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  • in reply to: Jaguar and Mirage F1-AZ cpmpared #2299964
    eagle
    Participant

    The F1AZ has the advantage of a ranging radar and refueling probe.

    Jaguar is equipped with a retractable refuelling probe:
    http://en.wikipedia.org/wiki/File:Jaguar_DF-SD-05-05511.JPEG
    Somewhat unusual on a French jet I must admit. πŸ˜€

    eagle
    Participant

    Just intresting for the take-off run, MTOW or at subsonic speeds. Only here the installed trust is comparable to some degree before the propulsion system takes over. Today you will not find F-15C or new built F-15E coming close to that former weights still to find on dated websites. The old Cs are around 14 tons the F-15 MISIP I/II in mind and the new built E/S are around 18 tons in the meanwhile depending on capabilities added.

    Do you have a source for the weight figures? The MSIP I Eagle is around 13 tons. What would increase the weight by 1 ton?
    Those 31700 pounds as stated on the af.mil factsheet seem to be correct – for the original F-15E without CFTs.

    Btw, mission time of 1 hour without ext. fuel is realistic for an air/air mission including combat.

    in reply to: NORTH KOREA Airforce and Air defences #2301063
    eagle
    Participant

    However the GBU 57 MOP has a slight disadvantage over the GBU 28, since the GBU 28 could be released from F 15E Eagle or F/A 18E/F Hornet but the GBU 57 could be employed only by heavy bomber as B 52H or B 2A Spirit since the GBU 57 has a mass of 30,000lb or 14,000kg.

    F-18E/F? I don’t think so. Apart from strategic bombers, the F-15 is the only jet cleared for the GBU-28.

    in reply to: F-35 debate thread. #2302548
    eagle
    Participant

    Here is LM’s range for a Hi-LO-LO-HI profile with various tank configs (all have a centerline tank).

    460 nmi with 370 gallon wing tanks.
    570 nmi with 600 gallon wing tanks.
    630 nmi with 600 gallon wing tanks and conformal fuel tanks.

    Loadout is 2x2k bombs and the tanks are dropped when empty.

    That can get expensive real fast.

    http://i619.photobucket.com/albums/tt271/SpudmanWP/jvoiR4_zpsf2ba7007.jpg

    Doesn’t seem right for a number of reasons:
    That is a hi-lo-hi profile. It’s only 100 miles, but still, reduces range.
    It says ALQ-184 doesn’t it. So no centerline tank. Latest F-16 52+ with full internal ECM gear can trade ECM pod for more fuel.
    On the other hand, 600gal tanks are not jettisonable iirc and are used mainly for ferry flights or if there is no threat (Israeli F-16Is over Gaza).

    Re expensive fuel tanks and limited availability: Please, if you’re going to war and drop PGMs, the cost of a drop tank is negligible. If you start running out of tanks, build some more. Any nation that can operate supersonic fighters has the industrial capability and strenght to mass produce streamlined barrels.

    eagle
    Participant

    If it has a new Fly-by-wire or FCS, why haven’t they gone the extra mile like with the Su-35S, and removed the huge air-brake in favor of more internal fuel?

    More internal fuel isn’t really needed thanks to CFTs. With CFTs, an A/G load and 3 tanks, MTOW is already exceeded. At least thats the case with USAFs F-15E hence they usually fly with 2 tanks.
    More likely than not, the F-15SA has gained weight and it uses the outer wing stations so…
    Also, deleting the air brake to add some fuel wouldn’t be my first choice. There is still some empty space in an Eagle. Don’t know how much of that is used in any F-15E variant, but I’m pretty sure the outer wing area is still empty as it wouldn’t make much sense to install A/G avionics there.
    Edit: No. 106 is dry: http://sobchak.files.wordpress.com/2009/06/f15e.gif

    in reply to: F-4E vs. Mirage F-1CT #2305799
    eagle
    Participant

    Why has the king of the supercruisers, F-22, got turbofans and not turbojets?Why did the Soviets replace the turbojet MiG-25 with the airliner-engined turbofanned MiG-31 (which flies just as fast as the Foxbat but at much greater range)?

    The F119 has a very low bypass ratio. It’s closer to a turbojet than most fighter engines let alone airliner engines.
    I’m not sure if I remember correctly, but I think the bypass is used to cool the engine itself and the exhaust.

    As for the MiG-31, it’s probably because the Soviets realised the MiG-25 was spending most of its life flying subsonic. The D30 is more efficient at subsonic cruising yet thanks to its huge afterburners, allows speeds of M2.83, plus supersonic speed at low altitude (B-1 πŸ˜‰ )
    Besides, the D30 is a low bypass turbofan aswell and not really suited for airliners. No modern airliner would use such an engine.
    Oh, and as you noted, at much greater range, take a look at a map, range might be useful over Siberia.

    in reply to: Airbrake effectiveness #2315338
    eagle
    Participant

    The canards on Gripen causes a formidable down force during landing,
    for a vehicle the front tire accounts for 70% of breaking power,
    an aircraft will not differ.
    Here is a good read up for those of us who never specialized in aerodynamics
    http://www.mach-flyg.com/utg80/80jas_uc.html
    http://www.airplane-pictures.net/images/uploaded-images/2012-10/29/246343m.jpg

    Aircraft differ because most the main gear carries most of the weight. As I mentioned, no front brakes except on Gripen. I imagine drag created by canards is more important for braking than down force. Look at the size of those front tyres, they’re not going to cope well with more than some % of breaking power.

    in reply to: Airbrake effectiveness #2315342
    eagle
    Participant

    Some planes, like alpha jet and Tejas and many with them have a brake in the rear pushing air up.
    This airbrake seems to me, pushes air up and no air down, the netforce exept direct brake pushes the plane down behind the main landinggear. This should also lift the nose gear up if on the ground? Make a less effective brake on the frontgear? This netforce should also make braking in the air pitch the nose up. The nose up will also make the angle of attack be a effective airbrake.
    http://upload.wikimedia.org/wikipedia/commons/f/f4/IAF_Tejas_Landing_at_Aero_India_2013.JPG

    Less weight on the front gear doesn’t affect braking. Gripen is the only jet that comes to mind to use front wheel brakes. Actually, pushing the nose up during landing does increase drag and so helps to shorten the landing distance without wheel braking. Like this F-15 https://www.youtube.com/watch?v=PivK29tlazE

    Then there some, like Gripen and F-16 that pushes air in two directions and therefore counterbalance the netforce. This generates no groundpressure in landings, but should be the most effective in the air?
    http://www.warped-photography.com/Other/Miscellaneous/Saabs-70th-Birthday-Air-show/i-WFw76Pf/0/L/Twin%20seat%20Gripen%20landing-L.jpg

    Not sure if it’s the most effective configuration in the air, but it’s a neutral configuration meaning there’s no pitch force.

    in reply to: Indian Air Force Thread 20 #2372627
    eagle
    Participant

    Indian AF don’t want HTT-40
    http://timesofindia.indiatimes.com/city/bangalore/IAF-HAL-cross-swords-over-indigenous-basic-trainer-project/articleshow/18395754.cms

    on a related note, why did they choose the PC-7MK2 instead of the PC-9 or PC-21?

    Probably because they were looking for basic trainer. They have the HJT-36 and the Hawk Mk132 for intermediate and advanced training so there is no need for the extra performance of the PC-9 or -21.

    in reply to: Iran to Unveil New Fighter Tomorrow – Qaher 313 ??? #2247037
    eagle
    Participant

    Its about as real as Donald Ducks 313 πŸ˜€
    I thought only Baghdad Bob can pull off a stunt like this with a straight face. But then again, I don’t understand Farsi so mabye they are selling this thing for what it is, a mock-up for a cheap Iranian war movie.
    Judging from this pic, they weren’t quite sure where to put the intakes… πŸ˜€

    in reply to: Is American aviation going downhill? #2258442
    eagle
    Participant

    No, this chap here:

    Yeah, I know about Rafale (and Gripen), but the original question was “Please, tell me one single mission that Eurofighter, Rafale or Grippen can do, but an F-15E can’t.”
    But we already came to the conclusion that anti-shipping isn’t one of them anyway. πŸ™‚

    in reply to: F35 News only thread for 2013 #2258454
    eagle
    Participant

    Seems they’ve lowered the performance again. http://www.flightglobal.com/news/articles/pentagon-lowers-f-35-performance-bar-381031/

    I would have expected more comments on this one, as the figures are absolutely appalling.
    43 more seconds to accelerate from M0.8 to 1.2? That’s not 43 seconds, but 43 on top of already not particularly good numbers.
    Does anyone have comparable numbers for other jets, i.e. Mach 0.8 to 1.2 times?

    in reply to: Is American aviation going downhill? #2258464
    eagle
    Participant

    Correct, but its not detrimental of what iΒ΄ve said, has off now thereΒ΄s not one single operational “E” with an Ashm capability. Would it be dificult to integrate such a capability in the “E”? Absolutely not. Are there Eagles with an Ashm capability? Yes there are.

    EF Typhoon and anti-ship?
    USAF F-15Es have anti-ship capability using AGM-65 or AGM-130 missiles.

    in reply to: T-50, M-346 and Yak-130 advance trainers future prospect? #2276277
    eagle
    Participant

    As it stands, both M-346 and Hawk cannot meet the USAF’s 6.5 G sustained g requirement and an extensive structural reinforcement is necessary, which increases weight and cost.

    The requirement isn’t really 6.5G sustained. The requirement is 6.5G “for no less than 15 seconds using no more than 15 degrees nose low attitude at 80% fuel weight between an altitude of 10,000 and 20,000 feet”.
    see here http://www.flightglobal.com/news/articles/usaf-releases-draft-t-x-kpps-377693/
    Maybe the current 5.6G sustained is already enough to cover those 6.5Gs in a dive. If not, more thrust is all thats needed. The M-346 is rated for 8Gs. Meaning structural reinforcing isn’t needed.
    Btw, nose down, top speed is around M1.2.

    in reply to: F-35 News thread. Part Deux #2283561
    eagle
    Participant

    But i would

    Although thrust differ at altitude, it differs for both engines,
    so relation should be same.

    a = F/m
    m= half between empty & loaded weight, as in 50% fuel

    F-16
    F=28600 lbf
    m=22700 lb
    m(amraam) = 335×4 = 1340 lb

    a1=28600/22700 = 1.26
    a2=28600/(22700+1340) = 1.19

    1.26-1.19= 0.07
    0.07/1.26= 0.05, =5%

    F-35
    F=43000 lbf
    m=39420 lb

    a1=43000/39420= 1.09
    a2=43000/(39420+1340) =1.05
    1.09-1.05=0.04
    0.04/1.09 = 0.036, ~4%

    in an apples to apples comparison then, F-16 drop acceleration by 5% when armed with 4 amraam,
    while F-35 drop acceleration by 4% when armed with 4 amraam.

    advantage 1% for F-35 with weapons loadout (compared to without)
    vs F-16 with weapons loadout (compared to without)

    But we also saw F-16 had a better thrust to weight / acceleration regardless if armed or not.

    2 points:
    First, you forgot to include drag in your calculations. We also don’t know if a clean F-16 out accelerates the F-35 or how exactly the engines behave at different altitude/speed settings. Your proposed 1% advantage is insignificant considering other factors like drag and thrust have more impact.
    Second, the F-16 in your comparison is at a significant range disadvantage. In reality, the F-16 carries 2 370gal fuel tanks which would be dropped before entering the fight. Internal fuel would be more than 50% in that case.

Viewing 15 posts - 781 through 795 (of 1,837 total)