Armstrong Siddeley Experimental Prototype 550F

This Frazer Nash project, 550F, was bought in 2008 from Howard Robinson near Heathrow London, without much background information other than it "existed" as noted on the Frazer Nash website and through a few lines in the various FN books.
The chassis appeared to be so well constructed - the radiator fitting down into the shape of the cross-member, brake bias bar, Pre-selector gearbox on the De Dion rear, inboard Al-fin drums and a Watts linkage, front independent suspension with coil over shocks and anti-roll Bar, Borrani aluminium-rimmed wire wheels ("Boadicea style"). The prospective new owner was impressed!

The original factory photos below were supplied by Bill Meredith. These are later than the "testing pics" as it has the big tank and different exhaust pipes to the earlier pics and a bespoke radiator, designed by Mr. Meredith.

The new owner contacted the Armstrong Siddeley (AS) club before buying it and was told where to look for the engine number. It is E340 FN2. After purchase, Mr. Robinson provided copies of the original AS engine notes from meetings marked "Secret" in which there are discussions about the eight high performance engines AS had been building, two of which were intended for FN.

The first engine (E340 FN1?) suffered main bearing failure during testing; this had a head the same as the Sphynx Allard, a race car owned by Tommy Sopwith (son of the owner of AS). These heads may have been aluminium and fitted with Weber carbs.

Work has not yet started on the car yet but the new owner has been collecting as much info as possible, from archives and the original draughtsman, Bill Meredith. Mr. Meredith lives in Gossport and has been visited by the Frazer Nash archivist. Mr. Meredith told the new owner that the car was called the 550F because the German designer Alex von Falkenhausen, who worked on it, stated it was developed from the 500H, designed by Alan Hart.

550F Drawings

Bill Meredith designed wire frame models of the bodywork to be fitted, inspired by the Uhlenhaut Mercedes coupe which Mr. H.J. Aldington liked after a trip round Le Mans in it. It had not been decided what body was to go on it when Mr. Meredith left Frazer Nash due to a fallout with H.J.  When it was found some 20+ years ago by Mr. Robinson, it had had parts of a Vauxhall PA Cresta body fitted to it. This had involved cutting the bulkhead/steering column support tube off the chassis and shortening the column. The car has the original large fuel tank intended Le Mans.
Mr. Meredith also supplied some great photos of the car being tested on the road and actually used it to commute from Orpington in Kent to Isleworth when his Daimler was off the road. He and others also used it to collect people from London airport (King Faisal) etc). He also said that HJ got Mike Hawthorne interested enough to have a drive in it and was hoping to get him in it for Le Mans. It was entered in both 1953 Le Mans (no. 125) and 1954 Le Mans (no. 87) for but little is known as to what happened.
Below Testing 1953?


From the Registrar, Frazer Nash Archives, Henley-on-Thames, England:

"The car is the Armstrong Siddeley Prototype which we thought was numbered 421/200/200. It turns out this was not its actual chassis number (it was never given one) but was given it by the registrar in 1976 (to fill a gap) and continued by Denis Jenkinson and Tony Bancroft in their books because they had no reason to believe otherwise. The design was given the number 550F and so the new owner and the Archives have agreed to use this number from now on."

February 6, 2009

Please visit the primary site for postwar Frazer Nash cars:

The Frazer Nash Home Page

The Frazer Nash-USA Table of Contents

or contact me, Bob Schmitt