In Warbirds WorldWide, issue #18, there is an article named Reinventing, not Fixing which discusses the differences.

1) The engine was totally redrawn. Rolls-Royce drawings were in 1st angle of projection compared to the Packard drawings which were in 3rd angle of projection. This can be put down to the lack of international standards.

2) Rolls-Royce had an apprentice system which trained the personnel to become skilled fitters. How tight a bolt should be fitted was done “on the feel”. Packards mass production lines didn’t allow this and they specified each nut and bolt on the drawings with the correct torque.

3) Roll-Royce maintained parts interchangability between different marks which necessitated the use of adapters. When Packard redesigned the engine, they adapted it for the use of american accessories and completely broke the interchangability.

4) Materials used in the engines were also to a non international standard. Packard had a hard time duplicating the nitriding steel for the crankshaft, a material superior to anything the americans had. On the other hand some of the aluminium castings were improved by developing an improved alloy.

Only a few samples, the whole read in WW #18.

Christer

Btw, if anybody has a detailed power output data for the Merlin 35, I’d be more than happy to see it!

This is what “Aircraft Engines Of The World” had to say (don’t remember which edition(s), I only have xerox copies of a few pages):

Merlin 35 (in the context of Merlin 130, 140 series):

De-rated engine similar to Merlin 130. 1,280 hp/3,000 rpm/take-off with 54.3 in. (1 381 mm) +12.0 lb boost; 1,245 hp/3,000 rpm/11,500 ft (3 050 m) and 1,060 hp/2,650 rpm/9,250 ft (2 800 m) military ratings; 755 hp/1,100 rpm/6,750 ft (2 050 m) cruising rating. 100/130 grade gasoline.

and from another edition:

Merlin 35 (in the context of Merlin 724):

De-rated military engine. 1-speed supercharger, 8.59:1. Weight 1520 lb (690 kg). 1,280 hp/3,000 rpm/take-off with 12 lb boost.

Christer

Here it is among others in different resolutions:

BBMF Photo Gallery

Christer

470 mph was the never exceed speed. Above that speed the controls stiffened up quite a bit.

The Mk.XVIII was actually a few mph slower than the MK.XIV due to its slightly higher weight.

Christer

Thanks Mark, for the clarification!

I just thought that mentioning Jeffrey Quills name but not Joseph “Mutt” Summers’ name, might leave those who don´t already know, believing that JQ actually made the first flight.

Christer

Hi Laurie!

These old threads, with answers from good old uncle keithmac, may be informative:

#1

#2

Hope it helps,
Christer