Dual thrust vs dual pulse missile propulsion

[ricebunny]

I am trying to understand why would a dual pulse solid fuel motor provide additional range over a dual thrust motor of same weight. I’ve read many times proposals that AIM-120 should be upgraded with a dual pulse motor to extend range beyond the current AIM-120D variant.

How would that work better than the current boost + sustainer burn? If an equal weight dual pulse motor has less fuel for the first burn, won’t it be flying slower in the mid course phase making it easier for maneuvering targets to escape its kill zone?

 

[Dilandu]

Well, the advantage of dual pulse is that you could have second burn on the desired part of trajectory - not only in the beginning. It allows to optimize the shape of trajectory - for example, boost to altitude, glide a bit, then boost again to prolong trajectory. Or, to have a terminal boost to maximize velocity & have better controls/

 

[ricebunny]

Well, the advantage of dual pulse is that you could have second burn on the desired part of trajectory - not only in the beginning. It allows to optimize the shape of trajectory - for example, boost to altitude, glide a bit, then boost again to prolong trajectory. Or, to have a terminal boost to maximize velocity & have better controls/

I found this blog (http://jaesan-aero.blogspot.com/2018/10/?m=1) that ran tons of simulations for various design parameters/configurations including dual-pulse.

The range improvement with dual pulse seems quite small (+4.6%) and trades off speed and time to target (extra 7% TtT)

 

[bring_it_on]

Dual pulse extends the "cruise/coast" phase of flight so you are essentially trading time for range and also improving end game kinematics if you time your second pulse to provide that terminal increase in speed. If you don't want or are being driven by time to target, then you obviously don't get much use out of it.

 

[NMaude]

I wonder if instead of a dual-pulse rocket-motor a hybrid rocket motor is used instead? Have a dual-thrust motor where the boost-phase is a soldi-rocket and when that BP charge has burned out the void left behind is the chamber for completing the combustion of the solid fuel and liquid oxidiser. For the sustain phase use a liquid storable oxidiser which can be metered and a solid fuel with the result is that you have a variable thrust sustainer so minimal thrust is used during the cruise phase to counter drag and full thrust for the endgame.

 

[sferrin]

What is a "dual thrust" motor? Single grain with a boost/sustain burn profile? Let's be very clear what a "dual pulse" vs "dual thrust" motor is. A "dual pulse" has two seperate motor burns, seconds or longer, apart. Not sure what a "dual thrust" motor is. I suspect probably a mistake in translation. A good example of a dual-pulse motor is the PAC-3 MSE. Below shows the second pulse starting (horizontal trail, no it isn't the divert thrusters firing) shortly before impact.

 

[ricebunny]

What is a "dual thrust" motor? Single grain with a boost/sustain burn profile? Let's be very clear what a "dual pulse" vs "dual thrust" motor is. A "dual pulse" has two seperate motor burns, seconds or longer, apart. Not sure what a "dual thrust" motor is. I suspect probably a mistake in translation. A good example of a dual-pulse motor is the PAC-3 MSE. Below shows the second pulse starting (horizontal trail, no it isn't the divert thrusters firing) shortly before impact.

View attachment 663124

Yes, dual thrust motors have two types od propellants, typically boost and sustain.

Dual-thrust rocket motor - Wikipedia

en.m.wikipedia.org

 

[NMaude]

What is a "dual thrust" motor? Single grain with a boost/sustain burn profile? Let's be very clear what a "dual pulse" vs "dual thrust" motor is. A "dual pulse" has two seperate motor burns, seconds or longer, apart. Not sure what a "dual thrust" motor is. I suspect probably a mistake in translation. A good example of a dual-pulse motor is the PAC-3 MSE. Below shows the second pulse starting (horizontal trail, no it isn't the divert thrusters firing) shortly before impact.

View attachment 663124

Yes, dual thrust motors have two types od propellants, typically boost and sustain.

Dual-thrust rocket motor - Wikipedia

en.m.wikipedia.org

This! An example of a dual-thrust rocket-motor is the Standard missile's Mk-104 sustainer motor.

 

[sferrin]

"Dual thrust" seems to be synonymous with boost/sustain. Some use a tailored grain profile, some use discrete grains, burning sequentially, with no time gap in between.

 

[Colonial-Marine]

Boost/sustain rocket motors seem pretty standard for medium/long range missiles. I think the term "dual-thrust" might be a bit obsolete due to the confusion it causes with dual-pulse rocket motors.

 

[NMaude]

"Dual thrust" seems to be synonymous with boost/sustain. Some use a tailored grain profile, some use discrete grains, burning sequentially, with no time gap in between.

Also in dual-thrust SRMs the boost-grain often uses a faster burning propellant loading than the sustain-grain.