Terry @ Aviaeology

That's a great photo find, Dave. Kudos! This particular tiered setup is indeed unusual in that it is on Mk.I/IB projectors, as photographed. I think this is the first time I remember seeing this particular setup. I wonder if it was a test setup or a field mod? Chris, do you have any gen on this? This is distinct from the two-tier setup using No. 4 Saddles on a Mk.III/IIIA projector setup on both Typhoons and Mosquitoes (Banff Strike Wing only) later in the war. These came into use only in 1945, if memory serves. The Saddle No. 4 + Mk.III projectors may have been used by other aircraft as well, but these are the only ones I am aware of. CT may know more. Postwar, the No. 8 Saddle arrangement and zero-length projectors (stub pylons with launch shoes, I forget the Mark Numbers) also became standard for two or more tiers of rocket rounds. All of these later setups could either salvo or ripple-fire the rockets, and, with the exception of test installations at Boscombe Down etc, all rockets had the normal cruciform four-fin fit. The fins on the lower tiers had a "notch" designed into the base of each at its rear and were referred to as Mk.2 fins in the documentation. This design facilitated the clamping of the lower rear No. 4 or No. 8 saddle around the rocket motor's rear end.

The “clips” being referred to are called “Saddles” in the technical documentation (especially AP2802A). The answer is found in the Saddles section of that AP. To summarize, all of the definitive wartime types, Saddles No. 1, 2, 3, 4, and 5, had two features in common. The No 4, being designed for tiered carriage, had an “upper” and “lower” clamping band (see below) of different designs. There was also a (possibly interim) Saddle type for which I have yet to find the identifying model number. It was used mostly on HE/SAP heads and concrete practice heads on the earliest Mk.I/IB projectors. This is the one that may look like unclamped loops of spring steel on either side of the rocket body, but most certainly isn’t. They also feature clamping bolts (again, see below). The No 8 was a “zero-length” projector development of the No. 4, and it may have also come into use by the war’s end. We see these on Tempests (CT will know more), later Fireflies and the early jets, IIRC. The common features of all were: • a “Clamping Band” and • one or, in the case of the No. 4 upper, two “Clamping Bolts.” The No 1 and No 2 Saddles were designed for Mk.I projector beams, while Nos 3, 4, and 5 were for Mk.III beams, which followed the Mk.I into service on some aircraft types. Each beam design had a latching mechanism at its rear to ensure the fully assembled round stayed on the beam when subjected to the host aircraft’s accelerations. In the Mk.III beam system, a part of the latching mechanism, was integral to the upper part of the rear saddle, so the front and rear saddles for these later systems could not be swapped around (those for the Mk. I system were common to the front and rear). I can only speculate that they were securely bolted to the round so that they did not become shrapnel that could potentially damage the aircraft or an RP fin or two during launch. The “Instructions for use” paragraph of the Saddles portion of the AP called for the Clamping Bands to be bolted securely to the rocket motor (i.e. body) via the clamping bolt(s), with the whole thing set in a jig to ensure proper positioning. The order of assembly to complete one round of RP ammunition was: • Motor to Fins; • then Saddles to Motor, with the help of the jig set; • then warhead (or Projectile, per the documentation nomenclature IIRC). The whole thing was one solid unit that could survive the high acceleration load during launch. I believe the bands were more a thicker mild steel plate pressings than a thinner high tensile (and probably more expensive?) spring steel. It was soft enough material to be secured to the RP body with one or two bolts anyway. The solid clamping required suggests that the whole round left the projector beam and met its terminal end as one unit. Photos of and from Beaufighter and Mosquitoes show the saddles still on the rounds after launch. I can’t speak for Typhoons, but the ammunition was virtually identical. I hope this helps, Terry @ SkyGrid Studio / Aviaeology Publishing / Canadian Aviation Historical Society Journal Note: I edited the paragraph referring to the interim Saddle type to correctly read "Mk.I/IB projectors, vice the Mk.III/IIIA I erroneously referred to in my original. Apologies… working too fast from scribbled notes!

Hi Jure, I don't post much here any more because many hours of work collating and posting related info has been summarily wiped without regard or consideration. I may have already posted on this subject… don't know!? Don't be surprised if this also disappears (as my other posts to this particular thread have) for similar reasons. Bristol's own leading particulars data for the length of the original aircraft (i.e. without the "thimble" nose or either model of conical spinner) are used in the Air Ministry's Principal Dimensions with the "aircraft in rigging position unless otherwise stated" published in Air Publication 1721A, F & J, Vol.1. This gives the length at 41 ft, 4 inches and span at 57 ft, 10 inches, among other useful bits. My scale drawings, which were based on a large number of Bristol's own dimensioned engineering drawings including station drawings, are 100% consistent these data. After considering all of the primary source materials I have been able to acquire, I am pretty confident in saying that the "rigging position" length is from the outermost curve of the rudder trailing edge to the tips of the pitch mechanism domes of the propeller type used on the majority of production aircraft from later Mk.Is through late 1944 TF.Xs. My drawings were published in Airfix Model World a few-ish years ago. Sorry, I can't give the links for fear of this getting taken down. However, if you can PM me with your email address I can give you some scans of the related pages from the Air Publication so you may post them here for others who may be interested. Cheers Terry @ Aviaeology

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