The whistling of mortars/rockets/bombs

[KrazyHorse]

A pitch rise would mean that (if we ignore all other effects and concentrate solely on doppler) that the component of the velocity vector of the bomb in your direction would increase. With bombs (which reach terminal velocity before getting to you) there is no reason to assume that this is the case.

[MRT144]

My math sucks too much to post

[MichaeltheGreat]

Originally posted by notyoueither
I have heard that mortar shells don't make much noise at all. Haven't had one fired at me, so I can't testify.

Depending on size, they're pretty close - the types we use (four deuce) are fairly long range, as are the common heavys (Soviet/Russky 120mm and imitations) used by the bad guys. You won't hear much unless they go long. Shorts you may hear barely before the explosion.

The smaller, man-portable stuff (60s, 81s, etc. although 81 is a ***** to hump around) is short ranged enough that you could hear it fired out of the tube, depending on what else is going on.

If anything comes close to you, you probably won't hear follow-on rounds real well, since your ears will be ringing a bit.

[MichaeltheGreat]

Originally posted by KrazyHorse
A pitch rise would mean that (if we ignore all other effects and concentrate solely on doppler) that the component of the velocity vector of the bomb in your direction would increase. With bombs (which reach terminal velocity before getting to you) there is no reason to assume that this is the case.

What are you assuming is the bombing mode? Terminal velocity is not necessarily the case, unless you're assuming high altitude drops of dumb bombs. Use of PGMs, drag bombs for low altitude CAS drops and such wouldn't see the bomb reach terminal velocity, although if you're close enough to hear it coming in, you probably have bigger issues than figuring out whether the pitch was rising.

[KrazyHorse]

From what I can tell from the effective range of mortars they operate at ~50% of the speed of sound (say 150-200 m/s)

[MichaeltheGreat]

The big tubes have ranges of several miles, depending on tube elevation and charge. Those will be close enough to the speed of sound that you wouldn't hear much.

[KrazyHorse]

Originally posted by MichaeltheGreat


What are you assuming is the bombing mode? Terminal velocity is not necessarily the case, unless you're assuming high altitude drops of dumb bombs. Use of PGMs, drag bombs for low altitude CAS drops and such wouldn't see the bomb reach terminal velocity, although if you're close enough to hear it coming in, you probably have bigger issues than figuring out whether the pitch was rising.

Actually, bombs released from jet aircraft are probably already going faster than terminal velocity. Remember the horizontal component of the plane's velocity counts.

Bombs probably spend their time slowing down to terminal velocity, and this probably happens fairly quickly (due to v^2 nature of drag forces)

[KrazyHorse]

Originally posted by MichaeltheGreat
The big tubes have ranges of several miles, depending on tube elevation and charge. Those will be close enough to the speed of sound that you wouldn't hear much.

I think I looked up the US Army 62(?) mm which is listed as having a max range of just over 2 miles. Ignoring air resistance this gives a maximum velocity of ~180 m/s. With air resistance you have to figure it's faster than this at exit from tube and slower than this at moment of impact.

[KrazyHorse]

Sorry. That was 60 mm. Designation M224. Range 3490 m

[MichaeltheGreat]

Originally posted by KrazyHorse
Actually, bombs released from jet aircraft are probably already going faster than terminal velocity. Remember the horizontal component of the plane's velocity counts.

For low altitude CAS drops, you want them to brake pretty fast, since the CAS aircraft has to clear the blast zone or else it has problems. That was the cause of the loss of the FB-111A that was lost when Reagan decided to slap Qaddafi around about a million years ago. The drop was too low, so the bombs didn't slow down enough from the drag fins.

PGMs have their own issues depending on operator control and terminal guidance. I wasn't an air weenie, so I don't know all the stuff from that end - just the stuff for calling it in.

[MichaeltheGreat]

Originally posted by KrazyHorse
Sorry. That was 60 mm. Designation M224. Range 3490 m

Check out the 4.2 inch (four deuce) IIRC, I think the vehicle mount is the M106.

Nobody would use a 60 on a target 3000 meters away. That max range is real TOAB in terms of small unit tactics.

[KrazyHorse]

The switchblade actually managed to down itself with its own bombs? Those must have been big mother****ers...

[KrazyHorse]

Originally posted by MichaeltheGreat


Check out the 4.2 inch (four deuce) IIRC, I think the vehicle mount is the M106.

Nobody would use a 60 on a target 3000 meters away. That max range is real TOAB in terms of small unit tactics.

It may not hit **** at that range, but that's how far it can go, and that's what I need to know for exit velocity.

Also, TOAB?

[MichaeltheGreat]

Tried to reply last night, but got the damned database maintenance message.

Yep - 2000 pound drag bombs at ~200 feet or slightly less. One theory was that the plane had to turn slightly to avoid AAA and lost speed. Another was bomb defect - the drag fins not deploying properly. Another was that they were just too low, but best evidence was that their own bomb's blast downed the plane.

TOAB = Tits on a bull.

[MRT144]

so if i have this right, the function of the bomb's deceleration is greater than the function of the closing of the gap of the bomb towards you. coupled with the fact that the audible range of the whistle would only be heard when nearing its impact area. right?