On 12/05/08 13:39, tscottme wrote:
There are a couple of techniques I've never been particularly good at while
flying, proper rudder work, and smooth turn onto a VOR radial without over
or undershooting the needle. What's a good way to smoothly know when to
start a standard rate turn onto the heading to intercept a VOR/GPS course on
the OBS?

My flying these days is with PC sims and often with an HSI. With an HSI you
have the lubber line and can keep the end of the lubber line on the needle
as it swings to get good results. What would be the non-HSI equivalent for
spam can flying?


This is a great question - plus it's aviation related!

Here are some notes I took during my instrument training. I hope you find
them useful:

- Choosing an intercept angle

This was pretty easy too, once I thought about it some. There
are some rules of thumb to remember:

- when within 3 miles of the station, use 30 degree angle
- when 3 to 10 miles from the station, use 30 - 45 degrees
- when more than 10 miles from the station, use 45 - 60 degrees

To select the intercept angle, just look at the side of the OBS
where the CDI needle is deflected. Then just count from the
top of the OBS toward the needle, the number of degrees of the
desired intercept angle. Then just fly that heading.

Assume we want to track outbound on the 090 degree radial.
We dial in 090 in the top of the OBS and see that the needle
deflects to the left. Because we are 5 miles from the station,
we select an intercept angle of 40 degrees. So now we just
count to the left from our radial (090) the number of degrees
of the intercept angle (040) and that gives us our heading
to fly: 050. Fly a heading or 050 and you will intercept the
090 degree radial at 40 degrees.

Wind will affect things here.

- Deciding when to turn on to the selected radial

The further we are from the station, the longer it will take
to move the needle. Therefore, when we're close to the station
(within 3 miles) we'll need to start our turn with about 2 dots
of CDI deflection.

However, when we're more than 10 miles from the station, we'll
need to start our turn when the CDI needle is much closer, say
within the "circle".

My CFII said this will just take some practice to get a good
feeling for when to turn.

Most of this assumes you know your distance from the station.
If you don't, you'll just have to make your best guess.


--
Mark Hansen, PP-ASEL, Instrument Airplane, USUA Ultralight Pilot
Cal Aggie Flying Farmers
Sacramento, CA