View Full Version : B17 vertical rocket installation - rare image
Although not strictly airfield related, this rare image is in the NARA collection.
As part of a scheme intended to attack enemy aircraft flying above B17 bomber formations, a trial was carried out in mid-1943 of a four tube upward firing rocket installation. The four launcher tubes were around 12 feet long and angle 4 degrees forward protruding through the mid-upper gun turret modified to remove the perspex and guns.
The trial aircraft was flown from Bovingdon to Pembrey and trial firing carried out successfully over Cardingan Bay. It is reported that the tubes could be reloaded in flight with the 3 inch rockets armed with a light HE warhead and time fuze.
The codename 'Sunflower' was used as a cover for the installation and 'Sunflower Seeds' for the rockets.
Here is an internal image of the installation:
Fascinating -knew nothing about it. Thanks
Many thanks for that information along with the relevant photograph Peter. I knew about the YB-40 B-17s that were used as gunships but have never heard of these rocket firing types. Very interesting. Cheers.
News to me! I take it that the project didn't work out?
A reply from "SHAEF44" to one of the enquiries about this installation I posted on a number of fora last year may be of interest:
Another scheme grew out of an Eighth Air Force request for an upward-firing rocket launcher to protect B-17 formations from planes bombing them from above. The development known by the code name SUNFLOWER SEED, was worked out in England, using a special British rocket, and a B-17 so equipped was flown to the United States for study.
At the same time technicians at Wright Field evolved a somewhat similar vertical-firing installation using the American M8 rocket; this was tested at both Aberdeen and Eglin Field during the spring of 1944.
The rockets behaved as the designers hoped, but the low velocity of the projectiles and the lack of flexibility in aiming them led to the conclusion that neither SUNFLOWER SEED nor its American variant would serve the intended purpose. By September 1944, with the cessation of overhead bombing attacks against Allied bomber formations, tactical need for such a weapon disappeared.
Results generally similar to those obtained with the vertical-firing rocket launchers followed when test data were assembled on a rearward-firing breech-loading 4.5 inch rocket launcher mounted in a B-17 bomber. Consequently, until scientists could develop rockets of higher velocity, even rockets with proximity fuses promised little for defensive air combat.
Source: US Army in WWII, The Ordnance Department, Planning Munitions for War, page 437.Peter's report on the UK trials was something I hadn't come across before, very interesting indeed.
All the best,
Thanks for providing some 'meat' Paul. From the account that I read of the UK trial (which involved RAF Boscombe Down personnel and USAAF) it worked successfully if somewhat frighteningly for the B17 crew. The howl of rockets as they fired was scary to the uninitiated. Both single, pairs and a salvo of four were fired and a reload carried out. It's not clear how the latter was achieved but it seems that the four tube assembly could be unlocked from the firing position and swung aft to reload with spare rockets carried inside the fuselage.
I know from experience how static electricity or 'stray volts' can inadvertently fire a rocket igniter when 'plugging-in' so that is not something I would relish in the confines of a fuselage!
Prior to the B17 trial, a British feasibility trial was carried out using an installation in a Hurricane. The canopy had to be removed because it would not slide fully aft due to the 5 inch diameter rocket tube protruding. The aircraft was flown to Pendine Sands, landed and parked on the beach and the tube loaded and fired out to sea remotely by a long cable. Success, so reloaded and the aircraft took off and flew parallel with the shore to enable good photos and the tube fired again successfully. Upon landing, it was found that the fabric covering on top of the fuselage had peeled back and was close to fouling the elevator.......
The 3" Aircraft Rocket, Air-to-Air used in these UK trials is covered in pages 317-319 of OP 1665 British Explosive Ordnance.
It appears it is the propelling rocket (Motor, Rocket, A/C Mks I and II) itself that is designated Sunflower Seed, as opposed to the entire rocket assembly.
The projectiles were fitted with a No.720 MkIV fuze.
This is an impact fuze with a self-destruct delay.
All the best,
Is it possible that maybe German intelligence heard about this 'Angled ' upward firing device and so designed their 'Schrage-Musik ?
I believe the development of Schräge Musik began in 1941, with it's first successful trial use in May 1943.
All the best,
The 3 inch motor was used in other applications. The Sunflower Seed motor was actually 3.25 inches diameter and shorter than the air-to-air RP and had a lightweight projectile - as shown in your diagram - that contained only 2 pounds (or so) of HE so that the the speed at burn out was sufficient to take it around 3 or 4 thousand feet above the firing aircraft before the delayed action fuze fired or an impact occurred. The shell was simple, i.e. not fragmentation (why not?) so the lethal radius would not have been high.
The intention was to defend aganst an enemy tactic to bomb Allied bomber formations from above whilst staying out of range of the defenders guns. But, the enemy changed tactics to attack head on with guns which gave closing speeds of around 600 knots and minimal reaction times so the rocket battery, although cleared for combat installation never went any further.
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