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dfwjim1
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Supersonic Business Jets?

Tue Jul 07, 2015 4:08 pm

Recently I saw an advertisement in the Wall Street Journal by Gulfstream touting their newest types of business jets. Got
me to thinking...is there any possibility that we might see business jets that can fly at supersonic speeds in the near future? Or
is this something that is out of the realm of possibilities?

Thanks for your responses.
 
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Stitch
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RE: Supersonic Business Jets?

Tue Jul 07, 2015 5:13 pm

Supersonic business jets have been proposed off and on for decades. Sukhoi and Gulfstream collaborated on one called the S-21 in the 1990s as did Tupoloev in the 2000s. In the United States, Aerion and Spike Aerospace are independently developing such planes as are HyperMach in the UK.
 
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LAX772LR
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RE: Supersonic Business Jets?

Tue Jul 07, 2015 7:07 pm

What Stitch said.

That, and they always claim to have LOIs/MOUs/etc from all these undisclosed carriers, that never really seem to come to fruition.

I doubt we'll ever see another Concorde again, but I wouldn't be surprised if there's a private SST. Just who's it going to be? Thought for sure Aerion would finally be the one, but they don't seem any closer now than they were a half decade ago.  
I myself, suspect a more prosaic motive... ~Thranduil
 
LH707330
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RE: Supersonic Business Jets?

Tue Jul 07, 2015 8:20 pm

I doubt there's a big enough market to justify the R&D for it, especially the engines. Aerion said they want to go with the JT8D-200s because of their low bypass ratio, but I've not heard much news there.

Some other drawbacks to SSBJs:
1. They're longer and heavier for the same capacity, thus harder to park and get in and out of smaller airports
2. Unless sonic booms can be mitigated, they won't be much faster over land than a G650/Global8000, limiting their utility to overwater flights
3. For the same price as an SSBJ, you could get a VIP airliner and travel in much more comfort
4. Range would probably be a problem

Between these factors, your use cases would be North Atlantic, North Pacific, and some Asia-Aus flying. The technology clearly exists to build one, but the absence of SSBJs suggests that these drawbacks make the market too small to justify the investment.
 
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Starlionblue
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RE: Supersonic Business Jets?

Tue Jul 07, 2015 10:32 pm

One huge issue is wing planform. Supersonic flight requires a rather different wing compared to the transonic wings of today.

Up to current airliner/BJ speeds, a supercritical swept wing is very efficient. While not ideal, it is also relatively good for approach speeds. However it has too thick a profile for efficiency past Mach 1. That's where a thin delta wing has advantages. (Once you go past Mach 2.5, you're actually better off with a thin straight wing like the F-104.)

Concorde had a gorgeous ogival delta wing. Great at Mach 1.5-2.5. The downside of this, and the absence of slats, was that it had to fly at a high angle of attack on approach. This meant a horrendous amount of induced drag (and an equally horrendous amount of noise) which led high fuel burn at low speeds.

Aerodynamically, the ideal might be a variable sweep wing like the F-111 or F-14. If you look at these wings, they are actually quite thick, allowing good low speed performance (and the carriage of good amounts of fuel). Once at high speed the wings are swept back and thus inside the Mach cone, meaning their thickness is not affecting their performance. However a variable sweep wing means a lot of added weight and complexity.

Quoting LH707330 (Reply 3):
2. Unless sonic booms can be mitigated, they won't be much faster over land than a G650/Global8000, limiting their utility to overwater flights

There's the rub. Going faster than the G650 but still subsonic just increases drag (and thus fuel flow) dramatically without a very big increase in speed. The speed range right around the Mach 1 is the worst. Once you're through the transonic range (over Mach 1.3-ish) you're over the wave drag hump. Sure, parasite drag is still increasing, but it is not doing so disproportionally to the speed increase.

"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
trijetsonly
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RE: Supersonic Business Jets?

Wed Jul 08, 2015 9:46 am

Now as Airbus works together with Aerion in developement of a SS business jet I really hope to see it coming.
Happy Landings
 
wingscrubber
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RE: Supersonic Business Jets?

Wed Jul 08, 2015 10:20 pm

The Aerion concept seems to be of the greatest merit thus far, and they are supposedly teamed up with Airbus to do design studies, but almost every airframer under the sun has had a go at a SSBJ concept publicly or in secret, including Dassault, Cessna, Gulfstream, Sukhoi, Lockheed, etc. etc.

The current fastest business jet is again, and still the Citation X+, after her crown was briefly stolen by the G650. In terms of knots per dollar, a Citation X is still the best bang for buck. G650 exists in an entirely different size, range and price category, but for domestic overland missions in the US, Citation X still can't be beaten by any civilian aircraft.

With overland flight seemingly out of bounds then, the limited business case for a SSBJ would be only to shorten the Atlantic crossings back to Concorde times, and the development work involved would be immense. It's much harder to certify aircraft today than it was in the 60s/70s when Concorde was designed and built, which makes me fearful that Aerion is a bottomless money pit. The engines they've selected aren't even close enough in terms of thrust, they also have no intake ramp technology and no afterburner to bolt-on to the JT8D-200s. The only viable powerplants that could actually do the job, i.e. the GE F110 or P&W F100 are military hardware and could not be sourced without a huge battle with the state department over dual-use. EJ200s are one other option, but again they are military. There simply are no other civilian afterburning turbojets capable of supercruise other than the Olympus 593s used on Concorde, cobbling together an all-new JT8D based powerplant capable of web thrust, let alone supercruise, is a tall order.

The main battle to fight, in my opinion, is to first prove that it can be done, the naysayers and environmentalists outnumber the optimists a hundred to one, and a proof of concept demonstrator needs to be built and flown before any of them will let go of their pessimism. That concept demonstrator needs to have hit a few milestone targets before a true SSBJ business case can be taken seriously. The best precedent is actually set by ground level supersonic efforts - look at Thrust SSC and Bloodhound, Thrust used a pair of afterburning Speys from a Phantom - bolt a pair of those onto a test mule airframe such as a Citation X or Falcon 20 with a modified wing and all-flying stabivators, and see if level flight supersonic flight can be attained - basically, build Thrust SSC with wings and a cabin. (I'm already on the phone to Richard Noble...)

After busting the mach barrier on wet thrust, and then after some tinkering eventually achieve supercruise on dry thrust in a privateer civilian test aircraft, then we can talk. Until that happens, all SSBJs and supersonic airliners are pipe dreams. Just building a demonstrator could be in the order of tens of millions of dollars at a low-ball guess, certifying and producing the whole package would be far in excess of that, those kind of development costs can't be recouped unless the project is funded by a government military contract, or is guaranteed a large airline orderbook. Business jets just don't sell in high enough quantities to recoup the cost... perhaps, a mini-Concorde is viable, the equivalent of a supersonic ERJ-145, a low capacity but medium range, high speed aircraft that could somehow still be marketed to the masses? It could happen one day. What an extremely frustrating age it is to be an aerospace engineer!!  
Resident TechOps Troll
 
LH707330
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 5:51 am

Quoting wingscrubber (Reply 6):
The engines they've selected aren't even close enough in terms of thrust, they also have no intake ramp technology and no afterburner to bolt-on to the JT8D-200s.

They don't need ramps, they're aiming for M1.6, not 2.04 like Concorde. Most newer fighters like the F-16 and F-18 have fixed intakes, the ramps are only important around M2.
 
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LAX772LR
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 6:49 am

Quoting trijetsonly (Reply 5):
Now as Airbus works together with Aerion in developement of a SS business jet I really hope to see it coming.

That was trumpeted by Aerion... but there doesn't appear to be the slightest confirmation of that by Airbus, when last I tried to find some.

I wonder.   

Seems to me that Airbus might've said "We'll take a look" and Aerion apparently released that as "Airbus is working with is!"
I myself, suspect a more prosaic motive... ~Thranduil
 
rwessel
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 7:04 am

Quoting LH707330 (Reply 7):
They don't need ramps, they're aiming for M1.6, not 2.04 like Concorde. Most newer fighters like the F-16 and F-18 have fixed intakes, the ramps are only important around M2.

I'm not sure that's true. Military aircraft often have substantial amounts of excess power, and a tolerance for very high fuel burns (and correspondingly short range). Even at Mach 1.6, a two shock inlet will offer a fair increase in pressure recovery over a single shock inlet. See:

https://en.wikipedia.org/wiki/Components_of_jet_engines#/media/File:Intakerecovery.gif

Even at Mach 1.6, you're still probably looking at a increase in pressure recovery of 15% or so with a better inlet, which at that speed probably translates into a reduction in fuel burn of 20-30%.
 
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Starlionblue
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 7:46 am

Quoting wingscrubber (Reply 6):
a Citation X or Falcon 20 with a modified wing and all-flying stabivators,

While an all-flying stabilizer is ideal, the trimmable horizontal stabilizer already there should be enough. As I understand it you don't really need rapid movement, just countering of mach tuck.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
Pihero
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 11:02 am

Quoting Starlionblue (Reply 4):
There's the rub. Going faster than the G650 but still subsonic just increases drag (and thus fuel flow) dramatically without a very big increase in speed. The speed range right around the Mach 1 is the worst. Once you're through the transonic range (over Mach 1.3-ish) you're over the wave drag hump. Sure, parasite drag is still increasing, but it is not doing so disproportionally to the speed increase.

That's the reason I've never, since day one believed that the Sonic Cruiser was anything more than a pub stunt.

Quoting wingscrubber (Reply 6):
a pair of afterburning Speys from a Phantom - bolt a pair of those onto a test mule airframe such as a Citation X or Falcon 20 with a modified wing and all-flying stabivators, and see if level flight supersonic flight can be attained

Aerodynamics in the subsonic, then sonic and then again supersonic areas are vastly different. You could put a lot of thrust in any subsonic frame but you won't beat the sound barrier
The Thrust vehicle is just a dart, no lift involved at all -some negative lift to keep it on the ground was needed, but in a very small amount, the vehicle body shape took care of that - so, basically it was a matter of dealing with the minimum drag they could attain.

Quoting wingscrubber (Reply 6):
perhaps, a mini-Concorde is viable, the equivalent of a supersonic ERJ-145, a low capacity but medium range, high speed aircraft that could somehow still be marketed to the masses? It could happen one day

A medium range supersonic flight would entail over land flight... no sonic boom allawed... Hence another dream.
Contrail designer
 
OldAeroGuy
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 1:18 pm

Quoting Pihero (Reply 11):
That's the reason I've never, since day one believed that the Sonic Cruiser was anything more than a pub stunt.

Especially since it was a canard configuration, about the worst possible choice for a commercial transport.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
LH707330
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RE: Supersonic Business Jets?

Thu Jul 09, 2015 3:14 pm

Quoting rwessel (Reply 9):
I'm not sure that's true. Military aircraft often have substantial amounts of excess power, and a tolerance for very high fuel burns (and correspondingly short range). Even at Mach 1.6, a two shock inlet will offer a fair increase in pressure recovery over a single shock inlet. See:

https://en.wikipedia.org/wiki/Components_of_jet_engines#/media/File:Intakerecovery.gif

Thanks for that chart. I'm not saying they don't need a two-shock inlet, what I'm questioning the need for is movable ramps to facilitate that. If they can get away with a design optimized for M1.6 that works acceptably at low speeds, they should be fine.
 
ThirtyEcho
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 1:46 am

I have yet to hear from anybody who could establish a need for an SSBJ, not to mention pent up demand that would form a financial basis for such a huge investment by a manufacturer. Why do we need the thing?

The fact that the first CEO who announced purchase of an SSBJ is going to face a mob of stockholders, board members and underwriters with pitchforks and torches at the first mention of such a thing is going to put a cork in the bottle most definitely
 
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akiss20
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 2:20 am

Quoting ThirtyEcho (Reply 14):
The fact that the first CEO who announced purchase of an SSBJ is going to face a mob of stockholders, board members and underwriters with pitchforks and torches at the first mention of such a thing is going to put a cork in the bottle most definitely

Especially in a time when more and more of the big companies who could potentially afford such a thing are attempting to brand themselves as eco-conscious. It would be a pretty bad PR move to have the CEO spend $100 mil on a jet that burns 2-3x the fuel to save himself a few hours. Imagine the first time someone accidentally booms a city. Crying babies and scared children from a rich CEO flying overhead? The media would lap it up.
Change will not come if we wait for some other person or some other time. We are the ones we've been waiting for. We are
 
prebennorholm
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 2:53 am

Quoting ThirtyEcho (Reply 14):
I have yet to hear from anybody who could establish a need for an SSBJ

Correct. There may have been a minor "need" forty years ago - at the time when SST development was going on in four countries. But with modern communication methods, that need has shrunk to a small fraction, if not totally evaporated.

Some people are imagining that most business jets are used by CEOs rushing from meeting to meeting. They are not. Flying, including supersonic flying, is much too slow for that.

They are much more used as ambulance planes, taxi planes when scheduled airliners are not practical, fast delivery of spare parts when things break down and more such things.

For future business jets it is much more important to be able to operate from small airports with shortish runways.
Always keep your number of landings equal to your number of take-offs
 
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akiss20
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 3:06 am

Quoting prebennorholm (Reply 16):
Some people are imagining that most business jets are used by CEOs rushing from meeting to meeting. They are not. Flying, including supersonic flying, is much too slow for that.

They are much more used as ambulance planes, taxi planes when scheduled airliners are not practical, fast delivery of spare parts when things break down and more such things.

While air ambulance and taxi obviously represents some portion of the BJ market, do you have a source on it being the vast majority (I ask not sarcastically but earnestly).

That being said, even if it is true, that certainly doesn't seem to be the market Aerion, the only "serious" SSBJ (I say serious with a massive grain of salt), is aimed at. Granted their website is sparse, but they are certainly going for the wealthy elite market. Not going to be a lot of SSBJs operating out of small airports with short runways, if at all (although I look forward to seeing how the PC-24 does with their grass capability).
Change will not come if we wait for some other person or some other time. We are the ones we've been waiting for. We are
 
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LAX772LR
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 6:28 am

Quoting Pihero (Reply 11):
That's the reason I've never, since day one believed that the Sonic Cruiser was anything more than a pub stunt.

  

Quoting ThirtyEcho (Reply 14):
I have yet to hear from anybody who could establish a need for an SSBJ

Heck, why stop there... I'm betting a huge fraction, if not majority, of those who fly privately don't have a need too, just a desire. Convenience, speed, image, etc. Same concepts sort of apply.
I myself, suspect a more prosaic motive... ~Thranduil
 
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Starlionblue
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 6:42 am

Quoting ThirtyEcho (Reply 14):
have yet to hear from anybody who could establish a need for an SSBJ, not to mention pent up demand that would form a financial basis for such a huge investment by a manufacturer. Why do we need the thing?

First rule of economics: With the exception of air, water and nutrition (but not any particular food), there are no needs. Only wants. We don't need iPhones, beer or even airplanes. Those are all wants. This makes the discussion very different. Is there demand for an SSBJ? Certainly. So why aren't there SSBJs buzzing about? Because the supply is at too high a pricepoint. Note that the price includes things like overcoming regulation and so forth.

Quoting LAX772LR (Reply 18):
I'm betting a huge fraction, if not majority, of those who fly privately don't have a need too, just a desire. Convenience, speed, image, etc. Same concepts sort of apply.

  
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
tommy1808
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 10:03 am

Quoting wingscrubber (Reply 6):
and no afterburner to bolt-on to the JT8D-200s.

I guess Volvo could help: https://en.m.wikipedia.org/wiki/Volvo_RM8

best regards
Thomas
Well, there is prophecy in the bible after all: 2 Timothy 3:1-6
 
dfwjim1
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 3:27 pm

Quoting Starlionblue (Reply 19):

Actually a lot of things that used to be wants like air travel and Iphones have become needs. Beer I am not sure about...LOL
 
LH707330
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RE: Supersonic Business Jets?

Tue Jul 14, 2015 7:04 pm

Quoting ThirtyEcho (Reply 14):
I have yet to hear from anybody who could establish a need for an SSBJ, not to mention pent up demand that would form a financial basis for such a huge investment by a manufacturer. Why do we need the thing?

Why do you need any biz jets?

Quoting ThirtyEcho (Reply 14):
The fact that the first CEO who announced purchase of an SSBJ is going to face a mob of stockholders, board members and underwriters with pitchforks and torches at the first mention of such a thing is going to put a cork in the bottle most definitely

I see the main user group being the same crowd who gets private 747s, it's the group who wants the best and biggest just because they can.

Quoting Starlionblue (Reply 19):
First rule of economics: With the exception of air, water and nutrition (but not any particular food), there are no needs. Only wants. We don't need iPhones, beer or even airplanes. Those are all wants. This makes the discussion very different. Is there demand for an SSBJ? Certainly. So why aren't there SSBJs buzzing about? Because the supply is at too high a pricepoint. Note that the price includes things like overcoming regulation and so forth.

Bingo.

Quoting dfwjim1 (Reply 21):
Actually a lot of things that used to be wants like air travel and Iphones have become needs. Beer I am not sure about...LOL

I know plenty of people who survive with Android devices, but beer is another story 
 
HaveBlue
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RE: Supersonic Business Jets?

Wed Jul 15, 2015 5:52 am

Quoting prebennorholm (Reply 16):

They are much more used as ambulance planes, taxi planes when scheduled airliners are not practical, fast delivery of spare parts when things break down and more such things.

I find this extremely hard to believe. I believe they are used to get important, rich and people of means to places they want to go with all of the VIP treatment that a business jet enjoys. They don't want to be standing in TSA or Pre Check TSA lines, they don't want to deal with delayed or canceled flights, and they certainly don't want to feel 'ordinary'. It may be meetings or it may be just a preference in travel, but I seriously doubt that most of these 30-60 million dollar jets are used for air ambulance and spare parts. A small fraction of them are to be sure, but that's mostly a niche in my opinion.
 
tortugamon
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RE: Supersonic Business Jets?

Thu Jul 23, 2015 9:03 pm

Here are 'plans' for a windowless 18-seat supersonic business jet capable of doing JFK-LHR in 3 hours for $60-80 Million that is scheduled for EIS in 2018 from Spike.

I am not sure I believe a single thing I just wrote but here is the article:

http://www.travelpulse.com/news/airl...ivate-supersonic-business-jet.html

tortugamon
 
LimaNiner
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RE: Supersonic Business Jets?

Sun Aug 09, 2015 10:34 pm

At NASA's Moffett open house last October, I spoke to a NASA guy who worked on quietening sonic booms.

I asked him about their collaboration with Gulfstream, and he said "They used to work with us, but they've gotten really quiet. The same guys still show up at all the conferences, but they're really tight-lipped."

I'll bet they're still working on it, but the key thing will be to get Congress to relax the rules on supersonic overflight over land. Without the ability to do East Coast - West Coast supersonic, an SSBJ is not a viable product.

http://www.flightglobal.com/news/art...ft-inlet-designs-in-patent-380364/
 
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Starlionblue
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RE: Supersonic Business Jets?

Mon Aug 10, 2015 12:31 am

Quoting LimaNiner (Reply 25):
I'll bet they're still working on it, but the key thing will be to get Congress to relax the rules on supersonic overflight over land. Without the ability to do East Coast - West Coast supersonic, an SSBJ is not a viable product.

Sure it would. The aviation world stopped revolving around the US market a long time ago. The Pacific Rim and transatlantic would be strong markets for an "over ocean only" SSBJ.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
GavinSharp
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RE: Supersonic Business Jets?

Mon Aug 10, 2015 2:08 am

Quoting Starlionblue (Reply 26):
The Pacific Rim and transatlantic would be strong markets for an "over ocean only" SSBJ.

An aircraft that is that constrained will necessarily have a significantly reduced market compared to its traditional counterparts, even with its speed advantage. That a lot of flying happens along those routes doesn't mean that an aircraft that is limited to only operating them (economically) will have a market - flexibility matters for most operators.

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