F-35A versus Saab Gripen NG

[spazsinbad]

Gripen E can take off in strips of road that are only 16m wide 500m long and can land in a 600m long road, without any tailhook or brake chute. This capability also allows the fighter to take off from small taxiways, small civil airfields or highways. A Gripen can also taxi using its own power to flightline positions for maintenance, refuelling and rearming, with the help of limited crew members. Gripen was designed for a minimal turnaround time - tasks like refuelling and rearming do not take more than 10 minutes, further increasing the operability and availability of the fighter.

Gripen was given a canard in order to be able to land on short airstrips and also to increase manoeuvrability. The canard, along with the wheel brakes, help Gripen to stop quickly after landing. “We use the canard and the wing rudders to create aerodynamic downforce to make the brakes more effective,” says Eddy de la Motte, head of the business unit for Saab Gripen E/F.

By making Gripen self-contained, the need for a large number of ground support equipment was eliminated. For example, the aircraft uses an auxiliary power unit, handles many of its start-up systems, and also performs diagnostic checks internally.

Other small functional details like the master arm switch for weapon system checks, access panels that can be opened and closed with the push of button latches, bolts that can be removed to detach the engine while disconnecting the fuel, hydraulic lines, and more, have been designed to save time on the ground and make missions last for a longer period of time.

https://www.flightglobal.com/fixed-wing ... ?adredir=1

I cannot see the text above at this URL: https://www.flightglobal.com/fixed-wing ... ?adredir=1 MY
OR: https://www.flightglobal.com/fixed-wing ... 16.article
using the same browser BUT could see the text using another browser (so much for the fightglobular B/S). To help those with the same predicament a PDF made via the other browser is attached. I'm too tired to copy fit the text but youse can read it OK.

[XanderCrews]

How it started
• It all started with Norway
• In November 2008 Norway did not select
the Gripen NG
• Dissatisfaction with the EWS of the
offered Gripen configuration
• Thorough scrutiny of the offered solution
• Operational capabilities studies SwAF,
FMV and FOI
• Industry studies
• Around 2011 operational ambitions and
a technical concept started to materialize

no no, I was assured by Gripen fans that the contest in Norway was simply "rigged"

Thank you for the PDF

By making Gripen self-contained, the need for a large number of ground support equipment was eliminated. For example, the aircraft uses an auxiliary power unit, handles many of its start-up systems, and also performs diagnostic checks internally.

Its tragic really, to forget such a basic thing.

Hats off to the pilots who fly with that ladder in their lap




here is the Harrier's self contained, high tech, smart fighter, marvel of engineering solution^ (6th generation)

[spazsinbad]

No doubt the Gripen probably has good brakes (canard only helpful at high ground speeds) however the question of snow / ice / water on an austere runway: does any of these conditions make operations not viable? I recall a Scandinavian Hornet country operating in snow using arrestor gear.... Photo: Hornet catching the wires. On the Arctic Circle 22 Jan 2012
http://theaviationist.com/2012/01/22/finnish-hornet/ & https://i1.wp.com/theaviationist.com/wp ... 314913.jpg

[loke]

no no, I was assured by Gripen fans that the contest in Norway was simply "rigged"

Thank you for the PDF

The Norwegian contest was definitely not rigged, however, they put on quite a show, since they managed to convince the Swedes they actually had a chance... Eurofighter and Boeing both left that competition because they realized the futility of competing against F-35 in F-35 partner country Norway...

Actually I recall one thing Norway did to keep Saab in the competition. I believe they covered some of the costs Saab had on the "Gripen NG" project. I don't recall the exact amount, perhaps a few million USD, it seems it was enough to convince Saab that it was worth competing in Norway.

You are welcome.

[loke]

No doubt the Gripen probably has good brakes (canard only helpful at high ground speeds) however the question of snow / ice / water on an austere runway: does any of these conditions make operations not viable? I recall a Scandinavian Hornet country operating in snow using arrestor gear.... Photo: Hornet catching the wires. On the Arctic Circle 22 Jan 2012
http://theaviationist.com/2012/01/22/finnish-hornet/ & https://i1.wp.com/theaviationist.com/wp ... 314913.jpg

I have forgotten most of my physics lessons at school, but I am believe a fighter having a small mass will have an easier time to stop than a larger, heavier fighter. Also, the landing speed of Gripen can be quite low.

So perhaps a combo of: low mass, canards that can be twisted to break, low landing speed, and good brakes. It all adds up.

[spazsinbad]

Any 'air brake' is only as good as airspeed. Effectiveness becomes minimal at low airspeed (in this case also ground speed). All modern military jets should have good brakes (in the past some did not - I'm told the SLUF did not have good brakes). Yes low landing airspeed at light weight will help but just generalising does not answer the question. Who knows if Gripen ops continue in the photo shown at the FightGlobules URL earlier: https://d3lcr32v2pp4l1.cloudfront.net/P ... x653fitpad[0]/6/3/9/71639_saabgripenbeinginspectedbymobilemaintenancecrewonsnowyflightlinecroyalswedishairforce_961688.jpg
Sadly the URL for JPG becomes BROKEN (kell surprise) so TINYurl: https://tinyurl.com/1a28tx1d

[sprstdlyscottsmn]

Even with perfect brakes the deceleration is limited by the friction coefficient if the tires and the landing surface. Weight is irrelevant to the braking physics assuming "perfect" brakes. A 20% heavier plane with the same friction coefficient will have a 20% higher normal force which will provide a 20% higher deceleration force, meaning the deceleration rate is constant.

Where light weight becomes a factor is landing speed and total energy needing to be dissipated (brakes overheating). But if we are talking icy roads then the rolling friction is going to be the limiting factor.

[spazsinbad]

Thanks. I did not want to be so specific because somewhere elsewhere in this F-35 sub forum is a discussion about these factors. I guess I should find it. From what I've read there is a lot of variation in measuring/reporting runway conditions.

[XanderCrews]

Even with perfect brakes the deceleration is limited by the friction coefficient if the tires and the landing surface. Weight is irrelevant to the braking physics assuming "perfect" brakes. A 20% heavier plane with the same friction coefficient will have a 20% higher normal force which will provide a 20% higher deceleration force, meaning the deceleration rate is constant.

Where light weight becomes a factor is landing speed and total energy needing to be dissipated (brakes overheating). But if we are talking icy roads then the rolling friction is going to be the limiting factor.

And this has been one of my big questions with Gripen E

Weighting 1200 kilos more empty, and with 30-40 percent more fuel than the legacy, I'm failing to see why its going to have identical landing and takeoff distances.

Maybe of little difference, or "close enough" but I think it goes without saying the Gripen E will not have as good shortfield performance (again how much that matters even within Sweden, and even less for nations that don't even try road operations is a matter of speculation that's likely irrelevant)

[spazsinbad]

Just as a side note (because I'm attempting to make a PDF for my records without going to a lot of trouble copy fitting - heh) before using the URL: https://www.flightglobal.com/fixed-wing ... 16.article I was 'logged in' as a NON subscriber. Using other browsers (NOT LOGGED IN) I could see the article but when printed to PDF all the text was seen as single line graphics (a nightmare for copy fitting). So in original 'logged in useless browser which makes good PDFs I LOGGED OUT. Now I can see the article to make a much easier copy to fit PDF!

Now that I'm rereading the article in question I see this to explain 'the effect of Gripen canards during landing':

"Saab decided to forgo the thrust reverser on the Gripen, instead using the canard and wheel brakes to stop quickly. “We use the canard and the wing rudders to create aerodynamic downforce to make the brakes more effective,” says de la Motte. “It’s like what you do on Formula 1 or NASCAR.”

Again airspeed is required for these 'effects' which decrease as aircraft slows. Probably all miljets at some point push the stick forward to increase weight on wheels for landing braking effectiveness. The A4G Skyhawk had WING SPOILERs for it.

This is quote is weird: (perhaps a misquote or misunderstanding by reporter)?

"Weapon system checks are also streamlined. “We don’t have to go to specific positions close to the runway and take out the safety pins,” says de la Motte. “We have a master arm switch instead.”

Again the A4G had a MASTER ARM switch (which was only placed to ON BEFORE commencing armament run) which was OFF most of ALL THE TIME especially with armament loaded with safety pins. These ONLY removed at holding point before taxi onto the runway itself with minimal time with rockets for example pointing in a bad direction ARMED. Recall the fire onboard incident with rockets being armed before taxiing to the catapult - TO SAVE TIME - yep and almost lost the ship.

FOUR Page COPY FITTED PDF article as noted above now attached.

[XanderCrews]

This is quote is weird: (perhaps a misquote or misunderstanding by reporter)?

"Weapon system checks are also streamlined. “We don’t have to go to specific positions close to the runway and take out the safety pins,” says de la Motte. “We have a master arm switch instead.”

Again the A4G had a MASTER ARM switch (which was only placed to ON BEFORE commencing armament run) which was OFF most of ALL THE TIME especially with armament loaded with safety pins. These ONLY removed at holding point before taxi onto the runway itself with minimal time with rockets for example pointing in a bad direction ARMED. Recall the fire onboard incident with rockets being armed before taxiing to the catapult - TO SAVE TIME - yep and almost lost the ship.

wasn't an "ordie" and I think something is lost in translation or communication... I guess theres nothing that says you can't remove the physical safeties from all ordnance before you even put it on the aircraft I guess, its just... not always recommended. or pulling them right after everything is loaded to satisfacation on the pylon, most aircraft do indeed have a master arm, I just don't think I've ever seen one that jettisons all the pins with "remove before flight" on them at the push of a button.



Ordie with a handful of the removed pins, not the airplane is on the cat, blast ramp up and the weaponry is the real deal (yellow and brown stripes on 'winder) Pins removed at nearly the last possible moment. supervisor on foreground looking to see if anything was missed.



Ordies work hard

[spazsinbad]

OVER on the OTHER Gripen THREAD <sigh> is the frisky corporeal article with this photo of SNOWY but HOOKY W/X.

viewtopic.php?f=58&t=25426&p=450266&hilit=complaints#p450266

"An EA-18G Growler from VAQ-132 during heavy snows at Naval Air Facility Misawa, Japan, showing that the aircraft doesn’t stop just because everything turned white. Source: U.S. Navy photo by Mass Communication Specialist 1st Class Kenneth G. Takada via Wikimedia Commons" https://corporalfrisk.files.wordpress.c ... 035559.jpg (1.2Mb)

[magitsu]

Landing to road bases is not as much length limited as is the common wisdom in this kind of discussions.

HX project leader in the FiAF's side, brigadier Juha-Pekka Keränen (more featured maj gen [ret.] Lauri Puranen is on the MoD's side) explains.

The Air Force is also investigating whether the US fighters will be able to land at Finnish road bases. Admittedly, no landings are made. According to Keränen, what matters is not the length of the road strip but how steadily the plane lands on it.

- We will find out by other means how stable the fighter is and how it can brake.

https://yle.fi/uutiset/3-11198548

It's been suggested that the F-16 might have had some problems with landing stability in the previous DX competition, which the classic Hornet ended up winning. We may note that at least Norway decided to used a brake chute with it, which is seemingly also becoming standard with the F-16 EPAF countries' F-35s. Finland didn't use a chute with Hornets. Their hook has been used more than an AF jet's hook would be, likely just because they could. It's been used to e.g. qualify one Lithuanian air field's arrest system in recent years. But air force fighter's higher placed hook would've served well enough in case of an emergency, which is why the arrest cables are really at the road bases.

There's also another quote about the road bases being very accommodating instead of being something that separates the wheat from the chaff.

Colonel Heikkinen also shot down the idea that some of the contenders would struggle with landing or taking off from road bases. “We’ve flown Draken from them”, he said, alluding to the Saab-built interceptor that the Hornet replaced in Finnish service.

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

[loke]

Even with perfect brakes the deceleration is limited by the friction coefficient if the tires and the landing surface. Weight is irrelevant to the braking physics assuming "perfect" brakes. A 20% heavier plane with the same friction coefficient will have a 20% higher normal force which will provide a 20% higher deceleration force, meaning the deceleration rate is constant.

Where light weight becomes a factor is landing speed and total energy needing to be dissipated (brakes overheating). But if we are talking icy roads then the rolling friction is going to be the limiting factor.

And this has been one of my big questions with Gripen E

Weighting 1200 kilos more empty, and with 30-40 percent more fuel than the legacy, I'm failing to see why its going to have identical landing and takeoff distances.

Maybe of little difference, or "close enough" but I think it goes without saying the Gripen E will not have as good shortfield performance (again how much that matters even within Sweden, and even less for nations that don't even try road operations is a matter of speculation that's likely irrelevant)

My understanding of what the Sprdsly Scotsman said was that weight probably does not make a big difference on breaking distance since a higher weight would make the friction bigger and therefore braking more efficient, compensating for the higher weight. Assuming that you avoid the brakes overheating.

But that highlights another factor of the canards: In addition to slowing down due the the "air brake" effect, the canards also push down the wheels, creating more friction and more efficient braking. This effect will abate when the speed is lower, but at lower speeds you can stop more easily, so problem is already solved.

[kimjongnumbaun]

There's a few things about landing on roads. One, the road needs to be able to handle the weight of the aircraft. There's a reason why in airfield charts there's a weight limit. Ever had one of your pilots land on an airfield not rated for the weight of the aircraft and tear it up? Try explaining that to the higher ups when the civvies want their airfield repaired.

And brakes are cool to use until they catch on fire.