Rhumbline track

[rpetersson]

Q: From N65 00 E010 00 to N65 E052 00 on a rhumb line, what is the distance?
a 1065 nm
b 2283 nm
c 1700 nm
d 2520 nm

I got it to 2520 just by taking E52-E10.. but im not sure if this is right can anyone confirm?

Q: An aircraft flies from N32 00 E020 00 for 1200nm on a rhumb line track of 090, what is the longitude of the new position?
a E013 58
b E043 35
c E050 00
d E040 59

This one i calculated again just taking 1200/60 = 20 and adding it to E020 and getting E040.....

But it doesnt seam to be correct if i look at the possible answers.. can anyone help me here? Thanks in advance...

(Im abit unsure when the question says rhumbline track if i have to deal with convergency or not....)

[rpetersson]

Found out...that....the departure formula is the **** :)

[alex230380]

concerning the 2nd question you propose:

If you keep a constant hdg of 090° means you're tracking a rhumb line and necessarily also a constant Latitude.
You need to use the departure formula which is:
Dep=ch long(in minutes ')*cos Lat.
1200nm=ch long(') * cos 32°
1200nm=ch long(')* 0.848
ch long(')=1200/0.848
=1415.1'
=23.58°
=23° 35' further east

new position: N32° (unchanged), E43° 35'

remember, the distance between two meridians spaced 1° is 60nm only at the equator, and 0nm at the poles. At 30°N is 60*cos30°=51.96nm , at 70°N is 20.5nm and so on.

ciao

[SunderlandMatt]

RP,

These questions both ask you for the rhumb line track along a line of latitude.

What they are after is the departure i.e. the distance between two points.

Departure = ChLong x Cos Lat

Q1. Departure = 42 (degrees between the two points) x Cos 65 (latitude)
= 16.9 (degrees at correct scale) x 60
= 1014 nm
I'd therefore go for answer a) as it's closest.

Q2. Here they want you to rearrange the Departure formula to obtain ChLong to find the new longitude.
Departure = ChLong x Cos Lat
ChLong = Departure / Cos Lat
ChLong = (1200 / 60) / Cos 32 (1200 is divided by 60 to get it into degrees)
= 23:35

So E020 + 23:35 = E43:35 which is answer b).

You use Convergency as soon as great circles are mentioned. Departure is used on rhumb lines.

Hope that helps.

SM.

[whiskey1]

Rhumb Line may be a straight line on a Mercator Chart.
It is a line of constant bearing. So a line of Latitude is a Rhumb Line (and yes the equator is both a Rhumb Line and a Great Circle).
A Rhumb Line is NOT a straight line on the Earth, a Lamberts Chart or a Polar Sterographic Chart.

[rpetersson]

Thanks for all the great answers, love you guys <3

[RichardH]

A Rhumb Line is NOT a straight line on the Earth, a Lamberts Chart or a Polar Sterographic Chart.

It is if it's along a Meridian of Longitude which is either 360 or 180 therefore constant direction. They are also great/semi-great circles.