Patch 4.10 - Development Updates by Daidalos Team

[Asheshouse]

"Fly a steady heading" --- not so easy.

Depends on prevailing wind strength and direction, both of which may be variable.

The actual heading of the aircraft may not be the same as the resultant course flown.

[Skoshi Tiger]

Originally Posted by MikkOwl

Isn't it possible to just do triangulation from a single beacon to know one's position? Taking two measurements from the same beacon at an interval instead of using the bearing from two different beacons.

1. Fly a steady heading
2. Measure bearing to beacon
3. Take that bearing minus 180 degrees, and draw a line on the map from the beacon outwards.
4. Fly for a determined while longer (maybe 3 minutes and 15 seconds - knowing exactly how far we have traveled in our straight line).
5. Repeat steps 2 and 3.
6. We now know three angles (all). First is our heading and the bearing to the beacon at the time of measurement one. Second is the same but at measurement two. Third is the two different bearings from the beacon to our positions of the two measurements. And we also know the length of one side of the triangle - our own distance traveled between measurement one and two.

http://www.mathsisfun.com/algebra/tr...triangles.html

We can use the law of sines to find out the lengths (distance) between our aircraft and the beacon at measurement one and two), which are the two missing sides of the triangle.

When those are revealed, we have our triangle drawn on the map, showing our distance from the beacon at the two measurements and the path our aircraft flew.

What your suggesting is not "triangulation". You still don't know the distance you are from the beacon. Also even though you have your airspeed with dymamic weather modling you don't know your ground speed (or as AshesHouse has pointed out) any effects of drift. To determine that you'ld probably have to use visual reference to land marks (unless you have a Nordon bomb site of course) in which case your using good old map and compas and dead reconing to determine your location.

If you have visual references you'ld be quicker ploting your bearing from the NDB onto your map and looking for landmarks along that line.

Using dead reconing you should have some idea where abouts ont the map you are (unless you get caught up in a furball and get completely lost.

Of course you could always get your longitude using your aviation sextant and see where that intersects your bearing from the NDB. Though it depends how accurate you want to be.

Cheers

[ElAurens]

You guys are really trying to take all the fun out of this aren't you?

[MikkOwl]

Originally Posted by Asheshouse

"Fly a steady heading" --- not so easy.

Depends on prevailing wind strength and direction, both of which may be variable.

The actual heading of the aircraft may not be the same as the resultant course flown.

That is correct. For decent accuracy, wind speed needs to be taken into account (and the pilot needs to compensate accordingly in his heading). No one said it was easy

Originally Posted by Skoshi Tiger

What your suggesting is not "triangulation". You still don't know the distance you are from the beacon.

It is triangulation "triangulation is the process of determining the location of a point by measuring angles to it from known points at either end of a fixed baseline, rather than measuring distances to the point directly. The point can then be fixed as the third point of a triangle with one known side and two known angles."

The range from aircraft to beacon (at both points of measurement) becomes known by using the law of sines. We have all three angles known in the triangle and we know one side (the distance traveled between the measurements).

even though you have your airspeed with dymamic weather modling you don't know your ground speed (or as AshesHouse has pointed out) any effects of drift. To determine that you'ld probably have to use visual reference to land marks (unless you have a Nordon bomb site of course) in which case your using good old map and compas and dead reconing to determine your location.

As I mentioned above in my reply to him, of course these things must be known to some degree. The accuracy of the method depends on getting those tricky variables right. There's no wind in IL-2 which is a shame. Maybe those wind and turbulence mods work, have to check it out.

If you have visual references you'ld be quicker ploting your bearing from the NDB onto your map and looking for landmarks along that line.

I would agree with that Though if can't see landmarks for whatever reason, or just don't have visual references, maybe it's worth a shot.

The lower the wind and the higher the aircraft speed, the more accurate it should be, right? Because the ratio will determine how much movement was from aircraft and how much was wind affected. Assuming we don't have a grip on the wind.[/QUOTE]

Originally Posted by ElAurens

You guys are really trying to take all the fun out of this aren't you?

Oh but this IS the fun! We're pouring fun INTO it


Question to all - is there any way of seeing how the wind is blowing relative to the aircraft? Both when seeing the ground (not having a map to compare to) and when flying without any visual on the ground. How did people figure this out in flight way up there?

[Insuber]

Originally Posted by MikkOwl

Question to all - is there any way of seeing how the wind is blowing relative to the aircraft? Both when seeing the ground (not having a map to compare to) and when flying without any visual on the ground. How did people figure this out in flight way up there?

If one sees the ground normally one can use landmarks to estimate position. No ground visibility = no landmarks and no way to determine the drift.
Over the sea at night, if visibility was good, bomber crews used to launch a flare with the rear gunner aiming at it from a distance.

Regards,
Insuber

[AndyJWest]

MikkOwl wrote

There's no wind in IL-2 which is a shame

Not true. If you select the rougher weather conditions on the FMB/QMB, there is definitely a wind - so much so that taking off crosswind can be impossible in some aircraft as they pivit into the wind before you even get moving. The wind seems to stop above a certain altitude, as can be shown by using 'wonder-woman' view to compare airspeed and groundspeed in different directions.

[Viikate]

MikkOwl is on right track here, but I think that normal triangulation procedure with single NDB would be following:

1. turn so that your plane is perpendicular to NDB. (NDB is at 270 or 90).
2. start watch and fly at constant speed maintaining the current heading.
3. stop watch when NDB bearing has changed 5 dec.
3. calculate distance flown during this time.
4. calculate distance to beacon. (distance flown/sin 5)

For example if we fly at 300km/h TAS for 135 seconds.

((300/3.6)x135)/sin5) = 129km. So the beacon is 129 km away.

I'm not 100% sure about the formula. I just did a quick scribbling on pen & paper. And this is without any wing correction.

[Blackdog_kt]

A lot of things are possible, but unless you're flying as a dedicated navigator you probably won't use most of it. It's not wrong, it's just not practical enough.

Whenever i dabble into stuff like that, i never do trigonometry. If i need to fly perpendicular to the beacon to obtain a distance fix, then it's clear i'm going off course to get a fix. Much better and faster to tune a second beacon and see where the lines intersect on the map, presto, you have a precise fix of your position.

Even if your plane doesn't have a second nav radio and a second ADF, you can tune the first beacon and draw the line, then tune the second one and do the same on your single radio. Unless you are very close to the beacon (where the bearing changes fast), it will be accurate enough.

There's lots of quick and dirty methods that give you enough accuracy without having to go all mathematical about it. For me, being able to obtain an accuracy equal to the visual range is good enough. For example, if the visibility at my current altitude and weather conditions is 10 miles, i won't mind at all if my radio navigation gives me a 5 mile error margin (it's actually lower than that most of the times, think 2-3 miles). And if flying at night, most aircraft that historically did it were better equipped to deal with it.

Tuning 2 beacons and getting the respective bearings can also help you determine wind drift. See where the bearing lines cross and that's your position, wait (the 3m 15sec rule from silent hunter is good here) and get a new fix. Connect them on the map and it you used a 3m15s interval, the amount of kms travelled times 10 will give you your ground speed in knots. For example, if you've travelled 10km then your ground speed is 100 knots. Compare the heading of the line connecting the two fixes on the map with your actuall compass readout and you can also see the amount of wind drift involved.

Some aircraft might also have specialized equipment. In B17 the mighty 8th, the navigator had a scope that looked down towards the ground. It had some continuous horizontal lines running across the scope view, as well as dotted lines that could be rotated. The idea was to rotate the dotted line lens until the view seemed to be moving without any drift (it's been a few years, don't remember it exactly), then you could read out the drift from the markings on the wheel that turned the dotted lines.

[_1SMV_Gitano]

Originally Posted by Viikate

MikkOwl is on right track here, but I think that normal triangulation procedure with single NDB would be following:

1. turn so that your plane is perpendicular to NDB. (NDB is at 270 or 90).
2. start watch and fly at constant speed maintaining the current heading.
3. stop watch when NDB bearing has changed 5 dec.
3. calculate distance flown during this time.
4. calculate distance to beacon. (distance flown/sin 5)

For example if we fly at 300km/h TAS for 135 seconds.

((300/3.6)x135)/sin5) = 129km. So the beacon is 129 km away.

I'm not 100% sure about the formula. I just did a quick scribbling on pen & paper. And this is without any wing correction.

Equation is correct except that it needs a 3600 instead of 3.6 to have kilometers per second, 3.6 is to convert to meter per second. Reassuming:

d_NDB = (v_TAS * t_flight) / (3600 * sin( delta_angle ) )

where:

d_NDB = distance to the beacon;
v_TAS = true air speed (as Viikate said, not corrected for wind);
t_flight = time in second;
delta_angle = variation of heading;

This formula is valid also for non metric units;

[Hoverbug]

Originally Posted by Blackdog_kt

Some aircraft might also have specialized equipment. In B17 the mighty 8th, the navigator had a scope that looked down towards the ground. It had some continuous horizontal lines running across the scope view, as well as dotted lines that could be rotated. The idea was to rotate the dotted line lens until the view seemed to be moving without any drift (it's been a few years, don't remember it exactly), then you could read out the drift from the markings on the wheel that turned the dotted lines.

This would have been a B-3 or B-5 drift meter. Pretty much any medium or heavy bomber would have had one. This was direct evolution of Harold Gatty's drift meter of the early 1930s.

http://www.nasm.si.edu/collections/a...d=A19500075025

Here's one with all the bits:

http://cgi.ebay.com/ebaymotors/Bendi...-/360240715244


Here's the B-5:

http://www.questmasters.us/sitebuild...er-423x366.jpg