Without going into version/revision numbers, builds, etc., is there something like a simple overview of types of nose and tail fuzes and the function they add to the bomb unit? Google's being very unfriendly on this one..
Without going into version/revision numbers, builds, etc., is there something like a simple overview of types of nose and tail fuzes and the function they add to the bomb unit? Google's being very unfriendly on this one..
I was going to say maybe we should all just wait for Noodle to answer
You mean real-world? Again, in DCS, the various fuze types and options make no difference at all.Originally Posted by JayPee
Off the top of my head...
The M904 and its derivatives are nose-mounted mechanical fuzes that use air-driven arming vanes. Depending on variant (E3, E4, etc.), it has a ground selectable arming delay of something like 2 to 20 seconds. It also allows for a function delay...between instantaneous and something like 250msec. Because the arming vanes are air-driven, there's a minimum allowable employment airspeed. It can't be used on LGBs because of the guidance kit.
The M905 is a tail-mounted mechanical fuze that also uses air-driven arming vanes. The M905 gives both an arming delay and a function delay capability.
The FMU-139 is an electric fuze that allows pilot selection of arming delay, perhaps function delay too...I'm not sure. The FMU-139 can be used as both a nose and a tail fuze, and has unique settings for both HD and LD weapons.
The FMU-152 is also an electric fuze, and represents the most versatile fuze available. It allows pilot selction of arming and function delays, can be used for both HD and LD, and also supports penetrator warheads.
The DSU-33 is a radar proximity fuze that provides airburst capability. The DSU will function at a height of 5 to 35 feet.
The FZU-39 is also a proximity fuze that provides a selectable HOF for the Tactical Munitions Dispenser (TMD) based weapons like the CBU-87/89.
The one fuze option that actually has an effect in DCS is setting FZU-39 to "NO" in the CBU-87 Inventory Settings page. This will revert to a mechanical timer mode, and the container will function when the timer runs out.
Yes, real world! Knowing that DCS does not distinguish between fuzes.
What is the difference between an arming delay and a function delay? Is the arming the delay time before the bomb becomes armed after being released from the pylon?
Yes. Function delay is the time between fuse activation (impact etc.) and the fuse firing and detonating the warhead. Delay fuses typically being used in penetration weapons so that the warhead explodes inside a target structure rather than outside it.
Delay fuse example:
Last edited by Eddie; 17Oct14 at 19:31.
So basically the arming delay feature of a fuse is a safety thing for the deploying platform while the function delay is a feature of tactical value. I've always wondered how they construct these bunker busters, on the one hand their casing is tough enough to pierce through the concrete by means of kinetic energy alone, yet it bursts open from the inside out due to the detonation of the explosive charge. Either there's something very fancy about the material of the casing, or the explosion is very inefficient because it loses a lot of energy breaking the casing.
These air burst fuses, do they use air pressure from the air moving along the body of the bomb during the fall to spool up a dynamo which in turn powers a mini Doppler RADAR to detect the distance above the surface/target? Or do they come with a battery in it? Because as far as I know a dumb bomb does not have a power supply and a RADAR does not function without power.
BTW I'm derailing this thread off topic but I guess a discussion like this never hurts those who are interested in the matter.
Last edited by JayPee; 17Oct14 at 19:58.
Yes, the arming delay is the nominal length of time between weapon release and fuze arming. I say nominal because there is about a +/-20% margin of error.
The arming process begins when the weapon is ejected from the pylon, and the arming lanyards are pulled. Once the arming lanyards are pulled, the air-driven turbines of mechanical fuzes are free to rotate, and a set number of turns brings the firing train into alignment. Once armed, impact forces drive a firing pin into the primer, which initiates the booster charge, which in turn initiates the main charge.
Similarly, for electric fuzes, pulling the arming lanyard activates the fuze battery. At the expiration of the arming delay timer, gas pressure is used to mechanically rotate the firing train into alignment and complete the arming process.
Function delay is the time between weapon impact and detonation. Anything less than 5msec is considered instantaneous. Function delay can range from 5 to about 250 msec for GP bombs, greater for penetrating weapons like the GBU-31(v)3.
EDIT: Sniped by a wide margin because I'm posting from my phone, and I spend more time fixing the damned auto correct than I do typing a reply.
Last edited by Noodle; 17Oct14 at 19:57.
Turn auto-correct off. For starters it's very annoying and besides it's way more fun to have it set to off when TUI.
The bomb doesn't, but the fuse does. Weapons typically use thermal batteries that are "one shot' but extremely reliable even in extreme conditions or after long storage periods. As Noodle described, the lanyard simply gets pulled and the fuse arming vanes/battery are enabled.
That fine, this isn't the ED forums, we like and encourage natural progression of discussions.
Yes, arming delay provides for safe escape of the aircraft should the weapon function as soon as it arms. Function delay provides for penetration of hardened or deeply buried targets (HDBT).
Proximity fuzes use an integral battery to provide electrical power for the emitter.
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