An Illustrated Guide to Prepping and loading an Atomic Bomb

I got this somewhere years ago and I thought some model makers may find it of use

I found that document on the Internet a couple of weeks ago.

On the first page, lower right hand corner, you can see a rectangular box installed in the bomb. That is recognizably an APS-13; it appears there are two of them installed in the weapon. The APS-13 is a UHF tail warning radar used on various aircraft including the P-51 and P-47. It appears that for the bomb the APS-13 was used to trigger it at the proper altitude. I presume that they used two APS-13's because they wanted to make very sure the bomb went off at altitude.

MIflyer said:

I found that document on the Internet a couple of weeks ago.
On the first page, lower right hand corner, you can see a rectangular box installed in the bomb. That is recognizably an APS-13; it appears there are two of them installed in the weapon. The APS-13 is a UHF tail warning radar used on various aircraft including the P-51 and P-47. It appears that for the bomb the APS-13 was used to trigger it at the proper altitude. I presume that they used two APS-13's because they wanted to make very sure the bomb went off at altitude.

Click to expand...

Excellent additional info, thank you.
It certainly makes sense to use proven off the shelf tech where possible and is a better choice than the AN/APN-1 radio altimeters of the day with their easy to damage antennas.

Thank you Mi

fubar57 said:

Thank you Mi

Click to expand...

Thank you for your thanks and all your many posts.
Like the vast majority here I joined to be educated and I would be what we call in Australia a bludger if I did not contribute to the best of my limited ability in return

I have an APN-1. Its normal max altitude setting is 4500 ft, the transmitter being a single 957 tube. When you are flying low enough to worry about hitting the ground you would not need any higher capability than that.

Presumably the APS-13 could be modified to get greater range.

A friend of mine tells me that the bombs had FOUR of those radar units, and at least two of them had to agree on height above the ground before it could detonate. SInce the radar would detect the airplane it was dropped from, a timer made sure it was far enough away before enabling the trigger.

MIflyer said:

I have an APN-1. Its normal max altitude setting is 4500 ft, the transmitter being a single 957 tube. When you are flying low enough to worry about hitting the ground you would not need any higher capability than that.

Click to expand...

If my memory is right the older ARN-1 was essentially an APN-1 with the maximum altitude set at 400 ft. Too close for comfort

I have seen some APN-1 marked as ARN-1. I have no idea why. R stands for Radio and P stands for Radar so an argument could be made for either designation. And the meter says "Radio Altitude." We even found at least one marked as, I think, APG-1, and it turns out there was a version made for launching torpedoes.

When they were starting to use the three letters designation system they did some weird stuff. The ARR-1 was marked as a radio receiver when in reality it was not; this may have been deliberate misinformation since the frequency dial deliberately left off the front digit. 234 MHZ looked like 34 MHZ.

The APN-1 meter I have has two selectable ranges, 0 - 400 ft and 0- 4000 ft. Personally I think the 0 - 4000 ft range must not be very useful. The main thing I could the set being used for is flying low over the ocean at night, which would be my favorite way to launch torpedoes at people who would get upset about it. The USN seems to have been the main user.

The APN-1 has the ability to be plugged into an autopilot, and I can see how, say, a PBY or PB4Y-2, wanting to sneak close to a target could use that very well.