BVE: All my apologies.

[ferrovipathe]

I made a stupid mistake in "BVE Utilities", the last sheet of "Loop making of".

Formulaes for computing switches' offset were wrong, and I didn't saw it. x(

That's as more silly as all computes and formulaes are rights everywhere else, except in last page. :-(

Computing an offset (a length...) with an angle (or PI) is so stupid....it's like computing speed with pounds...


So, you can find these corrected sheets here:

http://ferrovipathe.free.fr/Docs/For...pour%20BVE.pdf in French

and

http://ferrovipathe.free.fr/Docs/BVE%20UTILITIES.pdf in English.

Full corrected versions are still available on my site,

http://ferrovipathe.free.fr/Docs/Loop_making_of_Eng.pdf

http://ferrovipathe.free.fr/Docs/Loop_making_of_Fr.pdf

Just a request: If someone find an other error, don't understand something or just want to smooth my english, please send me a mail, it always will be a pleasure for me to progress.

All the best.

[mfonda]

RE: All my apologies.

I have corrected my copy of your article. In calculating the curve angle of 50 m switches you based your argument on 3.8m separation. Mine are 4m appart and according to your formula the angle should be 1.1453 (arc= 625.333). In practice I find that 1.123 looks better. Why should that be? Martin

[ferrovipathe]

RE: All my apologies.

Hi Martin !

I know nothing about your track map nor your source code.

But it's possible to compute some little things:

With 4 m separation, and 50 m length switches, we got:

Deviation = 4 / 2 = 2 m;
Radius = 50 * 50 / (2*2) = 625 m.
=>
- Direct:
- Angle = (180*37.5)/( PI * 625 ) = 3.437746771
- Offset = 25*25/(2*625) = 0.5 m

- Reverse:
- Angle = 1.4591559 (as 37.5/12.5 = 3, angle = 3.437746771 / 3)
- Offset = 0.5 m

You find that 1.123 look better. So yor switch is reversed and your effective radius is:
(180 * 12.5) / ( PI * 1.123) = 637.7535565 m

and separation between tracks = 2 * ( 50*50/(2*637.7535565) ) = 1.96 * 2 = 3.92 m.

I think there is a mistake somewhere, perhaps creating object with switch15: Use 625 m radius and 2 m offset:
Example : creating a lefthand switch:
lenght 50
offset right = 0
offset left = -2
....

and put it as freeobj(X,Y,.5,0,3.437) if you want to turn left on switch

or freeobj(X,Y,-.5,0,181.4591559) if you are coming from right on that switch reversed .

All the best.

[mfonda]

RE: All my apologies.

Thanks again, Jean-Louis. It is very clear now. I had arrived at the .5m offset not mathematically, but purely by eye; upon using your calculation I found that this was right. The angle seems to change a little owing to some obscure circumstance. The main thing is that it is possible to come to a ball-park figure that can than be 'queeked' to look good. I also had the occasion to look at your website again where I found a great deal of interesting work done by Italian BVE-ers. Very nice. Best wishes. Martin