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Maxima Iradia BVRAAM

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Description

The revised version of the previous "Aera Iradia" Long Range Air to Air Missile .

Despite the higher range performance offered by Aera Iradia's Ramjet propulsion compared to earlier version of Jihadist family AAM's there was still a concern related to its aerodynamic performance , namely pressure recovery of the Ramjet inlet , which will directly affect propulsive qualities of the Ramjet engine (thrust, combustion stability etc) .

Aera Iradia demonstrators uses 4 2-D (ramp type) inlet with "X" scheme for structural reason, as the higher performance "+" arrangement would require strengthening and enlargement of the inlet to accommodate equipments related to stowing on platform , this will penalize the design in terms of weight, and drag , thus simpler "X" scheme is preferred, despite lower performance compared to the "+" arrangement.

the 4 inlet layout was chosen based on fact that having "many" inlet flowing air to the combustor will improve Ramjet combustion ejector performance . However for air to air missile application where high AoA (angle of Attack) operation (thus means high maneuverability) is expected the 4 inlet layout have poor performance , this is due to "non uniform" flow phenomenon, where inlet located on the top and bottom of Aera Iradia "sees" different airflow, the bottom inlet will exhibit "good performance" due to lower local mach number and smaller angle of air flow field to the inlet . The top inlet however are in very opposite condition where local mach number and angle of airflow is larger than Aera Iradia's AoA , thus the upper intake will operate in much lower pressure recovery than the bottom inlet, this can cause loss of thrust , inlet flow reversal which will hamper the missile's operation.

Thus a decision was made, based on flight and wind tunnel test , to "cut" the number of inlets from 4 into 2 with arrangement of inlet in a manner of the OPFOR "MBDA-Meteor" (2 inlet 45 degrees from centerbody), this arrangement would provide superior AoA performance than the previously used 4 inlet , which is summarized in figure 1 below

Figure-1
[link]

As seen on the figure above the 2 inlet layout has superior AoA performance in shape of superior pressure recovery and capture area ratio than 4 inlet arrangement and nose inlet which also considered as "neutral contestant" .

The 45 deg arrangement of the inlets is based on following test data in figure-2

Figure-2
[link]

In the figure-2 readers can see that the inlet located right on the bottom (0 deg) have higher pressure recovery and capture area ratio . However this inlet arrangement may offer inferior ramjet combustion ejector performance , thus this arrangement is dropped from the selection board .

Based on above mentioned considerations , another demonstrator missile named as "Maxima Iradia" is made , the missile are in same dimension as Aera Iradia , but feature only 2 intakes and a pair of short strake , for stabilization and improving glide performance , this new missile would have higher AoA performance and better propulsive performance over Aera Iradia . However thiat came in cost of some complexity in flight control software , since a new Bank To Turn control scheme had to be incorporated, previously Aera Iradia used common "Skid To Turn" maneuver control law inherited from Jihadist missile for faster response during terminal phase and low miss distance due to reduced Radome error slope .

Maxima Iradia in other hand may have higher radome error slope thus higher miss distance due to incorporation of Bank To Turn control law . However it was decided that BTT laws will only used during mid-course/cruise phase of the missile , while during terminal phase where the seekers "lit on" the missile will switch into faster response and more accurate Skid To Turn (STT) control laws .

The Aera Iradia , despite its shortcomings in high AoA performance , will not be abandoned but instead will be adopted as a High performance low altitude Surface to Air missile , to intercept penetrating UAV's, Cruise missiles , Glide Bombs and Aircrafts .

At low altitude where AoA and Yaw angle does not very demanding, the Aera Iradia will likely provide superior performance over our current medium range SAM systems .


Bibiliography and Image Source

-Piercy.T.G.,Heins.A.E.jr.,Bendot.J.G., "Ramjet Air Induction System Design For Tactical Missile Application".,The Marquardt Company.,California.,1985
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Comments1
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BezGlaz's avatar
It looks like russian РВВ-АЕ, as to to me. Pretty cool.