sky-writing

[james ozzie]

On Sunday I observed the not unusual sight of a word being "written" in the sky and marvelled at how neat it was. As a PPL who used to fly just enough to stay dangerous, I was hugely impressed by the flying accuracy required.

Can someone explain how it is done? How does one do a letter "S" with the top & bottom lines coming out exactly at the right letter height? Hell, I don't think I could write that neatly on a piece of paper!

I guess GPS etc would help but this was being done long before the days of airborne GPS

Oh yes, no bloopers allowed - you cannot just erase hem....

[jimmythegong]

The procedure is technically not too complex; You have a number of aircraft flying a reasonably tight formation, in a very large circle, when a computer controls injections of diesel/dye into the exhausts of the aircraft, making a series off coordinatd puffs of smoke. Almost the same principle as the dot matrix printer, but very effective.

[james ozzie]

Thanks thegong; I can see how the dot matrix version works - as you say, in principle not too complex really.

I was more interested in the earlier method where a single aircraft actually traces out each element of the letter. I assume it is all stick & rudder/compass/ stop watch stuff, as there were few electronic aids in the old days when this was more popular. I remain in awe of the flying skills needed if this is in fact how it is done - anybody out there actually done this?

I assume it is helped by having an experienced cojock/observer on board as well as some ground support with radio?

[jimmythegong]

The earlier version took scary skill!

[krobar]

They just used to drag posters behind the planes before. Air writing could be a nice element in a accuracy contest though