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capttrob

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    question about AIM-120...

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    There is no way to IFF in the LockOn F-15 under any of the auto lock modes (Boresight, Verticle, etc...). You also cannot IFF when your target is locked. So if you lock someone, and you are unsure if he is friend or foe, you have to unlock, scan him in RWS or TWS, see the little rectangle.. and relock. PITA!

     

    The only way to IFF while flying the F-15 is in RWS or TWS mode and scan him to see a rectangle.

     

    The Russian birds are able to IFF when target is locked.. and/or boresight.. etc

     

    From what i understand, the real F-15 puts a a big X on the lock box if he is friendly. Hopefully ED fixes this in Blackshark.

     

    Hey GG.. LTNS :)

     

    Do you know if they fixed this? Can you say? lol

     

    :pilotfly:

     

     

    Edit: Let me also add.. there is an indirect way to IFF a target afte its locked, if you are clever. By process of elimination, you can check what your enemy team is flying. Once you lock a target, you will get target type on bottom center of VDS. So if you see a MiG-29 there, and you have no MiGs on your team.. fire away and blast that sucker to mars!

     

    Unfortunately.. there is alot of mix and match with planes among red and blue, so you gotta be careul with that one. I always try to know where my teammate migs/su's are. This way if i need to use boresight.. im good to go. Its all SA...

     

    hope this helps..

    Sim v Game

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    Its a game

     

     

    A Flight simulator you can log time in...

     

    A Flight training device (FTD) you can also log time in... (although im not 100% sure.. havent picked up the FAR's in a while)

     

    A Cockpit procedural trainer (CPT) you can use towards training requirements (which is basically a piece of cardboard replica of a cockpit)

     

     

    Thats what the difference is between the different products...

     

    you cannot log time when playing LockOn (although im sure some do...lol)

     

    hi everyone... miss me? :beer:

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    Its perfectly reasonable to get frustrated in a good debate and fact finding process. However its another thing to call a paying customer ignorant, no matter how ignorant they are, if you want to make money in your business. Maybe im the one who is ignorant, but it just doesnt make good business sense to me. And no matter how accurate he is, Fighter Ops is looking more and more attractive every day. Unless of course Yo-Yo has a hand in their development. As far as im concerned, the customer can call me names, tell me im a liar, or tell me my product sucks as much as he wants, and i'll smile back and say thank you every time if he is buying my product.

     

    I understand other possibilities which do make sense for the 25T behavior, such as the idle thrust settings we have discussed. I have no doubt that Yo-yo knows alot more about the 25T than i...However. for something that needs to be pretty precise as a weapons platform/bomber, it sure is a handful to get the thing to slow down.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    I am surprized... your ignorance shocked me. .

     

    Yo-Yo, do you work for ED? I see that ED Team is on your avatar, but not sure if that means you work for ED. I was a bit conused about the "ED Tester Team" signatures as well till Alfa clear it up for me that they are just regular customers like everyone else, chosen to do beta testing.

     

    If you do work for ED, and Swing Kid is a customer, did you just call your buying customer ignorant? Sorry, it just took me by surprise....:doh:

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    In all this has turned into an interesting thread to read, though some of the formulas make my eyes cross. As far as the expression "half again as much" is concerned, I've lived in America all my life and it's an expression I'm very familiar with. So it's definitely not just a British thing.

     

    Rich

     

     

    lol.. there is a very real possibility i have heard the expression, but always interpreted it as "half as much". Thank goodness im not a bartendar or i'd be shorting customers who asked for "half as much again" alcohol in their drink.... ;)

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

     

    Capttrob, you wrote few pages back that you had a ex-Marine flying FC

    (Frog?) and he left laughing... It`s funny coz... recently I saw Hornet

    driver (also a Jarhead) doing some FC flying. Well, he has it`s own copy

    of FC so it wasn`t the first time he did that. He flew the Mig and the Eagle.

    As he was doing some FCLPs at Sochi (hehe) in an Eagle he was smirking

    at the AOA. He was landing it at exactly the same AOA as in Hornet.

    A dragged in approach and no flare... and he liked it:noexpression: (he`s a

    Jarhead) - I hope he`s not reading it right now...

    Back to Frogs:doh:

     

    Yeah, he didnt fly the Frog though. I had him doing some practice in the F-15. He's too used to transport category aircraft now that i guess it was pointless to sit him down in front of LOFC.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

     

    I am familiar with it (drag's a fairly essential thing in soaring, we concentrate on it quite a bit), but I call it parasitic drag . . . . what is it they say about America and Britland? Two countries separated by a common language ;)

     

     

    .

     

    lol... good one... never heard that before either.

     

    Parasitic is the propery terminology. I guess i picked up a few bad habits since my CFI days... ;)

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    Hmmn, can't upload an Excel spreadsheet.

     

     

    I need better L/D values for it to work properly, but if you take maximum L/D, the Drag force for the F-15 at 300km/h is half as much again as the Su25T at 300km/h. Just due to the difference in L/D . . . . .

     

    And that makes sense. If the drag acting on the F-15 is half as much as the 25T at that speed, why does the F-15 slow down more rapidly than the 25T having double the drag, plus gear, flaps and speed brakes.

     

    I suppose the F-15 speed brake creates all that drag by itself... ?

     

    Edit: The residual thrust advantage on the 25T does lend to a better understand of why it seems slippery with all that drag hangin out though.... if in fact its 30% more than the 15 at idle.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

     

    Misunderstanding - I thought that this:

     

     

     

    Meant you thought the drag reduced simply because you were in a dive, not because you were accelerating.

     

     

    .

     

    Drag is decreasing when you are in a dive, induced drag (Induced drag decreases as speed increases). Parasite drag increases. Over-all drag increases as you accelerate. It doesnt remain the same...

     

    Are you familiar with the difference between induced and parasite drag? Just curious, not trying to be sarcastic.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    You are accelerating not because drag is decreasing, but because a component of your weight is now acting forwards through the airframe.

     

    I never said this. Where are you getting this from? Induced drag is decreasing because you are accelerating, not the other way around. Parasite drag is increasing, also because you are accelerating. The over-all combination of drag is less than the thrust vector because you are accelerating. But drag does not remain the same acellerating in a dive as you suggested earlier. Over-all drag increases as you accelerate any moving body. Drag will increase (as you accelerate) where it eventually catches up with the constant thrust force and equals out. In a dive, this is known as Terminal Velocity. Lift and AoA, depending on airfoil design, also does not remain the same while accelerating in a dive. As you also suggested earlier.

     

    That component acting forwards means your aircraft is no longer in equilibrium - forces acting forwards now are larger than forces (drag) acting backwards. You accelerate
    .

     

    agreed, until drag catches up with thrust and you hit terminal velocity, or impact the ground, or rip your plane apart. ;)

     

     

    My lecturers, my instructors, and me all call this "thrust" for a glider . . . . we make sure we include the quotation marks, but even so I suppose it could puzzle a power pilot. Thrust is only from engines for you guys, right? ;)

     

    No, i believe i stated earlier that the F-15C had an 8000lb thrust advantage over the 25T (speaking in simple terms), in an established dive at idle power, because the F-15C is 8000lbs heavier in my test. However, it didnt seem to have an effect since they both peformed rather equally in the clean configuration.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    Something to take into account is that as modelled in LO - at zero throttle the F15 produces zero thrust (which is why it sits still on the runway), while at zero throttle the 25T produces (from memory E.D. said - & it's 05:32 here so I can't be bothered searching) 30% thrust (which is why it doesn't). .

     

    And there it is! I always said it felt almost like i had a tailwind when landing the 25T, when it was the thrust acting like that tailwind. If the net thrust vector is 30% higher than the F-15, that explains everything! Well, at least it starts to make more sense.

     

    Mind you, we are talking about net Thrust vector and not thrust setting as seen on the guages, because they both show about 40% thrust at Idle IIRC.

     

    As far as being able to sit on the runway. Rhetoricallly speaking, If they were both producing 30% thrust, The F-15 will stay still because it is heavier while the 25T will need some brakes.

     

    All my dive tests were conducted at idle thrust.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    The aerodynamic drag force may be calculated from the equation:

     

    Fd = Cd * 0.5 * p * V^2 * S

     

    where Fd is the drag force, Cd is the drag coefficient, p is the air density, V is the speed, and S is the cross-section area.

     

    Let's consider the Flaming Cliffs 20% fuel Su-25T in a 700 km/h, 30 degree dive at idle power (no speed brakes).

     

    The accelerating force due to gravity would be (sin(30) * 9.8 N/kg) = 4.9 N/kg.

    The aircraft's measured acceleration in the dive is only about 4.0 m/s^2, so the aerodynamic drag force must be (4.9-4.0) = 0.9 N/kg.

    For a total aircraft weight of 12254 kg, this gives us a drag force of about (0.9 * 12254) ~= 11028.6 N = Fd

     

    V = 700 km/h ~= 194.4 m/s,

    p ~= 1.225 kg/m^3,

    and from diagrams, I estimate the frontal cross-section area of a Su-25T to equal about S ~= 9 m^2.

     

    So the measured drag coefficient in Lock On is:

     

    Cd = Fd / (0.5 * p * V^2 * S)

    = (11028.6 N) / (0.5 * 1.225 kg/m^3 * (194.4 m/s)^2 * 9 m^3)

    Cd ~= 0.05

     

    So, is the Flaming Cliffs Su-25T "slippery?"

     

    Consider:

    "a slippery road car has a Cd of about 0.32. A chunky one is 0.38."

     

    http://www.insideracingtechnology.com/tech102drag.htm

     

    The Flaming Cliffs Su-25T (Cd = 0.05) seems to be about 6 times more slippery, than a "slippery" road car (Cd = 0.32). So what's wrong, to say that it's "slippery?"

     

    -SK

     

    Can you do that for the Flaming Cliffs F-15? I'd be curious to see the difference since they both performed about the same in the dive test.

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    (to section in bold)

     

    Thing is though . . . . . . you don't ;)

     

     

    AoA is chord line of wing to velocity vector of the aircraft, has little correspondence to pitch.

     

    Your pitch angle rotates towards the ground in a dive, but so does your velocity vector. You are not suddenly flying at a lower angle of attack, you are flying at a lower angle of pitch.

     

    Angle of attack . . . . . is the same.

     

    Lift . . . . is the same.

     

    Drag . . . . is the same.

     

    "Thrust" increases, since you have your weight component acting forwards . . . . but you don't magically reduce the lift the wing is generating by aiming the nose downwards.

     

     

    Have you ever seen a L/D max chart? Why do you think induced drag increases with decrease in speed. Why do you think Parasite drag increases with speed? And what is the speed at which they cross? What happens to your speed when you point the nose down at idle thrust?

     

    AoA does not remain the same.

     

    Thrust only increases as you roll the nose over. It remains the same once established in the dive, however, you are accelerating. That doesnt mean thrust is increasing.

     

    Drag definitely DOES NOT remain the same. You are accelerating. Where did you get this from?

     

    You dont reduce lift by pointing the nose down, it will actually increase depending on airfoil design. So i dont know where you got that one from. What i was referring to is that you reduce induced drag as you increase speed (because you are diving). But you also increase parasite and form drag. As speed increases further, you'll start to get compression drag and wave drag. There are actually some high aspect ratio wing designs that will have a "negative" angle of attack at higher speeds to maintian level flight (or flight path/velocity vector)

     

    All better now?

    Parasite and Induced drag on Su-25/T

    in Lock On: Flaming Cliffs 1 & 2

    Posted

    The F-15 airframe clean is more draggy than the Su25T clean at these speeds . . . . . might that be why you're getting confused?

     

     

    Doest seem so in my dive test. They both performed pretty much equally.The F-15 gained 7 knots over the Su25T, same dive, clean config.

     

    Edit: But yes, i do understand your point that the F-15 design should get more draggy at lower speed in level flight. This is due to induced drag (higher AoA for a slower speed on the 15). However, you reduce the induced drag variable when performing dive tests (like changing the relative wind angle in a wind tunnel). And you're also right that im getting too tangled up in something i really could care less about since i dont even fly the 25T ;)

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