Super Hornet strikes again ...

[marcos]

Very interesting read, thanks, I should change the subject of the thread :=)

 

Coming back to my original post as an intermezzo, I think the new thing is that a second Hornet takes over the in-flight command of the JSOW. That offers some nice tactical possibilities.

I think the interesting thing is that it probably means a foot soldier can also take control of the JSOW. Whilst this is possible with the new GPS/laser-guided EPW via ground lasing, the JSOW has a far longer range.

 

We should also understand that while the Super Hornet, building on 4th generation technology, matures at an amazing pace and now sports an incredible long list of combat tested weapons. It also has a very performant data bus and strong networked communications. When the F-35C will start to be operational around 2016, it will not at all be with a complete suite of weapons, most probably with only a couple of A2G weapons.

 

I guess F-35 will only very slowly expand its mission portfolio, look at the F-22. That means an F-35 being able to do most Super Hornet missions is something for the late 2020's. By then Super Hornet will have had a midlife update and certainly have better integrated avionics than today. It will of course never be a stealth aircraft.

Well that all depends on what the people with the purse strings do and when, so no comment.:)

[MadMonkey]

why does anyone compare jet fighters to different jet fighters when they are

designed to take on different roles at the time of the design?

 

comparing an f/a 18 to an f16 or f15 is like comparing apples and oranges

even though each may out perform each other in one specific area it doesn't necessarily

make one aircraft better then the next.. depends on the pilot and the role the fighter is

assigned.

[marcos]

why does anyone compare jet fighters to different jet fighters when they are

designed to take on different roles at the time of the design?

 

comparing an f/a 18 to an f16 or f15 is like comparing apples and oranges

even though each may out perform each other in one specific area it doesn't necessarily

make one aircraft better then the next.. depends on the pilot and the role the fighter is

assigned.

We weren't comparing fighters we were considering the issue of whether the F-35 could supercruise and using a bit of physics and the abilities of other fighters to draw a conclusion. F-35 and F-22 are obviously designed for very different roles.

[tflash]

F-35 has a very small wing area, so wing load will be high for sure. That means lot of induced drag. And induced drag goes with the square of mass!

 

I really doubt F-35 has supercruise capability, it's not a matter of "how big" your engine is, it's also how good your aerodynamics are, and the shobby F-35 doesn't have the sharpness and styliness of an Eurofighter or Raptor, sorry.

 

Regards!

 

I'm not so sure about the "small wing area" claim for the F-35. I guess you took the data from Wikipedia? But how is it calculated? My impression is that F-35 has a blended wing + lifting body design. To me, about the whole underbelly of the aircraft is part of the wing area to a certain extent - and to a higher extent than on legacy planes, no?

 

So, I'm not sure the wing loading is so high. Some people have compared it to F-105, which is absurd. The unprecedented massive computing used in its design wasn't only for stealth, but also for the aerodynamics which are not as simplistic as they might seem.

The idea was to match the Hornets manoevrability at low speeds with the F-16's accelleration and dash speed.

[Razor5-1]

F-35 can NOT supercruise, it can reduce power to minimum afterburner when gone past Mach 1 but still requires some re-heat to keep it supersonic, albeit a small amount.

 

Increasing the wing loading (W/S), aircraft weight over the wing planform area of an aircraft will increase the maximum speed it can achieve at any altitude, does not mean it can supercruise though.

For an aircraft that has a rather seamless connection between the body and wing, it is actually the upper surface of the fuselage that creates lift, not the belly. F-15 for example.

 

The reason it has computers is not to match another aircraft's performance, but to keep it in the air! Stealth aircraft are not aerodynamically stable.

 

For what it's worth Concorde could supercruise, so it's not just some recent discovery by the F-22 ;)

 

Only the lightning prototypes could supercruise, not the production aircraft.

Edited August 26, 2012 by Razor5-1

[tflash]

F-35 can NOT supercruise, it can reduce power to minimum afterburner when gone past Mach 1 but still requires some re-heat to keep it supersonic, albeit a small amount.

 

Increasing the wing loading (W/S), aircraft weight over the wing planform area of an aircraft will increase the maximum speed it can achieve at any altitude, does not mean it can supercruise though.

For an aircraft that has a rather seamless connection between the body and wing, it is actually the upper surface of the fuselage that creates lift, not the belly. F-15 for example.

 

The reason it has computers is not to match another aircraft's performance, but to keep it in the air! Stealth aircraft are not aerodynamically stable.

 

For what it's worth Concorde could supercruise, so it's not just some recent discovery by the F-22 ;)

 

Only the lightning prototypes could supercruise, not the production aircraft.

 

Three little points:

 

- I wasn't talking about supercruise but on manoevrability;

- It is of course both the form of the upper surface and belly together that creates the bernouilli-effect and thus lift of a lifting body, I agree

- I wasn't talking about the computers the F-35 has on board, but the computers that were used to design it.

[Razor5-1]

- They were not all directed to you, sorry if there was confusion.

- For the second point you are right, I meant to say contributes the most to lift(F-14,F-15).

- I picked that up wrong when you talked about matching performance, anyway an aircraft is never designed to match another, it's designed to be better.

[marcos]

F-35 can NOT supercruise, it can reduce power to minimum afterburner when gone past Mach 1 but still requires some re-heat to keep it supersonic, albeit a small amount.

 

Increasing the wing loading (W/S), aircraft weight over the wing planform area of an aircraft will increase the maximum speed it can achieve at any altitude, does not mean it can supercruise though.

For an aircraft that has a rather seamless connection between the body and wing, it is actually the upper surface of the fuselage that creates lift, not the belly. F-15 for example.

 

The reason it has computers is not to match another aircraft's performance, but to keep it in the air! Stealth aircraft are not aerodynamically stable.

 

For what it's worth Concorde could supercruise, so it's not just some recent discovery by the F-22 ;)

 

Only the lightning prototypes could supercruise, not the production aircraft.

Most modern fighters are not aerodynamically stable. The Tornado was probably the last one to be inherently stable.

 

Do you actually have any hard mathematical evidence that the F-35 can't supercruise or is it just an assertion based on wikipedia information which I re-check regular and typically see that some asshat has changed it several times per month. At the moment it suggests we've got an aircraft that can take off and land vertically, minus weapons load, even though the weight is 15% greater than the thrust.

Edited August 26, 2012 by marcos

[Razor5-1]

I'm sorry but my knowledge goes way past wikipedia!

Yes I read the test pilots reports from the test flights. What I said about supercruise was actually said by a test pilot himself, not somebody on wikipedia.

The aircraft cannot reach Mach 1 without burner and this is in a test loadout, no weapons. It can reduce burner to minimum when past Mach 1, but not sustain supersonic speeds without it, but again test conditions.

 

No matter how much maths you do, the aircraft will never behave 100% to what the maths predicted, this is one of the reasons why flight testing is done. To see if the aircraft actually matches what you thought it could do. It rarely if ever does match the maths.

You need wind tunnel testing and flight testing to evaluate an aircrafts performance, not only numbers from theory.

 

There are also 3 variants of the F-35, A- Conventional, B- VTOL, C- Carrier

[marcos]

I'm sorry but my knowledge goes way past wikipedia!

Yes I read the test pilots reports from the test flights. What I said about supercruise was actually said by a test pilot himself, not somebody on wikipedia.

Well I'd like some kind of substantiation of that because the mathematical evidence does not support that claim, nor even feature in the same ballpark as that claim and I've heard plenty of counter claims originating from pilots.

 

The aircraft cannot reach Mach 1 without burner and this is in a test loadout, no weapons. It can reduce burner to minimum when past Mach 1, but not sustain supersonic speeds without it, but again test conditions.

 

No matter how much maths you do, the aircraft will never behave 100% to what the maths predicted, this is one of the reasons why flight testing is done. To see if the aircraft actually matches what you thought it could do. It rarely if ever does match the maths.

You need wind tunnel testing and flight testing to evaluate an aircrafts performance, not only numbers from theory.

 

There are also 3 variants of the F-35, A- Conventional, B- VTOL, C- Carrier

Yes but the maths don't even suggest that it's a close run thing. Maybe if the maths showed it was struggling with Mach 1.0 then you may have a point. The maths don't show it to be struggling with Mach 1.0 anymore than an F-22. I don't necessarily believe it can supercruise anywhere near as fast as an F-22 but I'd need very solid evidence to make me believe that it couldn't supercruise at all. 34,000lbf is a lot of dry thrust. How many other fighters are there with that much dry thrust? The F-22, the substantially larger and older F-15? Not many more really.

[Razor5-1]

I don't want to drag this thread down, so i'll finish on this.

You sound like somebody who is too stuck in books and theory, The mathematical theory is only a part of a larger design process. I have done flight testing, the maths is close but not exact.

 

It is wrong to dismiss what a test pilot who flies the aircraft at the edge of it's envelope has stated and instead claiming that he's wrong because your maths doesn't say he's right. Somehow backed up by "other" pilots.

 

You should do some more research about it I think. You can stick the biggest engines on an aircraft, doesn't mean it's going to go Mach 5 does it? So many more parameters come into aircraft speed than high thrust:weight ratio.

Remember the mathematical model for the F-35 cannot be determined by simply using standard aerodynamic formulas. It's shape demands a far more complex model.

[marcos]

I don't want to drag this thread down, so i'll finish on this.

You sound like somebody who is too stuck in books and theory, The mathematical theory is only a part of a larger design process. I have done flight testing, the maths is close but not exact.

 

It is wrong to dismiss what a test pilot who flies the aircraft at the edge of it's envelope has stated and instead claiming that he's wrong because your maths doesn't say he's right. Somehow backed up by "other" pilots.

 

You should do some more research about it I think. You can stick the biggest engines on an aircraft, doesn't mean it's going to go Mach 5 does it? So many more parameters come into aircraft speed than high thrust:weight ratio.

Remember the mathematical model for the F-35 cannot be determined by simply using standard aerodynamic formulas. It's shape demands a far more complex model.

All agreed but as mentioned, I've heard counter claims, and the evidence you've put forward is without substantiation or proof. In the light of that I'm inclined to stick with the maths.

 

Sure more factors come into it, like intake ramps and nozzle design but this has been worked on extensively, both through computer modelling and flight testing, in order to minimise total pressure losses and provide expansion that is close to fully reversible.

 

I fully accept that some engines with massive thrust can't break the sound barrier but this comes down to that discussed in the above paragraph. You need a con-di nozzle to properly expand the jet and you need to slow the intake air down via a series of oblique shocks prior to a weak normal shock to minimise total pressure losses in the supersonic regime. But hey, these engines are designed for supersonic operation, and the whole point of having a variable throat area within the nozzle is to keep the engine operating at the same designed operating point when the afterburners are lit by keeping the jet pipe pressure unaltered. So it's not as if lighting the afterburners fundamentally affects the operation of the engine core by a massive amount.

Edited August 26, 2012 by marcos

[wilky510]

I'm not so sure about the "small wing area" claim for the F-35. I guess you took the data from Wikipedia? But how is it calculated? My impression is that F-35 has a blended wing + lifting body design. To me, about the whole underbelly of the aircraft is part of the wing area to a certain extent - and to a higher extent than on legacy planes, no?

 

So, I'm not sure the wing loading is so high. Some people have compared it to F-105, which is absurd. The unprecedented massive computing used in its design wasn't only for stealth, but also for the aerodynamics which are not as simplistic as they might seem.

The idea was to match the Hornets manoevrability at low speeds with the F-16's accelleration and dash speed.

Correct on the blended wing + lifting body.

 

other peoples post: I'm almost positive the aircraft is more optimized for subsonic speed as just shown with the F-16. it's the most fuel friendly way to get to the target. I'm pretty sure even if it can't supercruise on dry thrust. Engine upgrades down the road it will certainly most able to. I read somewhere the F135 is downrated to 43,000lb max thrust. It can go to 51,000lb for future upgrades.

[Pilotasso]

Supercruise is 50% airframe design plus 50% engine design. The one on the F-35 is a larger bypass ratio and Fan. A smaller bypass is preferrable for supercruise, like the one on the F-22.

[mikoyan]

Another reason why the concord didn’t use turbofans was that the turbofan created more drag because of the big fan in the front in comparison with the turbojet.

The question is how much better is a Diamond wing than a swept wing like for example the su-27’s wing or a regular delta.

[Pilotasso]

Another reason why the concord didn’t use turbofans was that the turbofan created more drag because of the big fan in the front in comparison with the turbojet.

The question is how much better is a Diamond wing than a swept wing like for example the su-27’s wing or a regular delta.

 

Correct but with 2 quirks. Convenient to add to your sentence that Fan drag happens at transonic speeds and up. At higher altitude where an F-22 will be supercruising the Fan contribution for total thrust decreases and at high speed a large diameter one becomes an airbrake. High Bypass is good for subsonic acceleration and fuel economy. :)

 

Another reason is that, at that time very low bypass engines were more comon even on subsonic airliners (see B707). Technology was to catch up to produce larger diameter engines with High bypass and fans.

Edited August 27, 2012 by Pilotasso

[marcos]

Supercruise is 50% airframe design plus 50% engine design. The one on the F-35 is a larger bypass ratio and Fan. A smaller bypass is preferrable for supercruise, like the one on the F-22.

But the jet flow is still supersonic so the increased mass-flow rate, both through the core and bypass, multiplied by Vj-Va will still provide thrust above Mach 1.

 

You're also forgetting that the BPR on both the F-35 is variable and not fixed. Therefore at higher speeds, more of the flow will be directed through the core as BPR is reduced and the airflow aft LP turbine will be hotter leading to higher Vj.

Edited August 27, 2012 by marcos

[Pilotasso]

The flow is never supersonic inside the engines. Usually theres a shock wave before it reaches the fan or the core so that airspeed is always slower there than outside. It further decreases as it travels through the compressor. It becomes supersonic again as it leaves the trailing edge of the nozzle.

 

EDIT: I totally forgot to mention that Engine duct design also impacts supercruise ability, due to shock wave optimization (little on the F-35) and shape (F-35's S shape is much more pronounced leading to losses) and radar wave blockers.

Edited August 27, 2012 by Pilotasso

[marcos]

The flow is never supersonic inside the engines. Usually theres a shock wave before it reaches the fan or the core so that airspeed is always slower there than outside. It further decreases as it travels through the compressor. It becomes supersonic again as it leaves the trailing edge of the nozzle.

 

EDIT: I totally forgot to mention that Engine duct design also impacts supercruise ability, due to shock wave optimization (little on the F-35) and shape (F-35's S shape is much more pronounced leading to losses) and radar wave blockers.

Obviously. I'm talking about the jet flow aft of the nozzle choke point since this determines thrust along with the mass-flow rate. I've already talked about the minimisation of intake total pressure losses through variable geometry ramps and shock pattern. The F-35 actually uses a DSI system seen to incorporate an oblique shock before a normal shock:

 

http://www.f-16.net/index.php?name=PNphpBB2&file=viewtopic&p=181064

 

http://www.freepatentsonline.com/5749542.pdf

 

BACKGROUND OF INVENTION

 

Many of today's fighter aircraft must cruise supersonically while having low radar cross-section.

 

http://pdf.aiaa.org/preview/2010/CDReadyMASM10_1812/PV2010_481.pdf

 

Flow Field and Performance Analysis of an Integrated Diverterless Supersonic Inlet. In this paper the computed flow and performance characteristics at low angle-of-attack (AOA) of an integrated Diverterless Supersonic Inlet (DSI) are presented near its design mass flow rate. The subsonic characteristics are evaluated at M=0.8 while the supersonic characteristics are evaluated at M=1.7, which is near the design Mach number for the intake. In addition to the external flow features, the internal intake duct flow behavior is also evaluated. The results of this study indicate effective boundary layer diversion due to the “bump” compression surface in both subsonic and supersonic regimes. At M=1.7, the shockwave structure (oblique / normal shockwave) on the “bump” compression surface and intake inlet is satisfactory at intake design mass flow ratio. The intake duct flow behavior at subsonic and supersonic conditions is generally consistent with “Y” shaped intake duct of the present configuration. The secondary flow structure inside the duct has been effectively captured by present computations. The computed intake total pressure recovery at M?=1.7 exhibits higher-then-conventional behavior at low mass flow ratios, which is attributed to inlet design feature. Overall computed subsonic and supersonic total pressure recovery characteristics are satisfactory under the evaluated conditions and are also in agreement with wind tunnel test data.

 

The F-22 also uses the same fixed inlet according to wiki:

 

http://en.wikipedia.org/wiki/Lockheed_Martin_F-22_Raptor

 

Former Lockheed chief test pilot Paul Metz stated that the Raptor has a fixed inlet, as opposed to variable intake ramps

 

 

However, to be perfectly honest, a standard pitot intake with one normal shock will show no degradation in performance over a variable geometry system up to Mach 1.3 and very little up to Mach 1.6. An F-16 uses a standard pitot intake and I believe I've heard that it can supercruise whilst completely dry. The F-15 uses a 3 oblique shock system and only show an improvement wrt losses above Mach 1.3.

 

Edited August 27, 2012 by marcos

[marcos]

JSOW C-1 against ships.

 

http://www.sacbee.com/2012/08/21/4744000/raytheon-us-navy-begin-jsow-c.html

 

Another string on its bow. At this pace, by the time the F-35C can catch a wire, the Super Hornet will be able to do what? Fly underwater? Refuel an aircraft carrier? Visualize a stealth plane in 3D?

Is the JSOW really any more impressive than this existing munition?

 

http://en.wikipedia.org/wiki/AGM-130

 

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

 

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Edited September 15, 2012 by marcos

[tflash]

The answer is clear: yes, it is. What is shown in the JSOW film is *another Hornet taking over the command of the JSOW*. This allows very versatile tactics, which are of extreme importance against well defended naval targets.

 

The AGM-130 is very good but older and imho useless against ships.

 

The AASM is of course a very, very impressive weapon, just like Apache/Storm Shadow. But why you guys want to do diminutive about recent JSOW developments escapes me totally.

[marcos]

The answer is clear: yes, it is. What is shown in the JSOW film is *another Hornet taking over the command of the JSOW*. This allows very versatile tactics, which are of extreme importance against well defended naval targets.

 

The AGM-130 is very good but older and imho useless against ships.

 

The AASM is of course a very, very impressive weapon, just like Apache/Storm Shadow. But why you guys want to do diminutive about recent JSOW developments escapes me totally.

Mmmm, another plane can take over the datalink guidance of the AGM-130, and the AASM Hammer target can be lased from a 2nd source.

 

The JSOW has a longer range, but against a ship, I'm taking a 2000lb Mk-84 warhead (AGM-130) over a 500lb Mk-82 warhead (JSOW). But then both weapons are useless against ships because you'll never get that close. ASMP-C would be my choice against a ship. Mach 3, 5-600km range. Or maybe a Storm Shadow or KEPD 350. Don't want to get near a ship.

 

 

 

 

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Edited September 15, 2012 by marcos

[aaron886]

JSOW is not a cruise missile equivalent, marcos. Apples and oranges. The US Navy/Air Force found a need for something in-between, that's why it exists.

[marcos]

JSOW is not a cruise missile equivalent, marcos. Apples and oranges. The US Navy/Air Force found a need for something in-between, that's why it exists.

I guess, but it's a strange anti-ship weapon. I guess it could be fielded against ships with mediocre air defences. Whilst technically a glide-bomb, I think it is intended as a missile equivalent hence the 'AGM' in AGM-154.

 

But by the time the F-35 reaches this stage in its lifecycle, it may be able to take out an entire task force with just 2 missiles.

 

http://en.wikipedia.org/wiki/Perseus_(Missile)

 

With further weapon system integration, Perseus is also expected to eventually replace MBDA's Storm Shadow air-launched land-attack cruise missiles currently in service with the Royal Air Force and French Air Force.

 

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[aaron886]

Yeah, "many tools for the job" is hopefully the approach. (Seems to be just the opposite for aircraft these days, though.)