Wailing was its failing . . .

QUESTION Was the German Stuka dive bomber the only aircraft with a wailing siren?

While the sound of the screaming Junkers Ju 87 or Stuka (from Sturzkampfflugzeug, meaning dive bomber) was one of the definitive sounds of World War ii, the siren’s use was short-lived.

The first Stuka, the Ju.87A, ended its production run in 1938 after 260 machines had been delivered. A number went to Spain and were used by the Nationalist side in the Spanish civil war.

The diving technique made them devastatingly accurate and they were particularly successful in destroying bridges on the supply routes, ports and ships. Republican supply bases in Barcelona, Valencia and Tarragona were particularly hard hit.

The B-model appeared in late 1938 and became the standard luftwaffe divebomber of early World War ii.

it had aerodynamic spats over the landing gear and a more powerful, fuel-injected engine. it also had the infamous propeller-driven sirens known as Jericho trumpets.

This screaming siren was fitted to the undercarriage to give the plane its famous death scream — a psychological weapon designed to inspire terror. it was designed by ernst Udet, a World War i fighter ace, who joined the Nazi party at its inception and was heavily involved in the research and development wing of the luftwaffe.

By 1939, he had risen to be directorgeneral of equipment.

The immediate impact of the siren was devastating. One French officer noted: ‘The noise from the siren of the diving aircraft drills into your ear and tears your nerves. You feel as though you want to scream and roar.’

however, the sirens had many flaws. They reduced the bomber’s speed by 15 mph due to drag, which proved deadly when facing anti-artillery guns and Allied fighters. The psychological impact was quickly lost because the sirens became a warning that the Stukas were coming. And the noise was driving the Stuka pilots half-mad. By 1941, Stukas were being built without Jericho Trumpets, but the idea did not go away. The Axis and the Allies began fitting bombs with a whistling device that could instil fear without affecting the pilot. David Foulds, Gosport, Hants.

QUESTION Does consuming large amounts of soy cause a dip in testosterone levels?

The evidence is conflicting. Some research has shown that eating soy products such as edamame, tofu, soy milk and miso regularly may cause a drop in testosterone levels, which may protect against prostate enlargement.

Soy foods are high in phytoestrogens, plant-based substances that mimic the effects of oestrogen in your body by altering hormone levels and potentially reducing testosterone.

A 2005 study in the Journal Of Nutrition found 35 men drinking soy protein isolate for 54 days decreased testosterone levels.

A 2001 study of rats appeared to support this idea. But a Canadian metaanalysis of 15 studies in the Journal Of Nutrition in 2010 found soy foods had only minor effects on testosterone.

The idea of soy reducing testosterone levels has been used to back up the insult ‘soyboy’ — describing a man lacking in masculine qualities.

Dr Ian Smith, Cambridge.