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View Full Version : Monoplane sighting device location question.



Russell Peitz
08-09-2013, 07:40 PM
I have a One Design DR-107. I've never had a sighting device on a monoplane. On my Pitts it had the star pattern at perfect eye level at the 9 o'clock position.

On the 1D, it appears as though the sighting device's horizontal line will be well below my eye level. The vertical line of the triangle is easy to put in the correct fore/aft position so vertical rolls and such should be ok.

I guess my question is, unless the upper vertical/angled portion of the device is not at eye level will I have to compensate visually. Putting that upper point at eye level makes for one really tall sighting device.

Or do you want it to be more towards the center of rotation of the aircraft and not at eye level??

I was already looking down towards my wing for angles and such before so maybe I'm over thinking it.

Any thoughts or suggestions?

Thanks,

Russ

martymayes
08-10-2013, 05:25 AM
You are correct Russ, any sighting device has to be in the correct location to be of value. A straight line from the center of the left wing sighting device to the center of the right wing sighting device should pass as closely as possible through the pilots eyeballs while he is seated in the cockpit. You just have to fabricate/adjust your mountings until that is achieved.

RetroAcro
08-10-2013, 02:03 PM
Russ - IMO, exact height position of the horizontal line of the sighting device is not important. Like you say, the fore and aft location of the vertical line is more important. But even if the vertical segment doesn't sit perfectly on the horizon when you're perfectly vertical, you'll learn what it takes to make it so. I never reference the horizontal segment of my sighting device. It's vertical and 45 only. As long as you can see the segments of the device well enough to set vertical and 45 lines, that's all you need. And don't get too hung up on the sighting device. It's a good reference, but on hazy days with little or no horizon, you must get to the point of just "knowing" you're correct, especially on the vertical when doing vertical rolls. Part of this is muscle memory, and part is just the "feel" of your body weight when perfectly vertical. I flew the Wildwood, NJ contest in June, and given the view of the ocean on one side, the hazy air on practice day was a reminder that your sighting device is not the end all. There, the water and horizon blended, and if you weren't careful, your brain might actually try to force you to line your sighting device up with the shoreline, which looks like the horizon, even when your muscle memory should be telling you that you're off.

Eric

WLIU
08-11-2013, 03:56 AM
Many airplanes have sighting devices that are not exactly lines up with the pilot. As noted above, its not needed. You do not use the sighting device to eactly lay one of the legs of the 45 on the horizon and expect a score of 10. You learn what sight picture the judges on the ground call as good and you pitch the airplane to get that picture in your sighting device. Its different upright vs inverted. And its the judges opinion that counts.

Best of luck,

Wes
N78PS