Landing distance for a Hurricane

[Elmas]

Also in Italy the imaginary fence 15 m high ( +/- 50' ) was in use to evaluate landing and take-off.
For buildings, towers etc... around the landing strip the regulations require that from the borders all the buildings must be below an imaginary line with a slope of 7°.

 

[swampyankee]

Resp:
Since this post is knowledgeable about Hurricanes, can anyone tell me about the Irish Air Force. I was under the impression that Ireland sat out WWII. However, On britmodeller.com, there is a B/W photo of unusual 'roundel' marking on a row of Hurricanes. The caption reads 'Irish Air Force.' Thanks.

Ireland was neutral in WW2. While there were some (I don't have any idea how many) Irish who detested Britain enough to be active supporters of the Axis, there were some who were active supporters of the Allies, in opposition to the Axis. It probably didn't help Germany's position in Irish eyes as there were several bombing raids that struck Ireland, including Dublin.

 

[stona]

Ireland was neutral in WW2. While there were some (I don't have any idea how many) Irish who detested Britain enough to be active supporters of the Axis, there were some who were active supporters of the Allies, in opposition to the Axis. It probably didn't help Germany's position in Irish eyes as there were several bombing raids that struck Ireland, including Dublin.

Throughout the summer of 1940, Britain saw Ireland as a potential threat to her security. Eire was still technically part of the British empire at this time, but, unlike the other Dominions, her strongly nationalist government under Eamon de Valera, Ireland's Taoiseach, refused to back the Allied cause. On the contrary, Ireland adopted a stance of overt neutrality, reflecting her determination to assert her independence from Britain.

More importantly, in the context of the Britain's defences, in 1938 the Irish government took control of the three deep-water naval ports, one in Donegal and two in County Cork, that Britain had retained under treaty. As the invasion threat deepened in 1940, the British authorities grew increasingly concerned about the presence of an uncooperative Ireland on their western flank*. Some leading politicians, including Churchill, saw a graphic contrast between the staunch loyalty of Protestant Ulster, under the veteran prime minister Lord Craigavon, and the sullen hostility of Eire, under de Valera. Anger at the loss of the treaty ports was compounded by the belief that southern Ireland was riddled with Nazi sympathisers, fifth columnists and IRA terrorists who adhered to the traditional doctrine that 'England's difficulty is Ireland's opportunity.'

In fact the British were quite wrong about this. De Valera was never hostile to Britain's cause as his critics suggested, claiming that he 'personally had great sympathy for England and recognised that two-thirds of the Irish population were anti-German'. Moreover, since the mid-1930s his government had pursued an increasingly ruthless campaign against Republican extremists, who were regarded as a dangerous threat to the nascent state. Not only was the IRA banned but its members faced internment, military tribunals and even executions. Yet the political reality was that, after decades of the Irish struggle for freedom from British rule, there was little chance that Ireland would join the other Dominions in fighting for Britain. Neutrality was effectively an affirmation of sovereignty, and any declaration of war would have torn apart the fragile unity of the nation.

So what did ordinary Irish people do in the face of Nazism? Total figures on Irish volunteers and war workers remain uncertain, but the number of 'new travel permits', identity cards and passports issued to men and women in 1940-1945 was in the region of 200,000. To this should be added the 45,000 which the Department of External Affairs estimated went to the UK between September 1939 and the fall of France in June 1940, after which restrictions were imposed. In other words, out of a total population of approximately 2,968,000 (1936 census), over 8 per cent emigrated during the war. This is all the more significant when it is appreciated that those living in agricultural areas and all those under twenty-two years of age were prohibited from leaving the state, except in exceptional circumstances. If those under fourteen and over sixty-five are excluded, the figure rises to over 13 per cent and if we factor in the restrictions on those under the age of twenty-two, the number who travelled may have been well over 15 per cent of the eligible population.

Most Irish people wanted a unified Ireland. Few wanted a unified Ireland under a German jackboot.

My bold, it is the most pertinent point, in the context of which Irish neutrality must be understood.

*The Wehrmacht had no comprehensive plans to invade Ireland. General Günther Blumentritt, the operations officer of Army Group A, later explained that any thoughts about an early German landing in Ireland 'were quite unreal and they bear no relation to German resources at sea and in the air at the time'.

 

[pbehn]

The size of aerodromes also impacted Air Ministry Specifications. For example, the requirements for both medium and heavy bombers in the mid 1930s included a 'normal' take of distance (over that imaginary 50' fence) of 500 yards and an 'overload' run of 700 yards. Most aerodromes at the time had a diameter of 1,000 to 1,200 yards.

This was something of a problem when the Stirling, to B.12/36 turned up with a 1,400 yard take off on grass and 900 yards on concrete, which was uncommon on aerodromes at the time. It's one of the things that led to the bizarre scheme to use catapults to launch bombers. When the cost of a catapult rather optimistically deemed capable of launching three 60,000 lb aircraft per minute was estimated at £106,000 it was clear that concrete runways might in fact be a cheaper option. When such funds were not forthcoming it was decided, in October 1937, to operate bombers with reduced loads, which made a mockery of the original specifications!

In 1938 a new 1,000 yard take off distance was agreed for the 'Ideal bomber'.

In the end a combination of concrete and larger aerodromes would be the solution, but it would not be until after the start of the war that it was implemented.

I can only assume that pre war, most planning was based on a hope that the war wouldn't come and in the middle of a depression the worry about paying for lots of un used land. I raced on 7 race circuits made out of ww2 airfields, all used the triangle formed by the runways and the shortest was 1.5 miles long.

 

[stona]

I can only assume that pre war, most planning was based on a hope that the war wouldn't come and in the middle of a depression the worry about paying for lots of un used land. I raced on 7 race circuits made out of ww2 airfields, all used the triangle formed by the runways and the shortest was 1.5 miles long.

Those runways would have been in various lengths from 1000 yards up to 1800 yards*. They would all originally have been 46 yards wide. A lot of those old circuits also used at least part of the perimeter road (like Silverstone).

Many of the inter war aerodromes were just that and didn't have runways as such. The direction of take off and landing was determined by the wind direction.

*Some satellite fields would not have supported even 1000 yard runways. I have a plan of the defensive positions of Lympne, which did not have runways, but scaling from the map, which is a sketch purporting to be at 6" to the mile, the longest possible runway might be a little over half a mile. A 1933 source gives the maximum landing run (not distance) as 896 yards. Presumably after that you hit a fence or tree! The aerodrome dimensions were 1280 yards, by 823 yards by 914 yards, but obviously there were hangars and other buildings which limited the landing area.

 

[Navalwarrior]

Throughout the summer of 1940, Britain saw Ireland as a potential threat to her security. Eire was still technically part of the British empire at this time, but, unlike the other Dominions, her strongly nationalist government under Eamon de Valera, Ireland's Taoiseach, refused to back the Allied cause. On the contrary, Ireland adopted a stance of overt neutrality, reflecting her determination to assert her independence from Britain.

More importantly, in the context of the Britain's defences, in 1938 the Irish government took control of the three deep-water naval ports, one in Donegal and two in County Cork, that Britain had retained under treaty. As the invasion threat deepened in 1940, the British authorities grew increasingly concerned about the presence of an uncooperative Ireland on their western flank*. Some leading politicians, including Churchill, saw a graphic contrast between the staunch loyalty of Protestant Ulster, under the veteran prime minister Lord Craigavon, and the sullen hostility of Eire, under de Valera. Anger at the loss of the treaty ports was compounded by the belief that southern Ireland was riddled with Nazi sympathisers, fifth columnists and IRA terrorists who adhered to the traditional doctrine that 'England's difficulty is Ireland's opportunity.'

In fact the British were quite wrong about this. De Valera was never hostile to Britain's cause as his critics suggested, claiming that he 'personally had great sympathy for England and recognised that two-thirds of the Irish population were anti-German'. Moreover, since the mid-1930s his government had pursued an increasingly ruthless campaign against Republican extremists, who were regarded as a dangerous threat to the nascent state. Not only was the IRA banned but its members faced internment, military tribunals and even executions. Yet the political reality was that, after decades of the Irish struggle for freedom from British rule, there was little chance that Ireland would join the other Dominions in fighting for Britain. Neutrality was effectively an affirmation of sovereignty, and any declaration of war would have torn apart the fragile unity of the nation.

So what did ordinary Irish people do in the face of Nazism? Total figures on Irish volunteers and war workers remain uncertain, but the number of 'new travel permits', identity cards and passports issued to men and women in 1940-1945 was in the region of 200,000. To this should be added the 45,000 which the Department of External Affairs estimated went to the UK between September 1939 and the fall of France in June 1940, after which restrictions were imposed. In other words, out of a total population of approximately 2,968,000 (1936 census), over 8 per cent emigrated during the war. This is all the more significant when it is appreciated that those living in agricultural areas and all those under twenty-two years of age were prohibited from leaving the state, except in exceptional circumstances. If those under fourteen and over sixty-five are excluded, the figure rises to over 13 per cent and if we factor in the restrictions on those under the age of twenty-two, the number who travelled may have been well over 15 per cent of the eligible population.

Most Irish people wanted a unified Ireland. Few wanted a unified Ireland under a German jackboot.

My bold, it is the most pertinent point, in the context of which Irish neutrality must be understood.

*The Wehrmacht had no comprehensive plans to invade Ireland. General Günther Blumentritt, the operations officer of Army Group A, later explained that any thoughts about an early German landing in Ireland 'were quite unreal and they bear no relation to German resources at sea and in the air at the time'.

Resp:
I would like to believe what you wrote, and thank you for it. But a number of Irishmen went to England and enlisted (some became pilots). But upon their return to Ireland post WWII they were denied jobs, etc. for helping the British fight the Germans. Defies all logic.

 

[swampyankee]

Resp:
I would like to believe what you wrote, and thank you for it. But a number of Irishmen went to England and enlisted (some became pilots). But upon their return to Ireland post WWII they were denied jobs, etc. for helping the British fight the Germans. Defies all logic.

A number of members of the Irish Armed Forces deserted to join the fight against the nazis. These people were punished as such when the returned to Ireland, losing military pensions and the ability to work in government or government-funded positions.

 

[stona]

Resp:
I would like to believe what you wrote, and thank you for it. But a number of Irishmen went to England and enlisted (some became pilots). But upon their return to Ireland post WWII they were denied jobs, etc. for helping the British fight the Germans. Defies all logic.

Yes. Returning Irish people were very badly treated after the war. Many remained in the UK.

 

[Zippythehog]

A 50' threshold crossing height is standard for modern aircraft landing computations. This "still-in-the-air" distance is part of the number retrieved from the manufacturer's performance data, included in the POH or the AOM. It provides for a planned 3degree glide slope. This aids in a stable approach and increases the safety margin. Aircraft at an approach reference speed (based on weight), with power at idle, at 50' at the runway threshold, should be able to achieve the published landing distance. I expect the RAF had a similar protocol.
Zip