SchorschSo the Tornado could outrun the F-105 on the deck?
Depends.
The Tornado hardly flies clean, nor does the F-105.
If the one flies M0.93 and the other M0.98 is pretty much irrelevant.
The comparison Tornado vs. F-105 shows the progress in technology.
Schorschusing those points listed as the conditions of practical supercruise, based on the information known at this time about the Gripen Demo, do you really think it is capable of supercruise?
I think the present Gripen has some supercruise capabilities, too, but as it only have that under “show” conditions, it is never mentioned. Anyways, achieving supercruise means to reduce drag (which is difficult for an existing design) or increase the thrust of the engine-intake system at the relevant Mach numbers. Another option would be to increase the instability of the aircraft (reduce trim drag), but I think this option was already exploited on the Gripen.
As the Gripen-N still carries all of its weapons on pylons, I don’t think the Gripen-N will a useful tactically relevant supercruise capability. I think there have been no claims by Saab about that, which indicates, it is not planned.
Schorsch[…]
Thanks for the insight. Very useful post.
Let me make this item clear: I think the F-22 is a very useful aircraft and in an airwar that runs like USAF thinks the F-22 will be the winner.
But I think an OEW of 17-20 metric tons indicates that the F-22 will not exactly the standard aircraft of the future. I think further that American industry have done a huge step forward with the F-22 and that the F-35 will be the more reasonable application of these experiences.
Let’s face it: No other country has ever produced a stealthy aircraft, the USAF/USN/USMC now have the 3rd generation of stealthy aircraft*.
——————————————————–
*: 1st: Have Blue, F-117; 2nd: B-2, YF-22; 3rd: F-22, F-35
SchorschWhat you’re describing is useful, or functional, supercruise. Fair enough. Let’s stick with that.
1. The Mach number at which an aircraft passes the transonic drag “hump”, & can therefore be said to be cruising varies with airframe, so one shouldn’t really specify a particular number.
2. For a fighter, yes. That’s a useful load, & if we’re discussing useful supersonic cruise, then a useful load is necessary.
3. Is not relevant. It’s one of those “religious” things. A touch of afterburner to boost through the transonic drag peak can save fuel, depending on the particular aircraft. It would exclude Concorde, for example – but that flew at M2 across the Atlantic, which I challenge anyone to tell me was not supercruising. In fact, the afterburner/no afterburner thing is rather ideological. The SR-71, for example, supercruised by any definition I’d consider reasonable, & did it mainly on afterburner thrust, with the main engine providing only 20%.
Acceleration to supercruise Mach number without reheat does not make much sense, when it comes to fuel consumption.
Accepted. The dry acceleration is more an indicator for the little flight performance obsessed engineer (=me).
The Concorde was supercruisy. The SR-71 used afterburner, but when flying at Mach 3 this dry/reheat thing becomes a bit academical. The J-58 used the energy of the airflow to achieve favorable compression (resulting in the inlet delivering actual thrust) and just bypassed the conventional engine, it pretty much was a ramjet. For an aircraft optimized for a small Mach number band that is OK with the correct intake design.
Transonic drag rise, its peak and begin of the fully supersonic region is very dependent on the actual design. Still, anything below Mach 1.2 seems to me rather unachievable as the drag/thrust ratio should be rather miserable there.
By the way: a supercruise optimized aircraft would use a turbojet!
By the way II: Does the F-119 have a variable bypass ratio?
SchorschWhat has the number of engines got to do with anything? What matters are thrust, weight, & drag. It’s much lighter than any of them. Also, depends on your definition of supercruise. The claimed speed on dry thrust is not far above M1.
As for the range – under what conditions? How much external fuel? Quoted figures may not be comparable.
Supercruise for practical purposes means:
Anything else is nice but not truly relevant.
The whole issue about supercruise is to increase the specific range into a region that is comparable to the usual Mach .85 cruise.
The Eurofighter (Typhonn is a crappy name) is quoted with M1.3 with 4 MR-AAM and 2 IR-AAM and one external tank. Don’t know about altitude and atmospheric conditions, but considering the external tank there should be some performance reserves (means: without tank you can accept more ISA+ or different altitudes).
SchorschOf course this was highly speculative of my part, so i can not even argue it too much, since i have not any proven evidence the Su-24 can reach Mach 2.0 with inlets without any moveable ramps ( the Ukranian air forces says mach 2 but this might be simply the early prototypes or a mistake independently it is true or not).
I do not think its the thrust, the F-111 has even less thrust (worst thrust to weight ratio) and can reach 2.5, but i wonder if the AL-21 could work under those conditions with a fixed ramp inlet like the F-100 can at Mach 2 i mean if the inlet allows that ideal air flow rate for its air pressure ratio and if the AL-21 is also able to accept such flow distortions if indeed it can reach Mach 2 with its fixed inlet
Get a book about aircraft (preferably one of those without pictures) and read it.
Static thrust has nothing to do with supersonic thrust, the only thing we can guess from it is the region. F-111, Tornado and Su-24 play in one league, but the F-16 is two leagues higher.
Flow distortion is no problem as long as we fly straight ahead, and actually only the early engines and the A-model was affected. No problem on the F version.
The key word is “pressure recovery factor”.
Recommendation: Copy&Paste into Google, see what you find.
SchorschI think the Su-24 can reach Mach 2 with fixed geometry inlets but the manufacturer recommends a max operational speed of Mach 1.6 to extend the operational life of the Su-24, perhaps a user like the Ukranian air force pushes the Su-24 up to speed of Mach 2.
Given the installed static thrust it fairly unlikely it can reach more than the mentioned Mach 1.6 clean, with remaining pylons and self defense missiles we are at Mach 1.3 and any useful payload will keep it at high subsonic.
The F-16 has a dedicated intake for a wide Mach area, while the Suchoi has a fixed VG intake, which is by that optimized for lower Mach numbers. It will have tremendous pressure loss at speeds beyond Mach 1.5, much more than the F-16 intake.
SchorschCan someone give me a fairly accurate description of a representative mission for such an aircraft.
I guess something like:
Item 4,5,6 are flown wings fully forward, 7,8 with wings middle position
Opinions?
SchorschLow level flight is the easiest possibility to reduce the radar horizon of AD systems. The long wave radars, that might detect stealth aircraft, will have severe difficulties then.
But from the aerodynamic point of view the F-22 and the F-35 are not useful for low level flight, nor are F-4, F-16, F-15 (all versions) and the Eurocanards. The wing loading is too low, engines are not really optimized for such conditions. For some missions low level flight might be an option and in favorable weather conditions it is doable.
With current technology no aircraft needs a dedicated terrain following radar any more. Either use the radar in TFR mode, or use the precise navigation (INS/GPS) and a precise world map (you can fit the world in 30m resolution on 15GB) and have an independent system. It maybe doesn’t allow you to fly 100ft nap of the earth, but you’ll always have 500ft water under your keel.
SchorschThe B-1 IS subsonic for operational missions. In my 7 years around
B-1s, I never heard of one going supersonic at any time.
It may be capabale of it in combat situation, but I know they aren’t going supersonic in their current missions.
Any supersonic aircraft basically flies 99% of its time subsonic (the SR-71 was an exception). But the option to go supersonic makes the airframe&engine more expensive.
Not get me wrong: for the deep low-level penetration mission the B-1B is the perfect aircraft. But like so many Cold War designs (see Tornado, F-14) its performance for limited warfare is questionable, but as you have it in inventory (and already paid the bill), you use it.
SchorschThe computerized tfr probably made the Tornado fly too smooth for the Bucc pirates.
Or the automatic 5g pull-up maneuvers without any visual reference for the pilots made it less comfortable.
SchorschDuring the 1950s the Blackburn Buccaneer was designed and built with outstanding low level ride stability. Twenty years later the Panavia Tornado was built as a low level supersonic ground attack bomber but its low level ride characteristics are inferior to the aircraft it replaced.
Why is it designers in the 50s can build aircraft with very good low level abilities yet 20 years later as technologies improve designers seem less able to?
In what way were the Tornados characteristics worse than that of the Buccaneer?
SchorschSuch a claim is called split identity or my understanding of English is very bad.
He refers to the fact that using my very primitive assessment the Suchoi achieve 2136/2839 = 75% of the F-111’s range.
Have fun with relative numbers.
The statements
The Suchoi 24 achieves 25% less range than the F-111.
or
The F-111 achieves 33% more range than the Suchoi 24.
are equal.
People not used to math easily get tricked by relative numbers with unknown basis. Very popular with media and politicians, as you can basically let look any number very small or very huge, depending on the point you want to make.
As I said, my calculation does not have any direct connection to reality, it only displays the effect of SFC and slightly different fuel load on range for similar weights and L/Ds.
The SFCs I gave, however, resemble the reality pretty good.
SchorschBut still, the aircraft you mentioned reached their design goals. It seems strange that a country would cancel a state of the art, first fly-by-wire aircraft so suddenly. The U.S. canceled the XB-70 program, but at least we continued flight testing with NASA and collected data. Also, many people believe this aircraft was “aircraft 101” that set a course record of M1.89, which of course isn’t M3.
The XB-70 flew in 1964. Different era, Cold War was colder and the XB-70 was a technological marvel. And it was not totally of the agenda as back-up solution.
The T-4 flew 1972, different time frame. ICBMs better developed, other technology available. The Russians never had this USAF-affinity towards heavy bombers, and besides that, they lacked the cash.
So, while they were reasons and supporters for the Valkyrie, there was probably less support for the T-4. Many Soviet projects at that time had just cleared major obstacles (MiG-25, MiG-23) and the priority was set on investing into the conventional equipment, which was subsequently done.
SchorschWrong. Asa has been already pointed out…
The B-1 has the numbers that the B-2 doesn’t have…and sometimes in the mideast, thay have two B-1s loitering and more at a nearby base..I don’t see that happening with the B-2s.
Also, the B-1 offers capabilities (Block D mods) that the B-52 does not…and never will… have such as the capacity to carry & use three types of munitions at one time.
Also..and has alreday been mentioned, the B-1 force has allowed the USAF to trim the B-52 fleet by retiring the Gs and now about half the Hs. Think of the money getting rid of the Gs saved…overnight you cut supply issues in half.Right now, the B-1 is playing a useful role. That opinion is based on talking with friends who are senior operational B-1 guys who have flown combat.
Re: the A-7 vs F-16…if you were a USAF pilot in PGW1, what would YOU have preferred flying in an hostile environment?
Sometimes speed is very handy.About 5 years ago I did a story on this issue and interviewed the ACC commander. As you might guess the requirements…let alone any possible proposals…were then very fluid.
But the general was keeping the door wide open for a unmanned bomber.
Still, I’m glad to see any new aircraft use systems /designs (like the basic cockpit) of the B-2. Why spend money to re-invent the wheel? You might even get away with a common “type rating” like the airlines get with fleets of Boeings and Airbusses.Also, if you keep delaying a program waiting for new technology or betting there won’t be a war, you’ll be like the MOD of the 40s-50s-60s….with their infamous “No war for five year” plans. If you do it too often, eventually your industrial base is gone and your military is impotent
I was just looking at the airframe: The present mission (intruding undefended airspace and dropping PGM on targets), can be done by any aircraft that can haul the payload over a sufficient distance. The particular mission for the B-1B (high speed at low altitude with low RCS and lots of ECM) is lost and the money spent for it is sunk. Now it is recycled.
But the best aircrafts at the moment for the USAF missions (dropping bombs in Iraq) are subsonic aircrafts with lots of payload and range. A-7 and B-52 (if available in sufficient numbers) beat F-16 and B-1B here anytime.
That doesn’t make any design a “wrong” one (actually both are remarkable), but it demonstrates that it doesn’t need over-engineered swing-wing bombers to drop a bomb from 30000ft.
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