Beatrice the trailblazer
QUESTION What is the story of the aircraft safety measure known as Miss Shilling’s Orifice?
Beatrice (tilly) Shilling was a talented aeronautical engineer and amateur motorcycle rider and racing car driver.
She worked at the royal aircraft establishment in Farnborough, Hampshire, during the war and is famous for designing a simple, yet ingenious, device to stop fighter plane engines cutting out in the air.
raF pilots had discovered a serious problem during combat. as planes went into a dive, petrol in the engines’ carburettor float chamber would be thrown to the top and the engine would stall or cut out.
this issue did not seem to affect the enemy’s fighters. in May 1940, tests on a captured German Messerschmitt Bf 109 had revealed that its fuel-injected engine continued to run under negative gravity.
this meant that a pilot in a 109 could escape a pursing raF fighter by pushing the stick forward and going into a dive.
if a Spitfire or Hurricane pilot tried to do the same, their engine would cut out. rolling inverted before going into a dive kept the engine running, but wasted time, allowing the 109 to escape.
Shilling, who had married a raF flight lieutenant, came up with a device that could be retrofitted to carburettors.
it was a metal diaphragm with a hole fitted inside the float chamber so that it stopped most of the fuel being thrown to the top of the chamber under negative gravity. the hole permitted sufficient fuel flow under normal operation.
Shilling and her team went from base to base modifying every fighter engine. the official name for the diaphragm was the rae restrictor, but the pilots quickly dubbed it ‘Miss Shilling’s Orifice’.
in her book Bloody Brilliant Women time Forgot, cathy Newman blames the famous rolls-royce engineer Sir Stanley Hooker for the name, which she considered was an insult to Miss Shilling. But he was simply reporting what other people were calling it.
in his autobiography Not Much Of an engineer, he refers to Miss Shilling as a famous lady engineer who came up with a simple, but effective, device. it remained in use until 1942 when the Bendix-Stromberg carburettor was introduced. this had a flexible diaphragm instead of a float chamber and could cope with negative G-forces.
the use of a carburettor on the Merlin engine contributed to its high-power output compared with the Daimler-Benz engine fitted to the 109. the evaporation of fuel in the carburettor cooled the air by 25c, enhancing the supercharger.
Denis Sharp, Littlehampton, W. Sussex.
QUESTION We refer to CCTV footage despite film being obsolete. What other terms are misused in this way?
BeFOre photocopiers were common, duplicates were made by sliding a carbon sheet between two pieces of paper in a typewriter — thus a carbon copy.
this phrase is still used to mean an exact copy. the ‘cc’ in emails stands for ‘carbon copy’ while ‘bcc’ means ‘blind carbon copy’.
in a similar vein to cctV footage, a show reel — a short video showcasing a performer’s work — rarely uses film reel.
the word piano is short for pianoforte (‘quiet-loud’), so named to distinguish it from the harpsichord, which could only play quietly. Perhaps shortening it to forte would have been more accurate.
Jane Knight, Derby.
Back to square one is surely a misused phrase. it comes from the early days of radio football commentary when the radio times would publish a map of the pitch marked off in numbered squares. the commentator would refer to each square appropriately during the match.
Alfred Levy, Ilford, Essex.
QUESTION What is the function of the grand jury in the U.S. justice system?
tHOuGH grand and trial juries are made up of ordinary people called for jury duty, they serve different purposes. a grand jury examines evidence gathered by law enforcement agencies to decide if charges should be brought, while a trial jury gives a verdict in a criminal case. a grand jury must decide if there is ‘probable cause’ to proceed to trial. under the u.S. Fifth amendment, criminal prosecution of any federal crime punishable by more than one year of imprisonment must be initiated by a grand jury of 16 and 23 people called at random.
its origins can be traced to the assize of clarendon, issued by Henry ii in 1166. the assize required criminal accusations be ‘presented’ by juries composed of 12 ‘good and lawful men’ from a township.
the assize was designed to strengthen royal judicial authority as local jurors could present charges that otherwise might not be known to the crown.
Following the jury’s accusation, the defendant was subjected to trial, typically by ordeal.
By the end of the 14th century, the english criminal justice process had turned to trial by jury, and two separate juries developed.
the trial of guilt was before a 12-person petit jury, and the accusatory jury was expanded to 23, chosen from the county. this jury became known as le grand inquest, hence grand jury.
it remained an accusatory body that assisted the crown in finding criminals. it became a citizen’s safeguard against the crown, ensuring the accused was not being pursued for political purposes.
Deemed a key part of law, it was written into the u.S. constitution. the Fifth amendment says ‘no person shall be held to answer for a capital or otherwise infamous crime, unless on a presentment or indictment of a grand jury.’
John Richards, Birmingham.