Gambit..
There have been some alternatives to mechanical gyro's.. especially in the fibre optic kind but have lacked precision.
If we can assume that it may be possible that a Chinese manufacturer has achieved accuracy on a FOG that is close to ( perhaps even copied from) a particular FOG manufactured in czarland.. and due to the way the Chinese procurement system operates the economy of scale for the system is more favorable than ..say one manufactured elsewhere..the cost factor has come down.
Fiber Optics Gyros (FOG) are not new, more like known since the 1960s roughly the same era as the ring laser gyro came to outside laboratory experiments. When I was active duty, mechanical gyros are already well proven, from civilian to military to space applications, and the ring laser gyro's precision and accuracy was spoken with awe borderline on the magical, let alone any of us even heard of fiber optics adapted for gyroscopic purposes.
As time passed and experienced gained, inside and outside of the military, I have learned one very valuable thing about the military: Conservatism.
The military of
ANY country is inherently conservative. We have to be because whatever we use will be the method of last resort for the survival of the country if necessary. Nothing is perfect but as we gain experienced with the imperfect tools given to us by the scientists and engineers, from the infantryman rifle to the jet fighter to the rocket capable of reaching outside of the planet's atmosphere, we would prefer to deal with the knowns of these imperfect tools than with the unknowns of new technology. It is a necessary trait. Very very seldom do the military, instead of the civilian sector, will lead with a new technology. Examples of that are the fly-by-wire FLCS and 'stealth'. For 'stealth', the civilian airmen
WANT to be seen, so what need is there for the civilian sector to develop low radar observable flying bodies? The USAF had no choice but to take the lead. But usually, the military would rather let the civilians in the safety of their world develop and refine new technologies before we adapt it for far more dangerous purposes that often will have a one-time use.
The main thing about missiles and their keeping is that you do not have the chance to re-use them. You can only test each missile up to the point of launch, no further, and this is even more applicable to complex missile systems like an ICBM instead of the far simpler air-air individual combat missiles like the AMRAAM or the IR-ed equipped Sidewinder. A missile launch is essentially a financial write-off of a lot of money that has no guarantee of a return, which is the destruction of an enemy. It can be successful in hitting
ONE enemy target, but it does not assure his capitulation in the war. So we have no choice but make as much successful target hits as possible, from an individual enemy soldier, to an enemy tank, to an enemy aircraft, to an enemy strategic location on the other side of the world, to convince him that he can no longer benefit in continuing the war.
So from this conservative perspective, is it possible that the DF-21D's guidance system contains something more advanced like a fiber optics gyro (FOG) system?
Mmmm...Possible but in my opinion not likely.
Despite the American military that shares the same conservative trait as the Chinese or as the Russians or the Brits or the Spaniards, it has been US who have often if not usually lead the technological adaptations for military usage, derived from
YEARS or even
DECADES of civilian successes prior to said adaptations. For the specific technical issue we are talking about, the Chinese of modern day do not have that history in their military history. They could, of course, shock everyone with the news of this risky jump, but I think the Chinese military is even more conservative than US simply because they recognizes the technological hurdles they currently faced -- and have faced -- in their modernization programs.
The question is: 'If the American/Western civilian sector have limited successes with this X technology and their militaries continues to rely on the older A technology, why should we risk our national defense and deterrence capability with X?'
I do not think FOG will be in the DF-21D.
As another example..
A certain TI TMS320C6000 series costs around $295 .. till early 2010 this was the cost..still is if you buy TI genuine.
apparently.. after that.. some people near the Chengdu area got their hands on complete "fabrication" of this product.
Some of those test "facsimiles" went here and there.. they cost around $50 a pop..
They arent sold anywhere international yet, except to some cellphone manufactures.. and some to interested companies.
They do all that the TI Chips do..and cost 1/5th.
here is the catch.. 1 out of 5 "facsimile" chips have problems.. some wont have pins.. others wont work properly..some are bent.. and some dont work at all.
They heat up faster than the TI originals..
But newer lots keep coming in with less and less faults.
So if we take this as an example of sheer mass "facsimile" ability and gradual learning from mistakes.
It is possible.. not certain.. possible.. that eventually; while a BM system will still be more expensive to manufacture for the Chinese than a CM.. it may not be that much more expensive than one for a CM made by another nation.
I would not risk my nation's survival on this. Remember, a missile is essentially a throw-away weapon. Everyone know that fraudulent electronics, be it from being poorly copied or haphazardly reconditioned, have far lower reliability and uncertain performance under stresses. And the fact that in maintaining an ICBM fleet, you can only maintain each weapon up to the point of launch, not actually launch and re-use like an aircraft can be.
Can you simulate pitot/static pressures required by the autopilot system? Absolutely...With this...
TTU-205 Series Pressure-Temperature Test Sets | © 2011. TestVonics, Inc.
The TTU-205 is a rugged, self-contained flight line or hangar test system used to accurately simulate in flight pressure conditions by precisely controlling and measuring Altitude and Airspeed pressure to aircrafts pitot-static system.
But can you simulate the highly dynamic situations an aircraft or a missile will encounter in actual flight? No. And I say that from personal experience using the TTU-205, analog and digital versions. There is no way possible for a human to do so. Fraudulent electronics places the entire fleet at unreasonable risk. And yes, I do hope the PLA took that risk...
...It does not matter if we know about it or not. When a bunch of Chinese fighters, tanks, ships, and missiles starts failing in actual combat, we will change our tactics accordingly to take advantage of that foolish decision.
Which brings us to what does the guidance system control?
The DF-21D has been designed from the outset to kill ships.
Keeping that in mind, if I was project head.. Id keep post-reentry maneuverability a high priority..
But that is if I was the head.. there is no proof ..pictorial or otherwise to suggest that the actual project head has done the same.
And the sheer workmanship(if done properly) for a BM more expensive than a CM..
I would as well. And here is why...
In post 46 of this discussion, I mentioned proportional navigation (PN) in a composite guidance law set in a certain order. PN guidance is well proven with high successes against fixed and constant velocity targets, used by either powered or gravity driven attack bodies to compensate for their in-flight course deviations. In this case, the 'constant velocity' factor is appropriate because despite the fact that the target is a moving one, it is a ship constrained in a 2D environment, not an aircraft operating in a 3D one.
I will digress a bit for the interested lay readers...
We will dispense with the 'Unguided' type. We can call them 'artillery' or arrows.
For the 'Guided' missile type, the 'Nonhoming' guidance method is not so much the missile being 'guided' in the generally accepted context but merely the missile being programmed
NOT TO deviate from a fixed flight path. If the hardware is crap, then the missile will not hit the expected location. Same if the software is crap.
For the 'Homing' missile type we have true guidance and it is dependent upon the target providing some sort of 'feedback' to give us direction and location.
This is what those feedback look like...
The 'Homing' type is ideal against fixed targets and when they constantly produce some sort of signatures.
For the 'Direct' missile type, it is a more complex 'Homing' type and against moving targets,
REGARDLESS of how maneuverable are they. All air-air missiles, as in the visual example above, are 'Direct' guidance type missiles. The air-ground Hellfire missile is a 'Direct' guidance type missile because it can be used against moving targets like a tank or an automobile. Therefore, the DF-21D is a 'Homing' and 'Direct' type missile.
Under this 'Direct' category...
- The 'Command' type is when there is a greater intelligence making maneuver decisions for the missile and that greater intelligence can be a sophisticated guidance law algorithm, or a human operator watching some sort of visual feed of what the missile is actually seeing, or the parent launch aircraft is monitoring the target and is in link with the missile to command its maneuvers.
- The 'Beamrider' is the well known 'anti-radiation' type where it uses an EM transmission as a guide.
- The 'CLOS' stands for 'Command Line-of-Sight' guidance where the missile must maintain signature contact with the target at all time. This type is usually autonomous, but sometimes can be controlled by another, and require the highest level of technical sophistication possible by a country. Lose line-of-sight and lose the fight.
- The 'Pursuit' is the typical 'tail chase' situation.
The DF-21D is no doubt the most sophisticated of these types, regardless of if its target is maneuverable at several hundreds km/hr or just a few. If the target is maneuverable, then it must have variable target positions compensatory guidance laws. The DF-21D's problems are compounded by the possibility that the defense will produce countermeasures, either by deceptions as in chaff or by direct physical assaults such as the SM-3.
Here is what we do not know...
- Assuming the DF-21D has a radar sensor, is it capable of detecting interceptors and calculate avoidance maneuvers? Just because it has a radar, that does not mean it can detect bodies other than the signature it may be programmed to home in on. This may be because of a hardware limitation or it may be because of the high closing speed between itself and the target and any maneuvers may be structurally catastrophic.
- Assuming the DF-21D is capable of detecting interceptors and of formulating avoidance maneuvers. What is the capable altitude of said detection? Interceptors will naturally be in a head-on view -- the lowest radar signature. That imply said detection will be very very close. May be too close for any avoidance maneuvers.
- Assuming the above is true, what is the order of this composite guidance law set? In post 46 I speculated bang-bang/PN order. Bang-bang maneuvers are abrupt and extreme to the physically available ranges given by design. But if the DF-21D is a CLOS type and it most likely is, then what are the maximum possible of these extreme maneuvers so that the warhead will not lose line-of-sight, reacquire the target, and reposition itself through the more gradual and precise PN guidance algorithm? The designers must know how extreme are bang-bang maneuvers and cannot give the FLCS so much physical freedoms of movement that the warhead will lose target line-of-sight. This mean the DF-21D is vulnerable to interception by the SM-3, either by direct kinetic kill or by proximity fused explosion.
- Another problem for the DF-21D, assuming the best possible design type for it, is data integrity for the sensor, and we can safely assume it will be radar...
The 'L/D' mean radome's length to diameter ratio.
Shape 1 offer the highest aerodynamic efficiency and the lowest radar signature for the defense to act against. But it offer the sensor the lowest field-of-view (FoV) and therefore the highest odds of losing line-of-sight (LoS) if the warhead must maneuver to avoid interceptors.
Shape 2 offer the highest sensor data in terms of volume, data integrity, and field-of-view (FoV) but produces the highest drag and highest radar signature for the defense to act against.
Shape 3 is called the
tangent-ogive and is the best compromise.
Both shapes 1 and 3 suffers the most the 'radome abberation' effects...
Radome techs ensure pilots can see
The slightest aberration in the curvature of the radome can throw off the array signal, giving the pilot false readings.
...Because of their sharp slopes compared to the radar beam when it sweeps. The highest peak of the radome abberation error is furthest from the antenna: The tip. But...That is where the warhead would be looking for the target. Basically, if you must have an obstacle in front of your radar beam, it is best if said obstacle is as perpendicular to the beam as possible since that obstacle must pass through your radar beam. That is why the hemispherical radome offers the highest data integrity and the sloped shapes the lower.
So in effect, the DF-21D must deal with
TWO maneuvering targets: One to hit (ship). One to avoid (interceptor). The technical challenges are enormous and the cost will be high since every test launch is a financial write-off more than just moving a few troops across country or launching a few aircrafts in an exercise.
Am not going to touch countermeasures via deceptions.
however.. I wonder if the hypersonic capability adds much to the cost of a Brahmos compared to say a tomahawk.
It would be more because the engine must be more capable. But then again, this is a one-way journey so all the Indians has to do is design an engine that is powerful but not very durable. If you know your journey will last only one hour with no possibility of return for reuse, why would you design your engine to last 1.5 hr? The additional cost must be bearable to the Indians.