Waverider fails 16 secs , faulty fin..

[marcos]

Actually interestingly enough, because speed isn't directly related to the specific impulse of the fuel, a hypersonic transport, rather analogous to the Concorde (currently the Concorde holds the record for the most fuel efficient jet liner ever made, despite it's high speed and afterburning engines) actually has the ability to be CHEAPER to run in terms of fuel costs than other, more conventional jets.

 

One of the main reasons why Concorde flights were so expensive is their limited utility (routes), due to infrastructure and other considerations, as well as their limited production run. If they had a chance to develop as well as fly to an expanded set of fields, it may well have ended up costing less money per passenger than other more conventional jets.

 

Plus Hypersonic travel is a utility that MUST not be overlooked for extremely urgent business (i.e. medical emergencies, important government meetings, military reactions, intercontinental business emergencies, etc.)

Well all I can say is how come no airlines are looking for new Concordes?

 

Speed affects mass-flow rate which specific impulse is inversely proportional to and you can't just consider and engine in the absence of drag. A Concorde has 1/2 of the Specific Impulse of a 747.

 

http://en.wikipedia.org/wiki/Specific_impulse

 

If you work a few examples you'll see that high BPR turbofans enjoy far better fuel economy. There are all sorts of other problems like jet noise and not being able to go supersonic over land too.

Edited August 20, 2012 by marcos

[aaron886]

It's a combination. Friction heating makes up a good portion of surface heating. Remember there's a whole lot of "air on air" action out around the shock layer, and much of that is transferred to the fuselage through the boundary layer. Air isn't the best conductor, but it's just good enough to be an engineering PITA! :D (Not that I'm an engineer.)

[MadMonkey]

I'm sick of US playing world policemen...

...it all became like elementary school, where bigger and stronger bullied the others... frikkin child's games, but played with the lives of entire humanity... :cry:

 

I hate going political just because it can get messy so i will keep it short.

 

sorry to step on toes but 'correction' it's not just the U.S.

we are apart of the U.N. and so we actively take on a leading role and do our part.

but yes it is time to send the troops home.

[sobek]

Guys, you know the rules, stay away from politics.

[Pyroflash]

Well all I can say is how come no airlines are looking for new Concordes?

 

Speed affects mass-flow rate which specific impulse is inversely proportional to and you can't just consider and engine in the absence of drag. A Concorde has 1/2 of the Specific Impulse of a 747.

 

http://en.wikipedia.org/wiki/Specific_impulse

 

If you work a few examples you'll see that high BPR turbofans enjoy far better fuel economy. There are all sorts of other problems like jet noise and not being able to go supersonic over land too.

 

Well, it is as you say, the engine itself may not enjoy better fuel economy due to its LBPR, however the aircraft as a whole enjoys far better fuel economy than any other jetliner in existence, with maybe the exception of the B-787 (to my knowledge). It is precisely because of the absence of parasitic drag on the body of the Concorde that allows it to be so efficient and fast.

[aaron886]

I just don't think that's possible. You might have heard that the Concorde was at its most efficient when flying at cruise speeds, but as a rule, a pointy airplane (especially when it's being flown through transonic speeds) burns an awful lot of gas.

[Pyroflash]

I just don't think that's possible. You might have heard that the Concorde was at its most efficient when flying at cruise speeds, but as a rule, a pointy airplane (especially when it's being flown through transonic speeds) burns an awful lot of gas.

 

In cruise, the Concorde burns almost twice as much gａｓ as most HBP engines, however it also goes MORE than twice as fast, so it evens out to be a little more efficient in terms of fuel per kt. It makes sense really, and I can't find anything to disprove it.

Edited August 21, 2012 by Pyroflash

[aaron886]

It makes sense really, and I can't find anything to disprove it.

"Makes sense" does not equate to truth, unfortunately. Someone earlier was mentioning specific impulse and fuel efficiency at higher airspeeds... and I think that's the correct line of inquiry. If your theory was true, trust me, airlines would ALL be flying supersonic over long routes. They'll do anything to shrink costs in today's low-margin, high frequency environment, and fuel is always the number one concern. (This one is not a point of contention. ;))

[slug88]

I'd wager the Concorde is more efficient in terms of miles per gallon of gas, but loses in terms of people*miles per gallon. In other words, a Concorde may use less gas than a 747 travelling the same distance, but the 747 will have delivered so many more people that it's cost per passenger is far lower.

Edited August 21, 2012 by slug88

[cichlidfan]

There is also the overall cost to operate the aircraft.

[Pyroflash]

I'd wager the Concorde is more efficient in terms of knots per gallon of gas, but loses in terms of people*knots per gallon. In other words, a Concorde may use less gas than a 747 travelling the same distance, but the 747 will have delivered so many more people that it's cost per passenger is far lower.

 

This is probably true, and represents the main reason why I neglected to mention the 787. Apart from its massive carriage capacity, and unparalleled range, even by the 747, it's engines (and airframe) are EXTREMELY efficient.

 

Edit: I digress, until I have more information about this topic. It seems upon further research that I overlooked a key aspect. Although the specific impulse may be twice as much, that only counts for fuel usage per unit of thrust, however it does not account for how much thrust is actually needed to sustain flight.

Edited August 21, 2012 by Pyroflash

[marcos]

Well, it is as you say, the engine itself may not enjoy better fuel economy due to its LBPR, however the aircraft as a whole enjoys far better fuel economy than any other jetliner in existence, with maybe the exception of the B-787 (to my knowledge). It is precisely because of the absence of parasitic drag on the body of the Concorde that allows it to be so efficient and fast.

Really? Evidence?

[marcos]

"Makes sense" does not equate to truth, unfortunately. Someone earlier was mentioning specific impulse and fuel efficiency at higher airspeeds... and I think that's the correct line of inquiry. If your theory was true, trust me, airlines would ALL be flying supersonic over long routes. They'll do anything to shrink costs in today's low-margin, high frequency environment, and fuel is always the number one concern. (This one is not a point of contention. ;))

Especially with CO2 levies on top of fuel costs. It's not like there aren't a good many companies who could knock-up a modernised Concorde very quickly but there just isn't the demand.

 

Even looking at fighter jets with similar engine configuration (low BPR turbojet) on a smaller scale, they do not get the best range at Mach 2+.

 

The figure important is SFC - fuel consumption per unit thrust. The RR/Snecma Olympus turbojet consumes twice as much fuel per unit thrust as a turbofan:

 

http://en.wikipedia.org/wiki/Thrust_specific_fuel_consumption

 

Now given that drag, and hence thrust requirement, goes up in proportion to V^2 is it clear that the Concorde will not make up for this simply by covering ground quicker.

 

If a turbofan uses X amount of fuel at 600mph then the Concorde will use 2X and they both cover Y miles in one hour.

 

Fuel consumed per mile is proportional to X/Y for turbofan and 2X/Y for Concorde.

 

At 1200mph, the Concorde will uses 4X^2 amount of fuel but will only cover ground at 2Y. Fuel consumed per mile is proportional to (2X^2)/Y, i.e. 2X times more fuel per mile than the turbofan at 600mph.

 

Furthermore matters are far worse than that because the Lift/Drag ratio for the likes of an A340 is around 20 but for a Concorde it's about 9 at Mach 0.9 and 7 at Mach 2. So for a given load+weight and size, the Concorde design develops 2-3 times as much drag.

 

I'd wager the Concorde is more efficient in terms of knots per gallon of gas, but loses in terms of people*knots per gallon. In other words, a Concorde may use less gas than a 747 travelling the same distance, but the 747 will have delivered so many more people that it's cost per passenger is far lower.

It all has to be proportional to size and capacity. Airlines don't use Concordes for the same reason that public transport operators don't use GSXR-1000s.

 

There is also the overall cost to operate the aircraft.

And restrictions on noise and supersonic flight.

Edited August 21, 2012 by marcos

[Pyroflash]

Read my earlier post, I already admitted that I have no idea what I am talking about since when looking into this stuff I skipped a bunch of rather important ideas related to specific impulse and thrust values. :D

 

Though I did learn one thing. I always thought that the Concorde was similar to the SR-71 in that it needed afterburners to sustain supersonic speeds, however it appears as though a lot of the reasons that the Concorde's engines WERE rather efficient when compared to conventional turbojet designs is that the Concorde could take advantage of supercruise. In fact, the Concorde was most efficient at higher Mach numbers.

 

Edit: Actually, I am tempted to ask for a thread split, as I would like to pursue this question further where it doesn't skim along the surface of its parent thread in such a way that negates its importance.

Edited August 21, 2012 by Pyroflash

[marcos]

Read my earlier post, I already admitted that I have no idea what I am talking about since when looking into this stuff I skipped a bunch of rather important ideas related to specific impulse and thrust values. :D

 

Though I did learn one thing. I always thought that the Concorde was similar to the SR-71 in that it needed afterburners to sustain supersonic speeds, however it appears as though a lot of the reasons that the Concorde's engines WERE rather efficient when compared to conventional turbojet designs is that the Concorde could take advantage of supercruise. In fact, the Concorde was most efficient at higher Mach numbers.

 

Edit: Actually, I am tempted to ask for a thread split, as I would like to pursue this question further where it doesn't skim along the surface of its parent thread in such a way that negates its importance.

That much is true. The Concorde actually produced more than 80% of maximum thrust without re-heat. I believe the re-heat was only added because it improved overall transonic fuel efficiency during acceleration through the sound barrier. It still has more thrust than a B1-B even when running dry. And it has more dry thrust than a Tu-22M or Tu-160.

Edited August 21, 2012 by marcos

[Pilotasso]

Turbofan engines (with gearboxed fan) are fast aproaching energetic 50% efficiency. They are light years ahead of concordes afterburning engines in terms of fuel economy even though they were dsigned to work on different regimes.

[MadMonkey]

vision avionics flight has been talked/dreamed about for a long time

 

even billionaires have tried pushing the envelope

 

Who Knows? maybe one day after they perfect it we can buy a seat ticket sitting across

from Richard Branson & discuss what's next? while half naked playboy bunny stewardesses

make us cocktails... in the meantime there will be unexpected mishaps that will go wrong.

 

what I am wondering is..even Chuck Yeager wouldn't be stupid enough to sign up as a test pilot

for these types of things so I wonder how much they are willing to pay a test pilot to seriously consider it?

 

Edited August 22, 2012 by =MadMonkey=

[Pilotasso]

A half naked playboy bunny stewardesses is the farfetched part :D

[PeterP]

Half-naked?!

 

Man! You bought the wrong ticket !

Edited August 22, 2012 by PeterP

[marcos]

what I am wondering is..even Chuck Yeager wouldn't be stupid enough to sign up as a test pilot

for these types of things so I wonder how much they are willing to pay a test pilot to seriously consider it?

What they could do is force pilots who've been involved in friendly fire incidents to test them as a form of punishment or get someone to fly an F-22 for 60 minutes then, when they land suffering from oxygen depravation, get them to sign the contract.

 

Apparently, according to popular myth/rumour, the civil aviation authority requires that all aircraft be birdstrike tested at twice maximum speed. A Mach 12 chicken poses an even greater design problem.

 

It's nevertheless nice that we're almost back where we were 32 years ago:

 

http://www.designation-systems.net/dusrm/app4/asalm.html

 

In 1976, the U.S. Air Force issued a requirement for a new air-launched missile called ASALM (Advanced Strategic Air-Launched Missile). ASALM was intended as a nuclear-armed replacement for the AGM-69 SRAM (Short-Range Attack Missile) with a longer range and a much higher speed. Apart from its primary strategic air-to-ground mission, the missile was planned to have a secondary air-to-air role against AWACS (Airborne Warning And Control System) aircraft coordinating the enemy's air defenses. ASALM would have used inertial guidance in the cruise phase, and would have been equipped with a dual-mode seeker for terminal guidance against ground or air targets. The missile was to be of the same size as the SRAM so that it could be used from the same launchers. Two airframe/propulsion teams competed for the ASALM development contract, these being Martin Marietta/Marquardt and McDonnell Douglas/UTC.

 

 

Image: USAF

ASALM (Martin Marietta design)

 

 

The major innovation in ASALM was the integrated rocket/ramjet propulsion system. A solid-fueled rocket motor accelerated the missile to supersonic speed, when the now empty rocket casing served as the combustion chamber for the ramjet sustainer. Before ramjet ignition, an aerodynamic cover on the ramjet intake and the rocket nozzle were ejected. Between October 1979 and May 1980, seven flight tests of propulsion technology validation (PTV) vehicles were successfully conducted. These PTV vehicles were probably closely related to the Marquardt LASRM (Low-Altitude Short Range Missile), which reportedly tested integrated rocket/ramjet technology under Air Force program 655A. In one of the PTV tests, the missile accidentally accelerated beyond the planned speed, and eventually reached Mach 5.5 at 12200 m (40000 ft)! The planned cruise speed for operational ASALM missions was to be around Mach 4.5 for a range of about 480 km (300 miles).

 

 

Photo: USAF

ASALM (PTV vehicle)

 

 

ASALM development was put on hold after the completion of the PTV flights in 1980, and later cancelled. I have found no explicit reasons for the cancellation, but it was most likely connected to budget restrictions and the concurrent development of the AGM-86 ALCM (Air-Launched Cruise Missile).

 

In 1983, Martin Marietta submitted a derivative of its ASALM design as a candidate in the U.S. Navy's YAQM-127A SLAT (Supersonic Low-Altitude Target) competition. The design was eventually selected as winner, but SLAT was cancelled after the initial test phase.

 

Specifications

 

Note: Data given by several sources show slight variations. Figures given below may therefore be inaccurate!

 

Data for ASALM:

 

Length 4.3 m (14 ft)

Speed Mach 4.5

Range 480 km (300 miles)

Propulsion Marquardt integrated rocket/ramjet

Warhead Thermonuclear (possibly W-69 (200 kT))

 

Edited August 22, 2012 by marcos

[MadMonkey]

bad taste

 

What they could do is force pilots who've been involved in friendly fire incidents to test them as a form of punishment

 

that's a very bad tasted comment sir..

 

in war, accidents happen unfortunate as it is every pilot who realizes he made a terrible mistake has to live the remainder

of his life feeling emotionally damaged inside from dealing with very hard disturbing mental guilt..

 

no pilot or troop who have ever mistakenly killed their own in combat "friendly fire" due to:

a lack of combat awareness, Laser Target Marker -Battery Replacement GPS Coordinate malfunctions,

or other circumstances such as friendlies mistakingly wandering into aircraft kill boxes will ever forget it.

 

which is punishment enough.

Edited August 22, 2012 by =MadMonkey=

[marcos]

that's a very bad tasted comment sir..

 

in war, accidents happen unfortunate as it is every pilot who realizes he made a terrible mistake has to live the remainder

of his life feeling emotionally damaged inside from dealing with very hard disturbing mental guilt..

 

no pilot or troop who have ever mistakenly killed their own in combat "friendly fire" due to a lack of combat awareness

or other circumstances such as friendlies mistakingly wandering into aircraft kill boxes will ever forget it.

 

which is punishment enough.

In testing accidents happen too, so people who have experience with accidents are best suited to the task at hand.

 

Anyway I withdraw my comment. A bit of dark humour which may not be to the tastes of some.

 

I thought you'd be used to dark humour having been on SFOT for 10 years.;)

[Pyroflash]

vision avionics flight has been talked/dreamed about for a long time

 

what I am wondering is..even Chuck Yeager wouldn't be stupid enough to sign up as a test pilot

for these types of things so I wonder how much they are willing to pay a test pilot to seriously consider it?

 

 

First off, what is Vision avionics?

 

Secondly, test pilots for what things? The X-51 has no pilot (or the pilot is a really tiny midget).

Edited August 22, 2012 by Pyroflash

[marcos]

I imagine at those speeds that a microchip would be doing most of the flying even if it were manned.

[MadMonkey]

First off, what is Vision avionics? [/Quote]

 

typo

 

I meant Vision aviation, or visionary aviation, or Visionary Aircraft Concepts

..sound it out.. you know, like back in grade school ;)

Secondly, test pilots for what things? The X-51 has no pilot (or the pilot is a really tiny midget).

 

I was referring to test pilots for Richard Branson's aircraft who push the edge of our

atmosphere or other of these types of 'Visionary Aircraft Concepts"

 

the X-51 WaveRider is unmanned yes.. but for how long?

eventually others will try to use the technology for other means or be stuck basically

using a remote control plane that carries passengers? pfft not likely many will stick

with that idea.