Seeker Missile Launch Prevention

I ask because I don't know but are the real missiles (R-3, R-60, etc.) prevented from firing based on their seeker state or not? I can't find anything in the manuals or technical literature that says "if the missile won't fire it might be because seeker didn't have good enough signal, improve and try again" on the other hand I don't see the opposite "warning missile shoots when you push the button whether or not seeker signal is good or not".

I have a suspicion that it's free fire but I'm not sure and was wondering everyone else's thoughts.

Are we speaking MIg-21 Bis specifically or combat aircraft in general?

The bis but comparisons to other systems might be helpful. Did prevention of launch tech exist at all, rare, mixed, common, always?

It could be aircraft dependent.

AFAIK, on the F-16 and F-117 there is no protection except the mater arm switch. Using the stories form books like Viper over the storm or Palace Cobra, You kept you Mater arm on safe/training until you where ready to use that weapon to help minimize the chance of inadvertent weapons release.

Working on aircraft with live weapons, you where not suppose to put anything in front of the aircraft if it had forward firing munition (including missiles).

It seems to be a very common feature among Russian aircraft, with varying abilities of being overridden by the pilot. For example the Ka-50, Su-27 (if I remember correctly), MiG-29 (same as the Su) and so on have these types of systems as well. Western aircraft seem to be much more trusting on their pilots for safety.

It seems to be a very common feature among Russian aircraft, with varying abilities of being overridden by the pilot. For example the Ka-50, Su-27 (if I remember correctly), MiG-29 (same as the Su) and so on have these types of systems as well. Western aircraft seem to be much more trusting on their pilots for safety.

Do those systems prevent the missile from firing base on the missile seeker talking to the aircraft, or do the limit the missile launch base on predetermine range tables?

Mig21bis manual for R60 for example, states that pilot will be able to launch when one or more missiles send positive ir target signal.

What might be intereseting to know is that, for example you had selected 1-2 station as primary launching pylons, but if missile which is on 3-4 gets the target signal (and those on 1-2 do not), it will be the one which will launch first.

Do those systems prevent the missile from firing base on the missile seeker talking to the aircraft, or do the limit the missile launch base on predetermine range tables?

I can answer you only regarding Mig29... LA signal is generated by the range finder (radar/eos) + target signal by missile. However if you do not use (or range reading is disturbed for some reason) radar/eos, pilot can launch when missile sends positive target signal to aircraft.

Vatikus, source for R-60?

It can be difficult to separate cases where book text says "you are allowed" by rule of command, "you are indicated" by signal light, and "you can" not physically prevented.

I have gotten a little into SAMOLOT MiG-21bis (VERSJA 75A) Opis techniczny uzbrojenia, but my Polish is nonexistent. If someone speaks it natively reading would go much much faster. I'm trying to find clues of any kind of thresholding built into the R-3S. If it exists it might be in the missile or the airplane.

During radar self-test R-3R missile seeker is tested (port inboard priority) and tone sounds can be heard to verify seeker works. I believe tone comes from missile as selected to fire by weapon panel (might not equal to station # if that station is not priority type or is absent). In cases of salvo selection, port side missile?

If salvo is selected 1-2 then only 1-2 can be launched. The system should not skip 1-2 to shoot 3-4 simply based on seeker response. In case of hang fire the system will continue to attempt to shoot the hung missile until selection is changed to try to shoot something else.

It is said that emergency launch will not have missile guidance but prox fuze will function. I'm not sure what would happen if emergency launch button is pressed with good seeker signal, guided or not? Text says no but it presumes that normal button already failed. Does emergency launch deliberately disable guidance or is it just very likely that there is no guidance present in cases where emergency launch would be used. Both seem possible, deliberately off seems more likely, otherwise a "shoot and pray" IR missile would go bananas.

The R-3S must contend with launch conditions where range info is not available as all IR missiles must. Manuals constantly reference listening for the best tone strength. In DCS it is binary yes/no instead of a smooth ramp. Low altitude attack, clouds, sun in frame, etc. should give us ample noise even with no target present.

These older IR missiles are of spinning filter variety that seeker-point by maximizing signal and guide by minimizing seeker vector angular velocity. If the missile is thresholding then it has limited info to work with. The best it has is total signal amplitude and comparing min-max on reticle mask phasing. Any practical threshold would make it nearly worthless in low altitude attack and any threshold for a cluttered environment might as well not even be there.

It does say to attack transport (piston) aircraft by being below (cold sky). Piston have the weakest heat signature and looking down is the most cluttered. There's no mention of how to attack piston at low altitude, the most difficult situation for signal.

All of the mention of "if missile doesn't shoot 2s after holding button, safety and break away immediately" is really suspicious. If tone thresholding was really a thing it would say to keep trying until normal abort range. The way it's stated speaks to me like "if it ain't gone in 2s, you have a misfire or hang... this missile will not be firing today" like a serious mechanical fault. Although that could be a bad seeker too which would be compatible with signal thresholding to shoot.

It just occurred to me L-39 carrier R-3S. I want to know if it shoots on press or inhibits. L-39 inhibits on G "Don't shoot" light but otherwise is free to shoot R-3S at any time. Btw MiG-21bis "launch" light on ASP is also tied to G meter and will not shine if G is too high. No idea if launch light has anything to do with the physical ability to shoot though. If L-39 modeling is correct then R-3S itself has no inhibit launch built in. MiG-21 the airplane might still.

Frederf,

my source is technical manual for r60 of yuaf mig21bis. By reading it the system is done as such as to try to enable successful launch. So if one missile fails to launch, you do not need to switch anything, the system will skip it... if you select pair launches, pair which has locks on both missiles has priority over switch setting, etc.

Of course, if you have mixed missile types, you need to switch manually, as mentioned logic only works inside same type.

As for launching w/o lock or ejecting missiles... you have extra button: Emergency A2A missiles launch button (located behind the stick where pitot heaters switches are)

I could see that for R-60 as it can be double-racked and it is a newer design than R-3. Para 240 states "Should some missiles (or pair of missiles) fail to shoot off, set the armament selector switch to the position corresponding to the next-in-turn missile (or pair of missiles) and push the firing button another time." which says maybe it's physically required to bypass a hang. There is some Polish 75A manual (1982) which has a clearer description of failures to fire but I struggle to find it again. This manual only understands R-3, R-55, and R-13M.

All of the above might be true. Different models of 21bis or different missile types may have significantly different behavior. I would like to understand R-3S/R-3R most I think (no idea why) but all info is appreciated.

Playing with L-39 R-3S brings up another idea, seeker auto-thresholds and locks onto target and follows him many degrees sideways (20-30 deg maybe). In -21 module missile never really locks a moving seeker head. You move seeker ~1 deg away from target the tone stops. Maybe -21 module is correct and seeker is caged to bore until launch but L-39 behavior disagrees for same missile.

I know about the emergency launch button. I'm asking if the missile has lock and you press the E.L. button does the missile launch guided or unguided. Also it says it launches "all missiles" is it all selected (usually one) or every single missile on board?

Yes, each missile type has own launcher which is attached to the hardpoint. And launcher is the one which dictates the missile launching logic through its relays. Unfortunately I do not have any detailed info on the APU-13 series (launcher for R3 & R13).

Regarding the seeker fov... the lock fov is quite acceptable from my experience... However I do not know how is granulation of sound lock volume in real life. In DCS we have prety much on/off past 2.5deg.

For the E.L., the missile launches in the state it is, and you need to press button for every missile (if you have selected pair 1-2, you need 2 presses or 4 in case of double r60 launchers).

Playing with L-39 R-3S brings up another idea, seeker auto-thresholds and locks onto target and follows him many degrees sideways (20-30 deg maybe). In -21 module missile never really locks a moving seeker head. You move seeker ~1 deg away from target the tone stops. Maybe -21 module is correct and seeker is caged to bore until launch but L-39 behavior disagrees for same missile.

Yes, R-3S missile seeker is caged during launch ( the same front rudders and back gyroailerons ), uncaged, according manual, 0.5-0.7 sec. after launch. FOV for seeker mirror is -+ 1,65 deg. ( 3,3 total ). Mirror gimbal can be move -+20 deg. so total seeker FOV after launch is 43,3 deg.

The same about R-60, R-60M and R-13M, their's seekers are caged until launch. Mirror FOV for R-60 is 5 deg. total, R-60M 8 deg. total, R-13M 3 deg total. On newer aircrafts in R-60M case, is possible target cueing manualy by button on the control stick ( MiG-23 ) or automaticaly by weapon system ( MiG-29, Su-27 ), and then mirror gimbal is uncaged.

For the E.L., the missile launches in the state it is, and you need to press button for every missile (if you have selected pair 1-2, you need 2 presses or 4 in case of double r60 launchers).

According polish MiG-21Bis pilot manual if you have weapon switch in position 1-2 or 3-4 both missile will fired after pressing EL button, if double launchers are in use, pilot need press EL button twice ( firing first pair and then second ).

It can be difficult to separate cases where book text says "you are allowed" by rule of command, "you are indicated" by signal light, and "you can" not physically prevented.

I understand quoted manual ( Polish is my native language ) this way: for all missiles exist physical barier preventing from fire, this is "lock on" signal from seeker ( no "lock on", no missile engine start command ), for R-3S/R-3R is additional barrier for g-load over 2 ( blocking mechanismus ). For R-60 and R-60M generally no g barrier ( both can be fired up to 8g ), for R-55 ( up to 5g ) and R-13M ( up to 3,7g ) pilot have to remember about limitations because no technical devices for blocking over g fire.

According polish MiG-21Bis pilot manual if you have weapon switch in position 1-2 or 3-4 both missile will fired after pressing EL button, if double launchers are in use, pilot need press EL button twice ( firing first pair and then second ).

I stand corrected. I went and reread the yuaf manual and you are correct.

Always good to hear from foxbat.

I was comparing L-39 R-3S to MiG-21bis R-3S behavior. Is L-39 modeling of free seeker tracking up to 20° off bore before launch correct because L-39 is built different than -21 or wrong because R-3S is always caged before launch? L-39 dev does good modeling on many systems so I watch its behavior. Maybe L-39 is special aircraft which is sending uncage command to missile while still on rail (is possible?).

I am satisfied with your interpretation of blocking of motor ignition by seeker threshold. It is interesting that G limit is also physical blocking on R-3 but not on other missile.

For the E.L., the missile launches in the state it is, and you need to press button for every missile

I believe this, launching up to 6 missiles at once would have a bad effect on the engine. You say "in the state it is" will the missile uncage for normal guidance with EL or prevented from uncaging in flight?

Yes lock sound is binary tone/no-tone but this is a limitation of simulation I think. Is tone heard quietly from background which changes in headset when on target or is silenced until tone is some high level? I don't know. A tone which changes smoothly with angle away and distance (if accurate) would be a nice detail.

Difference between L-39 and MiG-21, well I never was reading anything regarding Albatros ( although I have some bunch of papers ). But situation when the same missile working a bit different on different aircrafts is possible, e.g. R-60M on Fishbed have blocked seeker, on Fulcrum not, so maybe reason is in the difference in weapon system capabilites. Maybe RP-22SM requires seekers looking straight ahead , because this is only situation, when she is able work out launch zones. On L-39 weapon system generally don't exist, it's just few electrical connections and switches and g limiter. No weapon computer ( whatever analog or digital ), no launch zones calculating..... just power on and shot.

Emergency missiles launch is just powering missile engine, no seeker power on, ailerons are blocked in 0 deg. position. Apart engine only time self-destruction mechanism is working.

About lock sound everything is very clear. R-3S, R-13M, R-60's missiles have bulit-in sound generator, which transforming electrical signals from seeker into sound. Intensity of that sound depends directly from lock signal strength, and pilot is able define how stable is target tracking by missile seeker. R-3R have as well some kind of "lock on" sound modulation because in missile description is wroted that seeker generating sound from 60Hz to 300Hz. And one more interesting stuff: R-3's bulit-in sound generator produces "noise" sound when missiles are power up and no "lock" signal ( and we have this in L-39 module ). In pilot's flight manual is stated "after appear maximum sound signal and light "Launch" is on, missile firing is allowed ", so seems that we should have in game some sound modulation.

I did some deeper reading of that weapon manual, so I have to write corrections to my last post, R-55 is more complicated like I thought. S-59 seeker is cooperating with BS-59M "connection box" instaled inside aircraft fuselage between frames 12 and 13. Missile seeker can be set in one of four modes: basic "Electric lock" seeker mirror along the longitudinal axis, "Horizont" ( seeker mirror is set 4,5 deg up ), "Altitude correction" ( seeker mirror is set 6,5 deg down ), "Exceeding" ( seeker mirror is set 6 deg up ). From the manual text appears that all that additional seeker settings are pre seted, but no words about purpose of that modes. It seems that missile seeker mirror is not caged before launch, because manual is saying "when gimbal will exceeds 20 deg from axis then BS-59M will produce "Lock on drop" signal and seeker will back to initial position". According MiG-21Bis pilot's manual, R-55 launch requiring only weapon system allow command - lamp "Ready 55 left" or "Ready 55 right", no word about sound signal.

Now few words about over g blokade. This function is provided by transmitter called MP-28MT, which produces signals for weapon system when R-3S, R-3R and R-13M missiles are hung under wings. MP-28 cooperate with altitude sensors WS-5500 and WS-12000, because maximum g value is change depending height. For R-3S and R-3R missiles maximum launch g is 2 on heights up to 12000 m, and 1,6 g for altitude over 12000 m, for R-13M is 3,7 g at all heights. In over g conditions MP-28 sends signal which block signals from launch button, and block "Launch" lamp.

So seems that only in R-55 case pilot have to remember about missile's g limitation and only R-55 have uncaged seeker before launch.

Excelent as always Foxbat.

It is said in manual that emergency launch also proximity fuze are working. R-3S and R-3R fuzes are different? Proximity for S and contact for R.

I couldn't believe 22 seconds time for R-3S... but it can't be lock time. It must be time to settle since power on switch from wall panel. AIM-9B was 11s but it was easier to build copy with longer time.

Honestly I not sure, in weapon manual is just stated that electric voltage is given to rocket engine igniter and ailerons control system and seeker is not power on. This is not combat launch, no target tracking so for me logically no need to power on proximity fuse but I can be wrong.

Both missiles have self-destruction timer ( 25-26 sec. after launch for R-3S and 26-34 sec. for R-3R ), contact fuse on the ailerons tips ( 4 pieces ) and optical proximity fuse for R-3S ( two independent channels ) and radio proximity fuse for R-3R ( two channels as well ).

Yes, according "papers" this is no less like 21 sec. of guided flight time. That why R-3S cannot be call a simple reverse enginering of AIM-9B. R-3S wasn't first Soviet IR missile, they had lot of technology in that matter. So why they copy AIM-9?, well Soviet IR missiles had one problem in that time - very complicated seeker construction. Soviet were suprised how simple,durable and effectiv Sidewinder seeker was. First production variant was R-3 ( straight copy of AIM-9B ), but production run was very short. Engineers changed many elements inside, but retained guidance seeker. Main change was new gas generator and new turbo generator. After that change missile's systems got twice more energy on board to power on systems, from 11 sec. to no less 21 sec..

Btw., I found lately nice photos of PARG-13MWW front ( antenna ) part.

From pilot's instructions "249. If the missiles have failed to shoot off the launcher in response to actuation of the firing button by the trigger lever, emergency launch may be used. To do so, depress the MSL, RGM EMERG. LCH button; then all the missiles will shoot off simultaneously and fly on an almost ballistic trajectory (no homing will be accomplished, but the proximity fuzes will stay operative)."

That good find Frederf :thumbup:.

But I think there can be a difference between EL after unsuccessful combat launch, and "normal" EL ( n.e. before emergency landing ). In first case all systems were already on, just engine didn't start from some reasons. In second case no weapon system activity, no communication between missile and aircraft, only signal to ignite missile's engine.

Anyway I found clear statement in manual text that R-55 is fired without sound lock signal, only lights indicating readiness for launch.

Explains why lights were installed!

Good theory on partial system activation. It wouldn't need to be modeled unless missile engine problems is included as a failure mode. I assume if missile launch by joystick button is blocked it blocks all systems, not just engine.

Well, honestly I don't think that any more complicated procedures will be modeled in predictable future, but generally this is interesting things, I saw few pictures with missiles after "dead" launch. From reality point of view this is nice addition to game ( but maybe only for some purist ).

I think this is aim of EL instalation work. EL circuits bypassing weapon system connections in order to simplifie whole operation and save time. EL button just igniting rocket engine and switches on aileron blokade ( missile should keep straight flight to avoid collision with aircraft ). In R-3S description I found information that engine have double electric igniters. So maybe first one is for "normal" launch and "normal" EL, and second is for forced launch after that first unsuccessful.