Royal Society memoir of Stanley Hooker with details not included in his autobiography

[overbeck]

Hooker's early work raised the Merlin's supercharger efficiency from 68% to 76%. Makes me wonder how much aerodynamics information the designers had; maybe a combination of rudimentary formulae and whatever seemed like a good idea.

 

[pbehn]

When Hooker studied it, fluid dynamics was quite a new subject new stuff was being learned all the time. a great read BTW.

 

[Deleted member 68059]

The papers initially used by Hooker to begin his work on dimensional methods (which are key to predicting compressor performance under different inlet conditions from which it is tested under) were by Capon & Brooke. They`re a bit heavy going but they`re available on my website for download:

Dimensional Analysis of Supercharger Compressors - Calum Douglas

 

[MIflyer]

The thing that amazes me about Stanley Hooker was he was a theoretical aerodynamicist, and "not much of an engineer."

But on the development of the Merlin with the two stage supercharger he did something absolutely brilliant and went to air-to-liquid aftercooler. Normally an aerodynamics guy would continue to do as he had been doing and focus on further refinement of the airflow to eke out whatever small gains in efficiency would be possible. But by going to liquid cooling he solved a whole host of problems. In other words, he thought "out of the air box."

His brilliance is shown best by the fact that nobody else implemented this same idea. Take a look at the attached article from the March 1943 Aviation Magazine. Intercooler design is discussed but it is all air-to-air stuff. The P-51B would be coming off the production lines a very few months later.

 

[pbehn]

The thing that amazes me about Stanley Hooker was he was a theoretical aerodynamicist, and "not much of an engineer."

But on the development of the Merlin with the two stage supercharger he did something absolutely brilliant and went to air-to-liquid aftercooler. Normally an aerodynamics guy would continue to do as he had been doing and focus on further refinement of the airflow to eke out whatever small gains in efficiency would be possible. But by going to liquid cooling he solved a whole host of problems. In other words, he thought "out of the air box."

His brilliance is shown best by the fact that nobody else implemented this same idea. Take a look at the attached article from the March 1943 Aviation Magazine. Intercooler design is discussed but it is all air-to-air stuff. The P-51B would be coming off the production lines a very few months later.View attachment 591021 View attachment 591022View attachment 591023View attachment 591024View attachment 591025View attachment 591026View attachment 591027

Wiki doesn't even mention his work on the Merlin in its description of him, though it does later on the article "Sir Stanley George Hooker, CBE, FRS,[3][4] DPhil, BSc, FRAeS, MIMechE,[5] FAAAS, (30 September 1907 – 24 May 1984) was a mathematician and jet engine engineer. He was employed first at Rolls-Royce where he worked on the earliest designs such as the Welland and Derwent, and later at Bristol Aero Engines where he helped bring the troubled Proteus turboprop and the Olympus turbojet to market. He then designed the famous Pegasus vectored thrust turbofan used in the Hawker Siddeley Harrier." A remarkable man.

 

[overbeck]

The real genius lay in considering the engine as a component of a complete system, i.e. the aircraft. As Lovesey said, "In a single seat fighter it was practically impossible to use an air-cooled intercooler in the space available, and the air ducting involved in this form of intercooler was a serious limitation to the pilot's view." They flight tested both. I doubt the engineers at Allison ever flight tested a P-39 or P-40 when deciding what component to use on their engine in 1940, but I may be wrong. The American focus on modularity for mass production may have hampered them in this area. Blurring boundaries between components always complicates things, and the trick is to know when to blur and when to get on with the job.

Edit: they took this even further when they calculated just how much intercooling to perform based on power gained vs drag added in the Spitfire.