I was surprised too by any such mention of a drawing, I only passed on what I understood what Rob told me. Rob & I had no less than 4 very long, most enjoyable conversation..... long distance phone calls (his dime) this past Memorial day weekend.
The Upholders uses a 7 blade prop too as built in the mid-late 1980's. The Dutch Walrus submarines do in fact use a 5 bladed scimitar though.
The scimitar 7 blade prop with only a moderate skew back would have been incorporated in the late 1960's on these Valiants. American 7 blade scimitar props appeared very secretly in the beginning of the 1960's. Thresher SSN 593 used one from the get go in 1962. She was using one at the time of her loss. The Thresher/Permits used these as standard when built. The Skipjack SSN's and Dreadnought used the same power and engineering spaces aft. The Skipjacks for speed would use their noisy 5 bladed 'power props'. But in the mid-1960's, the noisy Skipjacks retrofitted to the quieter 7 blade scimitars too. Dreadnought would have likely used & followed a similar arrangement. The Valiants came on in the late 1960's early 1970's. They where comparable in quieting to the Permits, also using raft technology in the engineering spaces to isolate the engineering from the hull. The Skates even in later times (1970's) incorporated a L & R hand small 7 blade scimitar props. Having a special relationship, the Royal Navy and the US Navy technologically are very close historically. EB & Vickers in origin (in submarines only) are practically sister companies. It is possible any British scimitar prop could have been developed independently too. The mission requirements, the need for silent props, and the mathematics are basicly the same. The concept theoretically was not new, only a secret technological threshold needed to be surpassed to make these special props by industry possible. Both the United Kingdom and the United States would have had such milling analog computers then.
In the later months of 1982, after the Falklands conflict was over, HMS Turbulent (second in the Trafalgar class) became the first operational SSN to employ a pump jet in the world. In that historical context, The Brits regressing back.......using a potentially noisier 5 blade prop in 1982? No way! Not likely. Going to the Falklands and WAR....would you and your valuable SSN's, crews...everything...opt for second best? Ridiculous!
Edited By Dolphin on 1117767876