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Thread: TPY-2 can be radar OTH ?

  1. #121
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    Quote Originally Posted by PeeD
    Good luck with applying specialized formulas for completely different problems... I take what "Tactical missile design,"s author tells over your models any day.
    Too bad when your models given result 7 bigger than it actually is, and completely different in what way? do you think aircraft aren't affected aerodynamic force or missiles with aircraft like airframe such as Tomahawk, Kh-20 ,AGM-129 does not exist?.
    If F-16 is so complex why don't you put the numbers for Kh-20 in and check the result? Unlike you, i only used 5 degrees AoA and 12 degrees tail deflection, both are extremely small value.



    Quote Originally Posted by PeeD
    Good and I hope you have now understood that airframe G's and aerodynamic G's are not the same.Good and I hope you have now understood that airframe G's and aerodynamic G's are not the same.
    Nice try but F-16 airframe can sustain over 9G, wrong excuse. Try again . With your calculation an F-16 will be able to pull 9G at all altitude with the only limiting factors be the airframe G limit. Flight manual data shown that clearly not the case
    Quote Originally Posted by PeeD
    dia 0,914
    lenght 7,28
    weight 1254kg
    missile AoA 10°
    control surface deflection 63°
    control surface area 0,16m² *2
    control surface aspect ratio 0,66
    speed mach 6,5
    So you pumped up the speed and wing area while reduced the dead weight, no wonder why you wouldn't want to show people your values, but whatever.
    Quote Originally Posted by PeeD
    Didn't talk about SM-6. For the others, check Wiki für max. altitude
    Since when Wiki is considered a reliable source?
    SM-6 is SM-2 with active seeker while retain all the control surface and motors, how exactly does it have different operating celling ?
    not even LM products card has celling and max range values for PAC-3MSE, yet you somehow think such information will be available on wiki ?
    Quote Originally Posted by PeeD
    It's not about speed, at around 32km the Iskander would reach its airframe load limit with 30G. How intercept a 30G target with reasonable PK? With luck the interceptors airframe might survive 50G.
    High speed is what help you generate lift, so it always matter for a missile.
    And Iskander pulling 30G at 32 km ( actually 94G according to your own previous calculation) ? in the same way that F-16 will pull 28G at 50.000 feet as well ? So accurate.
    Last edited by garryA; 17th May 2017 at 05:07.

  2. #122
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    @garryA

    Too bad when your models given result 7 bigger than it actually is, and completely different in what way? do you think aircraft aren't affected aerodynamic force or missiles with aircraft like airframe such as Tomahawk, Kh-20 ,AGM-129 does not exist?.
    If F-16 is so complex why don't you put the numbers for Kh-20 in and check the result? Unlike you, i only used 5 degrees AoA and 12 degrees tail deflection, both are extremely small value.
    Look garry, you have grave understanding problems here and I bet your or your friend did the same nonsense for the F-16:
    What you put into the spreadsheet for Kh-20 is simply wrong! You assumed that the complete rear wing/stabilizer deflects... Thats not the case, its a conventional wing surface with flaps. This calculation model does not work in this case. Even if you would just calculate the flaps, you would have to skip the wings.

    Hence if the Kh-20 would deflect the whole rear stabilizer (like the T-50/J-20 deflect the whole vertical one) it might be able to pull those numbers. But this is nonsense as this model is completely unsuited for such a aircraft-like case. However you can try it with the Tomahawk, that would be a representative case.

    Nice try but F-16 airframe can sustain over 9G, wrong excuse. Try again . With your calculation an F-16 will be able to pull 9G at all altitude with the only limiting factors be the airframe G limit. Flight manual data shown that clearly not the case
    Ok next try and this one might open your eyes: The most important limitator is the pilot, so even if airframe could do 15Gs, the human can just do 9 for limited period. So what G's a manned airframe can do via its aerodynamic design comes at the 3 place after the two other limits...

    So you pumped up the speed and wing area while reduced the dead weight, no wonder why you wouldn't want to show people your values, but whatever.
    My values are for the Iskander-M... i.e what the Russians would use against THAAD. What's your wing area again? Something that would change the results with a tolerance of more than 10%?

    Since when Wiki is considered a reliable source?
    SM-6 is SM-2 with active seeker while retain all the control surface and motors, how exactly does it have different operating celling ?
    not even LM products card has celling and max range values for PAC-3MSE, yet you somehow think such information will be available on wiki ?
    So no one can know the max. altitude of those systems because they are classified and wiki numbers are wrong. The vlaue of 15km for PAC-3 is wrong too and the PAC-3MSE somehow improved that to 28km (i.e twice)?
    Look I have no problems if you state that those wiki numbers are for disinformation, but also other endo-atmospheric systems around the world do not go beyond 28km (e.g S-300PMU-2 with TVC). So what kind of discussion do you want here?
    The only system with altitude above that (via wiki) are the SM-6 and the Buk-M3 (TVC), both have 34km. So we could do a calculation for the SM-6 yes but not for those missiles I stated.

    High speed is what help you generate lift, so it always matter for a missile.
    And Iskander pulling 30G at 32 km ( actually 94G according to your own previous calculation) ? in the same way that F-16 will pull 28G at 50.000 feet as well ? So accurate.
    As said there is a structural strength limit of the airframe. We don't talk about 94G for the Iskander or 28G for the F-16, both are beyond airframe limits.
    The Iskander might do 30G maneuvering at maximum and the THAAD KV might be able to survive 50G max.
    However I doubt you get that.

  3. #123
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    Quote Originally Posted by PeeD
    Look garry, you have grave understanding problems here and I bet your or your friend did the same nonsense for the F-16:
    What you put into the spreadsheet for Kh-20 is simply wrong! You assumed that the complete rear wing/stabilizer deflects... Thats not the case, its a conventional wing surface with flaps. This calculation model does not work in this case. Even if you would just calculate the flaps, you would have to skip the wings.

    Hence if the Kh-20 would deflect the whole rear stabilizer (like the T-50/J-20 deflect the whole vertical one) it might be able to pull those numbers. But this is nonsense as this model is completely unsuited for such a aircraft-like case. However you can try it with the Tomahawk, that would be a representative case.
    Are you sure that the whole rear fin can't be deflected ? 100% positive that they are fixed ?
    Mind telling me what are in those photos ?





    Not only that their whole rear fin can be deflected, they also have flap in the main wing.
    The deflection angle i put for the main wing is 0 degrees so don't even try to bring it in
    Before you babbling about how all 4 surface need to deflect, their own example is of an AGM-65 where only 2 fins deflect and the rest are stationary





    Furthermore if the model is completely unsuitable for aircraft like configuration then how come they gave Storm shadow and AGM-86 as example ?



    Quote Originally Posted by PeeD
    Ok next try and this one might open your eyes: The most important limitator is the pilot, so even if airframe could do 15Gs, the human can just do 9 for limited period. So what G's a manned airframe can do via its aerodynamic design comes at the 3 place after the two other limits...
    Nice try but as usual, wrong. Flight manual indicates machines performer, not pilot limitation. If pilot is the limit factor then how come the manual show that F-16 can pull 9G at sea level?. So far it wasn't airframe G limit. It wasn't AoA limit.It sure as hell wasn't pilot limit.But your sheet clearly shown that F-16 can some how generate enough lift to pull more than 28G with little more than 5 degrees AoA, not even one third of its AoA limit. You said the values make sense, so explain it then :what caused the reduction from more than 9G at sea level to 4G at 50k feet if not lift ?


    Quote Originally Posted by PeeD
    So no one can know the max. altitude of those systems because they are classified and wiki numbers are wrong. The vlaue of 15km for PAC-3 is wrong too and the PAC-3MSE somehow improved that to 28km (i.e twice)?
    Look I have no problems if you state that those wiki numbers are for disinformation, but also other endo-atmospheric systems around the world do not go beyond 28km (e.g S-300PMU-2 with TVC). So what kind of discussion do you want here?
    The only system with altitude above that (via wiki) are the SM-6 and the Buk-M3 (TVC), both have 34km. So we could do a calculation for the SM-6 yes but not for those missiles I stated.
    Point is, in reality, the agility of missiles, aircraft are not high above 30 km. That why it is often regarded as altitude limit. However, if we take your calculation as correct (in other words maneuverability was never a problem) then SM-2 , SM-6 can both easily intercept target above 30 km as both of them will easily reach that altitude and more. SM-3 used the same MK72 booster and MK-107 dual thrust rocket motor as SM-2 and SM-6, added a small third stage, yet it reached altitude more than 500 km.


    There is no information for PAC-3MSE altitude either, so no reason to exclude it

    Quote Originally Posted by PeeD
    As said there is a structural strength limit of the airframe. We don't talk about 94G for the Iskander or 28G for the F-16, both are beyond airframe limits.
    The Iskander might do 30G maneuvering at maximum and the THAAD KV might be able to survive 50G max.
    However I doubt you get that.
    No problem, let talk about airframe limit then, why flight manual indicates that F-16 can't pull 9G at 50K feet while at the same time shows that it can pull 9G at sea level ?
    Last edited by garryA; 17th May 2017 at 10:15.

  4. #124
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    @garryA

    Are you sure that the whole rear fin can't be deflected ? 100% positive that they are fixed ?
    Mind telling me what are in those photos ?
    Well they move, I was wrong about that old relikt. Your spreadsheet input is right and it can theoretically pull 25G at that speed and altitude if the airframe would be able to endure it. Absolutely no hint that anything is wrong with that formula. But I wonder how your friend calculated the F-16 with its conventional wings?

    Before you babbling about how all 4 surface need to move they give an example of an AGM-65 where only 2 fin moves
    I took 2 fins for my spreadsheet calculation, check again... furthermore 2 can move or all four can move but 2 is also representative for 4 as the difference in negligible.

    Furthermore if the model is completely unsuitable for aircraft like configuration then how come they gave Storm shadow and AGM-86 as example ?
    Try to calculate a F-16 with that spreadsheet like your friend did, want to se how you want to do it...

    Nice try but as usual, wrong. Flight manual indicates machines performer, not pilot limitation. If pilot is the limit factor then how come the manual show that F-16 can pull 9G at sea level?. So far it wasn't airframe G limit. It wasn't AoA limit.It sure as hell wasn't pilot limit.But your sheet clearly shown that F-16 can some how generate enough lift to pull more than 28G with little more than 5 degrees AoA, not even one third of its AoA limit. You said the values make sense, so explain it then :what caused the reduction from more than 9G at sea level to 4G at 50k feet if not lift ?
    You have some logic problems here... A G load of 28 wont be reached by the F-16 ever, because the air frame would disintegrate first. Similarly the pilot will pass out at 12G before structural limit of lets say 15 is reached.
    So what are you talking about???
    Secondly show be how you put the F-16 into that spreadsheet...

    Point is, in reality, the agility of missiles, aircraft are not high above 30 km. That why it is often regarded as altitude limit. However, if we take your calculation as correct (in other words maneuverability was never a problem) then SM-2 , SM-6 can both easily intercept target above 30 km as both of them will easily reach that altitude and more. SM-3 used the same MK72 booster and MK-107 dual thrust rocket motor as SM-2 and SM-6, added a small third stage, yet it reached altitude more than 500 km.
    Yes. If the FCS allows it to fly past 25km altitude it will fly past, SM-2 (SM-3 anyway) and PAC-2 have the necessary kinematic power. However due to decreased PK due to low aerodynamic maneuverability this might be outside their operation regime, at least all sources talking about their max. altitude tell that. You are welcome to calculate their maneuverability at 28km, why not, it's possible that they have such a special operation mode hidden somewhere or that all sources are disinformation by the defense agency.

    No problem, let talk about airframe limit then, why flight manual indicates that F-16 can't pull 9G at 50K feet while at the same time shows that it can pull 9G at sea level ?
    ... Good god... First present a adequate F-16 input for that spreadsheet. Logically the reason is the thin air which cause stall at high AoA and likely also stability problems with nose pointing/flight safety.
    Why have I always to go so off-topic in discussions with you? Now we are talking about the F-16...

  5. #125
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    Quote Originally Posted by PeeD
    Well they move, I was wrong about that old relikt. Your spreadsheet input is right and it can theoretically pull 25G at that speed and altitude if the airframe would be able to endure it. Absolutely no hint that anything is wrong with that formula.
    According to sheet values:
    A missiles with Mig-19 like configuration will generate enough lift to pull 25g at 50.000 feet
    The F-16 generate enough lift to pull more than 28g at 50.000 feet. (7 times bigger than real value)
    Missiles generated the most lift to pull high G when their body is at 90 degrees with the airflow
    Yet, you see nothing wrong with it ? are you even serious ?

    Quote Originally Posted by PeeD
    But I wonder how your friend calculated the F-16 with its conventional wings?
    Try to calculate a F-16 with that spreadsheet like your friend did, want to se how you want to do it.
    It was me who input the data for F-16, there was even a photo of F-16 dimension and the spread sheet there if you wish to in put data by yourself.
    Weight: 22000 pounds = 9,979 kg
    Length: 15.06 meters
    Body angle of attack: 5 degrees
    Main wing area: 27.87 square meters ( can be checked by google, take less than 10 seconds )
    Angle of deflection for main wing: 0 degrees
    aspect ratio for main wing : 3.09
    Rear fin area: 2.97 square meters
    aspect ratio for rear fin: 4
    Angle of deflection for rear fin: 12 degrees
    Air density: 0.1974 kg/m3
    Speed: Mach 1.85
    I didn't even take into account added benefit of slat and flap yet the chart told me F-16 can generate over 28g at 50.000 feet

    And tell me how F-16 provide any less lift than Kh-20 wing ?





    Quote Originally Posted by PeeD
    You have some logic problems here... A G load of 28 wont be reached by the F-16 ever, because the air frame would disintegrate first. Similarly the pilot will pass out at 12G before structural limit of lets say 15 is reached.
    So what are you talking about???
    Nope. According to the sheet, F-16 even at 50K feet can generate enough lift to pull more than 28G with only 5 degrees AoA.We know that F-16 structure limit is 9G, pilots limit is 9G too.The available lift far excess the aircraft structure and pilots limit .That would mean nothing will stop the F-16 from pulling 9g at 50k feet. The AoA i used is only 5 degrees as opposed to 15 - 25 degrees limit in manual so you can't babbling about AoA limit either. So tell me then, why does flight manual shows that F-16 can only pull 4g at 50K feet ? or let me repeat my previous question :what caused the reduction of maximum G load from more than 9g at sea level to 4g at 50K feet if not lift ?

    Quote Originally Posted by PeeD
    Yes. If the FCS allows it to fly past 25km altitude it will fly past, SM-2 (SM-3 anyway) and PAC-2 have the necessary kinematic power. However due to decreased PK due to low aerodynamic maneuverability this might be outside their operation regime, at least all sources talking about their max. altitude tell that. You are welcome to calculate their maneuverability at 28km, why not, it's possible that they have such a special operation mode hidden somewhere or that all sources are disinformation by the defense agency.
    So why wouldn't the FCS let the missiles fly past that ?
    kinematic clearly wasn't the problem as all standard missiles can easily reach that altitude ( SM-3 used the same MK-104 motor and MK-72 booster can even reach 500 km altitude )
    According to your own calculation even the Iskander with its tiny fin and tube body can generate enough lift to pull 94g at 28km with the only limiting factor being airframe structure G limit. Airframe g limit doesnot change with altitude .So how is there any decrease in aerodynamic maneuverability at all for SM-2, SM-6 ? They will both be able to reach their maximum G limit at 28km just like they do at sea level since the lift generated will be far bigger than airframe limit

    Quote Originally Posted by PeeD
    Good god... First present a adequate F-16 input for that spreadsheet. Logically the reason is the thin air which cause stall at high AoA and likely also stability problems with nose pointing/flight safety.
    .
    BS.
    F-16 max AoA limit is 15 degrees at 9G and 25 degrees at 1G. I used 5 degrees to put in the sheet, that is not any where remotely close to the AoA limit. There will be no stall at 5 degrees AoA. Nevermind that it will be much harder for an F-16 with Lerx , flap , slat to stall.



    Furthermore i present adequate F-16 input since previous page, unlike you trying to hide your inputs so no one can double check

    Quote Originally Posted by PeeD
    Why have I always to go so off-topic in discussions with you? Now we are talking about the F-16..
    You are the one who brought up Iskander, also the one who brought up AIM-54 and ICBM, also the one who can't distingush between nose pointing and turning, you are not really in the position to criticize me about whether iam off topic or not.
    Moreover my question is completely justifiable. You said result from the sheet make sense. Then how come it gives F-16 available lift 7 times higher than what indicated in flight manual ?. Your excuse that their formular is inaccurate for aircraft like configuration doesnot works as they give an example of Storm shadow and AGM-86 both have very similar if not the same configuration as aircraft. Your second excuse that aircraft can't move their rear stabilizor doesnot work either since they clearly do.
    Last edited by garryA; 18th May 2017 at 10:45.

  6. #126
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    Ok I accept your values for the F-16 you input is reasonable and conservative.

    So we have a problem here with the formulas and manuals. I can't identify the problem, stealthflankers spreadsheet seems alright, the F-16 manual is real. Its possible that they talk about different things e.g instantaneous turn and sustained turn. Or some more complex problems. Surely fight tested manual data is more useful than formula generated calculation data.

    Maybe Fleemans book and his presented formula is wrong. Who knows, but you certainly raised doubts.

    Missiles generated the most lift to pull high G when their body is at 90 degrees with the airflow
    Yet, you see nothing wrong with it ? are you even serious ?
    I don't know why you made that graphics with missile at 90° to flow, complete nonsense. But its of course true that missile at 90° would create max. body Cn at 90°, but why this useless exercise?

    So why wouldn't the FCS let the missiles fly past that ?
    kinematic clearly wasn't the problem as all standard missiles can easily reach that altitude ( SM-3 used the same MK-104 motor and MK-72 booster can even reach 500 km altitude )
    According to your own calculation even the Iskander with its tiny fin and tube body can generate enough lift to pull 94g at 28km with the only limiting factor being airframe structure G limit. Airframe g limit doesnot change with altitude .So how is there any decrease in aerodynamic maneuverability at all for SM-2, SM-6 ? They will both be able to reach their maximum G limit at 28km just like they do at sea level since the lift generated will be far bigger than airframe limit
    Agreed, you can blame me for sticking to open source max. altitude data. I told you that you could do the exercise for them and I will be happy to see then, no problem.
    However the problem is that the interceptor always needs excess G capability to intercept with reasonable PK. So if the Iskander does 30G at 34km what would the interceptors be able to do if aerodynamic capability is not the limiting factor but the airframe? 50G? Is that 60% extra margin enough for a solid PK? There are inertia effects and that extra margin should be lower for two objects of similar speed but for SAM vs. aircrafts, extra margins of 300-500% are proposed instead of 60%. A big question is whether THAAD or any other ABM system must have roughly equal G capability or a vastly superior one.
    This game is much simpler for the Iskander.

    ____________
    Ok now I will try to find a mistake in stealthflankers spreadsheet.

  7. #127
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    I have found the error in stealthflankers spreadsheet. He has counted dynamic pressure as pascal or N/m² into the last part, the G calculation where he counted it (N) against kg. Hence the final values are wrong by the factor of 9,81, (too high).

    So let me turn back to you initial claim for too high Cl @ 24km altitude.

    Here are the corrected max. G results for Iskander @24km altitude:

    2,12G for the fins @22° AoA (twice higher results can be reached for higher AoA)
    8,9G for missile body at 15° AoA consistent with a shallow dive of a terminal stage at a depressed trajectory

    TOTAL: 11G (This number is for evasive maneuvering for an endo-atmospheric interceptor, without the use of the gas system)

    The question if the interceptor is faster than the mach 6,5 Iskander-M and how much faster it is for successful interception. The faster it is the higher G it must pull for a high PK, to match the turn performance of a target that need less G load for the same turn performance. How much that is is disputed sources vary from higher G by factor 3 to 5, however I think that the higher speed compensates a low turn performance, 0,5 to 1 as additional factor might thus be enough for a high interception PK.

    This is the Iskander-M input I used with the corrected spreadsheet of stealthflanker:
    dia 0,914
    length 7,28
    weight 1254kg
    missile body AoA 15°
    control surface deflection 20°
    control surface area 0,16m² *2
    control surface aspect ratio 0,66
    speed mach 6,5


    Edit: For a double check: the F-16 calculation the numbers also make sense now. It would be able to do about 2G under the 45k feet mach 1,85 conditions. Your 4G from the manual would be likely reached with all the other stabilization surfaces, flaps etc.
    Hence double check is also consistent and conservative.
    Last edited by PeeD; 19th May 2017 at 13:49. Reason: F-16 data

  8. #128
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    Quote Originally Posted by PeeD
    Its possible that they talk about different things e.g instantaneous turn and sustained turn
    No, sustained turn is when excess power larger or equal zero, so the line is even lower

    Quote Originally Posted by PeeD
    I don't know why you made that graphics with missile at 90° to flow, complete nonsense. But its of course true that missile at 90° would create max. body Cn at 90°, but why this useless exercise?
    It isn't useless, the equation should work in all situation unless stated otherwise. The way the equation and their graph is presented, missiles will be able to generate more and more G as it approaching 90°, which is nonsense as lift should start reduce at 45°. I used extreme value only because it would be easy to see
    Quote Originally Posted by PeeD
    I have found the error in stealthflankers spreadsheet. He has counted dynamic pressure as pascal or N/m² into the last part, the G calculation where he counted it (N) against kg. Hence the final values are wrong by the factor of 9,81, (too high).
    Good to know, but that still doesnot answer the main problem: "equation shows missiles to have better maximum G when AoA approaching 90°"

    Quote Originally Posted by PeeD
    So let me turn back to your initial claim for too high Cl @ 24km altitude.

    Here are the corrected max. G results for Iskander @24km altitude:

    2,12G for the fins @22° AoA (twice higher results can be reached for higher AoA)
    8,9G for missile body at 15° AoA consistent with a shallow dive of a terminal stage at a depressed trajectory

    TOTAL: 11G (This number is for evasive maneuvering for an endo-atmospheric interceptor, without the use of the gas system)
    There are a few things:
    a/ Our dead mass and AoA for missiles are very different. You have your reason, i have mine, and i can't really be bothered to argue about that now. But the different even if only around 50% is rather big

    b/ In atmostphere the off center gas system won't add much for any other purpose rather for nose pointing. Same case on all missiles. So it doesn't really belong to the discussion

    c/ 11g at 24 km is very different from 30 g at 50 km or 92 g at 28 km that you proposed earlier. Moreover i havenot done the calculation, but 11g at Mach 6.5 seem like missiles change direction very slightly


    Quote Originally Posted by PeeD
    The question if the interceptor is faster than the mach 6,5 Iskander-M and how much faster it is for successful interception. The faster it is the higher G it must pull for a high PK, to match the turn performance of a target that need less G load for the same turn performance. How much that is is disputed sources vary from higher G by factor 3 to 5, however I think that the higher speed compensates a low turn performance, 0,5 to 1 as additional factor might thus be enough for a high interception PK.
    It really depend on how many interceptors you launched and at what point does Iskander started its maneuver. But generally without thrust ( or with much lower T/W ),very high G maneuver is not exactly the game to play. Since you will lose most of your speed after the first turn.
    Last edited by garryA; 19th May 2017 at 15:04.

  9. #129
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    @garryA

    It isn't useless, the equation should work in all situation unless stated otherwise. The way the equation and their graph is presented, missiles will be able to generate more and more G as it approaching 90°, which is nonsense as lift should start reduce at 45°. I used extreme value only because it would be easy to see
    The equation works now with the F-16 and can be regarded as benchmarked. Your objection confusing. The formula uses Cn (not Cl), the normal force coefficient. You surely know what that is at 90°? Sit as a passenger in a driving car and put you hand out of the window. The moment your hand palm faces flow direction you will experience the biggest force. For G load direction does not count, a strange missile at 90° to the flow will experience the biggest decelerating G loads possible.

    a/ Our dead mass and AoA for missiles are very different. You have your reason, i have mine, and i can't really be bothered to argue about that now. But the different even if only around 50% is rather big
    So you get 50% lower results with your Iskander input and don't want to talk about? Good, however in a discussion about max. G of Iskander my input is withing max. possible condition and hence applicable. But well if you want to apply favorable inputs to get ~6 G max. and call that low G capability, good.

    b/ In atmostphere the off center gas system won't add much for any other purpose rather for nose pointing. Same case on all missiles. So it doesn't really belong to the discussion
    The TVC system at the rear of the R-73 AAM gives it large G pulling ability. We don't know enough about the capability of Iskanders gas system to dismiss it...

    c/ 11g at 24 km is very different from 30 g at 50 km or 92 g at 28 km that you proposed earlier.
    I proposed wrong values earlier due to a identified error in an else very good spreadsheet of a member here of a post of this forum. Your objections made me suspicious and the problem is solved now.

    However 11G is quite good for your claim that:"For comparision, the flanker airframe ( with LERX, blended body, negative stability and what not) has CL of 1.2 at Mach 1 and AoA of 18 degrees
    In short, the Iskander will need the lift coefficient around 70 times bigger than Su-27 for it to be able to pull 30G at Mach 6 and altitude of merely 24 km ."

    Now we have 11G (or 5,5 with your unknown input) instead of 30, but we are far away from a capability "70 times bigger than Su-27". With that 70 times claim your probably should have expected 0,1G for the Iskander...

    Moreover i havenot done the calculation, but 11g at Mach 6.5 seem like missiles change direction very slightly
    Change of direction maybe, but how about change of position at 2km per second? Whats really important is what a even faster ABM interceptor will need in G's for the same direction change...

    It really depend on how many interceptors you launched and at what point does Iskander started its maneuver. But generally without thrust ( or with much lower T/W ),very high G maneuver is not exactly the game to play.
    One game are hard G's one is a continuous position change to force course corrections to a ABM interceptor. Under the same input conditions, at 45km altitude, just 5km below midpoint apogee, the Iskander would still be able to do 0,6G continuous "bleeding" maneuvers.

    Since you will lose most of your speed after the first turn.
    I have proven in this thread that the Iskander must loose something like 3,5 mach numbers until impact by either heating only or additional maneuvering, while you have never proven that the Iskander would loose most of its speed after one high G maneuver. 3,5 mach numbers excess speed sure sound like a good maneuvering margin available.

  10. #130
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    Quote Originally Posted by PeeD
    The equation works now with the F-16 and can be regarded as benchmarked. Your objection confusing. The formula uses Cn (not Cl), the normal force coefficient. You surely know what that is at 90°? Sit as a passenger in a driving car and put you hand out of the window. The moment your hand palm faces flow direction you will experience the biggest force. For G load direction does not count, a strange missile at 90° to the flow will experience the biggest decelerating G loads possible.
    I told you already, nose pointing is not the same as turning. You cannot consider G load from deceleration the same as G load from changing in direction.
    Quote Originally Posted by PeeD
    So you get 50% lower results with your Iskander input and don't want to talk about? Good, however in a discussion about max. G of Iskander my input is withing max. possible condition and hence applicable. But well if you want to apply favorable inputs to get ~6 G max. and call that low G capability, good.
    Max possible condition depending on the dead mass and possible AoA. You think the deadmass of Iskander is 1254 kg. I think it is around 2307 kg.
    You think the AoA is 15 degrees at Mach 6.5. I think it should be lower and vice versa. I can't be bothered to argue about it with you due to the same reason that i am not really fond of talking about aerodynamic with you, it takes too much time to get a simple point across. Admittedly you did find the mistake in stealthflanker sheet by yourself (or with his help ..idk). But still. There are many things that you could easily double check before you argue with me. Such as nose pointing versus turning, the Kh-20, F-16 rear fin, the F-16 data that i put in the sheet ( since i already post that in previous page),the F-16 AoA, The SM-2 vs SM-6 design, Instantaneous versus sustainable turn ... etc. It isn't about being wrong (for example I wouldn't really mind if you make a wrong calculation ) but rather the fact that most of your mistakes can be checked very easy by yourself. Before you wrote your argument and having me argue against.

    Quote Originally Posted by PeeD
    The TVC system at the rear of the R-73 AAM gives it large G pulling ability. We don't know enough about the capability of Iskanders gas system to dismiss it...
    The side gas system is not the same as real TVC. For once TVC will provide thrust toward direction of travel. On the other hand,even if the gas system of Iskander belong to the main motor( TVC), there is still problem , you can't expect a single stage ballistic missiles with solid propellant to have much fuel or any fuel at all for terminal stage. Because the burn rate of solid propellant can't be changed. Unlike a jet engine ( or to a very lensser extend liquid fuel rocket ). In other words, while different design can have different burn rate, the burn rate for a specific design remain the same, always end after a certain time T. To get the Iskander out of atmostphere, reach speed of Mach 6, thrust will be very high with short burn time. Furthermore, missiles reached terminal velocity at burn out so while there could be some improvement in agility added from the TVC, there are reduction from the fact that missiles didn't reach their terminal speed=> less lift to perform maneuver. One reason for TVC on short range AAM is that they can turn right after leaving the rail, before they reached required speed. On the otherhand,most long range AAM don't use TVC as their motor would be burned out before they reach target most of the time.



    Quote Originally Posted by PeeD
    However 11G is quite good for your claim that:"For comparision, the flanker airframe ( with LERX, blended body, negative stability and what not) has CL of 1.2 at Mach 1 and AoA of 18 degrees
    In short, the Iskander will need the lift coefficient around 70 times bigger than Su-27 for it to be able to pull 30G at Mach 6 and altitude of merely 24 km ."

    Now we have 11G (or 5,5 with your unknown input) instead of 30, but we are far away from a capability "70 times bigger than Su-27". With that 70 times claim your probably should have expected 0,1G for the Iskander...
    You still don't seem to understand the purpose of lift equation
    If you paid attention, you will noiticed that i didn't calculate the CL of actual Iskander. I calculated the CL that it will need to perform specific maneuver that you proposed. And because the CL would be so ridiculously big, the conclusion is that such maneuver in such condition isn't possible.
    http://forum.keypublishing.com/showt...46#post2390546
    http://forum.keypublishing.com/showt...34#post2390934
    Furthermore i don't think my input is that vague, Your input was 1245 kg ,mine was 2307 kg. Then there is also the fact that your calculation of wing area is 3 times bigger than mine (admittedly partly because i forgot and used only 1 fin). Since G and Cl related to mass and fin area, you can easily see where the different come from.
    Moreover, your calculation based on CN not CL, so you will have to divide that total force into drag and lift components since they are not the same things. Otherwise you will reach the same conclusion that missiles are most manuverable when their body is at 90 degrees with the airflow. Or the conclusion that all deceleration is the same as changing in direction.

    Anyway, coming back to my estimation, if i used your new value: 1234 kg instead of 2307 kg ,5 G instead of a 30 G, wing area of 0.32 m2 instead of 0.11 m2
    Lift = CL* air density* 0.5*velocity^2 *wing area
    1245*9.8*5 = CL * 0.046*0.5 * (297*6.5)^2 * 0.32
    61,005 = CL* 27429.4706
    CL = 2.22
    As you can see, the required CL change significantly when you don't have extreme value like 30G at 24 km
    Quote Originally Posted by PeeD
    Change of direction maybe, but how about change of position at 2km per second? Whats really important is what a even faster ABM interceptor will need in G's for the same direction change...
    Not all anti ballistics missiles are faster, many of which are slower. Before you say how can you intercept something going faster than yourseft. Remember that ABM is like throwing a stone in front of the car running so the car will colide with it, the intercetor doesn't actually chase their targets. Also , how do you come up with changing direction of 2 km per second ?

    Quote Originally Posted by PeeD
    I have proven in this thread that the Iskander must loose something like 3,5 mach numbers until impact by either heating only or additional maneuvering, while you have never proven that the Iskander would loose most of its speed after one high G maneuver. 3,5 mach numbers excess speed sure sound like a good maneuvering margin available.
    This F-16 lose 1200 Ps every second at 4G, Mach 1.85. AoA limit of F-16 is 15° so quite similar with AoA you used for Iskander. The Iskander move at 3.2 times faster than F-16 (Mach 6.5) and doesnot have any thrust to counter excess drag. How much speed do you think Iskander will lose consider that drag force raise with speed (proportional to square of velocity) and deceleration is proportional to resultant force ?.(which is why thrust is needed).
    Moreover, it not just terminal speed that is important, cruising speed is quite important too. Whether you fly at last 15-20 km with Mach 6 or Mach 3 make quite a big different even if the terminal speed is Mach 3
    I honestly don't get your logic. You think Interceptor with very high T/W will depleted of their kinetic energy if their targets making maneuver as low as 1.5G , while at the same time you think that ballistic missiles with no thrust can continously make 11G maneuver without worry about significant decrease in kinematic energy.


    Quote Originally Posted by PeeD
    One game are hard G's one is a continuous position change to force course corrections to a ABM interceptor. Under the same input conditions, at 45km altitude, just 5km below midpoint apogee, the Iskander would still be able to do 0,6G continuous "bleeding" maneuvers.
    whatever game you try to play, interceptors missles are the one with thrust hence sustain turn.
    Last edited by garryA; 20th May 2017 at 06:09.

  11. #131
    Join Date
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    @garryA

    I told you already, nose pointing is not the same as turning. You cannot consider G load from deceleration the same as G load from changing in direction.
    Moreover, your calculation based on CN not CL, so you will have to divide that total force into drag and lift components since they are not the same things. Otherwise you will reach the same conclusion that missiles are most manuverable when their body is at 90 degrees with the airflow. Or the conclusion that all deceleration is the same as changing in direction.
    No problem garry. Then, for you, Mr. Fleeman, his book and me are wrong on this. Fleeman counts the total G load, as we did for the Iskander, against the total G load of a aircraft in his AAM vs. aircraft scenario.

    Admittedly you did find the mistake in stealthflanker sheet by yourself (or with his help ..idk)
    as said by myself... ask him if you don't believe it...

    The side gas system is not the same as real TVC. For once TVC will provide thrust toward direction of travel.
    In mechanics it's the same minus the forward thrust.

    you can't expect a single stage ballistic missiles with solid propellant to have much fuel or any fuel at all for terminal stage. Because the burn rate of solid propellant can't be changed. Unlike a jet engine ( or to a very lensser extend liquid fuel rocket ). In other words, while different design can have different burn rate, the burn rate for a specific design remain the same, always end after a certain time T. To get the Iskander out of atmostphere, reach speed of Mach 6, thrust will be very high with short burn time. Furthermore, missiles reached terminal velocity at burn out so while there could be some improvement in agility added from the TVC, there are reduction from the fact that missiles didn't reach their terminal speed=> less lift to perform maneuver. One reason for TVC on short range AAM is that they can turn right after leaving the rail, before they reached required speed. On the otherhand,most long range AAM don't use TVC as their motor would be burned out before they reach target most of the time.
    Yes and the Iskanders gast system is a small liquid restartable one.

    Anyway, coming back to my estimation, if i used your new value: 1234 kg instead of 2307 kg ,5 G instead of a 30 G, wing area of 0.32 m2 instead of 0.11 m2
    Lift = CL* air density* 0.5*velocity^2 *wing area
    1245*9.8*5 = CL * 0.046*0.5 * (297*6.5)^2 * 0.32
    61,005 = CL* 27429.4706
    CL = 2.22
    As you can see, the required CL change significantly when you don't have extreme value like 30G at 24 km
    Fortunately you admit mistakes like number of fins, same as I admit mistakes. However in this case you should compare that "mild scenario" Cl with the complete airframe, twice higher, Cl of the Su-27 (1,2), don't you?

    Not all anti ballistics missiles are faster, many of which are slower. Before you say how can you intercept something going faster than yourseft. Remember that ABM is like throwing a stone in front of the car running so the car will colide with it, the intercetor doesn't actually chase their targets. Also , how do you come up with changing direction of 2 km per second ?
    You told this and it sounds reasonable against non maneuvering targets, I have the same theoretical thinking. What do you think happens if the Iskander does a mild turn with low G at 40km altitude that equals to a 5G hard turn at a delta of speed of mach 3,5 and a distance to interceptor of 50km?
    This is like the fastest WWII propeller aircraft trying to intercept a MIG-25 which did a lets say 2G turn at 50km distance. Would the WWII fighter be able to meet with the mach 3 MIG-25 after the 50km or would the resulting position change at the rendezvous point be too high for it to catch up? If it would be able to catch up, how much of its range/kinematic potential would have to be used for that task and how much would be left for its range capability i.e motion directly towards it?
    Would the active thrust be sufficient to compensate the speed losses due to reactive course changes in denser atmosphere?

    These are some of the problems a slower interceptor would have to face against the Iskander.
    (regarding your question: I said position change at 2km/s (Iskander) not of 2km/s)

    This F-16 lose 1200 Ps every second at 4G, Mach 1.85. AoA limit of F-16 is 15° so quite similar with AoA you used for Iskander. The Iskander move at 3.2 times faster than F-16 (Mach 6.5) and doesnot have any thrust to counter excess drag. How much speed do you think Iskander will lose consider that drag force raise with speed (proportional to square of velocity) and deceleration is proportional to resultant force ?.(which is why thrust is needed).
    Which imperial dimension would P be? You mean FPS? If yes a turn of 4G for a second would cause a loss of speed from mach 1,85 to mach 0,85? I'm not familiar with speed losses due to to turns but that one would sound like nonsense.

    I honestly don't get your logic. You think Interceptor with very high T/W will depleted of their kinetic energy if their targets making maneuver as low as 1.5G , while at the same time you think that ballistic missiles with no thrust can continously make 11G maneuver without worry about significant decrease in kinematic energy.
    No. I said the course correction losses of the ABM interceptor would be higher due to the atmosphere, and the thrust you want to use to compensate those losses must come from somewhere --> range/altitude performance will decrease.

    I proposed a Iskander with continuous course changes of 0,5-1,5G and now due to the data basis I have, several up to 10G maneuvers to evade a endo-atmospheric ABM interceptor. As said I'm open for a representative formula which estimates speed losses due to certain turn rates.
    The funny thing is that any country with offensive TBMs/BMs also needs a ABM capability and I challenge you to get a picture of ABM potential/physics.

  12. #132
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    Quote Originally Posted by PeeD
    No problem garry. Then, for you, Mr. Fleeman, his book and me are wrong on this. Fleeman counts the total G load, as we did for the Iskander, against the total G load of a aircraft in his AAM vs. aircraft scenario.
    Then for you. NASA and me are wrong on this. If you want to consider deceleration and turning is the same thing then it your choice. I would rather seperate them since i don't want to have the illusion that missiles at 90° to the air flow have the most maneuver capabilities.

    Quote Originally Posted by PeeD
    In mechanics it's the same minus the forward thrust.
    That the whole point, TVC will propelled the missiles toward the new direction that the nose was pointing at. Which is why they are useful for short range AAM

    Quote Originally Posted by PeeD
    Yes and the Iskanders gast system is a small liquid restartable one.
    The main motors is solid rocket. Moreover, we don't even have a picture of Iskander gas system, nor do we know for sure if it has one or not. How exactly do you know it is a small liquid one ? what if it is consist of many small solid pulse motors ?

    Quote Originally Posted by PeeD
    Fortunately you admit mistakes like number of fins, same as I admit mistakes. However in this case you should compare that "mild scenario" Cl with the complete airframe, twice higher, Cl of the Su-27 (1,2), don't you?
    The different in this case can atleast be explained due to significantly higher Reynold's number at Mach 6.5 vs Mach 1. On the other hand, if your CL is like 78 times bigger. There is no possible excuse.



    Quote Originally Posted by PeeD
    You told this and it sounds reasonable against non maneuvering targets, I have the same theoretical thinking. What do you think happens if the Iskander does a mild turn with low G at 40km altitude that equals to a 5G hard turn at a delta of speed of mach 3,5 and a distance to interceptor of 50km?
    This is like the fastest WWII propeller aircraft trying to intercept a MIG-25 which did a lets say 2G turn at 50km distance. Would the WWII fighter be able to meet with the mach 3 MIG-25 after the 50km or would the resulting position change at the rendezvous point be too high for it to catch up? If it would be able to catch up, how much of its range/kinematic potential would have to be used for that task and how much would be left for its range capability i.e motion directly towards it?
    Would the active thrust be sufficient to compensate the speed losses due to reactive course changes in denser atmosphere?
    If you go faster, you will need higher G for the same amount of turn rate. In otherword if Iskander do a mild turn at Mach 6, then Interceptor at Mach 3.5-4 will have to do even more mild turn to match the turn rate. Moreover, as elaborated before, Interceptor missiles are not trying to chase the ballistics missiles. They are trying to intercept. Ballistics missiles will come toward them anyway, the question is what point should they fly toward. Furthermore, your scenario also doesn't demonstrate the problem we have at hand. The normal Mig-25 has thrust. A ballistic missiles in mid-terminal phase has no forward thrust left. So every maneuver will consume significant amount of speed.While interceptors have very high T/W so they can sustain their maneuver.

    Quote Originally Posted by PeeD
    (regarding your question: I said position change at 2km/s (Iskander) not of 2km/s)
    You have not even calculate the turn rate yet. How do you come up with the position change of 2 km/s?

    Quote Originally Posted by PeeD
    Which imperial dimension would P be? You mean FPS? If yes a turn of 4G for a second would cause a loss of speed from mach 1,85 to mach 0,85? I'm not familiar with speed losses due to to turns but that one would sound like nonsense.
    Specific excess power is (Thrust[lbs]-Drag[lbs])*Velocity[ft/sec]/Weight[lb] .The units are ft/s. It represents the climb or decent rate that can be sustained in that moment. Climb or Descent angle is found by comparing the Ps with the total V.
    Now, to determine the acceleration/deceleration you alter the formula a bit.
    (T-D)/W
    There is formular to measure drag in Fleeman book, you can do it yourself. Or you can use normal force to determine drag


    Regarding the value of -1200 for f-16, you can find it in the chart


    Quote Originally Posted by PeeD
    No. I said the course correction losses of the ABM interceptor would be higher due to the atmosphere, and the thrust you want to use to compensate those losses must come from somewhere --> range/altitude performance will decrease.
    I proposed a Iskander with continuous course changes of 0,5-1,5G and now due to the data basis I have, several up to 10G maneuvers to evade a endo-atmospheric ABM interceptor
    To generate the same amount of lift for turning. It will cost more at higher altitude, even though the air density is thinner. The reason is that, you will either need higher speed or higher AoA for the same amount of lift at high altitude compared to sea level. That will generate more drag. The drag raise due to speed is faster than it does for air density

    If you look at the manual page i posted earlier. F-16 can sustain much higher G at low altitude. Moreover, you don't have several 10G maneuver, you have 10G normal force that need to be divided into drag and lift components. Furthermore, every maneuver will cost speed, less speed mean less lift to perform sequences maneuver.

    Furthermore, the energy for turning of ballistic missiles also need to come from somewhere, you cannot pretend like its range and speed are not affected. If we go with your way of estimation the air to air missiles will be able to chase aircraft around making several turns before their speed run out. Which is clearly not the case.

    Quote Originally Posted by PeeD
    As said I'm open for a representative formula which estimates speed losses due to certain turn rates.
    The funny thing is that any country with offensive TBMs/BMs also needs a ABM capability and I challenge you to get a picture of ABM potential/physics.
    I posted formular already. If you want to find the values , you can do it by yourself. Iam not gonna do all the Math for you, iamdon't have that much free time.
    Last edited by garryA; 23rd May 2017 at 09:53.

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