F-35A versus Saab Gripen NG

The F-35 compared with other modern jets.
  • Author
  • Message
Offline

loke

Elite 1K

Elite 1K

  • Posts: 1097
  • Joined: 14 Nov 2008, 19:07

Unread post22 Feb 2021, 21:26

XanderCrews wrote:
sprstdlyscottsmn wrote: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.
Offline

kimjongnumbaun

Senior member

Senior member

  • Posts: 405
  • Joined: 08 Dec 2016, 21:41

Unread post22 Feb 2021, 22:12

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.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post22 Feb 2021, 23:10

The canard 'air BRAKE' (it is not spelt BREAK) is not effective at low speed period. WING SPOILERS dump wing lift (which the A-4 had in spades at low airspeed) to put the weight on the wheels for good braking and for sure OVER HEAT the BRAKES & trouble including fire ensues. Are Gripen wheel brakes MAXARET (unlockable)? That is a big help for max. brake.

https://en.wikipedia.org/wiki/Maxaret Our Sea Venoms had these brakes which were just marvellous for braking short.
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post23 Feb 2021, 05:07

There are a few old 'news' items of the gripping variety probably still to come but this is getting close to last I hope....
GRIPEN STRIDES AHEAD FIRST SERIES PRODUCTION JAS 39E
Feb 2020 CA

"SAAB HAS FLOWN the first series production JAS 39 Gripen E (serial 39-6002), painted in a striking splinter scheme. The flight on November 30 saw Henrik Wänseth from the Swedish Defence Materiel Administration (Försvarets materielverk, FMV) in the cockpit for the 76-minute mission. It is the first Gripen E to feature the new wide-area display (WAD) and larger head-up display and it is joining the test program for acceptance and operational development flights.

This is the fifth Gripen E, following 39-8 (first  own on June 15, 2017), 39-9, 39-10, and the first Brazilian aircraft (4100), which flew on August 26, 2019. Sweden is due to receive 60 Gripen Es and Brazil has ordered an initial batch of 28 Gripen Es and eight twin-seat Gripen Fs."

Source: Combat Aircraft Journal February 2020 Volume 21 No 2
Attachments
Gripen 1st Series Prod Flies Combat Aircraft Feb 2020.pdf
(82.08 KiB) Downloaded 17 times
Gripen 1st Series Prod Flies Combat Aircraft Feb 2020.jpg
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline

loke

Elite 1K

Elite 1K

  • Posts: 1097
  • Joined: 14 Nov 2008, 19:07

Unread post23 Feb 2021, 08:46

spazsinbad wrote:The canard 'air BRAKE' (it is not spelt BREAK) is not effective at low speed period. WING SPOILERS dump wing lift (which the A-4 had in spades at low airspeed) to put the weight on the wheels for good braking and for sure OVER HEAT the BRAKES & trouble including fire ensues. Are Gripen wheel brakes MAXARET (unlockable)? That is a big help for max. brake.

https://en.wikipedia.org/wiki/Maxaret Our Sea Venoms had these brakes which were just marvellous for braking short.

Gripen E brake system:

As recently as Thursday 15 June 2017, SAAB's Gripen E made its maiden flight, equipped with Meggitt wheels and braking systems, making it an unprecedented 8 maiden flights which have taken to the skies with Meggitt wheels or braking systems onboard since the beginning of 2016.

This comes hot on the heels of Irkut's MC-21-300 commercial aircraft completing its maiden flight, also with Meggitt wheels and brakes, on May 28th 2017.

Thanks to a patented heat shield design which increases the speed of natural convection cooling, removing the need for fans, the MC-21 system weighs in at 13% less than equivalent in-service aircraft. At the same time, proprietary carbon anti-oxidant paint protects the brakes, allowing operation at elevated temperatures without losing life through oxidation. Overall, tyre pressure and brake temperature monitoring systems on the MC-21 enable a turnaround time of 25 minutes between flights, almost half that of many airlines today.

Chosen by aerospace leaders

Other maiden flights with Meggitt braking systems included: Gulfstream's G600; Bombardier's Global 7000; Textron's Scorpion jet; Turboprop ATR 72; Boeing's entrant in the USAF next generation trainer competition and Piaggio's military platform, the Maritime Patrol Aircraft.

In addition to providing the complete braking system for G600 and Global 7000, these aircraft are also equipped with brake temperature and tyre pressure monitoring as well as automatic braking.

Meggitt's Aircraft Braking Systems' (MABS) President Luke Durudogan commented:

"Supporting this number of maiden flights is remarkable; in my experience it's unprecedented for one company to accomplish quite so many within eighteen months. It's a testament to the team's innovation and dedication. We're now focussed on how to build on this success in the years to come."

A braking pioneer

Meggitt's pedigree in this field dates back to the 1920s, when both Goodyear and Dunlop Aerospace, later acquired by the Group, developed the first differential aircraft braking system and continued to lead the field post-war, supplying the first carbon brakes in the 1970s for the VC10 and Concorde.

https://www.airframer.com/news_story.html?release=38415
Offline

loke

Elite 1K

Elite 1K

  • Posts: 1097
  • Joined: 14 Nov 2008, 19:07

Unread post23 Feb 2021, 08:47

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

If they are cool they don't catch fire :P
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post23 Feb 2021, 08:53

The F-35 has a computer controlled braking system but the details escape me at moment.
Carbenix Military Brakes

"Honeywell’s Carbenix military brakes serves vital function in supporting domestic and international defense systems – supporting critical missions while operating in increasingly challenging environments. Military aerospace braking systems operate in extremely severe environments, support ever-increasing aircraft weight and stopping requirements, while ensuring quick turnaround time during combat situations.

Using Honeywell's Carbenix friction materials, our range of carbon brakes provide high reliability, improved weight savings and lower costs. Honeywell is continually investing in advanced friction and anti-oxidant materials, as well as new data-enabled services, to improve performance and lower the total cost of ownership.

Honeywell’s Carbenix brakes are used across a wide range of military customers on the following aircraft platforms:

• Boeing F-15
• Boeing F-18
• Boeing KC-46A
• Lockheed Martin F-22
Lockheed Martin F-35
• Northrop Grumman B-2

Photo: https://s7d2.scene7.com/is/image/honeyw ... ly_450x450

PDF 1.4Mb Brochure: https://aerospace.honeywell.com/content ... nload=true

Source: https://aerospace.honeywell.com/en/lear ... ary-brakes
Attachments
F-35carbenixBrakes.jpg
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post23 Feb 2021, 11:11

Canada in one of the countries concerned about runways in different conditions. I'll have to find the original quote on the Canadian thread however here is the quote in the SRVL thread:
""...Q3.16 Does the F-35A Conventional Takeoff and Landing (CTOL) variant need more runway to land than other comparable fighter aircraft?
A3.16 No. Upon landing the F-35 uses an efficient braking system, which includes computer directed flight controls and an advanced anti-skid wheel brake system. The aircraft is capable of unaided stopping distances equivalent to those of Canada’s current CF-18...." viewtopic.php?f=22&t=20304&p=240231&hilit=brake#p240231

Double the links for twice the benefit: viewtopic.php?f=58&t=24027&p=306990&hilit=comparable+skid#p306990 & viewtopic.php?f=58&t=24027&p=349917&hilit=comparable+skid#p349917

ORIGINAL source: http://www.forces.gc.ca/site/pri/2/pro/ ... ng.asp#f35 [sadly URL no work no longer]
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline
User avatar

XanderCrews

Elite 5K

Elite 5K

  • Posts: 6773
  • Joined: 16 Oct 2012, 19:42

Unread post24 Feb 2021, 03:15

loke wrote: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.



Norway invested 15 million Euros into the Gripen NG "concept" as an alternative to the Joint Strike Fighter in April of 2007 according to an announcement by Saab
Choose Crews
Offline

hornetfinn

Elite 3K

Elite 3K

  • Posts: 3381
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post24 Feb 2021, 13:13

kimjongnumbaun wrote: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.


True, the roads need to be built accordingly. They need to be long, wide, straight and strong enough (both underground and surface) and to allow effective air operations. Of course they also need to have provisions to accommodate fighters and necessary support and maintenance equipment and personnel. Finland has extensive network of road bases and there is actually a construction guidelines manual online in Finnish for them.

Pretty good (although not complete)resource for Cold War airfields and highway strips in various countries:
https://www.mil-airfields.de/airfields.html

European countries definitely had a lot of highway strips prepared to be used as road bases during Cold War. Of course many of those still exist and could be used if needed.

I doubt there is significant differences in abilities to use roadbases between modern fighter aircraft. Gripen has the advantage of being smallest, which makes it bit easier to maneuver in smaller roadbases. But on the other hand, you likely need more Gripens for similar effectiveness due to lower payload/range for example. Hornets and Rafale have been designed for carrier operations in mind which translates pretty well for roadbase operations (I know only Rafale M is actually carrier capable). Eurofighter has a lot of power and has short takeoff distance even with heavy loads. Rafale is not far behind and F-35 has similar power levels but also doesn't need to carry external EFTs and targeting pod. F-35A with landing chute definitely has short landing distance even in most extreme winter/icy conditions. I doubt stealth coating is any kind of issue for dispersed operations as it's obviously very durable.
Offline

hornetfinn

Elite 3K

Elite 3K

  • Posts: 3381
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post25 Feb 2021, 07:24

Finnish Air Force is currently training taking off from a road near Rovaniemi air field/base:
https://twitter.com/hashtag/Talvinorva2 ... htag_click

Image

Just doing some snow plowing before taking off...
https://twitter.com/i/status/1364456271991111680

Some basic info:
https://airrecognition.com/index.php/ne ... rcise.html

You can check what kind of road it is using Google Maps:
https://goo.gl/maps/CpqwzU9C3k7o1Fo3A

That road can be used for taking off, not landing except possibly in a dire emergency.
Offline

hornetfinn

Elite 3K

Elite 3K

  • Posts: 3381
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post25 Feb 2021, 07:55

I think F-35A with landing chute would be very good for road bases also in winter conditions. F-35C would naturally be good (at least equal to Hornets which have worked extremely well in Finland) with arresting gear and stronger landing gear and big wing. Not to mention F-35B, but those are likely too expensive for most operators. I don't doubt that JAS Gripen works well from road bases and in winter conditions. But same is true for all the competitors as well.

Norwegian experience from couple of years ago with F-35A in winter conditions:
https://nettsteder.regjeringen.no/kampf ... interfore/

Google translated, because my Norwegian is little rusty... :D

Larger margins and extra flexibility

The brake screen gives us larger margins: It makes it possible to handle larger variations from the optimum. We will especially cope with the combination of high weight and slippery runway better. In addition, it gives us extra flexibility by allowing for the use of runways where brake cables are not installed.

I had the pleasure of trying myself in proper Norwegian conditions both last Friday and on Monday. On Monday, I learned for the first time that the F-35 coped well with icing conditions. It was also positive to discover how easy it was to stop the machine on the runway that was covered by "slush". Some may agree to call this "winter-ready." At least it was more wintery than in Arizona.
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post25 Feb 2021, 09:34

Longer Earlier Dec 2017 Translation of same material posted by 'lamoey': F-35 is used on Norwegian winter conditions Article by Morten "Dolby" Hanche viewtopic.php?f=60&t=16480&p=382842&hilit=slush#p382842
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
Offline

hornetfinn

Elite 3K

Elite 3K

  • Posts: 3381
  • Joined: 13 Mar 2013, 08:31
  • Location: Finland

Unread post25 Feb 2021, 10:03

Thank you, could not find that for some reason when I searched...
Offline
User avatar

spazsinbad

Elite 5K

Elite 5K

  • Posts: 25431
  • Joined: 05 May 2009, 21:31
  • Location: ɐıןɐɹʇsn∀¯\_(ツ)_/¯
  • Warnings: -2

Unread post25 Feb 2021, 10:27

:twisted: :devil: I searched on SLUSH and found I had to use a BRAKE SCREEN - the EMERGENCY HOOK was TOO FLOPPY. :doh: :mrgreen:
A4G Skyhawk: www.faaaa.asn.au/spazsinbad-a4g/ & www.youtube.com/channel/UCwqC_s6gcCVvG7NOge3qfAQ/videos?view_as=subscriber
PreviousNext

Return to F-35 versus XYZ

Who is online

Users browsing this forum: No registered users and 8 guests