Yes, they do "bump" once in a while in the formation. There have been
numerous sheet metal "benders" through the years. Naturally, these are
wingtip hits laterally rather than nose hits :-) I remember one of these
occasions quite vividly during the 73 season.
The flow patterns in the diamond are unique to close proximity similar
aircraft. I say similar because in a close Diamond of dis-similar aircraft,
the flow patterns would not be as predictable.
Tip vortices on the left and right wing positions in close tend to cause a
roll away from the opposite aircraft and have to be countered. You can
really feel this as you get in close.
Lead and the slot position have their trim affected as the slot sticks his
nose in where it should be. Lead can actually "feel" the slot in position
and knows by his trim change if the slot slides out too far. The trim change
is nose down for the lead and nose up for the slot, again caused by the flow
patterns.
It's not nearly as smooth in the Diamond as it looks to you from the ground.
There is a lot of movement going on in the formation, especially through
rough air. It takes intense concentration to hold position.
On the cross over question. They use pre-selected hack and checkpoints
briefed by photo recon before the show as well as radio calls when visual.
Timing on the high show bomb burst is a hack call down from lead to the
split S pull on his cadence. There is a visual call by each opposing
aircraft (lead/slot) (left/right wings) and adjustments made during the
downside recovery for altitude and airspeed to seek co-cross at show center.
Naturally, both sides of the runway are used. It saves a hell of a lot of
sheet metal work after the show :-)
Hope this helps a bit.
Dudley Henriques



"three-eight-hotel" wrote in message
ups.com...
Our family went to the airshow in northern California last weekend. It
was a blast, to say the least. It blows me away to think about the
things people can do with planes and that they can have the
where-with-all to pull off some of the manuvers they do, and under the
G's they are pulling at times!

The Blue Angels were incredible, as were the rest of the performers,
but I left the show, as I'm sure others did, scratching my head
wondering how they do some of the things they do without tragic
results.

I heard that in some of the tight formation flying, they get as close
as 18 inches to each other. If this is true, and I have no reason to
believe it isn't, I have to wonder if they ever bump into one another?
If they were to bump into one another, would that be catastrophic, or
would they merely make contact and separate back into position? They
are all flying in the same direction, and at the same speed, so it's
conceivable that contact could be farily incidental.

Another question I had was regarding two Angels flying in opposite
directions and crossing by each other at a combined speed of 800 mph.
Do they have equipment on board that gives them precise situational
awareness, or do they use ground references? My thought was that one
of them could be lined up to fly right down the runway center-line, and
the other could line up just outside the runway which should guarantee
separation??? Their timing, so that they cross right at midfield is
amazing!

They put on an incredible show, and I'm glad my kids got a chance to
see them. I hadn't seen them in about 20 years, so I forgot how much
fun they were to watch.

Best Regards,
Todd