Recent Interview with Pakistani Nuclear scientist Dr.Samar Mubarakmand

[amardeep mishra]

You do not understand why he's being vague because, though you might be academically bright, you're a socially inept retard.

You are comparing the head of an organization that is in the public's eye, carries out very public launches and is primarily civilian, with a scientist who has worked for one of the most shadowy organizations and on Pakistan's most strategic weapons.

If that is your line of logic, then kindly compare the interviews or lectures of ex DG DRDO with Mr Mubarakmand.you'll quickly realize intellectual dishonesty of latter, unless of course you're a blind patriot.

 

[v9s]

If that is your line of logic, then kindly compare the interviews or lectures of ex DG DRDO with Mr Mubarakmand.you'll quickly realize intellectual dishonesty of latter, unless of course you're a blind patriot.

Oh the irony. Considering the outlandish claims of DODO and the pathetic results of their projects, the entire organization is intellectually dishonest.

 

[amardeep mishra]

Oh the irony. Considering the outlandish claims of DODO and the pathetic results of their projects, the entire organization is intellectually dishonest.

Hi dear @v9s
I knew you'd come to that.They,at least do not go about spreading false information about their adversary!
Having seen up close their research especially their missile labs,things are way different from what you imagine. DRDO has designed a lot of missile systems. And to be very honest,we all know where does the R&D of pakistani missile systems take place! I have seen this trend,over and over again,you sure can call DRDO whatever you want but please be reasonable enough to go through the plethora of research papers and patents produced by them annually- i know these are the two things pakistani research establishments are completely oblivious to!

 

[v9s]

Hi dear @v9s
I knew you'd come to that.They,at least do not go about spreading false information about their adversary!
Having seen up close their research especially their missile labs,things are way different from what you imagine. DRDO has designed a lot of missile systems. And to be very honest,we all know where does the R&D of pakistani missile systems take place! I have seen this trend,over and over again,you sure can call DRDO whatever you want but please be reasonable enough to go through the plethora of research papers and patents produced by them annually- i know these are the two things pakistani research establishments are completely oblivious to!

Hahaha...and i knew you'd come full circle.

 

[The Deterrent]

Emaad is more accurate than any other iranian missile

Proximity explosion is enough for non nuclear pay load... it wont disable the nuke... which will still fall on to the ground and explode...may b not on intended target but on same city is going to be enough....
Thats why US has abandoned proximity explosion fot THAAD and patriot pac 3 systems....hit to kill os way to go

So I read up on it, and it seems that the terminal guidance using fins is primarily for accuracy, not ABM avoidance maneuvers. Compared to Shahab-3 (same class system), the accuracy has been brought down to 500m from 2000m. I doubt its accuracy after conducting evasive maneuvers, because of the extreme speed involved.

Not really, if the arming system is damaged, the nuke won't go off. However dirty bomb type of effect may be observed.

Hi dear @The Deterrent I repeat again,entire RV is covered with heat resistant composites.
Secondly a "bang-bang" type optimal controller,wherein the control input can take only extreme values- either 0 or 1(on-off) is usually not used in the atmospheric leg of the final journey. You see,in very simple language RV must be stabilized in flight during the final leg of the journey- this stabilization can be either by externally mounted fins or spin stabilized.
As you have correctly pointed out that RV is spun rapidly just before re-entry to provide the stabilizing effect. The free-fall leg of the journey through atmosphere is pre-planned by the designers and hence it follows a pre-determined trajectory.Now lets suppose suddenly we wish to have some control over the trajectory,in theory we can manipulate the motion in the longitudinal plane,but any error in the flight path will see the RV missing itz target by atleast couple of 100 meters if not more!It is very very difficult to control a missile flying at close to 8-12M especially in the atmosphere. And we are not even talking about the limitations of a "bang-bang" controller!

I would really like a published quote on RV's heat resistant composites, except on the nose tip.

I'm not proposing destabilizing the RV or changing its flight path. To my knowledge, the trajectory during re-entry is more or less in a straight line. How effective can speeding it up be, in irregular intervals using a thruster along the axis?

 

[amardeep mishra]

I would really like a published quote on RV's heat resistant composites, except on the nose tip.

I'm not proposing destabilizing the RV or changing its flight path. To my knowledge, the trajectory during re-entry is more or less in a straight line. How effective can speeding it up be, in irregular intervals using a thruster along the axis?

hi dear @The Deterrent
yes,The RVs are indeed entirely covered with heat resistant composites,have discussed this issue with my colleagues number of times.Isnt that the case with pakistani missiles?
Now coming to the main question of firing thrusters along the flight path of RV.Well i am attaching a very simple free body diagram of the RV.

First we need to understand what is our aim?
Our aim from a purely control engineering perspective is to keep the RV in it's intended flight path.That is,we dont want to disturb in direction perpendincular to velocity or in the direction of lift as depicted above in the picture.When we are firing thrusters along the flight path direction in order to fasten the RV up,we are also effectively changing the dynamic pressure Q.Now the force in the perpendicular direction must be balanced,i.e L=Wcos(theta).
Where L=Q*S*Cl(Cl should not be confused with rolling moment coefficient).Now L should always be fixed to Wcos(theta).If we are varying Q(=0.5*rho*v^2) then we need to also vary(in couter direction) Cl to make L equal to Wcos(theta). Now Cl is again approximately equal to itz own first order variation(by taylor's expansion)- d(Cl)/d(alpha)*alpha.
Hence L can be re-written as Q*S*(Clalpha)*alpha------------------where Clalpha is nothing but the slope of the Cl-alpha curve which is fixed.Therefore what is the other parameter left to vary is alpha or angle of attack!
Concluding my explaination,if we want to increase speed we would ALSO HAVE TO CHANGE ANGLE OF ATTACK in order to balance the force in perpendicular direction.
After having explained the reason of changing the angle of attack,now lets delve into how we can change angle of attack of a RV during the final leg of the journey?
We can either vary alpha by externally mounted control surfaces or the flex nozzles inside the RV.At this juncture, We also need to take care of the velocity at which an ICBM RV is travelling which would be in hypersonic range. Control challenges become very difficult because there is inherently a "small lag"-------(mathematically modeled by exp(-s*tau),where s is the laplace variable s=sigma+j*omega and tau is the delay),however small,associated with any actuator(here in our case flex nozzles). Hence even a slight delay(tau) can result into different flight path and our RV will miss itz target!

 

[amardeep mishra]

@The Deterrent
Hi did you go through the post? Did it clarify your doubts?