Astra BVRAAM

[karn]

Hmm, that makes sense. Any studies/explanations which show how dual-pulse rocket motor increases range significantly ?

If you are considering only pure straight line range from the highest altitude possible.
-In single pulse the missile climbs to its highest possible altitude and accelerates to its highest velocity. Now despite the rocket motor burning there is no increase in velocity but no deceleration either. After the motor burns out the missile coasts to the ground.
- In dual pulse . The first pulse takes the missile to its highest altitude and velocity and burns out . It then coasts in the thin air until it start losing velocity + altitude. When the missile starts reaching a bit more denser air the 2nd pulse fires and takes the missile to the highest altitude again and finally coasts to the ground after the rocket motor burns out .. the flight profile in the 2nd case is more efficient.. it's like a car where you put max acceleration all the time will have bad mileage.
This is purely academic of couse since in its actual usage the objective is to have the missile have more energy to maneuver to its target

 

[Chinmoy]

Hmm, that makes sense. Any studies/explanations which show how dual-pulse rocket motor increases range significantly ?



Yes, it will be more maneuverable but will lose energy faster.

Lots of research paper are available on it. But let me lay out the bare simple fact here.

Rocket motors could be divided broadly into two types. One with high specific impulse which would give you huge thrust in very short duration. Second is low specific impulse which would give you comparatively low thrust for a longer duration.

In a single motor rocket engine, you could have any one of this. Although a compound thrust motor could be designed, but its too complex and generally avoided for dual pulse one. So in case of Mk-1, once the rocket motor starts burning, it can't be stopped. So in this case, after the missile achieve the desired altitude and starts descending towards the target, the rocket motor still keeps on burning. So it would have to perform the end maneuvers with what is remaining of its fuel. So basically we are wasting precious fuel here.

Now in case of a dual pulse rocket, we do use separators in between two rocket motors. The first motor is basically of high specific impulse which provides huge thrust to the missile and helps it to attain altitude quickly. After that it gets cut off and the missile basically coasts towards its target. So we are not burning any fuel during this time although we are maintaining the speed all because of the KE achieved earlier on. The second motor is for sustenance which kicks on after a specific time and it helps the missile to sustain its motion during the end game.

 

[Bleh]

How far are we from Mk2 and Mk3?

Mark2 a quite close actually, Mark1 might end up as a tech demo.. with bulk orders of Mark 2.
Especially know that the new Mark 2 model is basically enhanced Mark 1 with fatter mid-body, with the older configuration set aside...

 

[Dark Sorrow]

Mark2 a quite close actually, Mark1 might end up as a tech demo.. with bulk orders of Mark 2.
Especially know that the new Mark 2 model is basically enhanced Mark 1 with fatter mid-body, with the older configuration set aside...

Astra Mk.1 is not a technology demonstrator.
We have already given order of 648+ units.

 

[LondonParisTokyo]

How far are we from mass producing Mk2? What is holding us back from moving forwards?

 

[SwordOfDarkness]

How far are we from mass producing Mk2? What is holding us back from moving forwards?

Stuff needs to be tested before we make it in bulk and strap it to multi million dollar planes

 

[ym888]

How far are we from mass producing Mk2? What is holding us back from moving forwards?

It will take at least five more years

 

[SwordOfDarkness]

The touted range of 160km for Mk-2 is almost a 50% increase over the previous range. This range increase is too ambitious to achieve (in my opinion) just by improving rocket propulsion, without increasing the actual fuel content.

Second, Astra is by far the only new-gen. BVR with such a high surface area fins. The central support fins are actually massive and should contribute to significant drag at supersonic speeds. Not only those massive fins will cause more drag, but will make the missile lose energy faster at an endgame chase, where sharp turns will cause those massive fins to act like giant airbrakes.

Overall, the initial render of Astra Mk-2 with frontal canard fins would have been the predicted design choice.

Incorrect. Big wings increase range and maneuvarability.

Think of it this way - if we only use canard and rear control surfaces, they will simply give torque on the missile body. It will rotate, but for it to change direction, there needs to be a force on it. This will be basically proportional to the area of fins + area of body.

Similarly, the big wings in the center allow it to be closer to flight rather than being in free fall like a rocket.
But yes, it will marginally (maybe 5% or so) reduce speed during flight.

 

[Aniruddha Mulay]

I don't think testing+ induction should take more than 3-4 years given that Astra Mk2 is essentially a chonky Astra Mk1.

 

[LondonParisTokyo]

Stuff needs to be tested before we make it in bulk and strap it to multi million dollar planes

What can be done to expedite the testingn?

 

[SwordOfDarkness]

What can be done to expedite the testingn?

IG if govt insists on quick testing timeline, DRDO can do faster. Make more models and do testing one after the other.

 

[mist_consecutive]

Incorrect. Big wings increase range and maneuverability.

Think of it this way - if we only use canard and rear control surfaces, they will simply give torque on the missile body. It will rotate, but for it to change direction, there needs to be a force on it. This will be basically proportional to the area of fins + area of body.

Similarly, the big wings in the center allow it to be closer to flight rather than being in free fall like a rocket.
But yes, it will marginally (maybe 5% or so) reduce speed during flight.

Increase maneuverability, yes.
Increase range, no.
Increase drag, yes. => More drag -> Less Range.

Think of it this way - if we only use canard and rear control surfaces, they will simply give torque on the missile body. It will rotate, but for it to change direction, there needs to be a force on it. This will be basically proportional to the area of fins + area of body.

At high speeds, the canards and rear surface provide enough force for the missile to take turns. AIM-120 AMRAAM despite having small control surfaces is able to effectively work as a short-range A2A missile as well (and pilots love it for that).

Similarly, the big wings in the center allow it to be closer to flight rather than being in free fall like a rocket.
But yes, it will marginally (maybe 5% or so) reduce speed during flight.

Reduced speed can be compensated by a more powerful rocket motor (and dual-pulse motor). Also, if the missile is aerodynamically bound into a flight like a plane, it is in stable equilibrium which will make it a poor turning machine.

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Basically, if a BVR is hot on your tail, you will do evasive maneuvers (along with other measures like electronic) to shake it off. That said, the evasive maneuvers include zig-zagging, well as notching the missile. All these maneuvers aim to drag the missile into thicker air (toward the ground) and bleed its speed by forcing it to make a lot of turns. Astra will fare poorly in such a scenario.

You can read more about this in my article here - https://defenceforumindia.com/threads/modern-bvr-air-combat-part-2.82312/

In a nutshell, if I am being chased by Astra Mk2 and Aim-120D, I will have higher chances of shaking off Astra Mk2 by evasive maneuvers than Aim-120D.

 

[SwordOfDarkness]

Increase maneuverability, yes.
Increase range, no.
Increase drag, yes. => More drag -> Less Range.



At high speeds, the canards and rear surface provide enough force for the missile to take turns. AIM-120 AMRAAM despite having small control surfaces is able to effectively work as a short-range A2A missile as well (and pilots love it for that).

Do you know why AIM 120 D has a set of fixed center wings? hehe
More you can provide opposing force to turn you towards target, the better. Depending on thrust, weight, etc, designers can choose whatever size works best.

Increased range, as it will reduce fall velocity (by providing drag, opposing gravity, like how a paper airplane, which has just flat paper "wings" will go farther than a roll of paper) allowing for a straighter flight path rather than having to follow ballistic path.

Reduced speed can be compensated by a more powerful rocket motor (and dual-pulse motor). Also, if the missile is aerodynamically bound into a flight like a plane, it is in stable equilibrium which will make it a poor turning machine.

------------------------------------------------------------------------------------

Basically, if a BVR is hot on your tail, you will do evasive maneuvers (along with other measures like electronic) to shake it off. That said, the evasive maneuvers include zig-zagging, well as notching the missile. All these maneuvers aim to drag the missile into thicker air (toward the ground) and bleed its speed by forcing it to make a lot of turns. Astra will fare poorly in such a scenario.

You can read more about this in my article here - https://defenceforumindia.com/threads/modern-bvr-air-combat-part-2.82312/

In a nutshell, if I am being chased by Astra Mk2 and Aim-120D, I will have higher chances of shaking off Astra Mk2 by evasive maneuvers than Aim-120D.

Yeah, I know about A2A combat. But those things are assuming a direct head on, 1 on 1 combat.
Try watching simulations of 1v1, they will match the ideal scenario. Then watch simuls of 5 v 5 or 10 v 10, lot more targets and chaos, and missile hits are less complicated. Here, maneuverability becomes more important than energy management (especially since Astra MK2 is a dual pulse, so has higher terminal speed and energy anyway).

(also just saying more efficient than zig zag is to go in a helical path into thicker air. Notching may not work if opponent has radars on ground or aewacs elsewhere)

 

[BON PLAN]

PL-15 is of a different class of missile

PL15 is a 200+ kg missile. Impossible to compare such a heavy AA missile to a medium one, as ASTRA or ASTRA 2

 

[BON PLAN]

Wait, I must be blind because I see absolutely no physical difference between Mk1 and Mk2 ? I initially thought Mk2 must be thicker and longer (that's what she said), but after a side-by-side comparison between Mk1 and Mk2 launches, they have practically identical bodies.

But that means Mk2 might only have a marginal improvement in range due to improved rocket propulsion.

ASTRA mk2 is a dual engine missile. ie a second motor burn is selected when the target is very near, so as to keep so more kinetic energy to the missile. It increases the NEZ.

 

[BON PLAN]

It will take at least five more years

May be not 5 years. May be just 3 because the 2 missiles use the same frame so no need of new flight tests to integrate the missile to the fighter (exactly the way French develop MICA NG with the legacy MICA frame).

 

[LETHALFORCE]

 

[Rajaraja Chola]

Astra Mk.1 is not a technology demonstrator.
We have already given order of 648+ units.

248. not 648

 

[Dark Sorrow]

248. not 648

An initial order of 50 missiles was placed in September 2017.
Later an additional order of 248 missiles were placed for Indian Air Force and Indian Navy.
31 May 2022, Ministry of Defence signed contract with BDL to produce 350+ units of Astra Mk-1 for Indian Air Force and Indian Navy.

 

[Rajaraja Chola]

An initial order of 50 missiles was placed in September 2017.
Later an additional order of 248 missiles were placed for Indian Air Force and Indian Navy.
31 May 2022, Ministry of Defence signed contract with BDL to produce 350+ units of Astra Mk-1 for Indian Air Force and Indian Navy.

Oh. I didn’t know the third order for 350+ was placed.
Good to know if true