Why Did Soviet Aircraft Use Variable Ventral Air Intakes?

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Discussion Overview

The discussion centers on the design choices regarding variable ventral air intakes used in Soviet aircraft compared to the fixed intakes of American fifth-generation fighters. It explores the aerodynamic and operational considerations influencing these design decisions, including performance during high-G maneuvers and operations from austere airfields.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants note that Soviet aerodynamicists believed ventrally located intakes provided advantages during vigorous maneuvers, minimizing intake stall risks in high-G turns and high-alpha flight.
  • Others suggest that the differing designs reflect varying priorities between Soviet and American engineers, with each design being correct for its intended optimization.
  • One participant raises a question about the implications of operating from austere fields, suggesting that Soviet designs accounted for conditions requiring upper inlets.
  • Another participant mentions that many Russian aircraft feature movable covers over the inlets to prevent foreign object damage (FOD) when operating from rough surfaces.

Areas of Agreement / Disagreement

Participants express differing views on the effectiveness and rationale behind the design choices of air intakes, indicating that multiple competing perspectives remain without a clear consensus.

Contextual Notes

Some claims about the performance and operational requirements of the air intakes depend on specific definitions and assumptions that are not fully explored in the discussion.

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Air Intakes??

At an early stage of the fighter's development
it became obvious that the MFI was a
lot different from the American fifth-generation
fighters. For instance, the Mikoyan fighter
had a variable ventral air intake from the
start, whereas the F-22 had non-adjustable
two-shock lateral intakes optimised for supersonic
cruise and the rival Northrop/General
Dynamics YF-23 had non-adjustable dorsal
intakes. Soviet aerodynamicists believed a
ventrally located intake offered certain
advantages during vigorous manoeuvres,
minimising the danger of an intake stall during
high-G turns and high-alpha flight. Also,
the tail-first layout maximised lift and the
canards performed a pitch damping function
at critical AoAs. By comparison, the F-22 and
YF-23 utilised a more conventional layout
with trapezoidal wings and stabilators.

Source:
Russian Fifth-Generation Fighter
Technology Demonstrators
Yefim Gordon
Original translation by Dmitriy Komissarov

Question is simple; is Soviet thinking while choosing from 3 given air intakes is correct & why US think otherwise??
 
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It just sounds like the two sets of designers had different priorities in mind when designing the intakes. Each is correct for the priority it optimizes to.
 


Can anybody given me images of these 3 types of air intakes; I am fed up googling it
 


sorter said:
Russian Fifth-Generation Fighter
Technology Demonstrators
Yefim Gordon

This could mean war - '5th generation fighter' is a registered trademark of Lockheed (makers of the F35).
This just came up in a lawsuit in Canada over their decision to buy the F35, apparently the air force specification required a '5th generation fighter'.
The specifications were written with the aid of consultants supplied by an unnamed US aircraft maker.
 


In addition to the excessive angles of attack envisioned by Soviet aeronautical engineers, they also had to contend with operations from austere (grass) fields which required upper inlets.
 


mugaliens said:
In addition to the excessive angles of attack envisioned by Soviet aeronautical engineers, they also had to contend with operations from austere (grass) fields which required upper inlets.

What does this bold part means. The placement of air intakes with respect to cockpit is fairly equal that of Su-25/30/35 & F-15/35/22

With the exception of F-16/J-10(a copycat of F-16) all modern aircraft had 2 side air intakes. including the newbaby JF-17
 


Most russian aircraft have moveable covers over the inlets which can be partly closed to stop FOD when operating from rough strips.