Weapon spin

[SickSidewinder9]

Why don't weapons spin?  Are the animation so hard tied to weapon movement?  Basically every air launched weapon, every ground fired projectile, every missile and every bomb (exceptions being JSOW, SDB, maybe cruise missiles, that type of thing) will spin when released or fired.  I think it's actually important for stability and accuracy just like how gun barrels are rifled to impart spin on the projectile.  You can even see how the winglets and control surfaces on the GBU-24 are slightly staggered to promote spin.  It looks really weird in game that weapons never spin, especially weapons like laser guided bombs or Snakeeyes that have longer surfaces that pop out.  Once you see it, you can't unsee it.

Edited December 23, 2023 by SickSidewinder9

[Tank50us]

actually, if you watch closely, many unguided weapons do 'spin' on their way in, just very slowly. I'm not sure if this is by design, or a result of outside conditions, but it's certainly there... it's just inconsistent. Not that it really matters that much anyway since usually if you're the one that dropped the weapon, you're probably more concerned with avoiding a sudden interaction with the terrain to watch it hit the target.

[Iron Sights]

Perhaps it will be more defined one day. I think it’s just one of those things that will have to deal with right now as they work the modeling of the sim. All in all, I’m satisfied with all we have so far, but I will say most bombs fins I find do not have a twist. Now I do believe that CBU and most canisters should spin. Snake eyes pop out fins are for braking more than anything. But, I’ll take a deeper dive on this, not sure on LGB bombs.

[Vampyre]

4 hours ago, SickSidewinder9 said:

 Basically every air launched weapon, every ground fired projectile, every missile and every bomb (exceptions being JSOW, SDB, maybe cruise missiles, that type of thing) will spin when released or fired.  I think it's actually important for stability and accuracy just like how gun barrels are rifled to impart spin on the projectile. 

Not true. The point of stabilizing fins, particularly large stabilizing fins are to provide stabilization in flight. Weapons requiring spin stabilization typically are unguided and have small fins specifically for imparting the rotational force or, in the case of most gun and cannons, have no fins but require rifling in the barrel to spin the round as it is fired.  Fins that create spin also impart drag which reduces range. Spin is undesirable for weapons like guided bombs. Spin is of particular importance for unguided rockets, most CBU's and smaller missiles like the RIM-116, many SACLOS radio command guided missiles and various dumb bombs.

4 hours ago, SickSidewinder9 said:

  You can even see how the winglets and control surfaces on the GBU-24 are slightly staggered to promote spin.  It looks really weird in game that weapons never spin, especially weapons like laser guided bombs or Snakeeyes that have longer surfaces that pop out.  Once you see it, you can't unsee it.

 

Pertaining to the GBU-24, the offset rear stabilizers are not there to promote spin, the pop out surfaces needed to be of a wider chord on this particular weapon to provide better flight dynamics for its intended low altitude release parameters. The Air Force found that the larger surfaces caused clearance issues on the aircraft it was intended to be used on so the fins were offset symmetrically to allow for the fitment of the wide chord stabilizers. This offset, and the resulting spin, has a negative effect on the range of the weapon but, fortunately, the proportionate guidance system used on the GBU-24 was capable of dampening the rotational forces once it had a laser to lock on to. Basically, the offset stabilizing fins were a compromise to make it work. 

For Snake Eye, they don't always spin the same way or sometimes even spin at all so I think that has more to do with manufacturing defects in the fin kits or irregularities in the bomb build up than with any spin stabilizing intent. I wouldn't expect that kind of randomness to be high on ED's priority list.

 

[Gunfreak]

If you look av several unguided rockets, they will spin.

[Exorcet]

13 hours ago, SickSidewinder9 said:

Why don't weapons spin?  Are the animation so hard tied to weapon movement?  Basically every air launched weapon, every ground fired projectile, every missile and every bomb (exceptions being JSOW, SDB, maybe cruise missiles, that type of thing) will spin when released or fired.

Weapons do spin in DCS. Rockets are the most noticeable. Missiles will spin to the correct alignment when dropped (120 or Sparrow fired from F-15 semi conformal stations).

Quote

  I think it's actually important for stability and accuracy just like how gun barrels are rifled to impart spin on the projectile.

Rifles induce spin because their projectiles don't have fins. Most aircraft weapons do have fins for stability and don't need nor want to spin.

[SickSidewinder9]

Uhhhh, pretty sure they're all spin stabilized, what are you guys citing?

[ShuRugal]

7 hours ago, SickSidewinder9 said:

Uhhhh, pretty sure they're all spin stabilized, what are you guys citing?

What are YOU citing for "all projectiles are spin stabilized"?

This is patently untrue for most guided munitions.

Spin stabilization is only required for projectiles which fly on a ballistic course.  The reason this is required is to average out yawing/pitching forces induced by any irregularities on the surface of the projectile, so that it will actually follow a ballistic course and not go arcing off towards the side with the most drag.

PAVEWAY and JDAM munitions do NOT use spin stabilization, as the spin would fight the guidance inputs and require the fins to correct more (thus inducing more drag and shortening the range) in order to hit the target.  While these bombs are gravity-driven, they do NOT follow pure ballistic trajectories.

For certain types of seeker, spinning will actually render the guidance invalid.  The AIM-9 is a perfect example of this: versions prior to the AIM-9X, all the way back to the original model, have/had gyroscopically driven "rollerons" on the rear fins to cancel out ANY rolling motion and maintain the roll attitude of the missile in the same orientation as launch so that the seeker head could work properly.

 

The only spinning guided munitions you will find are very cheap SACLOS guided missiles, where the spin is used to allow the missile to have only one moving control surface, or rockets which have had laser-guidance packages installed.  In the case of SACLOS missiles has drawbacks, such as the missile being slow to change course, which are acceptable in a SACLOS missile, because the possible maneuver cone of the beam is very small and a properly launched missile should make only minimal course corrections.  In the case of 'guided rockets', the drawbacks of the spin are acceptable because of both the short intended range of use and the low cost of making this modification by only slapping on a seeker/guidance head.

Edited December 25, 2023 by ShuRugal

[rob10]

7 hours ago, SickSidewinder9 said:

Uhhhh, pretty sure they're all spin stabilized, what are you guys citing?

Here's one: "However, the high RPM inherent with spin stabilisation is not conducive to the use of tracking sensors or guidance hardware."

https://www.sciencedirect.com/science/article/pii/S2214914719302430

[SickSidewinder9]

Well, <profanity>.  I stand corrected.  Thank you all and have a Merry Christmas or Happy Isaac Newton's Birthday or whatever you do.