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skyfarmer
9th Feb 2004, 15:54
Any one out there remember the rule of thumb for calculating Max drift ?

Mind a blank this morning, and it was too simple and obvious, that I would never forget it, so never bothered to write it down!!!!

Field In Sight
9th Feb 2004, 16:14
The magic of the 1 in 60 rule strikes again.

60
----- X Wind Speed = Max Drift
TAS

For a light trainer
i.e. 60/90 = 2/3 so just use 2 thirds of the windspeed.

Oila.

FIS.

skyfarmer
9th Feb 2004, 16:17
Ah of course, so simple, never nuch good with the 1:60 either though!!!

Thanks

Irv
9th Feb 2004, 21:30
Depends how accurate you want it and whether you fly 'standard SEP training aircraft' - if you do, and you take into account

1- you are only using a forecast, and
2- forecast is for a set time at that

then I'd suggest 3° of max drift per 5 knots of wind might not be too inaccurate. (assumes aircraft cruises around the 85 - 115 kt range). so 20kt wind = 12° of max drift for these type of aircraft.

Airbedane
10th Feb 2004, 02:47
I use:

Windspeed in knots/TAS in nautical miles per minute

Same result, just a different way of calculation.

G-SPOTs Lost
10th Feb 2004, 04:47
Max Drift = 1/2 Wind Speed

Always works.

Probably because the errors are more than made up by the fact that I can't do an accurate rate 1 turn :} :} :}

LFS
11th Feb 2004, 19:02
Has senility finally started setting in on you down there in Jersey?

How is it going old chap (apart from the momentary lapse of memory)

Don't worry I won't let it be publically known that you're an Instructor..............

jsf NOT Dylan Dowd, Just stealing his Sign on!

PS Weather up here at the LBA is still as it always was.

scubawasp
12th Feb 2004, 17:39
Agree with Irv,

I arrive at max drift by

Total wind X 0.6. So as in Irv's case, at 90degrees to the aircraft assuming a wind of 20kts is 12degrees

BEagle
12th Feb 2004, 18:13
Max Drift.

He voss ein early Deutsche Flugzeugkapitan, und kompliziertes Maths voss not his bag, baby. "Ach so", he voss ein Tag musing, "Ve need ein simple method so dass wir das Wind Effect on unsere Flugzeuge compensating vor kann being are"

"Ve vill merely divide das Windgeschwindigkeit by unser TAS in nautisch Milen pro Minute. Das ist gut. I vill call it 'Max Drift'!"

And that's how it came about. All other simplifications for simpletons are at best a compromise. Airbedane's description is the only correct one on this thread.

Our hero Max also had a mate called Max in his Albatros Geschwader who was interested in manoeuvring. Having lost the odd wing or two attemptng to out dive die verdammte Tommies in their Sopwiths, he decided to try turning at high g instead. Because the Brits were all tanked up on rough French brandy and used engine castor oil, they couldn't keep up with Max.

His surname was Rate.

And that's how the Max Rate turn was born....

;)

witchdoctor
13th Feb 2004, 16:37
Max drift for SEP spamcans (90 - 100 kts) - 3 deg for 5 kts wind.

Max drift for light twins (140 - 150 kts) - 1/2 wind speed.

BEagle
13th Feb 2004, 17:04
Ach, du lieber Gott! Vy do zees verdammte Dumkopfs insist on such stupid und incorrect definitions? It is sooo simple:

Max Drift ist das Wind Speed divided by TAS in nm/min. Vich at 90 kts is WV/1.5 (fur dim Brits, ziss is der same as WV x 2/3), at 120 ist WV/2, at 180 ist WV/3......

So sei es!!

Say again s l o w l y
13th Feb 2004, 17:41
Why does anyone bother with complicated ways of working out drift. The method outlined by BEagle/Aerbedane makes life so much easier.

It's not rocket science, but could it be BEag's accent putting them off?

It works on the 1 in 60 rule. If doing 60kts TAS, then 1 knot of direct cross wind needs a 1 deg. heading change.
120 kts, 1 knot x-wind= 1/2 deg. heading change needed.
600kts, 1 knot x-wind=1/10 degree heading change needed to maintain track.
etc. etc.

This method just cuts down the calculation needed whilst giving the same result.

skyfarmer
13th Feb 2004, 23:50
Thanks all. just needed the brain kick starting again after no work for a few months....Been driving 20ton trucks around for the last few months.....and it pays more.

jsf.....good to hear from you again, might be back up your way some time. renew the twin and IR, nothing to fly with two donkeys here in C.I. ....talking of donkeys, am working out of Guernsy for the moment, till the other lot get busy again. If you fly with Charles E, I was with him down in SA, give him a hard time!!! tell him I said so.