SAAB Gripen and Gripen NG thread #4

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Yes, the F414 would fit and this has already been demonstrated in the Gripen Demo.

We aren't talking about the F414. We are talking about the F100-PW-229, a totally different and substantially larger engine.

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I am reminded once again never to assume you know what the discussion is about...

Quoting your own words:
Clearly the F414 isn't an ideal engine for Gripen NG, but that is what you get when you build your aircraft from off the shelf parts.
Post #122

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Quoting your own words:
Clearly the F414 isn't an ideal engine for Gripen NG, but that is what you get when you build your aircraft from off the shelf parts.
Post #122

Yes, I also mentioned the f414, the engine that powers the Gripen NG.(it fits!)

My apologies if you found that confusing but sometimes in a discussion of engines people will mention multiple different engines...

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Yes, the F414 would fit and this has already been demonstrated in the Gripen Demo.

The problem is that we aren't talking about the F414. We are talking about the F100-PW-229, a totally different and substantially larger engine.

Sorry. My bad.

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Sorry. My bad.

My apologies as well. It wasn't completely clear.

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I can't read Saab's mind(s) but if you look at some of the fighters currently in production the Gripen NG falls at the very low-end of the range. I suspect if the F414EPE were to become available Saab would be very quick to jump on it.

F-15E
Empty Weight: 31,700
Thrust: 58,000
Power/Weight: 1.83

Eurofighter
Empty Weight: 24,250
Thrust: 40,460
Power/Weight: 1.67

Rafale
Empty Weight: 21,270
Thrust: 34,000
Power/Weight: 1.60

F-16
Empty Weight: 18,900
Thrust: 28,600
Power/Weight: 1.51

F-35A
Empty Weight: 29,098
Thrust: 43,000
Power/Weight: 1.48

Super Hornet
Empty Weight: 32,081
Thrust: 44,000
Power/Weight: 1.37

Su-30MKI
Empty Weight: 40,565
Thrust: 55,120
Power/Weight: 1.36

JF-17
Empty Weight: 14,520
Thrust: 19,000
Power/Weight: 1.31

Gripen NG
Empty Weight: 17,600
Thrust: 22,000
Power/Weight: 1.25

Gripen
Empty Weight: 14,990
Thrust: 18,100
Power/Weight: 1.21

So F-18E heavier than F-15E even though F-18E only rated for 7.6G and made of composites. you can't compare non AESA F-16 wright with AESA GripenNG.

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The F414 is not the same as the F404. While maximum engine diameter is the same (35 inches), inlet diameter is not. It grew from 28 to 31 inches. So it's not exactly plug and play.

Edit: from this video:

...only limited changes were needed in the main engine bay and the main air intakes were widened to achieve correct airflow.
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Yes, I also mentioned the f414, the engine that powers the Gripen NG.(it fits!)
My apologies if you found that confusing but sometimes in a discussion of engines people will mention multiple different engines...

I've reread the whole discussion and am getting your point now.. It wasn't 100% clear which engine you had in mind, now it's obvious it was the F100.
Thanks for the clarification..
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The F414 is not the same as the F404. While maximum engine diameter is the same (35 inches), inlet diameter is not. It grew from 28 to 31 inches. So it's not exactly plug and play.
Some sources like MTU say 32 in. But looks like the redesign work from F404 to F414 ain't a major one, both SAAB and HAL have decided to go that route with the Gripen NG and Tejas Mk2.

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No fear fact is here. So far i have seen no figures for f135 fuel consumption. 2 Fuel consumption consists of 3 values Xg/kN·s the first value (weight) is the one that gets better if you improve engine fuel consumption. The second value is the power of the engine. The third value is for counting time.

Say that f135 draws 25g*190kn=4750g(4,75kg/s)/sec*60=285kg per minute. Now checkout if i change that value to gripens engine power 25g*98=2450g(2,45kg)/sec*60=147kg per minute.

Now to the interesting part. Lets assume LM outdid them selves hard when creating f135 and cut the fuel burn by 20% which is a lot, actually almost out of question. 20g*190=3800g(3,8kg)/sec*60=228kg per minute.

With an 20% lowered fuelburn you still have 65% more fuel consumption.

Taking known values for the (Volvo rm12) Gripen c's values, these are the theoretical values 3400kg/72kg/min=47,2 minuter=1180km full dry. WOW ! almost super cruise for the max range of the f-35 (i know, just teoretical without load)


I dont know where do you got these calculations but they are most certainly wrong
Firstly , F-135 doesnot generate 190 Kn on dry thrust
Secondly TSFC isnt a fixed constant coefficient , they varied significantly with altitude and speed

Conclusion A large and strong engine does not automatically get saved by good fuel consumption. And if f-35 use max throttle in dry thrust, it does not super cruise.(remember even if f-35 has exceptionally strong dry trust it can't super cruise).

why ?

The range of f-35 is 1200km. And there will be no fast travels in supersonic or with to much load. The point im proving here is that f-35 needs it's large tanks filled to get anywhere at all and whatever you think or wish for can't change that its pure fact and anyone with a calculator can see that.

range # combat radius
F-35 can achieve more than 700 nm ( 1300 km ) combat radius in both both AA and AG depending on mission profile
http://www.ontaero.org/Storage/29/2370_F-35_Briefing-Keith_Knotts,_LMCO-Oct_2,_2013.pdf
https://www.f35.com/global/participation/canada
according to Norwegian JSF/F-35 LM Brief, with 2 GBU-12 , 2 AIM-120 internally , F-35 combat radius is 728 nm ( 1348 km) for recon mission profile
https://i0.wp.com/s9.postimg.org/cq3o12cbj/New_Bitmap_Image_4.jpg
when comparing using the same air to air mission profile , Gripen with 3 external fuel tank achieved combat radius of 502 nm while F-35 on internal fuel alone achieve combat radius of 751 nm
Knowing gripen demo did mach 1.25 with dry thrust (takes alot) gets me to think flying gripens with 75% trust will be enough with full load and for quite some time over an hour easy on internals.

where does this logic even come from ?

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I can't read Saab's mind(s) but if you look at some of the fighters currently in production the Gripen NG falls at the very low-end of the range. I suspect if the F414EPE were to become available Saab would be very quick to jump on it.

F-15E
Empty Weight: 31,700
Thrust: 58,000
Power/Weight: 1.83

Eurofighter
Empty Weight: 24,250
Thrust: 40,460
Power/Weight: 1.67

Rafale
Empty Weight: 21,270
Thrust: 34,000
Power/Weight: 1.60

F-16
Empty Weight: 18,900
Thrust: 28,600
Power/Weight: 1.51

F-35A
Empty Weight: 29,098
Thrust: 43,000
Power/Weight: 1.48

Super Hornet
Empty Weight: 32,081
Thrust: 44,000
Power/Weight: 1.37

Su-30MKI
Empty Weight: 40,565
Thrust: 55,120
Power/Weight: 1.36

JF-17
Empty Weight: 14,520
Thrust: 19,000
Power/Weight: 1.31

Gripen NG
Empty Weight: 17,600
Thrust: 22,000
Power/Weight: 1.25

Gripen
Empty Weight: 14,990
Thrust: 18,100
Power/Weight: 1.21


Well, as your own calculations show the TWR for Gripen E is no worse than for Gripen C (at present slightly better). I have not heard any complaints that Gripen C is considered underpowered; have you? If not, then I don't see why Gripen E should be considered underpowered either.

I agree TWR looks low for both C and E; one potential explanation could be that "empty weight" reported for Gripen includes more than what is normally included. At least that's what I read some years ago (too long ago that I can easily find it now).

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empty weight is irrelevant, re-calculate with 50% fuel and 4xaam as is custom for a good reason

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Well, as your own calculations show the TWR for Gripen E is no worse than for Gripen C (at present slightly better). I have not heard any complaints that Gripen C is considered underpowered; have you? If not, then I don't see why Gripen E should be considered underpowered either.

I agree TWR looks low for both C and E; one potential explanation could be that "empty weight" reported for Gripen includes more than what is normally included. At least that's what I read some years ago (too long ago that I can easily find it now).

Underpowered? No. It does not have the acceleration or climb of the F-16 that the Gripen was benchmarked against, nor that of the other European offerings. It makes up for this somewhat in very good transonic acceleration due to strict adherence to area rule principle.

Every aircraft's empty weight is misleading- they are all actually heavier due to: unrecoverable fuel, lubricants, minor modifications, etc. There are probably minor differences in how each maker calculates MEW, but it's not like SAAB is throwing in ammo, pilot and matched luggage into calculation.

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Underpowered? No. It does not have the acceleration or climb of the F-16 that the Gripen was benchmarked against, nor that of the other European offerings. It makes up for this somewhat in very good transonic acceleration due to strict adherence to area rule principle.

Every aircraft's empty weight is misleading- they are all actually heavier due to: unrecoverable fuel, lubricants, minor modifications, etc. There are probably minor differences in how each maker calculates MEW, but it's not like SAAB is throwing in ammo, pilot and matched luggage into calculation.

The Specification MEW includes the weight of:[1]

Airframe structure – primary and secondary structures (fuselage, wing, tail, control surfaces, nacelles, landing gear).
Powerplant.
Auxiliary power unit (APU).
Systems (instruments, navigation, hydraulics, pneumatics, fuel systems (but not fuel itself), electrical system, electronics, fixed furnishings (but not operator specific), air conditioning, anti-ice system, etc.).
Fixed equipment and services considered an integral part of the aircraft.
Fixed ballast (if present).
Closed system fluids (such as hydraulic fluids).
For small aircraft, the MEW may include unusable fuel and oil.


https://en.wikipedia.org/wiki/Manufacturer%27s_empty_weight

I think oil (and also unusable fuel?) was included in the empty weight; however I think there was something else that was probably more significant, can't remember what it was.

How much would oil and unusable fuel typically weigh?

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https://en.wikipedia.org/wiki/Manufacturer%27s_empty_weight

I think oil (and also unusable fuel?) was included in the empty weight; however I think there was something else that was probably more significant, can't remember what it was.

In combat aircraft, unusable fuel and engine oil, etc. are not included. Again, there may be some variations between manufacturers, but you can count on them: A) giving the lightest possible version of "empty" weight B) there being considerable variation in weights given, even variations in same production block

You can see the differences in manufacturers claims of empty weight and what services claim.
(Ex. F-16C Block 50: weights range from 18,200 18,900 L-M, to 19,700 USAF)- But the operating weight (what it will actually weigh before full fuel and stores) is 21,300


How much would oil and unusable fuel typically weigh?

Probably depends on fuel system and 1 vs 2 engines. 400 Kg would be a reasonable ballpark.

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In combat aircraft, unusable fuel and engine oil, etc. are not included. Again, there may be some variations between manufacturers, but you can count on them: A) giving the lightest possible version of "empty" weight B) there being considerable variation in weights given, even variations in same production block

As said previously somebody told me Saab had a different definition; obviously I have no way of checking which information is correct. In any case it seems likely Gripen E will not be a particularly "kinetic" a/c, compared to most others.

Another number given by Saab is "airframe weight"; however I don't know how useful that is:


Maximum take-off weight will be 16.5t, with the type’s empty airframe weight accounting for just 20% of this, at around 3t.

https://www.flightglobal.com/news/articles/saab-reveals-full-gripen-e-design-cost-savings-396977/

With empty weight at 8t, it means that 5t is engine, computers, sensors, etc. etc. Sounds reasonable to me?

I am curious; what is airframe weight of the F-16? Of the Western a/c, it's the closest to Gripen E in size (although somewhat bigger of course).

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I see that many people think that if you have a bigger engine you have a better plane, it simply is not that easy. If you increase engine power, you have to increase the size of the aircraft if you are to have any type of range at all with internal fuel.
The bigger and stronger the engine, the bigger air intakes and body size(fuel,air intake channel,engine etc) and weight and the worse performance at takeoff and landing and at supersonic speed you get.Because of the drag created.

Saab has chosen that new engine carefully and is cheaper to run on dry thrust then rm12 but is 7%-23% stronger technically and has some other features that makes it a good decision. It is a tad thirstier at wet. They managed to push in a stronger engine and by changing landing gear whereabouts it made it possible to increase Gripen e's fuel capacity by 40% internally without fattening the aircraft. Balance right there. All the tests done in gripen E Demo has been outright success and above expectations. They have flew the demo to India.Talk about confidence.
Saab knows exactly what they are doing and this engine is perfect for the new gripen E.

@mig-31bm i know....i don't think i wrote something else either. f-35 has 125kn dry and is very strong in this area if you compare weight but still can't supercruise.

"Gripen with 3 external fuel tank achieved combat radius of 502 nm" Facts are against you here.....Gripen E has 800nm in air to surface radius according to the manufacturers.
http://saab.com/globalassets/commercial/air/gripen-fighter-system/gripen-ng/technical-brochure-gripen-ng-english-ver.2-jan-2015_low.pdf
By the way f-35 ranges might be true, but its a subsonic slow flight.

The calculations are right as far as i know, its the standard formula how to count fuel burn. I made it to show people how you count fuel burn and that the power of the engine is whats matter to calculations/consumption.

"where does this logic even come from ?" rough estimate, knowledge of old Gripens with one droptank (built inside gripen e) and the lower fuel draw in dry with f-414g proven with gripen demo. So its most logical.

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.
The bigger and stronger the engine, the bigger air intakes and body size(fuel,air intake channel,engine etc) and weight and the worse performance at takeoff and landing and at supersonic speed you get.Because of the drag created.

F-111,.F-15, F-22, Mig-31 are much bigger than Gripen but their performance at supersonic speed are much better too
.
@mig-31bm i know....i don't think i wrote something else either. f-35 has 125kn dry and is very strong in this area if you compare weight but still can't supercruise.

F-35 can fly 150 miles at mach 1.2 on dry thrust, Gripen can supercruise at mach 1.1 with 2 aam, so they are not that much different
.
"Gripen with 3 external fuel tank achieved combat radius of 502 nm" Facts are against you here.....Gripen E has 800nm in air to surface radius according to the manufacturers.
http://saab.com/globalassets/commercial/air/gripen-fighter-system/gripen-ng/technical-brochure-gripen-ng-english-ver.2-jan-2015_low.pdf

No, different mission profile lead to different fuel flow rate, mission profile that LM use including 1 minutes dogfighting at full afterburner
by contrast, mission profile that SAAB use only include crusing, release weapons and fly back to base, no loiter or dogfight time
.By the way f-35 ranges might be true, but its a subsonic slow flight.

same for Gripen , you arenot gonna cross 800 nm distance at mach 1.1, a Gripen isnot a concorde or B-1
. The calculations are right as far as i know, its the standard formula how to count fuel burn. I made it to show people how you count fuel burn and that the power of the engine is whats matter to calculations/consumption

sorry to say it but your calculations is wrong, just look at the fuel flow in any flight manual and you see why i said so
.
"where does this logic even come from ?" rough estimate, knowledge of old Gripens with one droptank (built inside gripen e) and the lower fuel draw in dry with f-414g proven with gripen demo. So its most logical.

what????? Can you elaborate how exactly you "rough" "estimate " it?
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F-111, F-15, F-22, Mig-31 are much bigger than Gripen but their performance at supersonic speed are much better too

MiG-31, without doubt.. F-22, too.. But F-111 and F-15, how did you come to that conclusion?

F-35 can fly 150 miles at mach 1.2 on dry thrust, Gripen can supercruise at mach 1.1 with 2 aam, so they are not that much different
That alone does not matter.. It all depends on if it's sufficiently easy to perform so that it can be used regularly.. With the F-35 I strongly suspect that you need to use a lot of burner to crawl through the transonic region to M1.2 and then after switching it off the speed slowly degrades to M1.0 which takes those mentioned 150 miles. If that is true, then it's not an operationally viable capability which saves fuel or increases range, just an useless PR stunt.

How the Gripen can do its M1.1, I don't know...

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F-35 can fly 150 miles at mach 1.2 on dry thrust, Gripen can supercruise at mach 1.1 with 2 aam, so they are not that much different

I don't believe this means what it sounds like: aircraft accelerates to M1.2 then maintains M1.2 in level flight on dry thrust for 150 miles. I see no reason why it should only be capable of maintaining M1.2 for 150 miles flying level. That suggests that the range of F-35 is 150 miles @ M1.2 + distance required to reach M1.2 and that does not add up to me.