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On 8 June, 14:57, Bruce wrote:

Please don't ask any more stupid questions. However, in the unlikely
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I have a question, or several. Why was Heathrow designed like that,
with six runways crossing each other in a sort of Star of David
shape? They obviously wouldn't have been able to use all of them at
the same time, was it intended that they would use two parallel ones
at any one time depending on the direction of the wind?

I thinks it's to do with early aircraft only being to take off safely within
about 30 degrees of a headwind. I believe most wartime airfields started by
marking out three sides of a triangle, as buildings developed around about
the basic triangle would remain in position even if the runways were
extended for heavier aircraft.

As aircraft were developed the need to take off 'very nearly into the wind'
reduced, so the number of runway directions needed at any given site would
reduce, and IMO you can see this on aerial views of many RAF airfields,
where they now use only one main runway, and others have gone out of use.

Why were only
three of these runways ever built? When, and why did the third runway
close?

I took off from Heathrow in a NNE direction shortly before closure of the
third runway, about 2001 - but everyone reckons it was very rare to use it
by then. But I think there was a short period when Heathrow did have six
runways. Basically threee pairs though as you cannot feasibly use more than
a parallel pair together? As you'll know nowadays there are many airports
that operate with one runway (albeit to/from either direction).

What are the numbers and letters at the ends of runways? The
letter always seems to be 'L' or 'R'; the only thing I can think of is
left and right, but that would depend on which direction you were
facing. Is there any significance to the numbers, or are they just
assigned the next free number? EWR seems to have similar numbers to
LGW and LHR, so I assume it must be an international thing.

Compass direction, with the 3rd number left off. So Heathrow's current
runways are 09 L and R if approaching from the west, and 27 L and R if
approaching from the east.

Why do airports and ex airports often seem to have been built in
clusters fairly close together. Heston, Heathrow and Northolt for
example or Waddon and Beddington (originally separated by just a road
and later merged to form Croydon), Kenley, Redhill, Biggin Hill and
even Gatwick not too far away.

One airfield and a few satellites. You would have all the domestic and
maintenance done at the main airfield, but if you had more aircraft than you
could scramble from your single runway, you could disperse a squadron or two
a couple of fields away and then there'd be more room for take off en masse,
and also somewhere else to land if you came back and found your main base
bombed to bits.

Paul