Concerns About Missile Fuel Burn Duration and Propellant Load

[erick33]

At present, the PL-15 missile is believed to carry enough rocket propellant for approximately 65 seconds of burn time. However, this figure raises significant doubts.

When compared to the AIM-120D AMRAAM, the missile most frequently compared with the PL-15, the AMRAAM carries propellant for only about 23 seconds. Admittedly, the PL-15 is considerably larger than the AMRAAM, so a longer rocket burn time is to be expected.

The comparison becomes even more questionable when considering the Meteor missile. The Meteor employs a ducted rocket propulsion system and cruises using a ramjet engine, a design specifically intended to dramatically extend thrust duration. Despite this, in CMO, the rocket burn time is listed as 17 seconds, after which the missile’s speed steadily decreases.

Even when looking at a much larger missile such as the SM-6, further doubts arise. The SM-6 has a rocket burn time of 29 seconds. Despite being equipped with both a Mk.72 rocket booster and a Mk.104 sustainer, its total burn time is still only 29 seconds.

Given this context, the claim that the PL-15 has a burn time as long as 65 seconds appears unusually high. Even taking into account the extreme scarcity of publicly available information on the PL-15, such a figure seems abnormally large and difficult to justify.

ven when considering the ratio between a missile’s total flight time and its rocket burn time, the figures remain highly questionable.

In the case of the AIM-120D AMRAAM, the rocket burn time is 23 seconds, while the total flight time is 116 seconds, meaning the rocket burns for only about 20% of the missile’s overall flight.

For the Meteor, the rocket burn time is 17 seconds and the total flight time is 135 seconds, amounting to roughly 12%.

The SM-6 has a rocket burn time of 29 seconds and a total flight time of 366 seconds, corresponding to approximately 7.9%.

By contrast, the PL-15 is said to burn its rocket for 65 seconds, with a total flight time of 123 seconds, meaning thrust is maintained for about 52% of the entire flight.

Even the ramjet-powered Meteor missile sustains thrust for only 17 seconds, so it seems almost impossible for the PL-15—equipped with a dual-pulse rocket motor—to carry enough propellant to keep its rocket operating for more than half of its total flight time.

This issue becomes even more severe in missiles such as the PL-17 and PL-21. In the case of the PL-17, the database indicates that it is equipped with a dual-pulse rocket motor, similar to the AMRAAM and PL-15, yet its listed rocket burn time reaches 3.7 minutes.

The PL-21, despite being equipped with a ramjet engine, is shown as having a shorter rocket burn time of 3.2 minutes than the PL-17.

What is particularly striking is that the total flight times of the two missiles are 192 seconds and 183 seconds, respectively—meaning that the rocket burn times exceed the total flight times.

While I understand that a boost-coast kinematic model is being used, the burn-time values assigned to these Chinese missiles appear excessively high. I am therefore curious whether these values are intentional by design or simply placeholders that have not yet been properly adjusted.

[TempestII]

I'd recommend posting your findings here instead so that the DB team can have a look:

https://github.com/PygmalionOfCyprus/cm ... sts/issues

[Dimitris]

Thanks. This is being looked at.

[Dimitris]

There have been a lot of tweaks related to this in the current public beta (B1817). Please have a look.

The PL-17 and PL-21 specifically remain problematic in the burn calculations because of some erroneous DB values. These will need to be revised on the upcoming DB releases.