hypersonic

Rxke · 2006-02-09 08:40:00

Oh, I see.
:oops: (bad case of word-image confusion, i thought you meant a hermetically closed cabin or something like that, w/ only a hatch to enter/leave while on terra firma...

SpaceNut · 2006-12-14 20:50:15

Looks like this is an attempt to avoid the x series of the past nominclature labeling them HTV.

Orbital Awarded $27 Million Contract by U.S. Air Force for Two Launches to Support Hypersonic Flight Testing

The two new missions will be used to support the FALCON program, which is being carried out by the Defense Advanced Research Projects Agency (DARPA). The Minotaur IV rockets will launch DARPA's Hypersonic Test Vehicle (HTV) technology demonstration systems, HTV-2a and HTV-2b, in 2008 and 2009, respectively.

Orbital's Minotaur product line was developed under the U.S. Air Force's Orbital/Suborbital Program (OSP). The initial five-year OSP contract was competitively awarded to Orbital in 1997 and the company also won the follow-on 10-year OSP-2 contract in 2003.

GCNRevenger · 2006-12-14 21:02:45

Not to be confused with the Orbital Space Plane concept

publiusr · 2006-12-22 16:05:37

sure...

SpaceNut · 2007-10-01 06:28:30

There has been so much work on getting flight beyound the mach 5 and higher. This has been talked of in many threads to say the least under terms of Australia Scramjet (HyShot Program) scram jet, ram jet and others.. from the x-41 to B-3 Hypersonic-2 and others by DARPA/U.S. Air Force/NASA X-51A hypersonic aircraft that is due to fly in 2009. With the key in collecting the oxidizer in flight to burn with the fuel that it is carrying. The the ships design getting into the TPS and RLV
Realistic solutions to the difficulties of SSTO?

With news of Hypersonic Jets Prepare to Soar

In September, Pratt & Whitney Rocketdyne (PWR) completed 10 months' testing of a sub-scale combustor for a hydrocarbon-powered, dual-mode ramjet engine designed to operate over a wide range of Mach-number speeds -- that is, multiples of the speed of sound.
Using JP-7 jet fuel, PWR ran the combustor successfully at a variety of Mach numbers from Mach 2.5 to Mach 6.0, demonstrating "desired operability and performance" at each speed,
A full-sized version of PWR's combustor will form the heart of the FaCET program, sponsored by the U.S. Defense Advanced Research Projects Agency (DARPA) and the U.S. Air Force. Lockheed Martin is FaCET prime contractor.
FaCET aims to develop a hypersonic test vehicle -- which could fly in 2012 -- that would take off and land by itself, use an advanced turbojet to get up to a speed of at least Mach 4 and then use a liquid hydrogen-powered scramjet to get to Mach 10 and beyond. Jet fuel can't be used as a scramjet fuel at speeds as high as Mach 10.

Tom Kalbfus · 2007-10-01 07:40:02

Mach 10 sounds like a useful number, the magic number being Mach 25. Perhaps a commerical application can be found for suborbital spacecraft.

SpaceNut · 2007-10-01 11:40:06

I am thinking that if it is used as a first stage booster, that the rest of the rocket gets considerably smaller.

SpaceNut · 2019-04-06 17:36:53

Time for a rvival of a topic in that the US Planning Five Hypersonic Test Programs in Marshall Islands

x-60a-hypersonic-flight-research-vehicle-program-hg.jpg

GW Johnson · 2019-04-09 16:49:44

What I think you will find if you research the topic is that the Isp of a scramjet is only a little better than a liquid rocket at speeds over about Mach 8-ish. At much higher speeds, the scramjet begins to look worse than a liquid rocket, in terms of Isp.

There's a whale of a lot more to it than Isp, however. There is the matter of frontal thrust density, meaning the biggest propulsive thrust divided by the frontal blockage area of the vehicle which is pushed by it. All airbreathers (piston prop, turbojet, pulsejet, ramjet, pulse detonation, and scramjet, and all of the combined-cycle concepts) have far lower sea level frontal thrust density than any of the rockets.

Plus, quite unlike the rockets, airbreather frontal thrust density decreases as the ambient air pressure decreases with altitude. They have a max altitude beyond which they cannot even maintain steady level flight, much less climb or accelerate. It's called "service ceiling".

And talking about using scramjet at 150,000 to 200,000 feet is just nonsense, precisely because of this effect. It was nonsense in the 1980's with the X-30 "Orient Express", and it's still egregious, utter nonsense today.

There have been a very few experimental ramjet vehicles that had service ceiling near 125,000 feet. There have been some more with service ceilings around 100,000 feet. Most are nearer 80,000 feet, or less. As for turbojet, the Concorde had a service ceiling near 60,000 feet, and the SR-71 near 85,000 feet.

The X-43A and X-51A scramjet tests were conducted at too high an altitude to get reduced aeroheating by the low density effect. As a result, they did not accelerate in airbreather mode. These were rocket-boost to test speed and altitude, and then just barely held speed as an airbreather.

My point: this scramjet stuff is more marketing hype than reality. There have been efforts trying without success to make scramjet practical since about 1960.

You can fly hypersonic right now with a rocket. But you will not cross an ocean that way. And unless you slow down to about Mach 4 or 5, you won't cross an ocean with a ramjet or a scramjet. Mach 4 is just about the min speed for scramjet. And unless you come up with some sort of unobtainium or manurium to make the turbomachinery out of, you won't ever fly a turbojet faster than about Mach 3.5.

If you fly faster than about Mach 5 or 6 for more than just several seconds, you will need some sort of unobtainium or manuriium to use as your heat protection. Steady state hypersonic aeroheating is quite unlike entry aeroheating (a brief transient fundamentally dependent upon heat-sinking, no matter what you use for a heat shield).

Steady-state, you cannot heat-sink! You must put the heat you absorbed out through the tailpipe. Such is almost, but not quite, impossible, even today. Lateral skins are tough, leading edges and nosetips far worse. But inlet structures are even worse than nosetips and leading edges.

Why fly hypersonic down in the atmosphere, when you can go exoatmospheric without aeroheating? Rockets do that job really, really well, with intercontinental ranges, too. None of the airbreathers can, unless you slow way down to only subsonic, or just a little ways supersonic.

Them's just the facts of life at this time in our technological history, guys.

GW

Last edited by GW Johnson (2019-04-09 16:59:14)

tahanson43206 · 2019-04-30 06:58:42

For IanM ...

How's your application coming along? Post #60 above is a good example of the spam you could remove. SpaceNut has gone to work and will not be able to clean up the mess until he gets home. The perpetrator may have paid attention to the time delay before crud is removed, so by creating the post in the morning there is a 12 hour stretch where it is exposed to forum readers.

(th)

elderflower · 2019-04-30 09:41:08

Same spam message has appeared elsewhere with a different author name.

tahanson43206 · 2019-04-30 10:37:47

For elderflower ...

elderflower wrote:

Same spam message has appeared elsewhere with a different author name.

Thanks for your observation!

The larger issue is that SpaceNut seems to be out on his own these days.

The registration system is open to anyone. That is a feature of FluxBB, no doubt, but perhaps there is a feature in the package that would allow vetting of applicants for membership.

Apparently there have been problems in the past of various kinds, and the solution seems to be letting newmars forum putter along on its own, with few new members being added (or adding themselves) who are willing to make a contribution.

You can see the substantial number of User ID's which are registering every day or week, by simply asking the User option button to show registrations in descending order. I wonder every time I look at that list why people are going to the trouble of registering.

One theory I have is that because the member status shows as "member" before registration is completed with the first login, there may be potentially valuable members who are hung up in the login fiasco where my application was caught for five months.

On the other hand, the ease with which spammers are able to open new accounts confirms that the registration system is working for them, for sure.

By any chance, from your experience with forums in general, do you have any insights about how to prevent spammers from gaining access to the forum, and at the same time, encouraging folks who are able and willing to contribute to do so?

(th)

elderflower · 2019-05-06 09:04:54

Tahanson. I don't have the kind of expertise that would be needed for that. I'm a mere retired mechanical engineer. I was pretty good at what I did whilst I was working, but it wasn't dealing with forums or spammers..
Being in the UK I may find the spam posts before the Americans do, if I log on in the morning, but that doesn't mean that I have any particular ability in that respect.

tahanson43206 · 2019-05-06 13:51:18

For Elderflower ... re #63

Thanks for continuing the discussion started by the spammer .... I'm hoping there is someone (or perhaps a team) working on the issue, behind the scenes. However, I note ONE benefit of the spammer's visit ... the Hypersonic topic is back in the Active list.

is there a member who would be willing to provide a post that allows us to get back on topic?

(th)

GW Johnson · 2019-05-07 07:55:28

Back to topic. Hmmmm. Well, how about the formal definition of "hypersonic"?

It is defined in terms of the geometry of the flow pattern and shock wave structure. In supersonic flight, these change as Mach number increases. Once hypersonic, the changes fade to nil. Not exactly zero, but quite close.

That is why constant zero-lift drag coefficients are a good, easy-to-use model in hypersonic flight. That is the justification for using constant ballistic coefficient (mass / blockage area x drag coefficient) in the entry portion of the usual entry/descent/landing models.

A good operational "definition" is that this occurs at about Mach 3 for blunt objects like space capsules, showing a big detached bow shock wave. For more "pointy" objects like aircraft or conical warheads, the critical speed is about Mach 5. Bow shocks are attached at the forwardmost point.

Nothing about that operational "definition" rules out an in-between speed for in-between object geometries. For example, a fat cone may show a detached bow wave anyway. See the cone shock charts in NACA 1135 to understand how and why that can happen.

GW

SpaceNut · 2020-05-19 20:15:14

Hypersonic Test Center for US Army speeds ahead

GW Johnson · 2020-05-20 12:42:25

I stand by what I wrote in posts 59 and 65 above.

For pointy missiles with attached bow shock waves, Mach 5 speeds would be "hypersonic".

The propulsion possibilities for flying that fast include rocket (has the thrust but range is inherently short unless boosted ballistically exoatmospheric), ramjet, scramjet, and not-very-bloody-likely turbojet. Of those, rocket, and ramjet are technologically mature and ready for off-the-shelf application. Turbojet is mature for speeds under Mach 3.5, and utterly not mature to fly any faster. Scramjet is not mature, period, end-of-issue.

Ramjet designs, properly done, like to cruise between about Mach 3 and Mach 4, with some designs (NOT ALL of them) capable of inefficient dash speeds exceeding Mach 4. Very clean vehicle designs with liquid-fueled supersonic ramjet propulsion can top-out in the Mach 5 to 6 range of speeds.

The flight test vehicle ASALM-PTV, designed to cruise at Mach 4, accidentally zoomed off the range at Mach 6 in a throttle runaway accident, way back in 1980. It was not boosted to this speed; the ramjet took the vehicle from end-of-boost at Mach 2.5 to Mach 6 fuel exhaustion in a matter of seconds. It could do this precisely because the flight was down deep in the atmosphere. Launch altitude was 20,000 feet.

ASALM-PTV was NOT designed to survive at such speeds in steady-state flight! It was designed to cruise steady-state at Mach 4, at 80,000 feet, way up in the thin air that reduces skin friction heat transfer rates. But not too thin: it still had to climb to that altitude at about Mach 2.5 to 3, and then accelerate to cruise at Mach 4. Significantly above Mach 4, there was nothing about its design that would survive steady state friction heating. That problem is actually worse lower down, where the higher density makes the heating rates higher.

Regardless of your propulsion, for sustained (steady-state) flight at hypersonic speeds, you must have a heat transfer/heat protection solution to survive the mission. Everything you absorb must exit with the tailpipe plume. Without that, there can be no such steady state flight, no matter what propulsion you elect to use.

And THAT steady state heat energy management problem is THE FUNDAMENTAL difference between steady flight hypersonics and atmospheric entry hypersonics! Entry is fundamentally a transient heat-sinking problem, no matter what kind of heat shield you use. Steady state flight is EXACTLY that: STEADY-STATE energy management!

The least challenging problem to solve is skin friction heat management. The driving temperature is severe, but the rates are low. The material is heated on only one side, and it can radiate to the environment to help manage the energy. You need to deal with what conducts inward. That goes into the fuel about to be burned, although you CANNOT allow boiling or coking to take place.

Everybody is pretty much aware that nosetips and leading edges are a whole lot more challenging than lateral skins. Not only is the driving temperature high, but also the heat transfer rates are very high. They are still heated on only one side, and can radiate to the environment.

Most laymen are unaware that air inlet structures are the most challenging energy management problem of all. Driving temperatures are high, heat transfer rates are high for reasons of being similar to leading edges, or for reasons of locally-high pressure. Many of these are heated on both sides, not just one. Many others cannot see the environment to re-radiate effectively. These are the worst possible cases. And every absorbed heat unit MUST be dealt with, real-time!

So there, THAT's the truth about hypersonics!

Believe in the rocket-boosted hypersonic "gliders". Those have been in existence for a long time. We used to call them maneuverable reentry vehicles. Warheads like that have existed for decades. Make it maneuver a bit harder, and you have a "new" technology to crow about in the propaganda wars.

Do NOT believe in airbreathing cruise missiles doing more than Mach 5 or 6 as powered by scramjets any time soon. Not only is the propulsion still very immature, the heat management technology is also still very immature. It's all still BS in any operational sense. Experimental test flights are NOT capability demonstrations, they are feasibility demos ONLY!

You might see a ramjet-powered missile that cruises long ranges at Mach 3-to-4, with a dash speed capability in the target area in the Mach 5-to-6 range. THAT we can do. We already did it accidentally with ASALM in 1980.

GW

Last edited by GW Johnson (2020-05-20 12:49:10)

Mars_B4_Moon · 2021-11-28 13:49:32

Russia produces deadly 'unstoppable' Zircon hypersonic war missile
https://www.dailymail.co.uk/news/articl … ssile.html

It’s Time to Stop Doing Anti-Satellite Tests
https://www.universetoday.com/153456/it … ite-tests/

Earlier this year there were reports that China Advanced its High-Speed Ramjet Engine, they were also testing something that looked like it was copied or inspired from NASA/JPL's design for a helicopter on Mars.

Last edited by Mars_B4_Moon (2021-11-28 14:24:29)

Mars_B4_Moon · 2022-08-17 03:50:18

American Airlines Says It Will Be Able To Fly From Miami To London In Under 5 Hours With New Supersonic Aircraft

https://www.thenextmiami.com/american-a … onic-jets/

Mars_B4_Moon · 2023-03-09 05:20:27

NASA’s plans for the end of the ISS: private space stations and hotels with an Earth view
https://english.elpais.com/science-tech … -view.html

Boeing sees Space Launch System rocket fit for Pentagon missions
https://www.channelnewsasia.com/busines … ns-3335096

Military before Space-Colony?

Hypersonic Weapons: Background and Issues for Congress

pdf

https://sgp.fas.org/crs/weapons/R45811.pdf

SpaceNut · 2023-03-09 18:49:21

It appears that we are able to achieve mach 20 which is quite the speed in the atmosphere.

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#51 2006-02-09 08:40:00

Re: hypersonic

#52 2006-12-14 20:50:15

Re: hypersonic

#53 2006-12-14 21:02:45

Re: hypersonic

#54 2006-12-22 16:05:37

Re: hypersonic

#55 2007-10-01 06:28:30

Re: hypersonic

#56 2007-10-01 07:40:02

Re: hypersonic

#57 2007-10-01 11:40:06

Re: hypersonic

#58 2019-04-06 17:36:53

Re: hypersonic

#59 2019-04-09 16:49:44

Re: hypersonic

#60 2019-04-30 06:58:42

Re: hypersonic

#61 2019-04-30 09:41:08

Re: hypersonic

#62 2019-04-30 10:37:47

Re: hypersonic

#63 2019-05-06 09:04:54

Re: hypersonic

#64 2019-05-06 13:51:18

Re: hypersonic

#65 2019-05-07 07:55:28

Re: hypersonic

#66 2020-05-19 20:15:14

Re: hypersonic

#67 2020-05-20 12:42:25

Re: hypersonic

#68 2021-11-28 13:49:32

Re: hypersonic

#69 2022-08-17 03:50:18

Re: hypersonic

#70 2023-03-09 05:20:27

Re: hypersonic

#71 2023-03-09 18:49:21

Re: hypersonic

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