Sparrow II active radar homing missile

[Heatloss]

Think they'd be able to make an 8" diameter X-band seeker that early?

A K-band seeker would be more or less worthless.

The Canadian document for it explicitly states attenuation of 1/10 db/mile to water in the atmosphere. K used to encompass Ku and Ka, and given that attenuation of 1/10 db/mile, I suspect it's a low Ku band seeker, so not far off from the upper bounds of X, which would suffer less against clouds and rain unlike the other frequencies in the K band.

Attenuation would be high in clouds, but that's something experienced by X band radars too. I wouldn't call it worthless.

 

[overscan (PaulMM)]

The Canadian document for it explicitly states attenuation of 1/10 db/mile to water in the atmosphere. K used to encompass Ku and Ka, and given that attenuation of 1/10 db/mile, I suspect it's a low Ku band seeker, so not far off from the upper bounds of X, which would suffer less against clouds and rain unlike the other frequencies in the K band.

Attenuation would be high in clouds, but that's something experienced by X band radars too. I wouldn't call it worthless.

Yep, the K band used for 1959s seekers is the low centrimetric range near X band not milimetric. It eases seeker design at small diameters a bit.

 

[overscan (PaulMM)]

You mean in general?

Before doppler beam sharpening Ku band radars were preferable for air to surface / ground mapping as the smaller wavelength was able to give higher resolution mapping, in addition to allowing smaller antennas with good gain (which was more relevant to missiles).

With the advent of multirole aircraft, the drawbacks to Ku band meant a general switch to X band with software techniques to improve resolution of mapping.

 

[Heatloss]

in addition to allowing smaller antennas with good gain (which was more relevant to missiles).

This was the answer. I realize you already answered it, so I deleted my comment. Sorry, I'm tired and I didn't read closely enough.
I get the other advantages to Ku/Ka over X, I just wasn't aware of that one and it didn't register when I read that.

 

[Scott Kenny]

I did just come to one potential benefit from continuing to develop Active Sparrow:

Datalinks.

Datalinks allowing both activation of the radar well after launch, and more importantly to provide midcourse guidance updates.

Which may allow for packing a Phoenix range capability into a small diameter missile sooner than AIM152.

 

[Larcrivereagle]

I did just come to one potential benefit from continuing to develop Active Sparrow:

Datalinks.

Datalinks allowing both activation of the radar well after launch, and more importantly to provide midcourse guidance updates.

Which may allow for packing a Phoenix range capability into a small diameter missile sooner than AIM152.

Normal SARH sparrows with datalink coming early enough to be useful as an MRAAM would also be big

 

[Scott Kenny]

Normal SARH sparrows with datalink coming early enough to be useful as an MRAAM would also be big

I'm not sure how much help a datalink would help with SARH missiles. It works for long range naval missiles because the ships have a really powerful radar able to light up the target. I'm not sure if airplanes have enough radar power to pull that off.

Need one of the missile heavies to weigh in on that, but I don't know who to ask. @Orionblamblam are you a missile heavy or do you know who on the forum is?

 

[Dilandu]

I did just come to one potential benefit from continuing to develop Active Sparrow:

Datalinks.

Datalinks allowing both activation of the radar well after launch, and more importantly to provide midcourse guidance updates.

Which may allow for packing a Phoenix range capability into a small diameter missile sooner than AIM152.

Erm. Recall the size and complexity of 1950s analogue electronics, and you would came with the missile probably even bigger than Phoenix.

Basically you are trying to fit into one missile:

* Active seeker - with all required equipment to process the signal and make sence of it;
* Datalink to the plane - capable of sending seeker data over significant distance;
* Some kind of command control - so the plane could control the missile;
* Some kind of beacon - so the plane could track the missile;

All this would require likely dozens - if not hundreds - of rather complex vacuum tubes, and a lot of electronics and electromechanics to operate. The resulting missile would be BIG.

 

[Dilandu]

I'm not sure how much help a datalink would help with SARH missiles.

Generally at this point it's simpler to go for track-via-missile guidance - removing processing and signal analysing circuits from the missile, and merely transmitting data from missile seeker back on plane (and receiving control commands from the plane).

Need one of the missile heavies to weigh in on that, but I don't know who to ask

Me)

 

[Firefinder]

One thing that naval SARH missiles use datalinks for is cruise guidance.

The ship tracks both the missile and the target to remotely guide the missile to the target via datalink until its in range for the SARH bits to take over.

This has a few MAJOR benefits over straight control all hte way.

First it allows the ship director to be smaller since it only needs to be on for a minute at most.

Gives you more accuracy over track via missile or guided all the way since you can fine tune the missile track as needed.

less warning to the target since the director engages less then 30 seconds from impact. The Target will know it is being track but not if there is a telephone pole flying toward it til its too late.

FAR more resisted to jamming since you can use the Firing system meater... EVERYTHING to brute force it.

Allows you to put more missiles in the air since you can now timeshare the director and radar since you can point the missile in a general direction letting the autopilot do its thing. This is a big one cause you can put up double or even quadruple the number of missiles up compare to directors, have the system glance at each one fine tune it course. And immediately switch up targets as it hits. Making Swarm attacking far harder to do.


Active Guidance is very much the same set up as above but remove terminal director with the active radar flashing on.

 

[Dilandu]

One thing that naval SARH missiles use datalinks for is cruise guidance.

Yes, but Navy control systems aren't as limited in size and weight as plane ones. Especially 1950s plane ones, with vacuum tube based electronic. Any kind of dual control would likely be far too heavy for 1950s AAM to operate.

 

[Dilandu]

One tech that MAY work for 1950s dual guidance missile is cruise beam-riding/terminal SARH using the same radar beam, tracking the target. The missile initially follow the beam path, then switch to SARH homing when echo become strong enough. The beam-riding equipment is relatively simple, and could be more or less integrated with SARH homing, if the same frequency range is used. Problem is, that missile cruise trajectory would be quite suboptimal - and interceptor could hardly allow to have separate radars for tracking & missile guidance.

 

[Scott Kenny]

Me)

Huzzah, there's already a missile heavy in the discussion!

Erm. Recall the size and complexity of 1950s analogue electronics, and you would came with the missile probably even bigger than Phoenix.

Basically you are trying to fit into one missile:

* Active seeker - with all required equipment to process the signal and make sence of it;
* Datalink to the plane - capable of sending seeker data over significant distance;
* Some kind of command control - so the plane could control the missile;
* Some kind of beacon - so the plane could track the missile;

All this would require likely dozens - if not hundreds - of rather complex vacuum tubes, and a lot of electronics and electromechanics to operate. The resulting missile would be BIG.

No, I'm not needing to send much data back to the launcher if we keep it ARH. I only need it to send "turn the active radar seeker on," "fly this compass heading," and "Commence terminal dive" from plane to missile; while sending "my radar is on" and "I have locked on" back to the plane. Maybe if we're being fancy we can include "now on commanded course" in the data to send back to the plane as well, to reduce or eliminate the need to track the missile as well as the target plane during midcourse.

A missile already has an autopilot of sorts built in, it's part of the guidance hardware. The guidance hardware has enough gyros to tell if the missile is at an angle or not, so that it knows which fins to move to get on target.

About all I'm expecting for pre-flight guidance instructions is "after launch, set course to X, climb at Y angle for Z long, then level off and continue on course X until further instructions." Midcourse updates are "adjust course to heading X'," with an implied "maintain this altitude" since there hasn't been a command to do anything but level off after so many seconds. Terminal instructions from plane is "set course to X'', dive at A angle, activate the radar transmitter, and tell me when you lock on."

This would offload all the heavy lifting in terms of "where is the target relative to the missile during midcourse" to the plane.

And frankly, for a long range shot, you could probably pre-program the "climb at Y angle for Z long then level off" so it's the same for every long range shot. Then all you're doing is telling the missile "long range shot" and "fly course X" during pre-launch. Plus, you could likely do the same for the terminal dive onto target as well, making it "tip-over and dive at A angle" every time. One less thing to compute at either end.

I'm not enough of a tube electronics guy to know how many tubes that would require, but I bet it'd be less than trying track-via-missile.

Also, the US has done most of this design work already, with Talos and probably Terrier. Then all that would have to happen is packing it into an 8"/200mm tube.

Though I guess this might be pre-supposing a Boost+sustain type rocket motor. Launch and climb to altitude on the boost portion, then level off and sustain while maintaining heading.

I'm also assuming a proportional guidance system once the seeker is on.

One tech that MAY work for 1950s dual guidance missile is cruise beam-riding/terminal SARH using the same radar beam, tracking the target. The missile initially follow the beam path, then switch to SARH homing when echo become strong enough. The beam-riding equipment is relatively simple, and could be more or less integrated with SARH homing, if the same frequency range is used. Problem is, that missile cruise trajectory would be quite suboptimal - and interceptor could hardly allow to have separate radars for tracking & missile guidance.

As you noted, beam riding is very suboptimal for getting good range.

What I'm basically hoping for is the "eureka" moment that since they already have most of an autopilot already just in the basic guidance system, they can add the datalink and a limited number of commands plus a high-altitude flight phase to get lots of range out of the missile.

 

[Dilandu]

No, I'm not needing to send much data back to the launcher if we keep it ARH. I only need it to send "turn the active radar seeker on," "fly this compass heading," and "Commence terminal dive" from plane to missile; while sending "my radar is on" and "I have locked on" back to the plane. Maybe if we're being fancy we can include "now on commanded course" in the data to send back to the plane as well, to reduce or eliminate the need to track the missile as well as the target plane during midcourse.

Problem is, that it would require from missile seeker to seek, track and lock on WITHOUT any help from launcher plane (if your guidance command are only for autopilot, not for the seeker). Consodering that the missile have zero idea how relative to target it is flying, it would be... complicated at best. And any kind of chaffs releazed by target would almost certainly cause missile to aquire them, not the target (unless a lot of complicated and likely not very efficient 1950s filtration & logic circuits)

 

[Dilandu]

What I'm basically hoping for is the "eureka" moment that since they already have most of an autopilot already just in the basic guidance system, they can add the datalink and a limited number of commands plus a high-altitude flight phase to get lots of range out of the missile.

There are several problems:

* The high altigude phase made it VERY problematic for the plane radar to track both the target and missile. A separate tracking/command antenna would likely be required;
* Without the guidance from beginning, the missile would require much more capable gyro system (and heavier, too) to maintain heading;
* Without the precise knowledge of missile heading and position, the fire control system would not be abe to pinpoint the target for missile seeker, forcing the seeker to initiate wide search pattern - without any kind of external control over what it may aquire;
* The low power and range of missile radar would make aquisition... problematic. 1950s tech required time to lock on the signal. Considering that missile did not know where the target is, its highly likely that (unless the missile by pure chance have target directly ahead) missile streaks past the target before its seeker could lock on properly;
* The fully autonomous aquisition would be highly susseptible to jamming and chaffs. Since missile have no idea how the signal from target supposed to look like (SARH missiles use illumination radar beam as reference point) it could only lock on strongest signal return it could find. So if there are a plane and a chaffs, it would track the chaffs, since the cloud is more reflective;

To summarize; such simple command guidance would likely NOT work at all. It relies too heavy on the missile very limited abilities.

 

[Scott Kenny]

Problem is, that it would require from missile seeker to seek, track and lock on WITHOUT any help from launcher plane (if your guidance command are only for autopilot, not for the seeker). Consodering that the missile have zero idea how relative to target it is flying, it would be... complicated at best. And any kind of chaffs releazed by target would almost certainly cause missile to aquire them, not the target (unless a lot of complicated and likely not very efficient 1950s filtration & logic circuits)

My assumption was that the midcourse phase commands would have the missile aimed so as to have the target roughly centered in the radar's field of view when it tipped over for the terminal dive.

And then the (very simple and compact) proportional guidance takes over. Somewhat suboptimal, I know.

[...]

To summarize; such simple command guidance would likely NOT work at all. It relies too heavy on the missile very limited abilities.

Damn. I was hoping to keep it simple.

 

[Dilandu]

My assumption was that the midcourse phase commands would have the missile aimed so as to have the target roughly centered in the radar's field of view when it tipped over for the terminal dive.

Problem is, that simple command guidance would not be able to do it. It could bring the missile close to target, yes. But how exactly missile would be oriented & positioned relative to target, it would have no idea. And it would not be able to "pinpoint" the target for missile.

And then the (very simple and compact) proportional guidance takes over. Somewhat suboptimal, I know.

The problem isn't proportional guidance, but making the missile seeker search, track and lock on target while not exactly knowing where the target relative to seeker is, and having no idea how the signal from the target is supposed to look like. And all this in the very limited timescale while missile and target are moving on high speed.

Damn. I was hoping to keep it simple.

Unfortunately, it's 1950s electronics. It could do some truly amazing feats, but it have its limitations(

 

[Scott Kenny]

Problem is, that simple command guidance would not be able to do it. It could bring the missile close to target, yes. But how exactly missile would be oriented & positioned relative to target, it would have no idea. And it would not be able to "pinpoint" the target for missile.

The fire control on the launching plane should be able to do that.

The USN made a freaking slide rule that could do that! (For torpedoes, but still. The extra zeroes in speed and range cancel out)

Unfortunately, it's 1950s electronics. It could do some truly amazing feats, but it have its limitations(

1) the Sidewinder is amazing! Was it 17x tubes in the entire missile?
2) I've been spoiled by much smarter systems with lots more space for brains

 

[Dilandu]

The fire control on the launching plane should be able to do that.

Yes - but only if provided with a lot of additional data from the missile. So you need a rather capable datalink, which would provide data from missile autopilot, allowing the FCS to figure out how exactly missile is positioned relative to target.

The USN made a freaking slide rule that could do that! (For torpedoes, but still. The extra zeroes in speed and range cancel out)

For the torpedoes - where dynamics is much less... troublesome.

1) the Sidewinder is amazing! Was it 17x tubes in the entire missile?

Amazing - undoubtedly. But it was a simple short-range missile, and with some very elegant solutions, like rollerons (which allowed it to not have the gyroscope-based autopilot at all).

2) I've been spoiled by much smarter systems with lots more space for brains

I understood your feelings completely, but unfortunately 1950s missile have way less brains than your average modern refrigerator. And those brains are analogue, hardwired to perform a limited set of functions.

 

[Dilandu]

P.S. One possibility that might be workable - is to use air-breathing missile, ramjet-powered, probably. It would be rather bulky, of course, but the constant thrust, provided by ramjet, would allow to use beam-riding/SARH combination with the same radar (yes, the trajectory would be suboptimal, but missile would not risk to lose too much energy, since its constantly under thrust)

The problem is, that central ramjet (like on Talos or Sea Dart) would likely not work, because it would leave too little space for any kind of dish antenna. And interferometer seeker is far from very sensitive (the plane radar likely would not be powerful enough to give meaningful echo from target on long distance, for interferometer to react on).

But it may be possible to use a pair of external ramjets - like on Bloodhound missile - or rear-placed ramject with hull-enveloping intake (like on Krug missile)

 

[Scott Kenny]

Yes - but only if provided with a lot of additional data from the missile. So you need a rather capable datalink, which would provide data from missile autopilot, allowing the FCS to figure out how exactly missile is positioned relative to target.

If the launching aircraft's radar is tracking the missile and the target, do we still need a lot of data back from the missile?

We've got the compass heading we told the missile to fly, we know the actual course it flew up til now so we can establish any skew angle due to wind, and we've got the bearing to the target. We've got the dive profile every time for the missile.


=============
After reviewing the wiki page for Track-via-missile, I've realized I've been trying to do very simple TVM with an ARH weapon.

*facepalm*

For the torpedoes - where dynamics is much less... troublesome.

Yes and no.

 

[Dilandu]

If the launching aircraft's radar is tracking the missile and the target, do we still need a lot of data back from the missile?

Firstly it's the problem of tracking them both. Unless they are on the same line - in which case you could just make missile ride the beam - the 1950s radar would be hard-pressed to have them both in the beam, using a simple rotating dish antenna. Or you would need a separate antenna to track the missile (not very useful on plane).

Secondly, while you would know the position of missile, you still would not know how exactly it's oriented relative to target. What if, at the moment when you would send seeker activation command, the missile would be turning - and the seeker would be looking into different direction?

Thirdly, it would not solve the problem of seeker having no idea what to seek and having extremely little time to lock on anything at all.

 

[Scott Kenny]

Firstly it's the problem of tracking them both. Unless they are on the same line - in which case you could just make missile ride the beam - the 1950s radar would be hard-pressed to have them both in the beam. Or you would need a separate antenna to track the missile (not very useful on plane).

I was torn between a second antenna and angling the main antenna upwards during a long range missile shoot.

Secondly, while you would know the position of missile, you still would not know how exactly it's oriented relative to target. What if, at the moment when you would send seeker activation command, the missile would be turning - and the seeker would be looking into different direction?

It's under gyro control to be on a specific heading and horizontal, it shouldn't be turning between course update commands.

Thirdly, it would not solve the problem of seeker having no idea what to seek and having extremely little time to lock on anything at all.

damn.

Sounds like the best bet for a long range, lofted missile flight path, AAM in the 1950s would be TVM. Which does not suggest a small missile, as even Patriot is some 11" in diameter.

 

[Dilandu]

I was torn between a second antenna and angling the main antenna upwards during a long range missile shoot.

It may lost the target then, and took time to reaquire (while missile could be found relatively easily by beacon signal, the target could very easily use the periodical beam shifting to change course & launch chaffs). Second antenna would be more workable; since it works with missile transponder beacon, it didn't need to be particularly big, and could be placed in hull or keel blister)

It's under gyro control to be on a specific heading and horizontal, it shouldn't be turning between course update commands.

Yes, but it would be turning under course update command, and it would likely need to correct the windage deflection and other instabilities. The missile flight under autopilot is rarely a straight line.

damn.

Sounds like the best bet for a long range, lofted missile flight path, AAM in the 1950s would be TVM. Which does not suggest a small missile, as even Patriot is some 11" in diameter.

Probably yes. Or beam-riding/SARH combination.

 

[Larcrivereagle]

There are several problems:

* The high altigude phase made it VERY problematic for the plane radar to track both the target and missile. A separate tracking/command antenna would likely be required;
* Without the guidance from beginning, the missile would require much more capable gyro system (and heavier, too) to maintain heading;

I think both of you are vastly overestimating the range a sparrow II would reach here.
There isn't going to be a high altitude phase, because it isn't a BVR missile. The only time the missile will have the time or energy to do that is when it is purposely launched in with massive lead pursuit above a target that is closing, because that's pretty much the only way it will be able to pull enough to hit that target in time.

Problem is, that it would require from missile seeker to seek, track and lock on WITHOUT any help from launcher plane (if your guidance command are only for autopilot, not for the seeker). Consodering that the missile have zero idea how relative to target it is flying, it would be... complicated at best. And any kind of chaffs releazed by target would almost certainly cause missile to aquire them, not the target (unless a lot of complicated and likely not very efficient 1950s filtration & logic circuits)

I agree with this point, but I'm not actually sure the people building this missile would yet know to ask these questions. The information existed, certainly but they're working in a world of firsts, here, and there is no internet to share information with. And also even those early countermeasures are equally likely to defeat the radar of the parent craft, so even with the validation provided by a good datalink the missile is likely to be defeated anyway.

As to your question Scott about what purpose data link would serve on a normal SARH sparrow, it's a shot quality thing. The INS (if it was included, like in the R24R and R27R), along with the data link to update it and validate the seeker all goes a long way to improve redundancy to both human error on the part of the RIO/Pilot, as well as keeps the missile from being defeated by brief soft kills like the target flying in a circle and accidently notching
The potential range is sorta improved yeah, in perfectly optimal conditions, but the sparrow itself at the point doesn't have the engine to take advantage of that most of the time.

 

[Dilandu]

I agree with this point, but I'm not actually sure the people building this missile would yet know to ask these questions. The information existed, certainly but they're working in a world of firsts, here, and there is no internet to share information with. And also even those early countermeasures are equally likely to defeat the radar of the parent craft, so even with the validation provided by a good datalink the missile is likely to be defeated anyway.

AFAIK, the Sparrow II was supposed to activate its seeker while still on plane hardpoint, and launch only after locking on target. I.e. the problem of autonomous aquisition didn't exist for it; the pilot controlled the aquisition (through connecting umbilical cable) and could always check that the missile locked on the same target as plane's own radar.

 

[Scott Kenny]

AFAIK, the Sparrow II was supposed to activate its seeker while still on plane hardpoint, and launch only after locking on target. I.e. the problem of autonomous aquisition didn't exist for it; the pilot controlled the aquisition (through connecting umbilical cable) and could always check that the missile locked on the same target as plane's own radar.

Which gets us back to the original problem with K-band seekers. Poor range. With activating the missile radar on the pylon, you're stuck with a 5nmi/8km range. Which is less than the range of a Sidewinder or Falcon.

 

[Scott Kenny]

I think both of you are vastly overestimating the range a sparrow II would reach here.
There isn't going to be a high altitude phase, because it isn't a BVR missile. The only time the missile will have the time or energy to do that is when it is purposely launched in with massive lead pursuit above a target that is closing, because that's pretty much the only way it will be able to pull enough to hit that target in time.

The base AAM-N-2/AIM-7A Sparrow I had a 26km range, the AAM-N-6b/AIM-7E got a new rocket for more speed and a 35km-50km range.

The idea I had was to try to get more than 8km range out of the stupid thing! It's got a rocket good for 26-50km as is, and I'd like to use all that range, not a tenth of it!

I agree with this point, but I'm not actually sure the people building this missile would yet know to ask these questions. The information existed, certainly but they're working in a world of firsts, here, and there is no internet to share information with. And also even those early countermeasures are equally likely to defeat the radar of the parent craft, so even with the validation provided by a good datalink the missile is likely to be defeated anyway.

If chaff will break the launching aircraft's lock, we're back to needing IR missiles. Not that a Sparrowinder wouldn't be a bad idea, mind you. Falcon missiles as well as most of the early Russian missiles had both radar and IR homing versions of the same missile airframe, with the idea to volley 1x IR and 1x radar missile (radar missile second so that the IR missile didn't lock onto the leading missile!) to improve P(hit).

As to your question Scott about what purpose data link would serve on a normal SARH sparrow, it's a shot quality thing. The INS (if it was included, like in the R24R and R27R), along with the data link to update it and validate the seeker all goes a long way to improve redundancy to both human error on the part of the RIO/Pilot, as well as keeps the missile from being defeated by brief soft kills like the target flying in a circle and accidently notching
The potential range is sorta improved yeah, in perfectly optimal conditions, but the sparrow itself at the point doesn't have the engine to take advantage of that most of the time.

Thank you!

 

[Larcrivereagle]

Which gets us back to the original problem with K-band seekers. Poor range. With activating the missile radar on the pylon, you're stuck with a 5nmi/8km range. Which is less than the range of a Sidewinder or Falcon.

The base AAM-N-2/AIM-7A Sparrow I had a 26km range, the AAM-N-6b/AIM-7E got a new rocket for more speed and a 35km-50km range.
...
The idea I had was to try to get more than 8km range out of the stupid thing! It's got a rocket good for 26-50km as is, and I'd like to use all that range, not a tenth of it!
...
If chaff will break the launching aircraft's lock, we're back to needing IR missiles. Not that a Sparrowinder wouldn't be a bad idea, mind you. Falcon missiles as well as most of the early Russian missiles had both radar and IR homing versions of the same missile airframe, with the idea to volley 1x IR and 1x radar missile (radar missile second so that the IR missile didn't lock onto the leading missile!) to improve P(hit).
...
Thank you!

Those are all highly optimistic ranges, esp for sidewinder. Period sidewinders (9A and 9B) have a functional effective range from cold of between 1-2km. 8km is around the maximal optimistic kinematic range of a hot target that does not defend, which the seeker isn't even capable of engaging anyway (R-3R, being a SARH 9B, could hit in that scenario).

Sparrow 1 will be reaching maybe 10 km due to "seeker" limitations. Initially, the beam guidance is boresighted from the gunsight as lined up by the pilot, APQ-36, with dual tasking tracking the target and guiding the missile automatically (and therefore taking advantage of the rest of the kinematic envelope) only came around later.
A, B, and C all have the same engine (source), which is what I'm basing my range estimations on. Actual ranges still vary slightly across A, B, and C due to different weights and aerodynamic changes.
E's range is equally optimistic, but is actually achievable (half of that is just being launched from better planes, in both Kinematic and electronic respects)

Re: chaff invalidating missiles, it is early days. No one you're shooting at will be carrying chaff as standard for nearly 10 years, IIRC, even if it was invented in the 40s. Integral jamming was more common, from what I remember, but that might just be US bombers at this point. I don't know as much about Soviet standards in the period.

If the program gets funded through cancellation and into the 60s, I think you'd have a better chance of achieving the ranges you want with better electronics (Also CW radars come around, which allow you to ignore chaff in Hot aspects). There were several other missile datalink programs I can think of in that period, so it's clearly feasible (maybe not within weight requirements, might have to sacrifice warhead or fuel?).

 

[Scott Kenny]

Are you measuring your ranges as "distance from shooter to target at launch" or "total distance missile travels"?

 

[Larcrivereagle]

Are you measuring your ranges as "distance from shooter to target at launch" or "total distance missile travels"?

Former

 

[Dilandu]

The base AAM-N-2/AIM-7A Sparrow I had a 26km range,

Erm... no, Sparrow-I only have a 10 km range. And Sparrow-III, AFAIK, have even less range (initially) due to being heavier and less aerodsynamic shape.

It's not only the guidance limitation; it's the engine limitations, too. The mid-1950s solid rocket motors are rather inept. Even the large missile, like Terrier, initially could produce only about 20 km range. To get something like that from relatively small AAM, you would need the air-breathing motor.

 

[NMaude]

Erm... no, Sparrow-I only have a 10 km range.

A six mile range while the AIM-7E IIRC had an aerodynamic range of 28 miles and the AIM-7F/M/P has an aerodynamic range of 62 miles.

 

[Dilandu]

A six mile range while the AIM-7E IIRC had an aerodynamic range of 28 miles and the AIM-7F/M/P has an aerodynamic range of 62 miles.

But AIM-7E was a 1963 missile with a completely new rocket motor. The basic Aerojet 1.8KS7800 burned only for 1.8 seconds. The improved Rocketdyne MK 38/MK 52 burned for about 2.9 seconds.

 

[Scott Kenny]

Former

Which would be correct for a tail chase. But radar-guided missiles are capable of head-on engagements, where you would be firing the missile at a target potentially in excess of the missile's aerodynamic range, such that missile and target meet at about the missile's aerodynamic range.

And that's what I wanted to take advantage of.

Erm... no, Sparrow-I only have a 10 km range. And Sparrow-III, AFAIK, have even less range (initially) due to being heavier and less aerodsynamic shape.

The very first Sparrow III, codified as AAM-N-6(no suffix)/AIM-7C, has a 26km aerodynamic range. And it has the same engine as the Sparrow I, the Aerojet 1.8KS7800. AAM-N-6a/AIM-7D has a Rocketdyne MK38, AAM-N-6b/AIM-7E has a Rocketdyne MK52.

 

[Dilandu]

The very first Sparrow III, codified as AAM-N-6(no suffix)/AIM-7C, has a 26km aerodynamic range. And it has the same engine as the Sparrow I, the Aerojet 1.8KS7800. AAM-N-6a/AIM-7D has a Rocketdyne MK38, AAM-N-6b/AIM-7E has a Rocketdyne MK52.

Aerodynamic range, AFAIK, means "how far the missile could fly at all before crashing to ground". It have little relation to maximum range (on which missile still have enough flight control to hit something) or effective range (on which missile could reliably hit the target).

 

[Dilandu]

Hm. I thought about using the same beam to track the target & to beam-ride the missile flying at higher altitude. Whst if we use Cassegrain antenna with two reflectors (inner and outer) and use different beam polarization from two feeding horns?

I.e. the small inner reflector is verticallly polarized. It reflect vertically polarized beam and let horizontally polarized beams go through to large outer reflector (which is horizontally polarized & reflect the horizontally polarized beams).

(Hope I didn't mix anything up here, I need to refresh my memory)

By sending vertically/horizontally polarized beams, we could got a narrow target tracking beam from big outer reflector and wide missile guidance beam from small inner reflector. The missile would initially follow the guidance beam in azimuth only, using radar/barometric altimeter to maintain pre-set altitude. Near the target, the missile would star to follow guidance beam in altitude too, moving toward the center - toward the narrow tracking beam. When it would enter the narrow tracking beam, it would switch on the semi-active guidance, and acquire the target.

It's still far from optimal trajectory, but it would let the missile follow the high-altitude flight.

 

[Scott Kenny]

By sending vertically/horizontally polarized beams, we could got a narrow target tracking beam from big outer reflector and wide missile guidance beam from small inner reflector. The missile would initially follow the guidance beam in azimuth only, using radar/barometric altimeter to maintain pre-set altitude. Near the target, the missile would star to follow guidance beam in altitude too, moving toward the center - toward the narrow tracking beam. When it would enter the narrow tracking beam, it would switch on the semi-active guidance, and acquire the target.

It's still far from optimal trajectory, but it would let the missile follow the high-altitude flight.

I think it'd be better to use a "maintain missile angle/attitude" gyro than to add radar or pressure altimeters to the mix.

 

[Dilandu]

I think it'd be better to use a "maintain missile angle/attitude" gyro than to add radar or pressure altimeters to the mix.

In that case you won't be able to pinpoint the target for missile correctly.

 

[Scott Kenny]

In that case you won't be able to pinpoint the target for missile correctly.

I don't know if it's the insomnia or just a failure to understand why that is, but I'm just not getting it. I'm sorry if this is frustrating for you to explain why constantly.