Finnish DefMin interested in F-35s, not Gripens

[lukfi]

You seem to be minimising the dry thrust. Australia did an intensive review, because of noise pollution requirements with AB. Perhaps you can tell us of the fighter aircraft that has better numbers.

Huh? Fighter aircraft in general are quite overpowered compared to civilian planes, and even the supposedly underpowered Gripen can take off from a 500m strip (with AB). I don't have videos to prove it, but with a light load (as in the F-35 video) and a long enough runway (the runway at Pirkkala is 2700 m) to reach the required speed, why shouldn't it be possible to take off on mil thrust only? Especially with fighters designed for carrier operations like the Hornet or Rafale, which need to be able to fly at low speeds because of carrier landings.

[sprstdlyscottsmn]

but with a light load (as in the F-35 video)

A configuration that can be used to carry two tons of precision A-G munitions well over 600nm? It's not about having the total length of the runway to take off, it's about having enough runway in front of you to abort the takeoff too. That is why take-off mil power can be a make or break for noise issues.

[spazsinbad]

I'm not following what this 'take-off' is all about. IIRC the runway at RAAF Williamtown was lengthened to 10,000 feet so that 'newbies' in F-35As could take off in military power (not afterburner) with a full load (whatever that is) SAFELY - as is suggested so that there is sufficient runway to abort the takeoff but also reduce noise. Few takeoffs will be with A/B at Willytown except I guess to demonstrate to the newbies what they have by way of OOMPH. Elsewhere on shorter 'expeditionary' runways they will take off with whatever load at whatever engine power is appropriate according to flight manuals / computers and such RAAF F-35A SOPs (Standard Operating Procedures).

For the 'players' (aerobatisists demoistas)

2019 USAF F-35A MANEUVERS PACKAGE "Minimum runway length and width is 7,000 feet x 75 feet." https://www.faa.gov/about/initiatives/a ... ackage.pdf

HOUSE OF REPRESENTATIVES - JOINT STANDING COMMITTEE ON FOREIGN AFFAIRS, DEFENCE
AND TRADE - Department of Defence annual report 2012-13
06 Jun 2014 (proof) HANSARD

..."Dr JENSEN: I would like to ask about Williamtown: why is the runway being lengthened? And how long will it be?
Air Marshal Browne: It will be—it is 1,000 foot at each end; I might just check with the project officer.
Air Cdre Roberts: It will be a 10,000-foot runway.
Air Vice Marshal Deeble: It will be a 10,000-foot runway, lengthened by about 1,100 foot to Medowie Road and 900 foot at the other end of the runway.

Dr JENSEN: And why is that?
Air Marshal Browne: Well, a couple of reasons. It is to do with the performance of the F-35 versus the F-18. And the other one is noise—it will allow us to take off without using the afterburner in the F-35 and, again, when you look at the noise footprint around Williamtown, we have done a lot of work to make sure that we can keep the ANEFs within certain boundaries.

Dr JENSEN: One of the things you mention is the performance of the F-35s, I guess, getting off the ground. How many other 10,000-foot runways do we have in Australia that would be available?
Air Marshal Browne: We are actually lengthening Tindal. It can operate off 8,000 feet. For me, one of the critical things with Williamtown is that it will be our main training base. We had many discussions with the project office about not lengthening the runway, but there were two factors: one of the main ones was just noise around Williamtown. At other airbases, where noise is not the same factor, smaller runways — and the ones that we've got at the moment — would be adequate enough...."

Source: http://parlinfo.aph.gov.au/parlInfo/dow ... dc/0000%22 [this PDF is attached in this forum somewhere....]

Facilities Requirements for the New Air Combat Capability RAAF Base Williamtown, NSW
June 2014 Aust. DoD

-“...Runway Requirements. Sufficient runway length is required to ensure the safety of pilots operating the F-35A. The key safety consideration is the reaction time which a pilot has available to abort a take-off and safely stop the aircraft within the runway length. Considerations used to calculate the safety margin include runway length, whether afterburners are used to accelerate the aircraft to take-off speed faster, and the weather. The F-35A requires a minimum runway length of 8,000 feet to safely operate. At RAAF Base Williamtown, because there is no two-seat version of the F-35A to allow trainee pilots to practice under direction supervision, a runway length of 10,000 feet is required to provide trainee pilots with an additional safety margin compared to that afforded to experienced pilots. Further, a 10,000 foot runway is required at RAAF Base Williamtown to support Air Force’s strategy for noise mitigation...."

Source: http://www.aph.gov.au/DocumentStore.ash ... bId=254100 (PDF 11.2Mb)

LUKE DAYS - FLYING THE F-35
Nov-Dec 2018 Andrew McLaughlin

"...The first time I noticed something different was on the takeoff roll. We did a mil power (non-afterburner) take off, and this was the first time I had felt the acceleration - the F-35A has more ‘go’ than the classic [Hornet RAAF], that’s for sure. We took off in mil power with 18,000 pounds of fuel, whereas the classic would have a maximum of 16,500 pounds with three external tanks and need to do a full AB (afterburner) takeoff...."

Source: ADBR Nov-Dec 2018 Volume 37 No.6 [pdf probably attached somewhere on this forum]

[optimist]

You seem to be minimising the dry thrust. Australia did an intensive review, because of noise pollution requirements with AB. Perhaps you can tell us of the fighter aircraft that has better numbers.

Huh? Fighter aircraft in general are quite overpowered compared to civilian planes, and even the supposedly underpowered Gripen can take off from a 500m strip (with AB). I don't have videos to prove it, but with a light load (as in the F-35 video) and a long enough runway (the runway at Pirkkala is 2700 m) to reach the required speed, why shouldn't it be possible to take off on mil thrust only? Especially with fighters designed for carrier operations like the Hornet or Rafale, which need to be able to fly at low speeds because of carrier landings.

What I was referring to was the portion of pounds of dry thrust/military power to the total AB thrust. I think if you go to wikipedia and look at other engines. The gripen's, russian's and f-35 for example, would show you that the f-35's engine is quite good. You may find the f135 has a high dry thrust/military power to AB ratio in comparison. The measure of an engine isn't always sea level, uninstalled thrust in after burner. Just dumping more fuel into the afterburner, to make the total number sound nice on a SU-30 spec sheet.
I'd do it and put it up, but it might be better understood if you do it. It will give more time for you to consider. Can you do those numbers and post your results?

[lukfi]

Afterburning thrust / dry thrust ratio
Volvo RM12 (Gripen C): 80.5 / 54 kN = 1.49
F414-GE-39E (Gripen E): 98 / 64 kN = 1.53
P&W F135 (F-35A): 191 / 128 kN = 1.49
So what exactly is the fuss about?

[lbk000]

It is a big fuss because while airframes and their engines may scale up and down in step, the weight of individual payload items don't. To use an extreme example, the same 300+lb AIM-120 constitutes a negligible mass for an F-15 yet would be obviously debilitating when carried on say, an Extra 300. Furthermore, payload is not just ordinance; the necessary electronics essential today constitute flat weights that represent proportionally greater sacrifices for smaller aircraft with smaller engines. The smaller the airframe design, the smaller the engine, the less headroom it has for upgrades. Never forget that everything you do comes with a cost; you can't simply say "well, why can't you pair a big engine into a tiny airframe to open up more payload?" because the large engine is going to need more gas, and all of that is going to add more weight, which means for the same performance you'll need more wing, which means you're going up in size, which means you're going up in weight, which means you need stronger structure, which means more weight, which means you need more thrust, more gas... all of a sudden you find yourself with an aircraft that is not "simply a small aircraft with a bigger engine".
To sum up though, in combat aircraft design, range, payload, and performance favors size -- why the top end performers are large (F-22, F-15, F-14, Su-27). Of course, there are many factors that do not favor size, such as material strength, spot factor, basing, cost, among others, but that is how you arrive at the different size factors. Aircraft size is not arbitrary at all, they are very closely tied to requirements for not just performance goals, but cost and service length goals and so conversely, they do not bend well when those requirements change. The problem with the Gripen is that it's trying to do exactly the latter; it's a design optimized for Sweden's localized defensive paradigm yet they're trying to shoehorn it to fit America's offensive expeditionary requirements, in competition with an aircraft that is natively designed around said requirements. The only card that isn't stacked against Saab is the sensitive LO technology card.

Anyways, an F-35 "comfortably loaded" carries more warload than a Gripen that is likewise "comfortably loaded" regardless if you're taking off AB or mil, because bigger is simply better.

[madrat]

The 'fuss' comment above was directed at the mistaken notion an F135 has a higher 'portion of pounds of dry thrust/military power to the total AB thrust'.

[optimist]

Afterburning thrust / dry thrust ratio
Volvo RM12 (Gripen C): 80.5 / 54 kN = 1.49
F414-GE-39E (Gripen E): 98 / 64 kN = 1.53
P&W F135 (F-35A): 191 / 128 kN = 1.49
So what exactly is the fuss about?

It is one measure and a place to start. I hadn't done it with Gripen. Next would be with enough fuel for a 2 hour flight, as a fuel measure. Then a representative weapon load. The numbers on the F-35 are impressive, from what I remember of the Aussie military power takeoff review Our Super Hornet F414-GE-400 would be 1.69
The example of Su-30 as one, would be 1.64
The E does't carry the same percent in military power, as the RM12

[eagle3000]

Afterburning thrust / dry thrust ratio
Volvo RM12 (Gripen C): 80.5 / 54 kN = 1.49
F414-GE-39E (Gripen E): 98 / 64 kN = 1.53
P&W F135 (F-35A): 191 / 128 kN = 1.49
So what exactly is the fuss about?

Most sources give 13k lbf dry and 22k lbf wet thrust for the F414.
28k / 43k lbf for the F135.

Using those numbers, F414 makes 59% of its total thrust without afterburners, F135 65%.
That's a noticeable difference. However, neither do we know if these figures are accurate, nor do they say anything about dynamic thrust or installed thrust.

[marsavian]

Full F-35 HX presentation

(Little Finnish at the beginning, afterwards English)

https://youtu.be/xgDZNXHs6KY

[marsavian]

[playloud]

Afterburning thrust / dry thrust ratio
Volvo RM12 (Gripen C): 80.5 / 54 kN = 1.49
F414-GE-39E (Gripen E): 98 / 64 kN = 1.53
P&W F135 (F-35A): 191 / 128 kN = 1.49
So what exactly is the fuss about?

Most sources give 13k lbf dry and 22k lbf wet thrust for the F414.
28k / 43k lbf for the F135.

Using those numbers, F414 makes 59% of its total thrust without afterburners, F135 65%.
That's a noticeable difference. However, neither do we know if these figures are accurate, nor do they say anything about dynamic thrust or installed thrust.

There are a couple sources that give 14.4k (64 kN) dry and 22k (98 kN) wet for the Gripen E. The most definitive was from an FMV presentation.

I don't know how this could be true considering it is using an F414. How would they substantially increase the dry thrust, without also increasing the wet thrust?

I'm not an engine guy, so maybe somebody here can explain it?

[magitsu]

Blog about how Boeing approaches the HX competition.

Most importantly, interesting description of NGJ.

https://corporalfrisk.com/2020/02/21/hx ... -stronger/

[fbw]

Afterburning thrust / dry thrust ratio
Volvo RM12 (Gripen C): 80.5 / 54 kN = 1.49
F414-GE-39E (Gripen E): 98 / 64 kN = 1.53
P&W F135 (F-35A): 191 / 128 kN = 1.49
So what exactly is the fuss about?

Most sources give 13k lbf dry and 22k lbf wet thrust for the F414.
28k / 43k lbf for the F135.

Using those numbers, F414 makes 59% of its total thrust without afterburners, F135 65%.
That's a noticeable difference. However, neither do we know if these figures are accurate, nor do they say anything about dynamic thrust or installed thrust.

There are a couple sources that give 14.4k (64 kN) dry and 22k (98 kN) wet for the Gripen E. The most definitive was from an FMV presentation.

Gripen E stats.jpg

I don't know how this could be true considering it is using an F414. How would they substantially increase the dry thrust, without also increasing the wet thrust?

I'm not an engine guy, so maybe somebody here can explain it?

They haven’t, the 13,000lbs of intermediate thrust listed in Wikipedia and elsewhere is wrong.The F414 has roughly 14,300lbs of intermediate thrust. No difference between the F-18E/F and the Gripen E in the F414 thrust, as far as what’s been reported, the only difference is that the F414-GE-400 engines are designed for twin engine installation, possibly some minor changes for adoption in single engine fighter.

Edit- That is What P&W reported the F414 produces static, uninstalled (or General Electric, duh. Proof-reading always a good idea)

[ricnunes]

They haven’t, the 13,000lbs of intermediate thrust listed in Wikipedia and elsewhere is wrong.The F414 has roughly 14,300lbs of intermediate thrust. No difference between the F-18E/F and the Gripen E in the F414 thrust, as far as what’s been reported, the only difference is that the F414-GE-400 engines are designed for twin engine installation, possibly some minor changes for adoption in single engine fighter.

Edit- That is What P&W reported the F414 produces static, uninstalled (or General Electric, duh. Proof-reading always a good idea)

Ok, I found the following Super Hornet NATOPS Manual lingering around the Hard Drive of my PC which I'll share it on the link below:
https://drive.google.com/open?id=1c6P5x ... F8Ob0Q4uad

In Page 1 of Chapter 2 (I-2-1) one can read the following:

The uninstalled military thrust (MIL) of each F414-GE-400 engine is approximately 13,900 pounds

So the Dry Thrust of the F414 is slightly less than 13,900 lbs.

Can we now "put to rest" the 14,300lbs dry thrust value for the F414, once and for all?