Rocket engine bell plugs and risk of hitting horizontal stab -- some screenshots

[Xavven]

I don't think we can come to IRL conclusions from DCS screenshots, so take this as you will, but here are some screenshots I took while in the mission editor. As some have pointed out, apparently rockets can have plugs in the engine bells to protect them, and they get blown backwards when the rocket motor fires. Some seem to have more clearance issues than others, just eyeballing it.

 

HARM on station 6

 

 

 

That 3rd Maverick on station 7

 

 

 

 

Hydra Rockets, LAU-3 on Station 4

Not sure if these have plugs

 

[Furiz]

So basically only that 3rd maverick looks like it can damage something.

[Ignition]

The screenshots are taken from above of the maverick, not even at wing level.

[Xavven]

2 minutes ago, Ignition said:

The screenshots are taken from above of the maverick, not even at wing level.

 

I lined up the view so that you can only see the back edge of the fins of the maverick. In my opinion this gives you the best representation of where the exhaust would fire -- directly at the viewer. Please feel free to get a better angle if you can.

[Ignition]

6 minutes ago, Xavven said:

 

I lined up the view so that you can only see the back edge of the fins of the maverick. In my opinion this gives you the best representation of where the exhaust would fire -- directly at the viewer. Please feel free to get a better angle if you can.

 

I tried after writing the post but its impossible since the camera is fixed and you can only change the view angle so its not optimal, besides its a 3D representation of the real plane.

 

[Xavven]

16 minutes ago, Ignition said:

 

I tried after writing the post but its impossible since the camera is fixed and you can only change the view angle so its not optimal, besides its a 3D representation of the real plane.

 

 

Noted. Thanks.

[Machalot]

There will be a random dispersion of where the cap goes from one missile to the next, plus I would bet the motion of that cap is dominated by the local aerodynamic flow field coming off the adjacent stores and the wing, rather than just a straight line from the missile. 

[SFJackBauer]

1 hour ago, Ignition said:

besides its a 3D representation of the real plane

 

What is that supposed to mean? Its a 3D accurate representation of the real plane. Are you implying the pylons, horiz stab or something else in the DCS model is wrong in relation to the real plane?

 

BTW the Hornet is similar in regard to the inner stations - and the stores are mounted in a downward angle so the exhaust is even closer to the stab

 

[Machalot]

1 hour ago, SFJackBauer said:

What is that supposed to mean? Its a 3D accurate representation of the real plane. Are you implying the pylons, horiz stab or something else in the DCS model is wrong in relation to the real plane?

There might not be any direct connection between the visual model and the equations of motion in the software. 

Edited September 12, 2021 by Machalot

[SFJackBauer]

22 minutes ago, Machalot said:

There might not be any direct connection between the visual model and the equations of motion in the software. 

 

 

Even if that was true (which I think its an insane supposition given that it would make the 3D model of the plane or missiles look completely wrong when doing flight maneuvering...), what that has anything to do with Xavven is doing? He is looking at the geometric relationship between the rocket exhaust bell and the plane body. No EoM needed.

[Ignition]

8 hours ago, SFJackBauer said:

 

What is that supposed to mean? Its a 3D accurate representation of the real plane. Are you implying the pylons, horiz stab or something else in the DCS model is wrong in relation to the real plane?

 

BTW the Hornet is similar in regard to the inner stations - and the stores are mounted in a downward angle so the exhaust is even closer to the stab

 

 

I'm not implying anything, just a representation. Everything from the aircraft to the pylons and weapons could be 100% accurate.

[=52d= Skip]

Not everything you drop goes in a straight line aft (or down)

 

 

 

[Glide]

2 hours ago, =52d= Skip said:

Not everything you drop goes in a straight line aft (or down)

Thanks for that!  That's why they get the big bucks!

[Machalot]

4 hours ago, SFJackBauer said:

 

Even if that was true (which I think its an insane supposition given that it would make the 3D model of the plane or missiles look completely wrong when doing flight maneuvering...), what that has anything to do with Xavven is doing? He is looking at the geometric relationship between the rocket exhaust bell and the plane body. No EoM needed.

I used the term EoM to also include their constant configuration parameters, part of which are the position and orientation of all the components such as pylons and stores.

 

ED recently changed the visual spacing between the pylons and wings. So that means for the pylons (and in general), it's possible that:

• The visual model is not accurate to reality
• The visual model unintentionally doesn't match exactly what the dynamics model assumes due to error, oversight, or misunderstanding
• The visual model includes nuances that are approximated away in the dynamics model or vice versa

So if they were hypothetically to track the motion of the nozzle plug to detect a collision, you wouldn't necessarily be able to rely on the visual model to predict the motion. 

[Bunny Clark]

23 hours ago, Ignition said:

 besides its a 3D representation of the real plane.

 

I'd be pretty surprised if it were more than a few inches off at most, and it's probably more accurate than that. Considering we've heard that damage to the horizontal stab is a major concern for the inboard Mav on a LAU-88, this matches expected reality well.

 

8 hours ago, =52d= Skip said:

Not everything you drop goes in a straight line aft (or down)
 

Indeed, and that's why separation testing is so important. Though a Maverick will pretty much go straight or not at all, since it's launched on a rail.