Battle of Britain Vectoring

[celticmarine10]

Hi all, thanks for the help on my last question,
I have another question concerning the vectoring of fighters to interception (Battle of Britain). I know that once the fighters had taken off and declared themselves airborne, they wee told to 'make angels' a number in thousands of feet, then told to vector (steer) to a specific compass degree to intercept enemy aircraft. In the operations rooms, how did they decide what direction to vector the fighters? If they ordered them to steer diecly toward the hostiles, fighter command would have to constantly change the vector degrees. Did they somehow calculate the interception angle? If so, how did the determine speed of the Hostile aircraft?
Thanks so much again,
regards,
Celtic

 

[stona]

In December 1939 Dowding circulated a note listing the limitations of radar that give us a good idea of what it could do.

Range and position were accurate to about one mile.
Height was accurate to plus or minus 1000' over the Thames estuary,2000' further out.
Up to three aircraft could be accurately counted.More than three could be as many as nine and more than nine could be any number over nine.
The lag between a sighting by a radar operator and the plot appearing on group and sector tables was about ninety seconds.

From the radar information it would be possible to estimate the speed and bearing of an incoming formation. Input from the much maligned Observer Corps would certainly help with altitude and bearing,the observers were trained to estimate these parameters. The performance of the incoming aircraft was known,Ju88s and He111s cruise efficiently in a narrow speed range.
Large formations couldn't make sudden large changes of course which must have helped as any change of course would take time to reach sector commanders.
The RAF often had good intelligence from its radio intercepts,the Y service and more debatably Ultra intercepts. (Ultra does not pertain solely to material decoded from Enigma,a common misconception). The Luftwaffe radio operators used poor signal discipline. It helps if you have an idea when and where the attack will come.
The system was more rudimentary than many realise today,but it worked.
Cheers
Steve

 

[pbfoot]

to determine speed They would use the old standby formula Distance equals Rate multiplied by Time . I'm going to assume the vector was the controller using the formula and a bit of intuition to position the interceptors

 

[Njaco]

Don't forget the forward Observer Corps that also related number, speed and direction. Between all these info they could direct sqdrns to approximate area of interception.

 

[TheMustangRider]

Excellent information stona, very helpful.

 

[Edgar Brooks]

Don't go too far down the Ultra route, since Dowding was not included on the list of recipients until October 1940. It's possible, even likely, that some information was passed to him, but not through official channels. A lot of the interceptions were entirely down to the intuition of the top brass, watching things unfold, at Bentley Priory.
Several times the Germans sent over a formation that consisted entirely of fighters, and Park just ignored them, possibly because they travelled too fast. He was also adamant that he should intercept with small formations, since they were easier to handle, and he could spread his response over a wider area; it's now generally agreed that Leigh-Mallory's "Big Wing" was a failure, but he allowed himself to be seduced by its over-claiming (this continued over into the operations over France, and cost the lives of hundreds of Allied pilots.)
Edgar

 

[Mustang nut]

Hi all, thanks for the help on my last question,
I have another question concerning the vectoring of fighters to interception (Battle of Britain). I know that once the fighters had taken off and declared themselves airborne, they wee told to 'make angels' a number in thousands of feet, then told to vector (steer) to a specific compass degree to intercept enemy aircraft. In the operations rooms, how did they decide what direction to vector the fighters? If they ordered them to steer diecly toward the hostiles, fighter command would have to constantly change the vector degrees. Did they somehow calculate the interception angle? If so, how did the determine speed of the Hostile aircraft?
Thanks so much again,
regards,
Celtic

from Biggin Hill Battle of Britain Trust
Tizard then came up with the idea of using the 'principle of equal angles'; at any stage of the interception a line could be drawn between the fighter and the bomber, which as the base of an isosceles triangle, prolongation of the bombers flight path became the second side of the triangle, the course given to the fighter became the third side. This formula was known as the 'Tizzy Angle' or the vector for the attack.

Basically forming an isoscelese triangle meant that in theory at least the fighter would arrive before the bomber at the interception point because it was faster.

If you google tizzy angle you get a lot of info.

Additionally the plotting table markers recorded the size dirction of a raid against a raid number H06 for example as a hostile raid. There was a color code on the marker which changed every 5 minutes from red to blue to yellow so looking at the colour of the arrow marker you could see how old the plot information was.

 

[stona]

Don't go too far down the Ultra route, since Dowding was not included on the list of recipients until October 1940. Edgar

That's why I said "debateably". He does seem to have had some unofficial back channel access but it is,unsurprisingly,difficult to show for sure.

Dowding should have got rid of Leigh Mallory in late 1938 after he sent his idiotic memorandum to Park showing just how little grasp he had of the basic concepts of fighter defence. Dowding could have done himself,Park and the pilots of 11 Group (after Leigh Mallory replaced Park) a huge favour.

Cheers
Steve

 

[merlin]

Dowding should have got rid of Leigh Mallory in late 1938 after he sent his idiotic memorandum to Park showing just how little grasp he had of the basic concepts of fighter defence. Dowding could have done himself,Park and the pilots of 11 Group (after Leigh Mallory replaced Park) a huge favour.
Cheers
Steve

Could you tell us more please about the 'idiotic memorandum' - sounds intriguing.

 

[stona]

From Vincent Orange's biography of Dowding.

"(in)..October 1938 he (Leigh Mallory) had sent Park a memorandum about the air defence of Britain north of London. It was based on the startling assumption,as Park told Dowding,that Britain would continue to be defended by slow lightly armed biplanes rather than by fast heavily armed monoplanes. It emphasised local defence at the expense of area defence,and showed no appreciation of the advantages gained by the extension of the searchlight area and improved wireless communication. To implement his plan Leigh Mallory asked for 29 of the command's 41 squadrons,leaving only 12 for London,the most vital area,and none at all for the rest of Britain.
Dowding agreed with Park. The memorandum,he told him,"shows a misconception of the basic ideas of fighter defence". It does indeed,and Dowding should then and there sought Leigh Mallory's replacement."

He had another chance just before the start of the war in August 1939. Leigh Mallory's report,following an exercise greatly alarmed Dowding.
First a low level raid caught some of Leigh Mallory's sectors by surprise. Leigh Mallory put up standing patrols for their protection,thus negating the force multiplication which a coordinated air defence system was supposed to achieve. Park thought Leigh Mallory had over reacted,diverting too many fighters to local defence from their major task of intercepting bombers threatening vital industrial targets.
Secondly,his operations room was evacuated during a night attack! Dowding directed Leigh Mallory that no operations room,group or sector,was to be evacuated unless so damaged as to be useless.
Keeping Leigh Mallory in line with other group commanders was an endless task,as evidenced by Dowding's increasingly frustrated letters and clarifications,sometimes about basic things like the command structure,sent to Leigh Mallory throughout late 1939. Dowding had good cause to remove him from 12 Group before the Battle of Britain but he stuck with him until he no longer had the power to get rid of him. This was a failing on Dowding's part. It cost him and Park their jobs and it cost many young pilots their lives.

Cheers
Steve

 

[merlin]

To stona:

Thanks for that, yes agree - he could have done it later, but much easier if it had been done sooner. But puzzling how Leigh-Mallory got it in the first place!?
Seems just as likely to have stayed in the Middel-East, gone to France, or maybe even the Far East!?
But who in his place?

 

[stona]

But puzzling how Leigh-Mallory got it in the first place!?

Politics. Leigh Mallory was a very astute politician and never shy of blowing his own trumpet. I think he had earlier become the youngest Air Vice Marshal in the RAF. He boxed clever and almost invariably backed or allied himself to winners. He never faltered in his ambition to reach the top and he ultimately succeded.
The in fighting and factionalism within the RAF and Air Ministry at the time of the BoB had been going on for years.

Steve

 

[merlin]

stona:

Yes, I can understand the 'office politics' when in the 12 Group post, but still strange as to how he got the post in the first place!
According to Royal Air Force Organisational History - his WW1 flying was in BE2s on the Western Front, then involved with Army Co-operation, he was Supernumerary, No 1 Air Defence Group in Dec 1931 (for a month) this seemingly being his only 'fighter/defence' experience! Immediately prior to his 12 Group appointment he was in the 'wilderness' as SASO, RAF Iraq - so who was his guardian angel!?