't change much whether you fly M1 or M1.8. Concorde was M2. Above M2 the premium starts to increase, let alone M3 (SR-71). The question for Aerion: will the less-than-Concorde speed difference be worth the extra cost?

Quoting francoflier (Reply 47):
They dropped the JT8 when they changed the design from a 2-engined to a 3-engined one.
That was driven by noise requirements I believe: 3 smaller, quieter engines...
They are in the process of choosing a new engine, which will likely be an existing design, probably a business jet engine, modified for supersonic flight.

Making performance promises without having selected an engine yet? If not even the engine is selected, it seems the design is still a long way from being frozen, whihc OTOH is consistent with 1st flight in 2021.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 1:11 pm

Quoting caoimhin (Reply 50):

I'm still very skeptical of the economics of this aircraft. It's range seems oriented toward TATL routes, and while I'm sure there are *some* passengers willing to pay the enormous cost of flying on one of these, I question whether it will be enough to support the program--especially if (when) fuel prices increase and the aircraft becomes significantly more expensive to operate.

Well, I mean, the only other commercial supersonic project I can ever think of operated exclusively TATL. It seemed to have a decent run.
A318/19/20/21, A300, A332/3, A343/6, A388, L1011, DC-9, DC-10, MD-11, MD-80, B722, B732/3/4/5/7/8/9, B743/4/4M, B752/3, B762/3/4, B772/E/W, B788/9, F-100, CRJ-200/700/900, ERJ-135/145/175/190, DH-8, ATR-72, DO-328, BAE-146
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 1:13 pm

Quoting r2rho (Reply 53):
I think the Airbus "involvement" is overrated.

Airbus are there to glean out any laminar flow wingset data they can find.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 1:25 pm

Am I the only one who believes this aircraft is inspired by TinTin: Flight 714 to Sydney  
It will forever be a McDonnell Douglas MD 80 , Boeing MD 80 sounds so wrong
 
2175301
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 3:17 pm

Quoting aviationaware (Reply 45):
I still don't get why anyone would want to do a Mach 1.2 plane.

They don't - I am surprised no one else from this site has checked the Aerion website in this age of sloppy journalism.


Per Aerion - the Aerion AS2 is designed for a maximum of M1.5, and most economical supersonic cruse at M1.4 (although subsonic cruse is more efficient - if you have the time...)

Please see the information and chart at:

http://www.aerionsupersonic.com/speed/


Note: concerning what the plane actually will look like; there does seem to be several different versions on the Aerion website (just count the windows on the different presentations).


Have a great day,
 
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caoimhin
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 4:01 pm

Quoting AA777223 (Reply 54):
Well, I mean, the only other commercial supersonic project I can ever think of operated exclusively TATL. It seemed to have a decent run.

And that project is no longer in operation. I have to imagine that if it were economically successful, it wouldn't have ended.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 5:13 pm

Quoting aviationaware (Reply 45):
I still don't get why anyone would want to do a Mach 1.2 plane. Terribly inefficient for very little speed gain... if you want to go faster you will have to eliminate the sonic boom.
Quoting r2rho (Reply 53):
M1.2 is only the boomless cruise. Cruise over ocean is M1.5. There is a big premium to pay once you go over the sound barrier, which doesn't change much whether you fly M1 or M1.8. Concorde was M2. Above M2 the premium starts to increase, let alone M3 (SR-71).

If you have a look at the Aerion website, they kindly offer up a speed/range graph, which neatly displays the fuel burn at different speeds.

http://i68.tinypic.com/33k6t6t.jpg

Both the Concorde and the Blackbird became more economical the faster they went above a certain speed. For Conc it was around M2.1, for the SR71 around 3.2; speeds above that would see a decline in fuel consumption. Such are the intricacies of high-mach aerodynamics.
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LAX772LR
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 8:05 pm

Quoting AA777223 (Reply 54):
Well, I mean, the only other commercial supersonic project I can ever think of operated exclusively TATL.

Which means you're forgetting the other commercial supersonic project, which was over land only.
Granted, it didn't last longer than about 50 flights... but still, very much a commercial SSC.


Quoting caoimhin (Reply 58):
And that project is no longer in operation. I have to imagine that if it were economically successful, it wouldn't have ended.

He said "successful," not "immortal."

34yrs flying, 27yrs in operation is a good run for any family of aircraft.
And contrary to popular lore, no airline is going to sustain such solely for "prestige" if indeed it was costing a net (tangible + intangible) loss to their system.

[Edited 2015-11-19 12:11:58]
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 8:14 pm

Quoting B777LRF (Reply 59):
Both the Concorde and the Blackbird became more economical the faster they went above a certain speed. For Conc it was around M2.1, for the SR71 around 3.2; speeds above that would see a decline in fuel consumption. Such are the intricacies of high-mach aerodynamics.

IIRC, skin temperature was the limiting factor in both aircraft on how fast they could go-the faster you go, the hotter the skin becomes. In metal, this was a concern because over a certain temperature, the metal started softening and would prematurely wear due to fatigue. Concorde was at the limits of what aluminum could do, and the Blackbird was at the limits of what Titanium could do  
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mfranjic
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 10:15 pm

According to those first drafts and the projects of the Aerion AS2 supersonic jet, its propulsion was including twin . JT8D-219 engines. Although a wonderful engine, JT8D-219 low bypass, twin-shaft turbofan [F+6LPC-7HPC ^ 1HPT-3LPT] with the BPR of 1,74:1, OPR of 21:1, fan diameter 49,2 in - 125 cm, rated at 96,53 kN - 21.700 lb s.t., is in the same time rather outdated, heavy (4.750 lb - 2154,5 kg) and noisy engine, and the materials used in its construction make it thermally inferior compared to the nowadays engines.

For the mentioned engine, besides the improved sealing, has also developed a new low-emissions combustion system (E-Kit) just to ensure the JT8D-200 engine could stay current with the environmental regulations. This E-Kit reduced JT8D-200 engine NOx, CO and smoke emissions in a great extent (A reconfigured JT8D-219 engine powers the U.S. Air Force’s re-engined E-8C JSTARS aircraft).

However, last year Aerion canceled the original twin-jet design, powered by JT8D-219 engines and unveiled the larger and longer-range AS2 which design imposes uniquely challenging requirements for a propulsion system. While the commercial turbofan engine manufacturers have focused on developing very high BPR (bypass ratio) and OPR (overall pressure ratio) systems, a supersonic engines require a comparatively low BPR and CPR (compressor pressure ratio). Too large fan diameter creates too much frontal area drag, but also the massive volume of cool exhaust flow is not able to move fast enough to push the aircraft to supersonic speeds.

On the front end of the engine, the FPR (fan pressure ratio) affects the specific thrust (thrust divided by the inlet airflow) and indirectly the speed of the air through the engine. And while the low bypass engines tend to have very high specific thrust values, those large high bypass turbofans have a very low specific thrust. Civilian turbofans usually use one large fan whereas high performance military turbofans typically use 3 or more fan stages for this exact reason. Retaining still for a moment on the engine´s propulsion efficiency, the exhaust nozzle has to be mentioned as a highly important part of the whole story. In ideal conditions, a jet engine exhausts the flow at the ambient pressure so it could produce a stable area of thrust. However, a given engine can push the air out at a higher pressure than is the ambient one, but this flow will simply over-expand, collapse in at its LP core and possibly re-expand. This phenomenon causes inefficiency and could be dangerous to the aircraft’s operation. To allow the higher than the ambient pressure flow to expand under control, so the energy is translated more axially rather than radially, a divergent section of nozzle is required. Each angle designed considering the convergent and divergent sections has a specific Mach number and pressure ratio associated with it. Knowing that fact, it is not hard to conclude that the aircraft would have maximum efficiency across a wide range of Mach numbers with the variable convergent-divergent nozzle at its exhaust. But, such a type of nozzle is very complicated to build and requires a system to activate it, just like hydraulic one or bleed air. A fixed nozzle has much lower efficiency, but also and much lower cost of construction...

Considering the thermal efficiency of the engine; all until the TIT is kept constant, specific thrust expound a maximum in its variation with CPR, because as the compressor pressure ratio is increased, the combustor´s inlet temperature is also increased. This means that the fuel to air ratio must be decreased to avoid overheating the turbine, and if the CPR was large enough, the maximum allowable temperature would be achieved at the compressor outlet and any addition of the fuel would overheat the turbine. In this way, a turbojet engine with high CPR can´t produce thrust at high Mach numbers without exceeding the maximum allowable TIT. No matter of the fact the thermal efficiency is increased with the higher CPR, the attendant decrease in specific thrust, at the higher Mach numbers, makes high-CPR turbojet engines impractical for supersonic flight. The optimum CPR reduces quickly with the increasing Mach number, in supersonic flight. On the other side; for the subsonic flight, high(er) CPR is welcome just to attain better engine´s thermal efficiency and lower specific thrust. However, for the supersonic flights, lower CPRs are typically used to accomplish higher specific thrust.

All that put the engine in question architecture closer to the category of military turbofan engines, but on the other side, the commercial Aerion application requires better SFC and significantly lower take-off noise than a typical military aircraft engines´ have...

Each of the three Aerion AS2´s engines would be rated at a roughly 16 klb of thrust, but the lower BPR alludes the engine´s core should have the geometry closer to that of the 30 klb thrust range engines, and aimed for a modern commercial turbofans. And who knows; if the whole story would go far enough and get the required weight, there is no doubt that the appropriate core will be found ...

.
*Aerion’s AS2 Supersonic Business Jet (SSBJ) is getting closer to reality through a partnership with Airbus




Nice regards

Mario
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Thu Nov 19, 2015 11:35 pm

Quoting bhill (Reply 16):
Where you gonna put the gas??

All that space between the last window and the wing is not there just for show...  
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 7:30 am

Interesting that they decided to go with a 4wheel mains
I myself, suspect a more prosaic motive... ~Thranduil
 
r2rho
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 9:22 am

Quoting KELPkid (Reply 61):
IIRC, skin temperature was the limiting factor in both aircraft on how fast they could go-the faster you go, the hotter the skin becomes. In metal, this was a concern because over a certain temperature, the metal started softening and would prematurely wear due to fatigue. Concorde was at the limits of what aluminum could do, and the Blackbird was at the limits of what Titanium could do

Yes, that is mainly what I meant with increasing difficulties for going faster.

Quoting B777LRF (Reply 59):
Both the Concorde and the Blackbird became more economical the faster they went above a certain speed. For Conc it was around M2.1, for the SR71 around 3.2; speeds above that would see a decline in fuel consumption. Such are the intricacies of high-mach aerodynamics.

My post was not very clear. Indeed, in terms of fuel consumption, going faster does not necessarily mean burning more fuel for a supersonically designed airplane, as the graph nicely points out.
 
BMI727
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 1:18 pm

Quoting LAX772LR (Reply 64):
Interesting that they decided to go with a 4wheel mains

I bet it's either a packaging thing or they want to use higher speed tires such as would be fitted on military aircraft (I don't know how aircraft tires are specified so that's just a WAG).
Why do Aerospace Engineering students have to turn things in on time?
 
ndhair37
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 2:09 pm

Would indeed be nice to see companies like British Airways (on account of the A318-styled J only flights) offer some J or F flights around parts of the world. Candidates must include JFK, IAD, DXB and the likes of PEK or PVG?
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 3:39 pm

Quoting r2rho (Reply 53):
I think the Airbus "involvement" is overrated. I guess they are keeping a handful of otherwise idle engineers busy, now that no new developments are being designed.

I'm also of the opinion that Airbus is only seeking technological returns here. In fact, there is a chance they don't really care if the project ever comes to fruition as long as they get the data and research they're after.
What does bother me is that they're willing to invest resources into a relatively far fetched and risky project like this one while repeatedly denying ATR any help with a new large Tprop...

Quoting columba (Reply 56):
Am I the only one who believes this aircraft is inspired by TinTin: Flight 714 to Sydney

No, you're not.

Minus the swing wing, of course...



 
I'll do my own airline. With Blackjack. And hookers. In fact, forget the airline.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 3:50 pm

Quoting francoflier (Reply 68):
What does bother me is that they're willing to invest resources into a relatively far fetched and risky project like this one while repeatedly denying ATR any help with a new large Tprop...

Because this project competes with exactly zero of Airbus's current planes. Meanwhile a large Tprop would interfere with the lower end of the A320's market, and of course the A320 family is Airbus's bread and butter.
 
dare100em
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 4:41 pm

Is any expert here qualified to enlighten me why a swinging-wing mechansim isn't seen as benifical (enough?) anymore, especially given the fact that this plane will obviously operate in very different circumstances, sometimes 50/50 sub-and-supersonic? Because of the planes size this mechanism shouldn't be monster-heavy like e.g. in the 2707-200.

E.g. like the 2707-200 or the TU-160:

https://en.wikipedia.org/wiki/Tupolev_Tu-160

Any ideas?

[Edit:] I just saw the laminar flow concept. Wondering what makes them so sure about it given Boeings recent remarks for such a system. Seems like some risk to me.

[Edited 2015-11-20 08:46:37]
 
2175301
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 6:17 pm

Quoting KELPkid (Reply 61):
Quoting dare100em (Reply 70):
Is any expert here qualified to enlighten me why a swinging-wing mechansim isn't seen as benifical (enough?)

My memories from various articles I read was the swing wing mechanism were maintenance intensive and needed parts were costly.


Have a great day,
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Fri Nov 20, 2015 11:40 pm

Quoting 2175301 (Reply 71):
My memories from various articles I read was the swing wing mechanism were maintenance intensive and needed parts were costly.

Not to mention being very heavy, complex and, with the ability to build a laminarflow supersonic wing, not needed.

Come to think of it, attempting to certify a swing-wing aircraft under civilian, commercial, rules would be an absolute nightmare.
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Sun Nov 22, 2015 2:16 am

Quoting ndhair37 (Reply 67):
Candidates must include JFK, IAD, DXB and the likes of PEK or PVG?

I'd imagine that the candidates for any such flights operating on behalf of BA/AF would be to the places that formerly had scheduled Concorde service: JFK being the obvious one, but also BGI, IAD, MIA, DFW, GIG, etc.
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Mon Nov 23, 2015 5:35 am

Quoting B777LRF (Reply 59):
If you have a look at the Aerion website, they kindly offer up a speed/range graph, which neatly displays the fuel burn at different speeds.


That's helpful. I know they've talked about the boomless cruise hopefully getting them permission for overland Supersonic flight. However, some playing around GC mapper says you'll save about an hour (3:15 vs 4:10) flying JFK-LAX at 1.15M vs .9 However, that difference grows dramatically for TATL. for JFK-LTN, you go from 5:45 at .9M to only 3:30 at 1.5M. It can work going to Asia as well even with a fuel stop. LAX-ANC-NRT is 6:15 flight time while LAX-NRT non stop at .9M is 9:10. LAX-PKC-HKG shows as 7:52 flight time at 1.4M vs 12:13 at .9M non stop. LAX-HNL-SYD @1.4M vs LAX-SYD @.85M (you'll have to slow that G650 down to make it non stop) is 8:14 (flight time) vs 13:20. All would allow time to do a quick turn fuel stop and stay ahead.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Mon Nov 23, 2015 2:02 pm

Quoting francoflier (Reply 68):

I'm also of the opinion that Airbus is only seeking technological returns here. In fact, there is a chance they don't really care if the project ever comes to fruition as long as they get the data and research they're after.
What does bother me is that they're willing to invest resources into a relatively far fetched and risky project like this one while repeatedly denying ATR any help with a new large Tprop...

Indeed. I assume it is due to the risk aversion that is the trend these days. With Aerion, Airbus loses nothing if the project fails, and at worst still gets some technology research done. With the new ATR, Airbus would invest money and resources into half of a full aircraft program, fully commit to it, and carry the consequences of success (very likely) or failure (unlikely).

Quoting Polot (Reply 69):
Because this project competes with exactly zero of Airbus's current planes. Meanwhile a large Tprop would interfere with the lower end of the A320's market, and of course the A320 family is Airbus's bread and butter.

Not wanting to derail the thread, but the new ATR that Airbus is blocking would have around 100 seats. Even a stretch would put it just below the A319NEO, which itself is not selling at all. So it would be an ideal complement to its product line below, and would in no way compete.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Mon Nov 23, 2015 2:03 pm

Quoting francoflier (Reply 68):
What does bother me is that they're willing to invest resources into a relatively far fetched and risky project like this one while repeatedly denying ATR any help with a new large Tprop...

Perhaps there is no market for a large turboprop.
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mrocktor
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Tue Nov 24, 2015 2:50 pm

Quoting LAX772LR (Reply 64):
Interesting that they decided to go with a 4wheel mains

I would not trust this artist's conception to that level of detail. That engine inlet geometry, for one, looks sleek - but not correct.
 
RIX
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Tue Nov 24, 2015 5:29 pm

Speaking of 4 wheel - looks reasonable for higher impact/pressure on higher speed landing?
 
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caoimhin
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Tue Nov 24, 2015 8:56 pm

Quoting LAX772LR (Reply 60):
He said "successful," not "immortal."

34yrs flying, 27yrs in operation is a good run for any family of aircraft.
And contrary to popular lore, no airline is going to sustain such solely for "prestige" if indeed it was costing a net (tangible + intangible) loss to their system.

I don't think anybody would disagree with that. But businesses tend to reproduce patterns that work, until they don't work any longer. The "immortality" of a type may be described differently as its sustainability. And that aircraft was not sustainable in the long term. I assume this was the same math that drove airlines disinterest in the Sonic Cruiser.

The entry of a new aircraft merits scrutiny, especially where that aircraft is entering a sector that was indeed unsustainable in the current environment, which places high value on efficiency and environmentally-conscious practices, and less on luxury and conspicuous consumption.

As for your point about the prestige value of keeping an underperforming aircraft in production, I'll bite.    I think those who argue that the A380 is only maintained because of the egos in Toulouse aren't completely wrong. From the Aboulafia thread:

Quoting Revelation:
Since I'm not an insider I don't know for sure, but it's my opinion that there were a lot of rose colored glasses being worn (and a lot of testosterone was pumping in a lot of veins) in the executive suite at Airbus when the A380 decision was being mooted.

I don't think this is that unreasonable of an argument, because hubris drives many large corporations--especially those trying to claim bragging rights over their competitors (one can even make the same argument for the 748i). If I were an EADS or Boeing shareholder, I wouldn't want the company to make decisions based on the pursuit of bragging rights unless there was a real business case for that decision.

Just one man's opinion.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Tue Nov 24, 2015 9:19 pm

Quoting tjh8402 (Reply 74):
I know they've talked about the boomless cruise hopefully getting them permission for overland Supersonic flight.

Be interesting to see if the likes of Canada would let them do it over northern areas, or Australia over the outback.



Quoting caoimhin (Reply 81):
I assume this was the same math that drove airlines disinterest in the Sonic Cruiser.

I'd say it was probably its mission profile in general:
...an aircraft aimed at operating/staying in the ultra high-drag transonic area?   
I myself, suspect a more prosaic motive... ~Thranduil
 
aryonoco
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Tue Nov 24, 2015 11:41 pm

Quoting LAX772LR (Reply 82):
or Australia over the outback.

Some people live in the outback.
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 1:44 am

Quoting aryonoco (Reply 83):
Some people live in the outback.

No one's claiming that there isn't.
But we're talking about an average density of less than 0.09 humans per square kilometer.

https://ckrao.files.wordpress.com/2013/10/aus-low-density-areas.jpg


Every area shown in red features a density of at least 0.1 humans per km2.
Not too many....
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 2:16 am

Quoting LAX772LR (Reply 82):

I'd say it was probably its mission profile in general:
...an aircraft aimed at operating/staying in the ultra high-drag transonic area?

Not much more drag to just push it to supersonic...   Plus, you've already solved most of the difficulties of getting above the speed of sound if you've engineered it for high transonic.
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 2:25 am

Quoting KELPkid (Reply 85):
Not much more drag to just push it to supersonic.

In fact, quite the opposite... if it'd "just" get a little faster, the drag would decrease considerably.

That's why Concorde kicked in its afterburners at around the area the Sonic Cruiser was aimed to fly in:
it was actually less fuel-intensive to use reheat and speed up well past it, than it was to stay in that speed range for any length of time!  Wow!
I myself, suspect a more prosaic motive... ~Thranduil
 
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 3:05 am

Quoting LAX772LR (Reply 84):
Every area shown in red features a density of at least 0.1 humans per km2.
Not too many....

You're obviously removed from Australian politics.

There is no way an Australian government is going to approve supersonic booms over the land mostly lived by Aboriginal people just so some rich fat cats can fly a bit quicker.

It would be political suicide.
 
BMI727
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 3:21 am

Quoting LAX772LR (Reply 86):
That's why Concorde kicked in its afterburners at around the area the Sonic Cruiser was aimed to fly in:
it was actually less fuel-intensive to use reheat and speed up well past it, than it was to stay in that speed range for any length of time!

Well that's just the two basic strategies to deal with wave drag: you can do as most aircraft do and delay it as long as possible while you edge closer to Mach 1, or you can just punch through it if you have the thrust.
Why do Aerospace Engineering students have to turn things in on time?
 
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LAX772LR
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 4:13 am

Quoting aryonoco (Reply 87):
You're obviously removed from Australian politics.

Yeah, no joke... a government that works on behalf of the poor instead of for the benefit of the wealthy in all situations? That's like a political unicorn!  Wow!
I myself, suspect a more prosaic motive... ~Thranduil
 
Norlander
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 11:49 am

If it flies at M 1.5 it will get from New York to London in 4½ hours - highly desirable, and only about an hour slower than Concorde.

Tokyo to San Francisco could be done in anything from 5 to 7 hours depending upon wind, as they are able to go supersonic pretty much the whole way from HND to SFO.

WolframAlpha calculates the time at 4½ hours if it's straight great circle and constant M 1.5.
Longtime Lurker
 
motif1
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RE: Flexjet Orders 20 Aerion AS2 Supersonic Jets

Wed Nov 25, 2015 1:51 pm

How high would that plane fly at supersonic speeds? Does anyone know?

M1
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