Folding "+" or Non-folding "X" Rear Fins?

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Discussion Overview

The discussion centers around the design choices of rear fins on missiles, specifically comparing folding "X" fins to non-folding "+" fins. Participants explore the implications of these configurations on performance factors such as drag and control, as well as potential reasons for design changes over time.

Discussion Character

  • Debate/contested
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes the confusion regarding the design progression from "X" fins to "+" fins, suggesting that the latter may provide advantages such as reduced drag or weight.
  • Another participant proposes that if the latter missile has moveable control surfaces, a "+" configuration might be easier to engineer compared to an "X" configuration.
  • A question is raised about which fin configuration might result in lower drag, prompting a discussion on the parameters affecting drag.
  • One participant argues that there should not be a notable difference in drag unless the shapes of the fins differ significantly.
  • Another participant insists that there must be some reason for choosing "+" fins over "X" fins, hinting at factors beyond drag.
  • It is suggested that ease of control or positioning the fins out of the wake of the wings and intake could be reasons for the preference of one configuration over the other.

Areas of Agreement / Disagreement

Participants express differing views on the implications of fin configurations, with no consensus reached on the advantages or disadvantages of "+" versus "X" fins. The discussion remains unresolved regarding the specific reasons for design choices.

Contextual Notes

Participants do not clarify the specific shapes of the fins or provide detailed engineering analyses, leaving assumptions about drag and control unverified.

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+ or X Rear fins??

[PLAIN]http://img124.imageshack.us/img124/2054/c6xxvp3.jpg

Notice the folding rear fins and fact that they are at 45 degrees X relative to the intake.
[PLAIN]http://img208.imageshack.us/img208/363/c602xxxnm5.jpg

But clearly the rear fins r "+"

Now provided that former missile is oldy with respect to the latter one; I am confused at this
A design progression where the "x" fins didn't work out so they changed to non-folding "+" fins which probably give more range (less drag?, less weight?) but take up more space?
 
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I don't really know much about missiles, but one thought comes to mind. If the latter version has moveable control surfaces on the tail-planes, which I can't determine from the photo, a cruciform rather than X configuration would be easier to engineer. Individual elevators and rudders take less co-ordination than multiple stabilators.
 


talking about Drag parameter only; wht you suggest; either + or X configuration will have more than the other??
 


There shouldn't be any notable difference in drag unless the fins are different shapes.
 


Guys,, but their must be some difference b/w choosing + over x
 


Either ease of control as stated before or because they may get the fins out of the wake of the wings and/or intake. Those are the only things that jump to mind.
 

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