Who was talking about using afterburners?

Would be pretty daft in a talk about supercruising wouldn’t it…

That is a question of engine intake operating conditions, and the ram pressure effect it has – see the post about operating pressure ratios earlier in the thread.

I would not be an expert in this field, so correct me if im wrong.

Let me get the simplest of calculations with the same A/C:

1. 250nm on max military thust, let say mach 0,9
2. 250mn on max military thust, let say mach >1,2 (with a short afterburn)

If the dragkoefficient is about the same, i guess no 2 will burn 0-20% more fuel on the same stretch, depending on special effects (engine, intakes, afterburn time), velocity^2 – >33% shorter burntime etc. BUT will be there >33% FASTER!

Also, isnt that efficient to widen the flight envelope, so that the pilot can use the supersonic speed with much much less penalty as it used to be?

1.5hrs flight roughly equals 720nm range at 480kts cruise. Normally fuel flow is ~15% higher at cruise speed than max endurance speed, so it should be less than 720nm, but let’s give SAAB the benefit of the doubt and assume that the time on station is spent at lower altitudes where max endurance fuel flow is higher than optimal and about the same as cruise fuel flow at >30k ft. Divide 720nm by two to get 360nm radius, add to 200nm, and that gives you a radius of roughly 550nm.

The wing loadings on this chart are OK – all aircraft are shown with 4 AAMs:

Gripen NG: 65lb/sq.ft. x 323 –> ~21,000lbs
Rafale: 57.5lb/sq.ft x 492 –> ~28,200lbs
Typhoon: 57lb/sq.ft x 551 –> ~31,400lbs

To check this:
Gripen NG: 15,700lb empty +3,650lb (50% fuel) + 2*350lb AMRAAM + 2*200lb IR AAM + 2*100lb pylons + 200lb pilot + 200lbs chaff/flares/liquids = 21,050lb
Rafale C: 21,500lb + 5,200lb + 2*350lb + 2*200lb + 200lb + 200lbs = 28,200lb
Typhoon: 24,250lb + 5,500lb + 2*350lb + 2*200lb + 2*100lb + 200lb + 200lbs = 31,450lb

All pretty spot on. The problem is with the thrust loadings:

Gripen NG: 0.882 x 22,000 thrust = 19,400lb combat weight
Rafale C: 0.9 x 32,800 = 29,500lbs
Typhoon: 0.825 x 40,000 = 33,000lbs

So SAAB have subtracted 1,600lbs from Gripen NG (basically all stores including the pilot!), while ADDING 4x AAMs to Rafale & Typhoon (1,300-1,600lbs). Alternatively, they are assuming 23,800lb thrust to maintain 21,000lb combat weight. If so, then that’s news, because SAAB and GE have always advertised the F414G as being an F414-GE-400 derivative with 22,000lbs thrust (20% more than RM12).

Looks like SAAB are counting on the F414 EDE, without telling anyone. That’s OK, but if so then we should be also use higher thrust numbers for the M88-4 and improved EJ200 versions to keep it apples-to-apples. Also, we’d have to reduce Rafale and Typhoon’s loads to 4 AAMs, which would give something like:

Thrust loadings with 4 AAMs
Gripen NG: 0.88
Rafale C: 0.83-0.86
Typhoon: 0.78

They allways stated more than 20% more thust over RM12 that means “more”. So it should be the engine flying…and is probably weighted against requirements in specifide cases.
To state “Full load” and only load 4 AAM would be lying.
So the case its probably more thust than you expected.

i found the source Saab probably uses in this case:
http://www.defenseindustrydaily.com/files/2008_RAND_Pacific_View_Air_Combat_Briefing.pdf

This presentation actually betrays Gripen NG’s key weaknesses: its poor thrust-to-weight ratio, and its draggy, closely spaced, side-by-side stores!

Page 33
The Gripen NG to Typhoon comparison is meaningless, since the Gripen NG is carrying only half the # of AAMs, and carrying more external fuel (2x 1,700L vs. 2x 1,000L). No wonder it can fly farther – but it certainly can’t perform as well. Thrust loading in for the Gripen NG is 1.41 lbs/lbf versus 1.06 for the Typhoon, i.e. 33% worse. Even without tanks, the Gripen NG’s thrust loading is still 1.11, i.e. 10% worse than Typhoon with 4 AAMs and 2x 1,000L tanks. Apples-to-oranges.

Page 34
1.5hrs endurance at 200nm with 4xAAMs and 4x GBUs!!! says Saab. The exclamation marks are trying to spin what’s actually quite a poor performance. This converts to a radius of only ~550nm, versus >800nm for a Rafale in a same configuration. This puts Gripen NG in about the same category as an F-16, which makes sense since although Gripen NG is a bit lighter than early F-16Cs, the F414 has a slightly higher SFC. The draggy side-by-side underfuselage stores probably do the rest.

Page 42
This is by far the worst slide. Utterly false advertising on SAAB’s part. 😡 They compare thrust loadings of a bunch of fighters with 6-8 AAMs. The Gripen NG seems to do quite well – but that’s because it’s carrying only 4 AAMs and SAAB are estimating ~24,000lbs 😮 thrust for the F414. In reality, the Gripen NG’s thrust loading on that slide should be 0.97 instead of 0.88. That’s worse than almost all competitors, e.g. 12% worse than Rafale (0.87) and 24% worse than Typhoon (0.79), once you adjust AAM loadings.

I’ll give it to SAAB though. I was impressed by the presentation, until I started fact checking. They’re masters at spin. :rolleyes:

I’d like to think that they haven’t lied on costs though. Would love to find out whether Gripen’s REAL cost of ownership is as low as advertised.

Spin spin etc. 🙂 the data is valid and is in a way to present Gripens case. If you write a similar case for EF, it would probably look different.

page 34
I dont see how you get those numbers, but they are probably not right ;). Combat radius with 6 AAM and one external tank is stated >810nm. It is genally known a smaller AC degrades more with more stores, but 550nm is a little bit to far. I also seen numbers for rafale better than 1000nm for longrange strike.
I do not see anything that present Gripen as a longer striker than than Rafale ither, which otherwise would of couse be very wrong.

page 42
Maybe SAAB knows more of the real thust than you? 🙂 The only stated thust of the NG is the minimum thust. How do you recognise Gripen as 4 AAM= full AAM load? it should be 10AAM, and 12AAM for ex F-18
That means the data i still credible for a “Full load” comparison.
As for all the other datas the source is presented and seems to me, valid.

More than likely considering its more costly than the F-35 and yet offers less capability.

Rafale is probably better on many areas.

At the moment F-35 does not have any capabilites proven. But will probably have a great sensorsuit and good stealth, still there are some countries prefer AC preformance…
Please dont flame this. This is my opinion and you could not prove me otherwise.

More like it is revealing of policy at the time the decision was made.

Speaking about engine tech, how are those American engines on the Gripen 😉

really great thanks

Perhaps if we limit the discussion to wingtip Sidewinders and conformally carried MRAAMs. It most certainly does matter when you’ve got EFTs, 2000lb bombs, sensor pods, and the pylons, etc… hanging under the wings.

as i said:

The history of flight can tell you alot, and maybe get you out of the spin youre in.
History tells you:
1. Supersonic AC has always hanged things on the wings and belly. (and therefore it was better to hang it there rather than to house it) (there are exeptions like B-1B, and that for capacity)

2. Subsonic AC can use the luxury of carring bombs internaly made the capacity bigger for that (like B-52).

Why? think of it!

The total crosssection is smaller if you hang things on the belly rather to build housing around it (hopefully the bomb is not a brick). Crosssection is extremly important. So even loaded (same load) a tradional AC goes faster with the same thust.

This is also one of the main reasons why M1.6 can only be achieved with stagering 191kN. Many loaded fighters can go faster even when loaded with a EFT with half of that power.

I can go with you, when it comes to hanging 4 2000lb bombs, sensorpod and sidewinders on a f-16, but than again F-35 cant take that much internally. so it would not me fair.

Back to the Counter-thead

F-35 will come out with things that many other fighters can only dream of when it comes to sensorsuit, this, together with some stealth, better the oponent, it will probably be a good day for the F-35.
The “anti-cloaking” needs to be better and more robust (for tracking) for anyone get the edge over it i BVR.

So what is an anti cloaking device? 🙂
1. a Hi power, Hi range, radar with some stealth tweaks X-band worst, L- best?.
2. IRST coupled with a longrange LRF
3. Radar triangulation of some kind
4. Spotting C02 emissions? with what?
5….

Than an F-16 with a comparable load? You all are smoking some good dope.

Hey there smoker!
Have you ever wonder why internal bombays are rare on supersonic AC:s?
And external loads is used?
Total RCS is the no 1 key factors for going fast, add a boxy aerodynamics to that does not help.
A “clean” F-35 isnt “clean”, its a big box with a big engine to compensate for that.

The first 2 mach birds, those are super “clean” when clean, adding a small tank and AAM did not suffer that much as a big boxy housing for bombs and fuel adds to the total RCS did in the first place. Thats why F-104, Mig-21 and Draken looks the way it does, and dont use internal loads, and internal Bomb was abandoned until F-22.

Internal bombs isnt new, but only used in low-speed systems.