Author Topic: General Hypersonic Flight Related Topics  (Read 53890 times)

Offline JQP

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Re: General Hypersonic Flight Related Topics
« Reply #120 on: 03/27/2018 11:29 am »
Quote
It's excellent news if you want the Chinese government to waste a very large sum of money on a wild goose chase.
Or blaze the trail, so we can spend money chasing proven technology, instead of burn it proving it can even work. Of course Chinese nationalists will crow about it forever, but the Chinese have copied everything from the West for a centuries, so a bit of turnabout would be welcome.

Quote
How could so many learned people be wrong? The answer is the same way the people who studied Phrenology or Eugenics could be.  :(

There's nothing wrong with eugenics, or its study.

Quote
[Magnetohydrodynamic propulsion] also turned out to be a total fantasy.

Great movie though. :)
« Last Edit: 03/27/2018 11:30 am by JQP »

Offline Star One

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Re: General Hypersonic Flight Related Topics
« Reply #121 on: 03/27/2018 08:32 pm »
Pentagon advisory panel calls for establishment of near-term hypersonic defense capability


Quote
An influential Pentagon advisory board has recommended the U.S. military quickly develop and field an interim capability to defeat hypersonic weapon threats, launching a program to develop a defensive capability against a new-class of ultra-high-speed strike systems that are the focus of an race between Washington, Beijing and Moscow.

Missile Defense Agency Director Lt. Gen. Sam Greaves previewed findings of the not-yet-public Defense Science Board's 2017 summer study on hypersonic strike weapons in written testimony prepared for the Senate Armed Services strategic forces subcommittee on March 21.

Greaves said the Pentagon's $120 million request in fiscal year 2019 to advance the new-start hypersonic defense program MDA launched in FY-18 at congressional direction carries out the DSB's advice.

"This effort will execute the Defense Science Board’s recommendations to develop and deliver a set of materiel solutions to address and defeat hypersonic threats informed by a set of near-term technology demonstrations," Greaves wrote.


The DSB study on Countering Anti-Access Systems With Longer Range and Standoff Capabilities is not yet public; an unclassified summary of the final report is expected as soon as April, according to Pentagon spokeswoman Lt. Col. Michelle Baldanza.

Last summer, the Defense Intelligence Ballistic Missile Analysis Committee in collaboration with the Air Force's National Air and Space Intelligence Center identified hypersonic glide vehicles -- being developed by Russia and China to penetrate U.S. ballistic missile defenses -- as an "emerging threat." For a decade, the U.S. military has been developing technologies to support an intermediate-range hypersonic strike weapon; the Pentagon plans to identify a formal acquisition program for an offensive capability in 2020.

Meantime, MDA -- established in 2004 to focus primarily on ballistic and cruise missile threats -- is now leading the new effort to develop a fledgling program to counter hypersonic boost glide threats. Intercontinental ballistic missiles move at hypersonic speeds -- 20 times the speed of sound -- on trajectories that are predictable.

Hypersonic boost glide weapons fly a different path. After being lifted by rocket near the edge of the atmosphere, the experimental payload separates from its booster rocket near space and flies a flatter, non-ballistic trajectory, gliding unpowered at speeds of at least Mach 5 to its destination. Their ability to maneuver gives this potential new class of weapons the ability to penetrate current air defenses.

The new hypersonic defense program, according to Greaves, consists of a number of efforts, including systems engineering and efforts to "identify and mature the full kill-chain technology" to counter hypersonic threats.  MDA is looking for "target-of-opportunity events" and execute near-term, "space-sensor technology and multidomain command-and-control capability upgrades to address defense from hypersonic threats."

"An integrated set of enhancements will provide incremental capability measured by progress and knowledge points in the following areas: establishment of systems engineering needs and requirements to identify alternative material solutions; execution of a series of sensor technology demonstrations; modification of existing BMDS sensors and the C2BMC element for hypersonic threats; and definition of weapon concepts and investments in key technologies to enable a broad set of solutions, including kinetic and non-kinetic means," according to Greaves.

MDA is currently conducting an analysis of alternatives to explore potential materiel solutions for a hypersonic defense capability. That analysis, often a precursor to a major weapons program, is running behind schedule.

The FY-18 omnibus appropriations act cut MDA's $75 million request to launch the hypersonic defense program to $60 million, peeling back $15 million because the funding was "Early to need pending completion of analysis of alternatives." The FY-18 budget request anticipated the AOA being complete this spring; the FY-19 budget request anticipates the AOA being complete this summer.

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #122 on: 03/28/2018 12:44 pm »
To put a little more detail on the idea of a SABRE powered hypersonic research vehicle I looked up the Maximum Takeoff Weights of various aircraft.

https://en.wikipedia.org/wiki/List_of_airliners_by_maximum_takeoff_weight

The SEI study reckoned you'd need a T/W of 0.7 to get to M8 for their TSTO so a 20tonne thrust engine that gives about 28 tonnes.

These are all in the range 23-30 tonnes. The Dash_8 is just about at the 28t mark.  The Vickers Viscout around 30tonnes.
https://en.wikipedia.org/wiki/Bombardier_CRJ200
https://en.wikipedia.org/wiki/Bombardier_Dash_8
https://en.wikipedia.org/wiki/Vickers_Viscount

People will think of the D21 reconnaissance drone, but this was about 5tonnes, while the SRB needed to launch it from the B52 was even heavier (coincidentally it burned for about the same time, 85secs, as the main X-15 engine), more than doubling the package size.

OTOH the little known Tupolev Tu 123
https://en.wikipedia.org/wiki/Tupolev_Tu-123
Was about 35t and designed to cruise around M3 using the expendable version of the Tumansky R15 turbojet which in full after burner had about a T/W of 4.16:1.
The Tu-123 Wiki article uses the afterburner thrust level, suggested it was on permanent AB after launch.
Note that unlike D21 it was designed to be ground launched with a RATO pack. The whole vehicle had a payload mass fraction of about 3 although RATO mass is not listed.
The X-15 itself weighed 15420Kg yet needed a rocket thrust 2.07x that to get to test speed, probably due to its (by air breathing standards) very poor Isp.

Which I think suggests there are reasons to believe you could build a useful ground launched hypersonic test vehicle around the SABRE test engine.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Hog

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Re: General Hypersonic Flight Related Topics
« Reply #123 on: 03/28/2018 03:28 pm »
D-21 detaching from M-21



THE M-21 accident which brought M-21 launching D-21's to an end and D-21 into B-52 SRB usage as mentioned above
Paul

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #124 on: 03/29/2018 07:38 am »
D-21 detaching from M-21


THE M-21 accident which brought M-21 launching D-21's to an end and D-21 into B-52 SRB usage as mentioned above
So the moral of this story is what exactly?

Don't launch from an aircraft with inward canted tails?

Don't launch from an aircraft with inward canted tails in level flight (the earlier ones had been with the SR71 flying in an outside loop, with the D21 on the outer face).

IIRC no D21 mission, even the ones from the Stratofortress, were successful. Given their nature I would guess telemetry able to diagnose what went wrong, was limited.
OTOH most of the 199 X15 missions flown were successful, suggesting reusability is pretty useful for finding, and fixing, bugs in the basic system.

AFAIK the Tu-123 did not any launch issues, but it's cost was prohibitive to the cash strapped Soviet Union of the time. That suggests ground launch can be less problematical.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Hog

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Re: General Hypersonic Flight Related Topics
« Reply #125 on: 03/29/2018 12:21 pm »
D-21 detaching from M-21


THE M-21 accident which brought M-21 launching D-21's to an end and D-21 into B-52 SRB usage as mentioned above
So the moral of this story is what exactly?

Don't launch from an aircraft with inward canted tails?

Don't launch from an aircraft with inward canted tails in level flight (the earlier ones had been with the SR71 flying in an outside loop, with the D21 on the outer face).

IIRC no D21 mission, even the ones from the Stratofortress, were successful. Given their nature I would guess telemetry able to diagnose what went wrong, was limited.
OTOH most of the 199 X15 missions flown were successful, suggesting reusability is pretty useful for finding, and fixing, bugs in the basic system.

AFAIK the Tu-123 did not any launch issues, but it's cost was prohibitive to the cash strapped Soviet Union of the time. That suggests ground launch can be less problematical.
I wasn't trying to imply any moral to any story, just adding some "colour" to a thread using some fine examples of the technological "intestinal fortitude" as someone had mentioned the D-21 earlier.
Paul

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #126 on: 03/29/2018 04:04 pm »
I wasn't trying to imply any moral to any story, just adding some "colour" to a thread using some fine examples of the technological "intestinal fortitude" as someone had mentioned the D-21 earlier.
Part of the reason for the D21 being (relatively) cheap was (AFAIK) a fixed geometry vehicle. Prefectly reasonable for an operational programme, which the M21/D21 system was meant to be.

For a research programme you probably want something a bit more flexible.

Of course if people think they already know all they need to know about hypersonic flight then they can go straight to designing the equipment directly.

The fact no one has fielded an operational system in this area (despite M21/D21 expecting to go to such a system at M3 half a century ago) suggests there are still pretty big gaps in the basic knowledge of extended flight at M5+ speeds
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Star One

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Re: General Hypersonic Flight Related Topics
« Reply #128 on: 04/05/2018 07:23 am »
Hypersonic Weapons Explainer

https://carnegieendowment.org/2018/04/02/hypersonic-weapons-explainer-pub-75957
That sounded remarkably balanced.

Bottom line. Russia and China can already deliver nuclear weapons at M12+ (by ICBM). It's precision that allows the use of non nuclear payloads.

I especially like the part about the DoD having to decide why they need a hypersonic programme before spending a shed load of cash on it.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline JQP

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Re: General Hypersonic Flight Related Topics
« Reply #129 on: 04/05/2018 12:28 pm »
Air Force looking to additive manufacturing to expand hypersonic flight capabilities

Quote
ARNOLD AIR FORCE BASE, Tenn. – The Air Force is testing materials produced through ceramic additive manufacturing to advance their potential future use in hypersonic flight vehicles.

Scientists with the Air Force Research Laboratory Aerospace Systems Directorate recently entered into a Cooperative Research and Development – Material Transfer Agreement with HRL Laboratories to test additively manufactured silicon oxycarbide (SiOC) materials.The geometric complexity of components that can be produced through additive manufacturing in conjunction with the refractory nature of ceramics holds enormous potential for a variety of future Air Force applications. One such possible application is hypersonic flight, which exposes materials to extreme environments including high temperatures.

The potential of the HRL-produced materials for demanding Air Force applications became apparent while Aerospace Systems Directorate scientists were searching for new thermocouple radiation shields. The SiOC materials were produced through an additive manufacturing process utilizing a pre-ceramic resin. Following part fabrication, the pre-ceramic resin was heat treated to convert the component to a fully ceramic state. AFRL scientists became interested in HRL’s novel process taking advantage of state-of-the-art 3D printing capabilities and pre-ceramic resin chemistry as well as the possible performance of the final SiOC materials at high temperatures.

“If a material can withstand those temperatures – roughly 3,200 degrees Fahrenheit – it could be used for hypersonic aircraft engine components like struts or flame holders,” said Jamie Szmodis, a hypersonic research engineer with the Aerospace Systems Directorate.

Kudos to Wright-Patterson AFB for having a page that retains basic functionality sans Javascript, and offers a simple hyperlink to a printer-friendly version. I hope someone there shows NASA how that's done...
« Last Edit: 04/05/2018 12:30 pm by JQP »

Offline Star One

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Re: General Hypersonic Flight Related Topics
« Reply #130 on: 04/05/2018 12:57 pm »
Hypersonic Weapons Explainer

https://carnegieendowment.org/2018/04/02/hypersonic-weapons-explainer-pub-75957
That sounded remarkably balanced.

Bottom line. Russia and China can already deliver nuclear weapons at M12+ (by ICBM). It's precision that allows the use of non nuclear payloads.

I especially like the part about the DoD having to decide why they need a hypersonic programme before spending a shed load of cash on it.

I expect if asked their justification would be because other countries are developing them, seems to be the way the argument is going.

Offline Katana

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Re: General Hypersonic Flight Related Topics
« Reply #131 on: 04/09/2018 07:23 pm »
Either you have an interesting definition of "excellent news" or my sarcasm detector is malfunctioning again.
It's excellent news if you want the Chinese government to waste a very large sum of money on a wild goose chase.
Quote from: Lar

I do wonder why they keep trying this
As Francois Truffaut character in Close Encounters of the Third Kind puts it "It is en affaire sociologique" IOW
A toxic mix of (semi) plausible arguments (that a child can follow), seductive maths and group think.

How could so many learned people be wrong? The answer is the same way the people who studied Phrenology or Eugenics could be.  :(

SCramjet research is like a "Grail quest".
The endlessly long list of hints that maybe will lead to a solution.
The vast riches and glory to the discoverer at the end.
If we just try a little harder. If we just had a little bit faster computers. We are so close. If, if,if.
Add in a few researchers who might not be overly scrupulous in checking their assumptions and an Air Force general with a large budget and keen desire that "Something must be done" and the rest is history.  :(

Then of course there is the huge Kudos of doing something the US has spent (since Johns Hopkins APL work in 1960)  North of $10Bn (in 2018 $) to do and still failed to deliver an operational vehicle with.
The dream that we will be the Wright Brothers successful efforts to the USG's lavishly funded (but failed) efforts to build a "Heavier than air flying machine."

Note that IRL rockets and regular ramjets have got operational flight vehicles up to M5+ for decades and AFAIK no one has really tried to find the upper limit of conventional ramjet action, or even what a viable Mach operating range is. 3 Mach numbers is a "rule of thumb" that does not seem to have a reference basis beyond "After that we have to start to think seriously about the problems."

Hypersonic flight is a challenging field in terms of aerodynamics and structures that can survive prolonged (greater than 15 minutes roughly) without refurbishment at reasonable weight.
OTOH SCramjet development continues to look like a bottomless money pit.

When a SCramjet proponent writing in Aerospace America says essentially "The only way to develop a full size SCramjet aircraft is to do develop a full size SCramjet aircraft,"  because between the uncertainties of the maths driving the CFD simulations and the scale factors when you use models that is the only way to be sure you'll get a working vehicle you have to ask "Why bother?" (with SCramjets). :(
LACE / precooled concepts also have long, unsuccessful and costly history similar to scramjet, since HOTOL and RB525. Sabre may be as successful as X-43, but Skylon could come nowhere near BFR, by payload ability or by project TRL.

The sadness of ramjet means that no CUSTOMER really NEEDS hypersonics at M5+.  Boasting new types of engines for investment is another "business model".

Navaho got wiped out by ICBM in 1958. Presumeably all airbreathing hypersonics would be wipe out if BFR becomes operational and USAF buy a dozen as reuseable ICBM.

Russia and China are also nowhere near to copy BFR, though they would struggle for it at enormous cost even if USAF does NOT buy it. (See the neighbor thread how Russians got horrified of Shuttle).
« Last Edit: 04/09/2018 07:29 pm by Katana »

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #132 on: 04/10/2018 06:53 am »
LACE / precooled concepts also have long, unsuccessful and costly history similar to scramjet, since HOTOL and RB525.
LACE certainly was. By US standards HOTOL and the RB525 were accounting errors, literally 0.1% of NASP (0.4% in then year dollars), and NASP is still just a fraction of what the US has spent chasing the SCramjet dream.

Quote from: Katana
Sabre may be as successful as X-43, but Skylon could come nowhere near BFR, by payload ability or by project TRL.
Is this really the place you want to have that conversation?
Quote from: Katana
The sadness of ramjet means that no CUSTOMER really NEEDS hypersonics at M5+.  Boasting new types of engines for investment is another "business model".
Well passengers might like to chop the journey time from London to Sydney non stop from 17 hours to
less than 4 hours.
Quote from: Katana
Navaho got wiped out by ICBM in 1958. Presumeably all airbreathing hypersonics would be wipe out if BFR becomes operational and USAF buy a dozen as reuseable ICBM.
Navaho was M3 and you really have no idea how the launch market works do you?
But given BFR is basically a giant ICBM it should surprise no one it can be turned into one quite easily.

Quote from: Katana
Russia and China are also nowhere near to copy BFR, though they would struggle for it at enormous cost even if USAF does NOT buy it. (See the neighbor thread how Russians got horrified of Shuttle).
Funny how Russian and Chinese prowess in hypersonics goes up and down to suit the programme being funded isn't it?

Some of the programmes that drove the design choices for Shuttle were militarily insane. :(
It's (probably) true neither Russia nor China could build a vehicle to match BFR.

But they can definitely build the small nuclear weapons they could launch in barrage to fry anyone that comes over their territory and BFS is very large relative to an ICBM warhead.

The Cold War ended in 1989. Let it go.
« Last Edit: 04/10/2018 06:21 pm by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Katana

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Re: General Hypersonic Flight Related Topics
« Reply #133 on: 04/10/2018 01:00 pm »
Hypersonic aircraft market is different to launcher market. Navaho could only be capable of M3, but M3 is already "hyper" enough for aircrafts in early 1950s, many years before SR71 and Concorde.

Passengers always want to travel at M3 between continents since then, but they don't need it: none could afford it (Remember the failed M3+ Boeing 2707). How could they afford M4~5 or "real hypersonics"?

Airliner service is an extremely hash low cost market.

Ironically, almost all hypersonic projects ongoing in this thread are sliding into military, including SABRE and Skylon. Hard to imagine BFR as a low cost hypersonic exception that stays civil forever.

One probable reason:
Payload cost in $/kg of F-16 and B-52 lies between the $/kg of ICBM or launcher, and $/kg of passenger airliners. Getting down (in cost) from launcher market to airliner market would inevitably cross the regime of fighters and bombers, much earlier than finally reaching airliner market.

 USAF have talked about fitting ICBM with non nuclear tips, similar concept of HTV and AHW, though all too expensive for their purpose.
https://gizmodo.com/5518192/non-nuclear-us-icbm-can-strike-iran-in-30-minutes

It's wise for America NOT to waste too much money on HTV and AHW similar to Russian and Chinese HGV.

But BFR may solve the cost problem. "ICBM" as cost effective as F-16 or B-52 could be well suited for conventional warfare.

And it may become best chance for America to win the "loosing" hypersonic race against Russia and China.
« Last Edit: 04/10/2018 01:55 pm by Katana »

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #134 on: 04/10/2018 06:40 pm »
Hypersonic aircraft market is different to launcher market. Navaho could only be capable of M3, but M3 is already "hyper" enough for aircrafts in early 1950s, many years before SR71 and Concorde.
Not really. A12 was already being thought about (I think Lockheed reckoned the U2 had maybe a 3 year life expectancy).
Quote from: Katana
Passengers always want to travel at M3 between continents since then, but they don't need it: none could afford it (Remember the failed M3+ Boeing 2707). How could they afford M4~5 or "real hypersonics"?
No. Because it never flew. Turns out building the biggest swing wing aircraft ever built in Titanium was too tough.
I do remember Concord flying for 30 years with a near perfect safety record and people being able to have breakfast in London, lunch in New York and dinner in London. Concorde's biggest mistake was in fact the 2707's only really good point. It was close to being big enough to being fully economically viable. AFAIK every study since by Boeing or Airbus has reckoned 300 passengers is the minimum size you need for this. It's not even clear if they had managed to solve the "super cruise" problem, which Concorde had.
Quote from: Katana
Airliner service is an extremely hash low cost market.
True. Practically because none can offer more speed. AFAIK no one ever thought SST would be "mass market."  It's a premium service at a premium price. As the Concorde operations division found most passengers did not know what their ticket cost (so they asked them what they thought it cost and increased the actual price to what most of their passengers thought they were already paying)
Quote from: Katana
Ironically, almost all hypersonic projects ongoing in this thread are sliding into military, including SABRE and Skylon. Hard to imagine BFR as a low cost hypersonic exception that stays civil forever.

One probable reason:
Payload cost in $/kg of F-16 and B-52 lies between the $/kg of ICBM or launcher, and $/kg of passenger airliners. Getting down (in cost) from launcher market to airliner market would inevitably cross the regime of fighters and bombers, much earlier than finally reaching airliner market.

 USAF have talked about fitting ICBM with non nuclear tips, similar concept of HTV and AHW, though all too expensive for their purpose.
https://gizmodo.com/5518192/non-nuclear-us-icbm-can-strike-iran-in-30-minutes

It's wise for America NOT to waste too much money on HTV and AHW similar to Russian and Chinese HGV.

But BFR may solve the cost problem. "ICBM" as cost effective as F-16 or B-52 could be well suited for conventional warfare.

And it may become best chance for America to win the "loosing" hypersonic race against Russia and China.
And yet in another thread you advocate selling BFR (well actually BFR services since LV mfgs don't sell vehicles, they basically sell tickets to ride their vehicle, although it's more like a lottery, given flight safety records) as an orbital weapons delivery system.

So what is it? Orbit capable systems or hypersonic systems, or just whatever has the biggest funding available?

« Last Edit: 04/10/2018 06:45 pm by john smith 19 »
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline Katana

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Re: General Hypersonic Flight Related Topics
« Reply #135 on: 04/11/2018 04:49 am »
For SST, cost and size (=initial cost) is hash.
For hypersonic airliner, safety becomes more hash.

M2+ aircraft were conventional for 50 years. But hypersonic manned (X-15) / suborbital tourism (SS2) vehicles remained dangerous vehicles flying by test pilots up to now. Lethal casualty rate stays at best 1/100, same to orbital flight, 5~6 magnitudes more dangerous than airliner.

SS2 claimed to be "more safe", but have taken more lives than X-15 while delayed for nearly 10 years, not hypersonic, and incapable of P2P transport.

"Hypersonic P2P transportation" of passengers remains a distant dream up to now, but it's an EXISTING FACT that those projects are shifting to "hypersonic P2P transportation" of weapons, except BFR.

Of course BFR could still stay civil, if stay in the orbital launcher market and stay away from "hypersonic P2P transportation" of anything.
« Last Edit: 04/11/2018 04:55 am by Katana »

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #136 on: 04/11/2018 06:54 pm »
For SST, cost and size (=initial cost) is hash.
For hypersonic airliner, safety becomes more hash.
I'm not really sure what you mean by this.
Concorde flew for 27 years with no crashes prior to the Air France disaster, when it was grossly overloaded.
Quote from: Katana
M2+ aircraft were conventional for 50 years. But hypersonic manned (X-15) / suborbital tourism (SS2) vehicles remained dangerous vehicles flying by test pilots up to now. Lethal casualty rate stays at best 1/100, same to orbital flight, 5~6 magnitudes more dangerous than airliner.
Maybe because one was a test aircraft whose mission was to find the problems of hypersonic flight and the other was in its test phase prior to being declared fit for service? In the case of SS2 that was due to a frankly bizzare  decision to have no safety interlock on a key flight control.
Quote from: Katana
SS2 claimed to be "more safe", but have taken more lives than X-15 while delayed for nearly 10 years, not hypersonic, and incapable of P2P transport.
If not hypersonic why are you even mentioning it?
Quote from: Katana
"Hypersonic P2P transportation" of passengers remains a distant dream up to now, but it's an EXISTING FACT that those projects are shifting to "hypersonic P2P transportation" of weapons, except BFR.
In fact most hypersonic projects have been military funded and are for weapons research already.
Quote from: Katana
Of course BFR could still stay civil, if stay in the orbital launcher market and stay away from "hypersonic P2P transportation" of anything.
Personally I think you could take the Concorde ticket prices, adjust for inflation, double that (implying M4 or better, not necessarily hypersonic, but damm fast) and you'd have a pretty healthy market.

The fact Concorde did make a profit for its operators suggests there is a strong market for people who want to go from A to B much faster than M0.95. The problem is how to do develop it profitably.

I don't doubt that a service at > M1 can make a profit. I'm rather more doubtful about what architectures will make that work.
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Offline Katana

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Re: General Hypersonic Flight Related Topics
« Reply #137 on: 04/12/2018 04:56 am »
To go M4+ with 300 passengers and fly everyday for 20 years, conventional aircraft architecture with turboramjet engine (turbofan mods) still applys.

Modern turbofan mods should provide much better performance than J58, which is modified from a single shaft turbojet.

Critical architecture choice maybe the airframe material, nickel alloy / titanium alloy (simplified Skylon? rebirth of 2707?) or composite (special high temp resin CFRP? C-C?)

BTW, going beyond M5 (up to M25 of BFR) would have insignificant benefit compared to M4+, since the time cost for 12000km is already 3~4 hours at M4. If going faster, land traffic and waiting time becomes significant, especially when available flights are not as frequent as typical airliner.
« Last Edit: 04/12/2018 05:42 am by Katana »

Online john smith 19

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Re: General Hypersonic Flight Related Topics
« Reply #138 on: 04/12/2018 08:11 am »
To go M4+ with 300 passengers and fly everyday for 20 years, conventional aircraft architecture with turboramjet engine (turbofan mods) still applys.
In 1972 maybe.   :( When the base price of oil per barrel quadrupled over night that was no longer viable.

What people forget about Concorde was that it cruised at M2 without using afterburner. Getting twice the thrust for 3x the fuel consumption is not a viable strategy for commercial airliners.
Quote from: Katana
Modern turbofan mods should provide much better performance than J58, which is modified from a single shaft turbojet.
Not really. The issue is frontal surface area and the heat release when air is slowed by so much. There's a reason why there's a precooler in the front of the SABRE compressor.
Quote from: Katana
Critical architecture choice maybe the airframe material, nickel alloy / titanium alloy (simplified Skylon? rebirth of 2707?) or composite (special high temp resin CFRP? C-C?)
I was actually thinking more in terms of the difference between a conventional "single stage" aircraft and Musks BFR for P2P use.  :(
But designing a fuselage and wing structure that can survive prolonged M5 heating (even at very high altitude) is not a trivial issue.
Quote from: Katana
BTW, going beyond M5 (up to M25 of BFR) would have insignificant benefit compared to M4+, since the time cost for 12000km is already 3~4 hours at M4. If going faster, land traffic and waiting time becomes significant, especially when available flights are not as frequent as typical airliner.
Actually the EU target for LAPCAT was M8, which the Germans attempted with a Kerosene SCramjet. Despite the theoretical benefits of the much denser fuel they still couldn't make the design close with the range necessary to avoid overflying built up areas.
BFS. The worlds first Methane fueled FFORSC engined CFRP structured A380 sized aerospaceplane tail sitter capable of flying in Earth and Mars atmospheres. BFR. The worlds biggest Methane fueled FFORSC engined CFRP stainless steel structured booster for BFS. First flight to Mars by end of 2022. Forward looking statements. T&C apply. Believe no one. Run your own numbers. So, you are going to Mars to start a better life? Picture it in your mind. Now say what it is out loud.

Offline docmordrid

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Re: General Hypersonic Flight Related Topics
« Reply #139 on: 04/12/2018 03:14 pm »
>
The Cold War ended in 1989. Let it go.

In case you haven't noticed, Cold War II started on March 4, 2012 with Putin's reboot.
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