Detective,

I believe that the naming by the RAF is true. US aircraft did not have official names until early in WW2, when it was realized that the official designations might give away too much information, such as the state of development i.e. P-51A, P-51B, P-51C… The attack version, A-36 that was the first large-scale order for US use, was initially to be named Invader (later used by the A-26), but renamed to match the fighter.

Roger

Schneiderman,

Thank you, I did find the oldmachinespress website (see post 10) and it did clear up some mysteries.

Detective,

Thank you also. As you say, the two XP-51G were built in the US. One was provided to the RAF, and one remained in the states to hopefully be eventually restored to flight status http://xp51g.com/XP51G/Welcome.html. I am trying to identify the specific Rolls Royce mark number of the (British-supplied) engines. RM.14SM, as Sabrejet shows in an official Army document, is a rating specification if I understand the British system correctly. The best source that I have available is Lumsden, and he shows 18 experimental Merlin 100 or 101 built rated as RM.14SM. Perhaps at least two of these were sent to the US for this purpose. I remember reading (I unfortunately do not remember where) that Hap Arnold was anxious to have a 100-series Merlin for test in the US. Other RM.14SM rated engines include the Marks 102, 130 to 134, 140, 300, 600, 620, and 621.

Sabrejet,

Thank you for reminding me of this important document. I do have a copy. I was looking through the 1945 and then 1946 editions and I remembered another US Merlin mystery in the Douglas XC-115. This was a Merlin-powered C-54 that was not built. Most sources list the engine as a Packard V-1650-209 of 1650hp. The Army Model Designations of 1946 shows “Packard V-1650-20SM. Could this have been a proposed Packard-built version of the 600-series Merlin or yet another typo? Lumsden lists no RM.20SM.

Thank you all for your continuing help and interest.

Roger

Some more digging might indicate that both the 600 HP Ricardo and the Cruciform were to be built by Brotherhood, and that the Cruciform was a Ricardo project. See here:

http://www.crossandcockade.com/forum/forum_posts.asp?TID=265

Ricardo had some form of working relationship with the Brotherhood company.

Roger

Sabrejet,

I am little bit distant from the National Archives as I am in the USA. The listings you show look like a promising start. Maybe someday…

Andy,

The Napier V-12 of 1925/26 is mentioned on page 206 of Development of Aircraft Engines and Aviation Fuels by Robert Schlaifer that can be found here:

https://books.google.com/books?id=lo9TAAAAMAAJ&pg=PA206&lpg=PA206&dq=napier+v-12+1925&source=bl&ots=WxEdReK7uh&sig=6RMw7W0bQD1vVQUQDWwt_vlaJqg&hl=en&sa=X&ved=0ahUKEwjCqebN6-DKAhXMPB4KHROPCbgQ6AEIKDAC#v=onepage&q=napier%20v-12%201925&f=false

Napier was apparently offered a contract to develop a Curtiss D-12-like engine. Instead, they designed an individual cylinder and head V-12 based on Lion practice. Turbo and then gear-driven superchargers were tried. It appears to me that at least one was built and tested. The project was dropped in 1927 when Napier decided to concentrate on Lion production. Rolls Royce instead took up the challenge and the result was the Kestrel.

Roger