How to get wind from drifting?

[old,not bold]

Ancient Mariner;

The drift sight I mentioned above could be used over the water so long as you could see the apparent direction of travel and line up the hairlines accordingly. This was normally easy - in daytime - as long as the surface was visible and at least slightly rippled. The rougher the sea the better.

[DeanoP]

Ref: Drift Sight

Whilst measuring drift angle, it could also be used for a ground speed check by timing, in seconds, an object on the ground, or a wave on the sea transiting from one graticule to the other and using the computer on the LH side. Set height against time to give ground speed. Calculating an accurate ground speed was a problem as height measurement requires an accurate QNH. However a radio altimeter would have solved this problem but were not fitted to my vintage of A/C. The 'Kipper' fleet operating more or less at sea level would have made full use of the drift and groundspeed sight.


On the Hastings a/c we could check the correct alignment of the sight by checking the drift angle along the rivets on the starboard side of the airframe. On the Valetta it was checked by tying string from the pitot tube to the port wheel strut. (and removing before flight!!)

A good bit of kit if you could see the surface.

Black shoe polish on the eye piece was something the Nav had to check before using. Always caused a laugh!

[Fareastdriver]

I used to get my wind from this.

[old,not bold]

Apparently the RAF can only navigate when flying at multiples of 60 kts.

And there was me thinking that ground attacks were flown at 420 Kts from cab rank departure point to pull up point just to make it easy for us pongo FACs who had to work out how long it would take, as we huddled in a slit trench in the rain.

Or at least they were when it was Hunters from Chivenor.

[nimbev]

Whilst measuring drift angle, it could also be used for a ground speed check by timing, in seconds, an object on the ground, or a wave on the sea transiting from one graticule to the other and using the computer on the LH side.

The orientation of the graticules on the driftsight assumed that the driftsight was looking below the aircraft. On the Beverley the driftsight was not level in the horizontal plane but tilted slightly above the horizontal so that the side of the aircraft didn't interfere with the view. Hence one could get an accurate drift reading but the groundspeed was unusable. This made navigation even more 'interesting' as we had virtually no navigation aids.

[teeteringhead]

In the AAC we used to cruise at 135 kts and there was an 'intermediate pitch stop'

Trouble with the IPS Rosev, was that it was a fixed power (ok - pitch) setting so the actual IAS achieved varied with AUM (and other stuff, like how good the donk was).

135-ish was a good average, but (readies hat, coat and flak vest) I suppose "ish" was OK for the AAC!

[Rosevidney1]

All up mass? Well that sounds like a weird religious rite to me! In my day we had weight and that was understandable to a mere Pongo. I've had 5 on board a number of times especially in Ulster but don't recall the IAS varying too much - unless the rear doors were open when there was a considerably lower limit imposed, can't now remember what it was.