The GB 1 Glide bomb

a WW2 stand off weapon

By Friis

The GB-1 Glide bomb.

While the German advanced air to ground, both the Fritz X guided bomb and the Henschel Hs 293 series of guided missiles are the best known examples of advanced weapons, most nations experimented with more advanced designs than the normal free falling bomb or the unguided rocket.

In this article we’ll look closer at the glide bomb GB-1 that was actually used in combat by the B 17 flying fortress

During 1942 the USAF had been watching the mounting RAF losses over Germany with great concern. It became quite clear that German AA gunnery was a major treat to the allied bomber fleets. The B17 fleets that were to bear the brunt of the daylight strikes would encounter more and more Flak as they ventured further into Germany’s territory. Thus the idea of a stand off weapon system was born. As the B17 and B 24’s didn’t have the ability to fly above the AA fire, (The Superfortress was to address this problem) the idea of the bombers being able to evade the Flak concentrations by launching the payload beyond effective AA range seemed like an attractive idea. Unlike the German weapon systems witch were meant as precision weapons, especially against shipping, the US weapon system was a stand off weapon to preserve crews.

Early in 1941 experiments with glider bombs showed that a weapon that was launched from the bomber and then glided towards the target was indeed possible.

Different types were looked at, and while both radio and TV control of the weapon system was considered (Like on the German systems) it was decided that these systems needed too much development time to be available within a short timespan.

Thus the Aeronca GB 1 was born.

The GB 1. Picture from Military rockets and missiles

 

The GB 1, as the pictures show, was a truly simple weapon. A workable glider was fitted to a standard 1000 or 2000 Pound bomb. The glider had a 12 foot span, and was constructed with wooden wings and steel tube main spar, that was bolted to the fuselage frame that extended aft as twin booms to which a twin tailed wooden empenage was bolted. A complete GB1 weighted in at 2456 Pounds. Glide speed was approx 370 km/h. Aspect radio was 4.36 and the lift/drag ration was 4.97. Range after a drop from 15.000 feet was about 32 km, giving a significant stand off capacity.

The GB weapons. Pictures from Flying Review April 1963

 

Beside its stand off capacity the glider weapon had another advantage, as the angle of attack made it more likely that it hit sides of buildings, vertical falling bombs were more likely to hit the ground and do less damage to structures.

Aiming of the weapon was done by the bombardier on the bomber by aligning the plane to the target and then compensating for wind drift and trajectory. To compensate for roll, ailerons were provided and attached to a rudimentary automatic pilot.

Trough 1943 the GB 1 was tested with the B17 E , which could carry 2 weapons beneath its fuselage. The weapons could be launched separately or together.

Boeing B 17 with dual GB1 bombs. Picture from Flying Review April 1963

 

 

In September 43, all was ready for starting using the weapon in anger. 40 GB1 equipped B17’s arrived in England on the 29 of September. They were earmarked for the 41st combat bomb wing of the 8th’s 3 bombardment division.

But on arrival the commanding officers decided that although the weapon did have stand off capacity it lacked the accuracy for daylight raids. Also, by this time, the Luftwaffe’s fighters were the main treat to the 8’th air fleet, and standoff weapons against flak seemed less important. and it was put back on the shelf.

During 44, the Luftwaffe fighter arm was reduced to a shadow of its former might, and the lure to try out the GB 1 in combat arrived again. On the 28 of May, the 41 special combat wing attacked the Eifeltor Marshalling Yard at Cologne. About 60 B 17’s flew off in bright weather with good visibility. For miles away the target was clear, and just outside the flak gunners range, 54 B 17’s released 108 GB 1’s.

One part of the mission was a success. No B17's were brought down by AA fire. But the GB 1’s showed a poor accuracy and only a few hit near the marshalling yard. Many drifted far off or glided more or less sharply than the bombardiers wanted.

So, although no losses was inflicted on the bombers, tactically the GB1 was a failure.

Launch of GB 1. Picture from Flying Review April 1963

 

 

Still, more than 1000 GB 1 was later dropped over the Reich.

The GB 1 showed the capacity of a stand off bomb but without any guidance system it offered little advantage in daylight attacks.

2 other versions that was used in the war tried to remedy just that.

While the GB1 was still waiting for its first combat test, the GB 8 was constructed. It carried a radio receiver and 5 flares mounted behind the wing leading edge, so the bombardier could guide it towards it’s target (much like the flares on the X guided bomb and the Henschel Hs 293 Misslie )

The GB 8. Picture from Military rockets and missiles

 

It was used in 1945 against the E boat pens in Le Havre and La Pallice, and while accuracy was somehow better, it was still no super weapon. Like the German Hs 293 weapon, it required the launching plane to keep slow and level while guiding in the bomb.

Another version, the GB 4 had a small TV camera in the nose, sending a picture back to the Bombardier. While it was a good idea, the unreliability and lack of sharp image made it a weapon system that only worked in the best weather conditions.

Only a few were used in combat.

While the GB series of weapon made no major impact on the war, like their German counterparts, they showed the path towards the future, where guidance systems and stand off capacity would take humongous leaps forward during the cold war.

 

Sources:

Kenn C. Rust "The Bomb which diden't quite"- Flying Review April 1963

The GB series- Directionary of US military rockets and missiles (with permission)

 

 

 

 

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