Tuesday, December 24, 2024
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Anatomy of the Hatf-VIII Ra’ad Air Launched Cruise Missile

Hi dear @Oscar
Designing various aircraft components particularly wings,etc is the job of aerodynamicist- it is entirely different from flight dynamics. Control Engineering aspect of aircraft comes in the end when the an aerodynamicist has done his job. I am basically a control engineer,(no amount of aerospace will turn me into an aerodynamicist lol) and as a control engineer one must know the dynamics of any process(be it aircraft,nuclear reactors,nuclear submarines or your oil rig!) he/she wishes to control.

On more serious note though,ADA has already designed the wings and the basic layout of AMCA is frozen. System level design will commence soon.A lot of engineers working on AMCA are also research assistants/pursue MS/PhD at IITs.And Unlike pakistan their research is definitely published or patented!- our research is very transparent

Again, no disagreement. But for a system of this sort of flight dynamics(such as Ra'ad) , you may not need to go too much in depth. And yes, unlike Pakistan a lot of research in India is transparent; something that is both good and negative.
Good, because it ensures a high level of secrecy as to what is going on.. and bad..because many a good engineer is left unable to state their accomplishments to the fullest.
 
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i would say look at the som missile for "influence". as for shorter ranged alcm? the c802 would do just fine after a software change.
@Bilal Khan 777 what do you think?
You mentioned SOM for influence and then mentioned "for shorter range" a C802. You said "as for short range ALCM" like SOM was something else. The range of both is somewhat same. They will fall in same category as far as range goes so what am i missing?
 
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\Control Engineering aspect of aircraft comes in the end when the an aerodynamicist has done his job.

That is a TERRIBLE idea lol. But you knew that. Control engineers should be kept in the loop from the start even though sometimes they aren't.
 
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You mentioned SOM for influence and then mentioned "for shorter range" a C802. You said "as for short range ALCM" like SOM was something else. The range of both is somewhat same. They will fall in same category as far as range goes so what am i missing?
yes turkish tech....
and im looking at both avenues
 
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yes turkish tech....
and im looking at both avenues
Ok so it is not that C802 is "for shorter range ALCM" they both are both are!! However since the technology is different (sources are) so both interests you individually. Makes sense now. :) :tup:
 
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That is a TERRIBLE idea lol. But you knew that. Control engineers should be kept in the loop from the start even though sometimes they aren't.

@JamD
Yes i know man and believe me thats not really a productive method of designing,but that is how aerospace research is conducted in india.A more balanced approach would be to incorporate control engineers right from the beginning. And Aerospace Control is perhaps more demanding vis-a-vis traditional application of control theory like controlling a reactor,heat exchanger etc etc because of the fact
1)That it is highly non linear! It gets a bit tricky to get answers that converge- especially when you're trying to use optimal control theory.
2)that an aircraft is desired to operate at multitude of equilibrium points(in contrast to this boilers,reactors etc operate at only one or at max a few eq pts).This means linearization of NL eqns around those points-but this might sometimes give mis-leading answers as to what really happens around that point- for instance around "centers","non-isolated fixed points","star" or other degenerate cases
3)Control Engineer must also ensure stability of these equilibrium points and how they behave using bifurcation theory and branch-continuation.Thats where auto07p like tools come in handy.hint flutter,wing drop etc etc
 
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Ok so it is not that C802 is "for shorter range ALCM" they both are both are!! However since the technology is different (sources are) so both interests you individually. Makes sense now. :) :tup:
pick your favourite. see what the turks have and get it same applies to china and use it where usefull. but the c802 is the obivous choice you pakistan since its in use, but them som would be preferable, as it means the turks will help with mini turbo engine development as they are making an engine to replace the tri-40 also they have a varient that can fit internally in the f35 so that may be usefull to pakistan when it gets its own 5th gen fighter. thinking ahead is the aim of the game here
 
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pick your favourite. see what the turks have and get it same applies to china and use it where usefull. but the c802 is the obivous choice you pakistan since its in use, but them som would be preferable, as it means the turks will help with mini turbo engine development as they are making an engine to replace the tri-40 also they have a varient that can fit internally in the f35 so that may be usefull to pakistan when it gets its own 5th gen fighter. thinking ahead is the aim of the game here
Yeah yeah i understand all this detail. Was just confused when you mentioned C802 as "for short range" as if SOM was any different in terms of range. It is understandable how they offer different technology insight. :tup:
 
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I don't have much to add, but we need to remember, the Ra'ad is principally for strategic - i.e. nuclear - strike. While a great conventional munition, the PAF is not factoring the Ra'ad in as a conventional stand-off weapon (SOW). This is important. If the Ra'ad is not a conventional SOW, then the need for the JF-17 to be armed with it (for the time being) is not that urgent. Yes, the JF-17 needs conventional SOWs, but it can make due with H-2/H-4 and glide-bomb variants of the Mk-83 and Mk-84. The Mirages have to go eventually, and in light of that, a Ra'ad II and/or new fighter platform could rise, but that is many years away.

Agreed !
 
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Introduction
The Ra’ad Air Launched Cruise Missile (ALCM) is a peculiar system. It has long been rumored that it is too big to be carried by anything but the Mirage aircraft of the PAF. The purpose of this article is twofold: understand the design decisions made while designing the Ra’ad and what can be done to evolve the design. Hopefully, by the end we will appreciate why the Ra’ad is the way it is and try to think of ways to evolve it.

Basics
Weight
At 1,100 kg the Ra’ad is a rather heavy air launched weapon. However heavier ALCMs exist (Storm Shadow, Taurus) and are carried by aircraft with less clearances than the Mirage. Weight is not the key issue here.

Size
The Ra’ad is a significantly large missile. The following drawing has been made after many pixel-counting exercises and is a good ballpark estimate of its size.

View attachment 313914


DISCLAIMER: Pixel counting by its nature is inaccurate and these numbers could be off by up to 10%. Nonetheless these numbers give us valuable insight which we previously lacked.

Role
The Ra’ad is designed with a payload of 450 kg. This suggests that it is primarily designed to carry a nuclear payload or a large conventional payload against hardened targets. This differentiates the Ra’ad from other smaller stand-off weapons like the SOM, H-2/H-3, JSOW. Perhaps the most similar system to the Ra’ad is the AGM-158 JASSM picture below:

View attachment 313915

The JASSM is a 1000 kg system with a payload of 450 kg as well.

Design of the Ra’ad
A casual glance at the Ra’ad shows the “simple is better” approach being employed to the fullest. It is perhaps the most basic design one would come up with for a 1,100 kg ALCM. This is not necessarily a bad thing. Being the first ALCM designed by AWC it makes sense to start off with the basics.

The fuselage has a square cross section allowing easier manufacturing and at the same time reducing the height for the same volume (only slightly).

Another upside to using a rectangular cross section is that it reduces the tail area needed for stability (more on this later).

Issues
Probably the biggest issue people have with the Ra’ad is that it is too tall and wide to fit under most aircraft operated by the PAF. I will now attempt to break down why this is so.

As pointed out earlier the Ra’ad is a very large and heavy system even though it needs to fly like an aircraft. The reason aircraft have a vertical tail now comes into effect. Ideally speaking we want any small disturbances in the desired trajectory of flight to be taken care of “naturally” by the design of the aircraft. I will try to explain how this is achieved by the vertical tail as simply as I can to make it accessible to most of our readers. This is called positive stability.
View attachment 313924
An effect similar to the tail is provided by the fuselage with respect to yaw stability. A square fuselage provides more of this effect.

Roll Damping
As one would imagine the heavier the aircraft the more tail and wing area is required for “enough” positive stability. The Ra’ad is a heavy aircraft with very small wings so roll damping is small. This would mean for enough roll damping the designers have to compensate with more tail area in the form of ventral fins. The farther away they are from the center of mass of the missile the better they will perform as they produce more moment for the same area. It is for this reason they extend below the fuselage (in contrast to the vertical tail that are in line with the fuselage).

View attachment 313917

As the above image illustrates the vertical tail adds little or no roll damping and it is for this reason two ventral fins are there (among other reasons).

Yaw Stability
Yaw stability is provided by the vertical tails. It is evident that because of the mass of the missile a large vertical tail area is needed which is provided by two vertical tails.

View attachment 313918

The JASSM on the other hand employs one rather large vertical tail.

Pitch Stability and Authority
For very similar reasons an aircraft also needs a horizontal tail for stability. On top of that it needs it to have authority over pitch of the aircraft. Again the heavy weight of the Ra’ad means rather large horizontal tails are needed which make the missile 1.25 meters wide.

Reasons for Large Mass
The above argument begs the question why is the Ra’ad such a heavy system for the capability it provides.

Ra’ad
1100 kg
350 km range
4.88 m length
450 kg payload

JASSM
1021 kg
1000 km range (ER version)
4.27 m length
450 kg payload

The reasons for this can be only speculated but I suspect that:

1. The Powerplant being used is heavy and inefficient compared to JASSM (definitely true).

2. The subsystems are not evolved enough to be compact and light. These include INS systems, hydraulics/pneumatics/electric actuators.

3. The subsystems are not designed or modified for the Ra’ad to save costs and therefore pack poorly inside the missile.

Geometry
All this brings us to the issue of integration on PAF platforms.

View attachment 313919

The Mirage 3 can easily carry the Ra’ad ALCM and most importantly the addition of the cruise missile does not decrease the maximum permissible rotation angle (highlighted in red).

tnTIPm.png


The situation is very bad with regards to the JF-17. The maximum permissible rotation angle is halfed and there is very little clearane with the ground. This makes it all but impossible for the JF-17 to carry the Ra’ad on its centerline hardpoint.

Perhaps it is also important to consider whether the wing hard point can carry the Ra’ad.

View attachment 313921

Even though vertical clearances are taken care of but the Ra’ad is so wide that it will interfere with the landing gear/ventral fin of the JF-17 and possibly any weapon system mounted on the hardpoint next to it.


@The Deterrent
 
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Great thread, topics like these reflect the spirit of what this forum should be known for. Kudos, @JamD !

As I said previously, since I don't have much knowledge of both Ra'ad's dimensions and JF-17's hard-point limitations, I cannot comment on it with certainty. But what I am certain of is that both the strategic planners of these weapons systems and their end-users are aware that Mirages will be phased out, sooner or later. Therefore, Ra'ad will be made compatible with JF-17s as it is going to be the main workhorse of PAF.

Right now, IMO either of the following can be true:

1. The analysis regarding the dimensions of Ra'ad is a bit flawed, the author might have overlooked some critical parameter. Ra'ad in its present form poses no problems for JF-17 integration as far as physical parameters are concerned.
2. The analysis is correct, however an easier fix in the form of fold-able fins will solve the problem.

P.S. those who believe JF-17 will not assume strategic roles are gravely mistaken.
 
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Great thread, topics like these reflect the spirit of what this forum should be known for. Kudos, @JamD !

As I said previously, since I don't have much knowledge of both Ra'ad's dimensions and JF-17's hard-point limitations, I cannot comment on it with certainty. But what I am certain of is that both the strategic planners of these weapons systems and their end-users are aware that Mirages will be phased out, sooner or later. Therefore, Ra'ad will be made compatible with JF-17s as it is going to be the main workhorse of PAF.

Right now, IMO either of the following can be true:

1. The analysis regarding the dimensions of Ra'ad is a bit flawed, the author might have overlooked some critical parameter. Ra'ad in its present form poses no problems for JF-17 integration as far as physical parameters are concerned.
2. The analysis is correct, however an easier fix in the form of fold-able fins will solve the problem.

P.S. those who believe JF-17 will not assume strategic roles are gravely mistaken.
This was the thread i was talking about. Seems you were already tagged and replied. Thanks
 
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