US Air Force Crazy Process to Start $2 Billion Stealth Plane

แชร์
ฝัง
  • เผยแพร่เมื่อ 22 ก.ย. 2024
  • Welcome back to the Fluctus Channel for the story behind the insane design and complex processes around the world’s most expensive stealth bomber ever made.
    Fluctus is a website and TH-cam channel dedicated to sea geeks. Whenever you are curious or an incorrigible lover of this mysterious world, our videos are made for you !
    We publish 3 videos a week on our TH-cam channel and many more articles on our website.
    Feel free to subscribe to not miss any of our updates and visit our website to discover additional content.
    Don’t forget to follow us on twitter:
    / fluctusofficial
    Please keep the comments section respectful. Any spam, insults or troll will be deleted.
    To contact us, make sure to use our email in the about section of this channel.

ความคิดเห็น • 292

  • @wolfmobile3693
    @wolfmobile3693 ปีที่แล้ว +185

    So, what was the crazy process to start the 2 billion dollar stealth plane?

    • @davidguerra9994
      @davidguerra9994 ปีที่แล้ว +14

      Still waiting to see what that's about too,

    • @cfusername
      @cfusername ปีที่แล้ว +21

      Probably pushing a button.

    • @williamgibb5557
      @williamgibb5557 ปีที่แล้ว +10

      Recoil just like your gas mower! Choke and pull hard! Check oil and for gas first though.

    • @jiggyv6139
      @jiggyv6139 ปีที่แล้ว +1

      @@cfusername id probably think more than one button lol

    • @JenniferA886
      @JenniferA886 ปีที่แล้ว +20

      Good point… please TH-camrs, just be honest

  • @08hahahah
    @08hahahah ปีที่แล้ว +64

    Im so glad they talked about the "crazy process" of starting a $2Billion Stealth plane... absolutely mind boggling

    • @randysmitchell4810
      @randysmitchell4810 ปีที่แล้ว

      f u n n y

    • @matthammer3488
      @matthammer3488 ปีที่แล้ว +11

      I was thinking the same thing. thumbs down

    • @mikecimerian6913
      @mikecimerian6913 ปีที่แล้ว +1

      Don't get me wrong, this is an awesome airplane but one can get a s*itload of 10,000$ drones for two billion. Yet bombers are still needed as they can be recalled. For me the craziness is in the cost.

    • @5455jm
      @5455jm ปีที่แล้ว +2

      I came here to write the exact same thing.

    • @blimeycrikey
      @blimeycrikey ปีที่แล้ว +2

      More of an advert

  • @johnhanson9245
    @johnhanson9245 ปีที่แล้ว +3

    This is the crazy process of not explaining the cray process of starting a B-2. Thanks for 10 mins of my life I can't get back. Im going to workout to gain 5 mins back now.

  • @maximusaviationchannel
    @maximusaviationchannel ปีที่แล้ว +9

    Wow I never knew you had to change the worn out tires to start the B-2 Bomber.

  • @Algo_RL
    @Algo_RL ปีที่แล้ว +7

    8:59 "the absence of a tail reduces the aircraft's radar signature, while enhancing stability and control."
    Tailless aircraft actually are very unstable, and need constant adjustment from computers.
    2:35 "the B-2's spirits insane design ... renders it invisible to the radar"
    The B-2 is not invisible to radar. Lower frequency radar can find their rough position, but not locate the exact location of the plane.

    • @kurtgriffin4163
      @kurtgriffin4163 ปีที่แล้ว

      same thing knowing the general area of a plane moving faster than the speed of sound isn't going to do them much good they'll know there's a stealth bomber coming but can do nothing to stop it

    • @denali9449
      @denali9449 ปีที่แล้ว

      Calling them unstable is an understatement! Jack Northrup learned all about the instability issues with the XB-35 and then the YB-49.

    • @rtbrtb_dutchy4183
      @rtbrtb_dutchy4183 ปีที่แล้ว

      @@kurtgriffin4163 it’s not moving faster than the speed of sound.

  • @jgfakjshfdgkajshd
    @jgfakjshfdgkajshd ปีที่แล้ว +4

    I found really crazy that it uses fly by wire and "incredible trust that propels the aircraft forward". Mind blowing.

  • @eugenescoj
    @eugenescoj ปีที่แล้ว +2

    watched twice to see a crazy starting process... i missed something. you should see the process for starting an SR-71!!! high powered car engines in a cart under the SR's engines that have a geared hydraulic shaft that lifts up and engages the engine to crank it to start it.

    • @wrstew1272
      @wrstew1272 ปีที่แล้ว

      And wasn’t it two super engines and godawfull expensive? I read something somewhere about the $ that was involved with just the start cart….

    • @eugenescoj
      @eugenescoj ปีที่แล้ว

      @@wrstew1272 yes it was expensive to operate the plane and the starting carts were not in the cost... they are considered ground equipment but here we were talking about start ups

  • @patriotmob3227
    @patriotmob3227 ปีที่แล้ว +1

    The paint guy is only spraying air out of the paint gun. Lol quality work guys.

    • @planetcaravan2925
      @planetcaravan2925 ปีที่แล้ว

      It wouldnt be stealth paint if you could see it..

  • @johnswick4593
    @johnswick4593 ปีที่แล้ว +2

    I love America!

  • @mooonie6634
    @mooonie6634 ปีที่แล้ว +4

    Am I alone in wondering why, at this particular moment in current world events, a vlog like this shows up on YT?

  • @threethrushes
    @threethrushes ปีที่แล้ว +7

    I've never seen an aircraft that looks so much like a bird from profile view.
    Beautiful and powerful creations.

    • @UncaDave
      @UncaDave ปีที่แล้ว

      Take a gander at an old Lockheed Constellation.

  • @spidermight8054
    @spidermight8054 ปีที่แล้ว +5

    The F117 wasn’t revolutionary in its use of fly-by-wire. The F16 was the 1st.

  • @ashleycrashdissinger8021
    @ashleycrashdissinger8021 ปีที่แล้ว +3

    Didn't say a damn thing about how they start it. I guess ya got me. Yay, you.

  • @garymiller5937
    @garymiller5937 ปีที่แล้ว +7

    Those are some other worldly aircraft. I'm so glad they belong to us! 😊😊😊

  • @joewilson5452
    @joewilson5452 ปีที่แล้ว +3

    It starts with an APU just like any other jet.

  • @Crush0819
    @Crush0819 ปีที่แล้ว +3

    Thing looks like a sparrow hawk from the side view

  • @Hughes500
    @Hughes500 ปีที่แล้ว +2

    Americans have the coolest stuff!

  • @BHALT0S
    @BHALT0S ปีที่แล้ว +2

    whoa, when that mid flight fuel flap turns back to closed, no gaps can be seen... thats some precision there.

    • @g2145cal
      @g2145cal ปีที่แล้ว

      UARRSI Universal Air Refueling Receptacle Slipway Installation....first time i saw a UARRSI rotate like that was on the F-117's...i was blown away, because the receptacles are usually under doors that slide open or completely in the open

  • @randysmitchell4810
    @randysmitchell4810 ปีที่แล้ว +1

    And the "US Air Force Crazy Process to Start $2 Billion Stealth Plane" was WHERE in the video?

  • @Glofilter
    @Glofilter ปีที่แล้ว +1

    I see a lot of comments about how crazy it is that this aircraft cost $2billion. It doesn't really cost that much. It does, but it doesn't. What happened was back in the 80s they awarded a contract to Northrop to produce something like 200 aircraft to replace the aging B-52 fleet. I'm speaking in general numbers because I don't remember the exact details. I was an Air Force contractor at the time with the B-2 program. Anyway, they ordered around 200 airplanes for $20 billion. They started assembly of the first 10 or so when the Soviet Union fell, and Congress decided they didn't want to buy all those airplanes, so they tried to cancel the order after the first 20 were in production. Northrop said, uhh, we just spent several billion in research and development on this thing, and we have a signed contract for $20 billion- so we're going to need that $20 billion, please. So the Air Force, being legally bound by a $20 billion contract, paid $20 billion to Northrop for 20 airplanes. Had Congress not cancelled the order, the original run of B-2s would have been around $100million each, about the same as we pay these days for an F-22 fighter aircraft. The reason it is $2 billion today is because over the years the Air Force has had several $billion contracts to upgrade the avionics and other systems of the B-2, so each one of these airplanes, since there are only 20 of them, is now worth $2 billion- if you look at it that way. Had their been a 200 airplane fleet, each would be a $200 million airplane. This is a prime example of the genius that is our government...

    • @rtbrtb_dutchy4183
      @rtbrtb_dutchy4183 ปีที่แล้ว

      Nah, you miss some key points.
      First of all, it was initially 132 aircraft and later changed to 75. Then the Soviet thing happened and was further reduced to 20. Each plane was around $700 million each. Northrop offered an additional 20 for around $500 each.
      However, what made the program cost go up, was the need for larger hangers, which also required airconditioning, as well as the purchase of other equipment to support the B2.
      If you take all the “support” expenses into account, each airplane would be around $2 billion.
      Had they bought 132, they would’ve needed more hangers and more support equipment as well. So only taking 20 actually saved the tax payer a lot of money.

    • @Glofilter
      @Glofilter ปีที่แล้ว

      @@rtbrtb_dutchy4183 Sounds like you visited Wikipedia. The initial order was 165, however if you had asked the Pentagon brass back then, they would have told you that they intended to buy at least 200. I know, I was there. Wiki says 132, but it was agreed that at least 165 would be purchased prior to the first one being built and later reduced to 132, then ultimately to 20. But believe what you want- they certainly don't cost $2 billion each from the factory.

    • @rtbrtb_dutchy4183
      @rtbrtb_dutchy4183 ปีที่แล้ว

      @@Glofilter I didn’t say $2 billion from the factory.🙄
      Yup, I did use Wikipedia to get some numbers, it’s been a while, so I couldn’t recall.
      Point is, reducing to 20 was still cheaper than taking 200.

  • @buddymac3993
    @buddymac3993 ปีที่แล้ว +3

    Jump start or do you have to push it and pop the clutch and hope for the best???🇨🇦😄

  • @olsmokey
    @olsmokey ปีที่แล้ว +1

    Very interesting, but nothing on the starting process.

  • @timoniinisto6292
    @timoniinisto6292 ปีที่แล้ว +1

    Just, this is just humand kind madness, to, pay that kinds amounts of cash, simple plane, that's just fly high in the sky, 🤯🤯😪😪🤗🤗

  • @lonewolf9290
    @lonewolf9290 ปีที่แล้ว +2

    🎉تشبه صقر الشاهين

    • @LUVUTV
      @LUVUTV ปีที่แล้ว

      watching it fly in the sky is so cool

  • @lumtantara7070
    @lumtantara7070 ปีที่แล้ว

    Beauttiful technology leading the world to peace...🎉🎉🎉

  • @JuanPabloRojasW
    @JuanPabloRojasW ปีที่แล้ว +5

    14:32 What a honor as a passenger to see and know that there is a Stealth airplane landing in the same runway where we are taking off!!!

    • @5455jm
      @5455jm ปีที่แล้ว

      Guam, when I come up from Australia to Guam it is a common sight.

  • @pyrovania
    @pyrovania ปีที่แล้ว +2

    This is why I almost joined the air force. Problem: too short to be a pilot.

  • @truth-Hurts375
    @truth-Hurts375 ปีที่แล้ว +1

    And what is so crazy about staying ahead of your enemies????

  • @kdavis1492
    @kdavis1492 ปีที่แล้ว +1

    I was expecting something like the B-52 startup I watched elsewhere.

  • @boogerdog5247
    @boogerdog5247 ปีที่แล้ว +2

    It's awesome to stand in a hanger at Whiteman and view up close and personal.

  • @ariavalencia-213ua
    @ariavalencia-213ua ปีที่แล้ว +19

    So, what was the fascinating process behind starting the 2 billion dollar stealth plane? 🛫💸

  • @howtousemetallathemachines6478
    @howtousemetallathemachines6478 ปีที่แล้ว

    Excellent, Thank you👍

  • @raykeinath9409
    @raykeinath9409 ปีที่แล้ว +1

    Nock nock boom 😂 special deliverys

  • @error7329
    @error7329 ปีที่แล้ว

    Hopefully one day I will steal it ......
    In GTA 🤣🤣🤣🤣🤣

  • @mariapaiva3238
    @mariapaiva3238 ปีที่แล้ว

    A prodigy of technical in all senses!

  • @hanthostaal7131
    @hanthostaal7131 ปีที่แล้ว +1

    And that crazy process would be what exactly?

  • @spinnenbein1
    @spinnenbein1 ปีที่แล้ว

    Gebrüder Horten lassen grüßen!

  • @kurtwm2010
    @kurtwm2010 ปีที่แล้ว +1

    so, what's the startup process?

  • @crumblenaut9776
    @crumblenaut9776 ปีที่แล้ว +1

    So how does it start???

  • @johnnynguyen6458
    @johnnynguyen6458 ปีที่แล้ว +2

    Love 😍😍Un&nato 🇺🇸🇺🇸🇺🇸

    • @saltapozo
      @saltapozo ปีที่แล้ว +1

      NATO is loosing today..

  • @lindakelly3494
    @lindakelly3494 ปีที่แล้ว

    I still have my “first flight” tie tack that was given to all who worked on her.

  • @ljube01
    @ljube01 ปีที่แล้ว

    The F 117 is very famous for its invisibility, said anti-aircraft crew from Serbia...

  • @brucedodd7564
    @brucedodd7564 ปีที่แล้ว +2

    It is a tribute to Jack Northop

  • @pokerEEUU
    @pokerEEUU ปีที่แล้ว

    Thats a beauty..i want one of those for my birthday🇺🇸🇵🇷😳👍

  • @mariapaiva3238
    @mariapaiva3238 ปีที่แล้ว

    Technical development I bean!

  • @LUVUTV
    @LUVUTV ปีที่แล้ว

    flying in the sky like a flying bat.awesome.i love your video

  • @jerryhermann7233
    @jerryhermann7233 ปีที่แล้ว +1

    Well if your not a AF Vet a pre trip inspection mite be what they are calling a weird start up. Its more then a CDL pre trip inspection as that has alot to look at. I had a CDL-A.
    Just my thoughts

  • @abdulmalek5462
    @abdulmalek5462 ปีที่แล้ว

    serbian= heyyy Stealth bomber..remember me..

  • @silentabove119
    @silentabove119 ปีที่แล้ว +3

    Fly-By-Wire technology didn't start with the F-117. It's been on the F-14, F-15, F-16, and almost every subsequent military aircraft since.

    • @thatg6838
      @thatg6838 ปีที่แล้ว

      The F-14 didn’t have FBW…

    • @rtbrtb_dutchy4183
      @rtbrtb_dutchy4183 ปีที่แล้ว

      @@thatg6838 right. And neither does the F-15. He only got one out of 3 correct. 😂

    • @planetcaravan2925
      @planetcaravan2925 ปีที่แล้ว

      ​@@rtbrtb_dutchy4183could be worse

  • @jasonross9212
    @jasonross9212 ปีที่แล้ว +1

    WOW !
    NOTHING SPECIAL ABOUT STARTING THE ENGINES!!

  • @ericcarabetta1161
    @ericcarabetta1161 ปีที่แล้ว

    Perfect timing with the B2 that was spotted over Miami Beach the other day (June 9, 2023).

  • @miker3298
    @miker3298 ปีที่แล้ว +1

    The brits had the AVRO Vulcan bomber that had the radar cross section of a seagul in the 1960's

  • @manuelbeltranmeza
    @manuelbeltranmeza ปีที่แล้ว

    Greetings from Mexico.

  • @BestFarmROI
    @BestFarmROI ปีที่แล้ว +6

    Many years ago during my executive job coaching days a man contacted me to help with his job search. He told me he had invented the coating to scatter radio waves and go stealth and sent me a newspaper article to prove it. Our govt confiscated his patent "in the interest of national security" and didn't pay him for it.

  • @dloui5214
    @dloui5214 ปีที่แล้ว +1

    13:01 me , dad , and gramp flying together

  • @WILDSRB
    @WILDSRB ปีที่แล้ว

    Greetings from Serbia. We didnt know that it was invisible sorry

  • @rajarchanagarre7306
    @rajarchanagarre7306 ปีที่แล้ว

    Awesome Engineering. Like to fly in one of those.

  • @redadz9105
    @redadz9105 ปีที่แล้ว +1

    Russia showed the NATO who is the master in Weapons, without too much noise. The price is not a reference, again Russia is the Number ONE in this field

    • @pegasusted2504
      @pegasusted2504 ปีที่แล้ว +4

      What time does your "stand-up" comedy act start this evening?

    • @bpo6955
      @bpo6955 ปีที่แล้ว

      Ha ha ha ha ha. Oh yeah. NATO bombed the heck out of Kosovo while Russia watched on the sideline. Most of the targets were struck by the B-2.

    • @planetcaravan2925
      @planetcaravan2925 ปีที่แล้ว

      Showed when and where? I guess we all missed that event

  • @فوازالدوسري-ع2ك
    @فوازالدوسري-ع2ك 10 หลายเดือนก่อน

    الله اكبر والعزة لله

  • @just435
    @just435 ปีที่แล้ว

    Watching you from dubai
    Good night ahead 😴

  • @moehoward01
    @moehoward01 5 หลายเดือนก่อน

    Good grief! It's the Batplane!

  • @coolcrazy2957
    @coolcrazy2957 ปีที่แล้ว +1

    日本にも配備してくれ。売ってくれ。

    • @LUVUTV
      @LUVUTV ปีที่แล้ว +1

      Japan is also a developed power

  • @todaylets2583
    @todaylets2583 ปีที่แล้ว

    One would think they could afford new tires on a 2 billion $$$$ plane!!!

  • @RobertPotokar
    @RobertPotokar ปีที่แล้ว

    everything is fine, but why does it have motors on the top side? heat detectors don't detect it, but today satellites are in the game anyway

  • @amorosogombe9650
    @amorosogombe9650 ปีที่แล้ว +4

    The F-117 is 60 years old. I remember first seeing them in the first Gulf War as a child. It looked so otherworldly then. Still does now.

    • @MyBelch
      @MyBelch ปีที่แล้ว +1

      Hopeless Diamond began in 1975. First DARPA contract awarded in 1976. Maiden flight 18 June 1981.

    • @wzman2006
      @wzman2006 ปีที่แล้ว +3

      Check your math.

    • @amorosogombe9650
      @amorosogombe9650 ปีที่แล้ว +1

      @@wzman2006 2023 - 1973? You're right 50 years old.

    • @danfreeman9079
      @danfreeman9079 ปีที่แล้ว

      Thinking about the SR-71??

    • @g2145cal
      @g2145cal ปีที่แล้ว

      @@MyBelch Have Blue

  • @danfreeman9079
    @danfreeman9079 ปีที่แล้ว

    Try the SR-71 Blackbird Inspection. An aircraft whose skin temperatures reach over 900 degrees. Your uniforms are not clean, dry when finished.
    I have the original Training manuals for the Pre-Flight and Post Flight inspections among others.

  • @kailashsingh9737
    @kailashsingh9737 ปีที่แล้ว

    Very beautiful sweet sir

  • @d.martin7692
    @d.martin7692 ปีที่แล้ว

    Oh, and such a diverse and inclusive work force! So natural and unforced.

  • @mayandas9581
    @mayandas9581 ปีที่แล้ว

    Matlock super sar

  • @word2RG
    @word2RG ปีที่แล้ว

    thats the annual budget for the LAPD

  • @deltaskyhawk
    @deltaskyhawk ปีที่แล้ว

    The B2 is like my ex-gf .... high maintenance!

  • @shawlork
    @shawlork ปีที่แล้ว

    Learning about stealth technology is like learning about a nuclear bomb... you feel guilty but is so intriguing

  • @am4793
    @am4793 ปีที่แล้ว

    When these stealth airplanes were first seen in the late 1980s, people were reporting triangular UFO in the US and UK.

  • @pegasusted2504
    @pegasusted2504 6 หลายเดือนก่อน

    Wouldn't that be "the b2s wing flexes ever so slightly" and not wings? It is after all a flying wing plane suggesting only the one :~)

  • @matthiasweidmann8135
    @matthiasweidmann8135 ปีที่แล้ว +1

    ? crazy start? Where?

  • @shawlork
    @shawlork ปีที่แล้ว

    Bravo

  • @DeluxGamers
    @DeluxGamers ปีที่แล้ว

    Love ur vidios

  • @malfunction8165
    @malfunction8165 ปีที่แล้ว +2

    The first time I had seen one was at the IAT at Fairford and it looked like nothing created by man, it was awesome, the Battle of Britain Flight was also there and I thought aircraft have gone from the Lancaster to the B2 in a single lifetime. Having said that, I suspect it's like the Tiger Tank, a superb bit of kit, but too expensive, too complicated and too few in number to make an impact, the Russian T34 and Sherman tanks showed how it should be done, cheap and easy to make, and lots of them.

    • @MyBelch
      @MyBelch ปีที่แล้ว

      Only 66 years between first powered, controlled flight at Kitty Hawk, and moon landing.

    • @planetcaravan2925
      @planetcaravan2925 ปีที่แล้ว

      It still has special bombing uses, no wonder its not mass produced tho

  • @B1221C
    @B1221C ปีที่แล้ว

    Had absolutely nothing to do with starting the aircraft...

  • @markcargill9734
    @markcargill9734 ปีที่แล้ว +1

    i could hot wire this in 30 seconds.

  • @_apey
    @_apey ปีที่แล้ว

    Thought this vid was supposed to be about starting the plane. What happened?

  • @فوازالدوسري-ع2ك
    @فوازالدوسري-ع2ك 10 หลายเดือนก่อน

    لا اله الا الله

  • @wiesenbefeuchter
    @wiesenbefeuchter ปีที่แล้ว +1

    Why crazy ?

  • @mhdchannelguys7566
    @mhdchannelguys7566 ปีที่แล้ว

    Hadir guys👍

  • @nour-eddineeljouak6108
    @nour-eddineeljouak6108 ปีที่แล้ว +1

    What a Beauty ❤
    What a great German 1940s design 🥹

  • @hanhuiliao4127
    @hanhuiliao4127 ปีที่แล้ว

    powerful US military👍💪💪💪

  • @rdprdputube
    @rdprdputube 4 หลายเดือนก่อน

    Never saw the process if starting the plane.

  • @fadzilsaid1028
    @fadzilsaid1028 ปีที่แล้ว

    Rather the super expensive coating wrapped in super difficult to start bomber plane.

  • @MarttiSuomivuori
    @MarttiSuomivuori ปีที่แล้ว

    OK, a pretty plane. Now take out the nukes in Belarus!

  • @robgoald
    @robgoald ปีที่แล้ว

    6:12 through 6:17 isn't even the real plane!! It's some type of training mockup.

  • @pk7422
    @pk7422 ปีที่แล้ว +3

    WHITE-man Air Force Base............ Whiteman. Sheesh.

    • @thilde007
      @thilde007 ปีที่แล้ว

      Don’t forget about White Sands or as I like to call it now, Sands

  • @ZorroComputers
    @ZorroComputers ปีที่แล้ว

    There is something alien in the Northrop Grumman plane

  • @omarsalem2340
    @omarsalem2340 ปีที่แล้ว +1

    You can't compare any Russian plane to stealth B2 because this bird is very secret

    • @planetcaravan2925
      @planetcaravan2925 ปีที่แล้ว

      So were russian planes during soviet times, for example the drama behind the foxbat

  • @tonytor5346
    @tonytor5346 ปีที่แล้ว

    Most people don’t know that the B2 use electrogravitics to save fuel. Positive 2 million Volts on the slats, negative 2 million volts on flap area. This when ingaged during cruise can save 35% fuel utilization.

    • @rtbrtb_dutchy4183
      @rtbrtb_dutchy4183 ปีที่แล้ว +1

      LOL. No it doesn’t. 😂. On a side note, it doesn’t have slats either.

  • @williamgibble8361
    @williamgibble8361 ปีที่แล้ว

    Computers were required to heavily augment input from the PIOLET, because of its radical design. Hence the fly by wire system 😉.. he blew right over a good talking point..

    • @street-level
      @street-level ปีที่แล้ว +1

      I think that the F16 had FBW 15 years earlier than the B2.

  • @alowatsakima8950
    @alowatsakima8950 ปีที่แล้ว

    Not what I expected

  • @michaeldinanno
    @michaeldinanno ปีที่แล้ว

    What push it and then let the clutch out

  • @tmenzella
    @tmenzella ปีที่แล้ว

    The way you start the B2 is:

  • @christopherpate6611
    @christopherpate6611 ปีที่แล้ว

    So… does it have 2 crew members or 3 crew members, because all the pics I have seen during refueling in refueling have a third ejection seat/ cut through line on the aircraft outer hull???

  • @mikeeihusen5194
    @mikeeihusen5194 ปีที่แล้ว +1

    Its not witman AFB its Whiteman AFB