How Far Bombs Travels To Arm

[ghostdancer]

For the life of me I can't find the exact reference but I know that a bomb must travel a set distance before it arms.

What is the distance it has to travel .. not alt .. but distance which is generate by a combination of alt and speed of the plane that releases it.

[Flossy]

I'm pretty sure its 1000 ft, but not able to find an official reference to it.

[Flossy]

OK found it in the Version 1.08 Released announcement

Added fuzes to all bombs. A bomb will not arm unless it’s traveled 1000 feet. This translates to about a 100 foot drop at 250 miles per hour. The faster you travel, the less altitude is required and vice versa.

 

[fuzeman]

Doesn't that indicate its time related?
Faster giving less altitude means less time.
With my math, who knows if this is close, I get 0.27 seconds for a bomb to arm.

[ghostdancer]

Nope still distance. Basically altitude and speed create the arc that a bomb travels from its release point to the point it hits the ground.

If you were in  a helicopter and had no forward motion and released a bomb at 100 ft. it would travel straight down (travel 100 ft.) since there was no forward motion.

Now say you were moving at 100 mph. When you release the bomb it has the same energy state as the plane so it is moving at 100 mph too so it has forward motion as it falls. Basically moving in the horizontal and vertical as gravity brings it down, creating an arc.

The faster it is moving the greater it moves in the horizontal while it moves in the vertical (falls) and covers more distance.

Now its not exactly time related because a really fast moving plane .. say a fighter not a bomber can heft a bomb doing 400 mph say at 200 ft. That bomb would arm faster than a bomber doing 200 mph at 200 ft. Because its travelling the required distance (1000 ft that HTC setup) than the slower moving bomber.

[fuzeman]

It's a rate, time, distance problem.
Both rate and distance will vary, unless you drop at exactly the same speed and altitude above target. That's nearly impossible when your dive bombing. The only other factor is time, which would be the constant.
Am I doing a fairly good Einstein imitation?
My brain hurts, I best stop cogitating so hard.

[ghostdancer]

Agreed that time would be the constant. And normally in the Real world that is actually what fuses were based on. You had delayed action fuses .. set to go off after a set period of time.

Here though in 1.08 they based it on distance traveled.

So yes, rate and distance .. Einsteinian things to hurt head.

[MOSQ]

Actually it's the distance that is constant. 1000. Period. It doesn't matter if it takes .1 or 10 minutes, the bomb has to travel 1000ft.

"The arming vane, a small propeller, is rotated by airflow after weapon release. A specified number of rotations arms the fuse."
 
Bombs have a minature propeller on them that spins, arming the warhead. The propellor has to spin the distance of 1000 feet before it arms. If the bomb is going fast, the propeller spins fast, same if the bomb is travelling slowly, it arms more slowly. But the net effect is the bomb has to have 1,000 feet worth of air moving over the propeller before it arms.

[ghostdancer]

Really? I didn't know that is how they armed a bomb .. the mechanics that is.

[fuzeman]

Yep, I've seen the little props on US bombs in the historic films. What about delayed detonations and other countries, same type?
If the quote states 1000ft, I'l shaddup and flipflop my logic.

[MOSQ]

Not all bombs use the arming vane. And some bombs use multiple arming devices. The arming vane is a safety device, if you accidentally drop a bomb on the runway you don't want it going off.  Secondary arming devices include delayed action fuses so the bomber can fly past but the bomb explodes 10 minutes later. These were used at Ploesti, however the bombs started detonanting at the same time the second wave of B-24s arrived and took out a couple of them.

Torpedos have the same safety device, it just uses water instead of air flow.