• Ratty's Ramblings - Drifting

    Ratty's Ramblings

    Ratty's Ramblings - Drifting

    By Ian Radcliffe

    Drifting

    Unless you always land on runways pointing directly into the wind, you're familiar with drift. And of course it's one of the effects of those pesky winds at altitude. Even when you're on autopilot following the magenta line, if there's any sort of crosswind your plane is flying sideways a bit. Exactly how much depends on your speed and heading, and the strength and direction of the wind.

    I recently elected to fly from Southern California to Sydney, Australia. Don't ask. I decided to go via Hawai'i and Pago Pago, making the trip three hops of a little over 2,000 miles apiece. There are not a lot of landmarks and navaids in the South Pacific, but using a GPS seemed like a kind of heresy as I was flying the A2A Lockheed Constellation.

    In the Connie, the onboard map looks like this:

    Ratty's Ramblings: Connie onboard map

    I can see that wind from the east northeast is pushing me off to the right, so I'm heading 191 degrees to get my desired track of 193. This is, of course, more information than would be available in real life. Back in the day, forecast winds aloft were all you had, and landmarks and beacons had great significance. But those are in short supply over the Pacific, so you need another way to tell where you're going.

    Drift sights were invented in WWI as a bombing aid, but after that, many aircraft were fitted with them as navigation aids that allowed the pilot or navigator to look downwards to observe the relative motion of the surface and measure how much the aircraft was drifting due to wind. I like that they add a little bit of mystery to a flight. Drift information alone doesn't tell you how much your ground speed is affected, so while you can be more certain you'll reach your destination, you won't be able to calculate exactly when. (Some drift sights incorporated "speed lines" to get a ground speed reading by measuring the time it took for an object on the surface to move between the lines and then factoring for altitude.)

    The Connie's map is a great stand-in for a drift sight, but if you don't have an onboard map like that, how do you get the drift information? I've found that a simple protractor works just fine; the ones with radial lines and no holes are the best. Go to your top-down view in the sim and set it as "aircraft-oriented". Put your protractor on the screen over the aircraft with the 0-degree mark at the top, and watch the surface slide by. You'll be able to see the surface movement relative to your plane. Read off the drift angle and correct for it. After a couple of minutes, check again and make any necessary adjustments. That's it. Congratulations, you're on course!


    8 Comments
    1. sfgarland's Avatar
      sfgarland -
      Enjoy your articles immensely. I would mention there is an excellent Drift Meter gauge available, I think still found in the FS9 sections here.
    1. ianhr's Avatar
      ianhr -
      Quote Originally Posted by sfgarland View Post
      Enjoy your articles immensely. I would mention there is an excellent Drift Meter gauge available, I think still found in the FS9 sections here.
      You're right! I had forgotten about that. It's in the FS2004 Panels section as drift7.zip by Dave Bitzer, and comes with an excellent manual explaining its use. I used it in the Sim-outhouse London to Melbourne race in 2014, flying a Percival Mew Gull. The race recreated the 1934 MacRobertson event, and the only navaids available were NDBs.
    1. sfgarland's Avatar
      sfgarland -
      Quote Originally Posted by ianhr View Post
      You're right! I had forgotten about that. It's in the FS2004 Panels section as drift7.zip by Dave Bitzer, and comes with an excellent manual explaining its use. I used it in the Sim-outhouse London to Melbourne race in 2014, flying a Percival Mew Gull. The race recreated the 1934 MacRobertson event, and the only navaids available were NDBs.
      Cool! I have never attempted to participate in groups flying/racing. Keep up the great work on your articles . . .
    1. flightman's Avatar
      flightman -
      Excellent article. I've tried formation flying before and failed miserably so this inspires me to have another go and keep at it.
    1. lnuss's Avatar
      lnuss -
      if there's any sort of crosswind your plane is flying sideways a bit.
      A slight clarification for some folks who may misunderstand: That is sideways in relation to the ground, but the aircraft is going straight through the air mass, not sideways, unless you are uncoordinated, that is, unless the ball is not centered. It's just that the air mass is moving over the ground in a different direction than the desired course, thus the drift.

      The reason I mention this is that I've become aware that some folks think that if you're flying sideways that you need to hold rudder to correct. There are other misunderstandings about this, too, so I always feel the need to be explicit about the distinction between the path through the air and the path over the ground, just in case.
    1. bjl345's Avatar
      bjl345 -
      Want to be serious about drift handling? If wind direction is known before hand the best help is a wind triangle.
      More about it on https://www.youtube.com/watch?v=f84jvBu_tGU
      Or if you want to acquire practical knowledge, the use of the wind face of a fly computer (plastic or metal Jeppesen) will give you a helpful hand.
      Good landings.
    1. AlyMac's Avatar
      AlyMac -
      191 degrees? 193 degrees? Yer a better man than me Ratty I always round it off to the nearest 5 degrees
    1. amcclymont's Avatar
      amcclymont -
      Thanks for all the great articles. I try formating on AI aircraft doing circuits around Meigs. It is hard to join up without zooming past. Last time I tried I joined up successfully and was edging closer, when it said "aircraft collision!" and dumped me back on the runway. I was at least 100' away! So thanks also for the advice about turning off collisions - maybe now I can revist that earlier (FS98 or FS2002?) "challenge" of flying inverted under Eifell Tower. My Eiffel Tower appeared to be surrounded by bulletproof glass!
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