Projects HARP (High Altitude Research Program) & Babylon

Below a few HARP gun pics (source internet for all).

HARP Guns at Yuma Arizona Proving Grounds:

The larger gun is 16+" with a 119 foot tube and I think the smaller one is 5".

Original 16" HARP install at Barbados (65 feet, before tube extension):

Here is some original video of the Barbados HARP gun being installed and fired:

I’ve not listened to the audio, but the video is good.

BTW, the HARP gun at Yuma still holds the altitude record for artillery at 180km (111 miles) high.

And below a report from C. H. Murphy and Gerald Bull on HARP:
Review of the High Altitude Research Program (HARP) BRL R 1327 (1966).pdf (6.3 MB)

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As I recall, Bull met an untimely end when he got himself stuck in an Iraqi “sticky-wicket”. The inventor of such a large gun was brought down by a lowly .22.

Yes, I think that’s right. It’s too bad that his work on HARP did not continue.

Sad that he chose to work with such an evil dictator, Sadaam. No wonder he was killed. I have seen some of the projectiles he used and they were as neat as the gun system.

It seems that Bull was too caught up in his work or perhaps too mad at the US for sending him to prison for arms dealings to realize just how bad that decision was. Very sad as you said.

Here’s a section of “Big Babylon” (100cm gun tube), reportedly now located at the museum of the Royal Armouries, Fort Nelson, Portsmouth, UK (source:

And for those interested here is a CIA report on Project Babylon: Project Babylon - The Iraqi Supergun (1991) DOC_0000266049.pdf (1.3 MB)

Some text is redacted (looks mostly like names), but still interesting and readable. It includes a summary of Project HARP.

Here is another interesting report on HARP that shows how the apogee record of 180km (590,000 feet) was accomplished:

The figure below (from the attachment) shows the Yuma PG 16" gun chamber (note the bore of 16.4" after reboring to smooth bore):

Not a great photo, but the figure below (also from the attachment) compares powder grain geometries used in the HARP guns:

One thing of interest in the report is “shear lips were placed on the sabot base plates to hold the shot until a breech pressure of 10,000 psi was reached.”

Hopefully this report does not violate the IAA Forum rule on reloading! :-)

I don’t read French, but this 1963 article on the HARP installation in Barbados may be of interest (‘McGill Fires in the Caribbean Sky - For High Altitude Research’):


And some higher-resolution photos from the same source…
Martlet 2 being fitted with sabots:

The original 16" 65-foot gun tube (later it was extended to 119 feet breech to muzzle):

And the gun being painted with “nose art” so-to-speak:

Seems Jason is on the hunt now for the APFSDS proj. of his lifetime! :-)


Alex, perhaps one of these?:

I wonder if any were recovered and if they still exist or were destroyed? Maybe one of the vendors still has one sitting in a warehouse (one can always dream). :-)

Larry, maybe never made since the gun was “lost” early?

Wish we had the factory drawings of this one!!!

Alex, according to the CIA report some of these S32 subcaliber projectiles were shot from the S-350 gun (see caption under projectile sketches above). There were also some proof test slugs fired from the same gun:

Who knows, maybe someone recovered one…

But for the 1000mm gun, I’m sure you are right. Probably no projectiles were made. If a drawing could be found there is always the possibility of 3D printing! Some of the largest printers can make parts 1000mm square, so it possibly could be built in sections (or just make it from wood).

Larry, I will never stop hunting for one of these mega historic, APFSDS specimens! LOL

Holding breath … Now!


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I should probably read the attachments before typing, but I think I remember he was shipping the barrel sections as either water or sewage pipes when he was ‘caught’ on the arms smuggling charges.
Either way, too bad…

Not to mention that he was apparently warned off a couple of times by the Mossad and chose to ignore the warnings. Oh, well.

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