Recent content by Thorvald

That does not give me an answer? Finite element method programs? If yes, then what program?

FEA? What you mean? :-)

I know Supertiller. But the problem is that the program has never run perfectly for me. I don't know if it is because my Microsoft Office is too old or if the program is just too unstable.

Hello. This actually sounds quite interesting. I have recently been thinking about to develop a software tool in Excel, based on formulas and calculations (no macros). But as you might know as well, it can be difficult to get the time and the motivation to do such a work. I wish you all...

You are right about the white background in graphs. I normally do that too (but haven't doen it yet in this one... :-) ) - Well, done it now... Yes, I am now using the cos/sin-formulas for the ellipse - hey, did you write wrong again? Shouldn't you use sin for y?? Or is it cos for both x...

How to rotate the ellipse in the point (0,-b)?? The formulas you have given, rotates it around (0,0). I'd like to move the ellipse (shouldn't be difficult), use part of the ellipse (not difficult, either) and then rotate it at what was originally (0,-b).

It looks like you have made a mistake here. I couldn't understand why, when I used this formula the "a" was smaller than the "b" - but it's logic, because a is the biggest value along the x-axis, so "a" should be in the formula for x.

Aaaah - wait again - it may be the case, it's just the grid/axes that teases me...

Hmmm., wait - when I rotate the ellipse 90 degrees, I would expect that it would "stand up". I.e. the long part of ellipse, being vertical. Why that is not the case?

You're right - it looks ok. I know why it didn't look exactly correct - because as values changes the axes in the graph changes... Is it possible to automatically control the graph grid, so it is the same in the different pictures?

Does this look correct? It does not look like the curve have been rotated 45 degrees? I may want to use the formulas for creating the whole ellipse and then just take out what part of the ellipse, I want to use. But this was just for now to see if it works.

Hmmm., thanks for your replies - very useful. I have used this formula to calculate points (or at least the 1/4th of the ellipse) in excel: y = sqrt(b^2*(1-x^2/a^2), where I choose values for a and b. Does your formula y = b cos(t), give the same result (possibly giving the whole ellipse)? And t...

Hi. I know about the general formula for an ellipse: x^2/a^2 + y^2/b^2 = 1, that can be used to isolate y and calculate x,y points in excel. That's great, so far so good. That will create a ellipse, with horizontal A (x) axis and vertical B (y) axis. But what if one wants to rotate the...

Hi. I am searching for software, where the following is possible: - Input a bow design - perhaps in 3D, perhaps more simple. Can be the whole bow or mainly the "spring" part of the bow: The limb(s). - Must be able to handle recurve style limbs. - If it can handle different laminations in...

Maybe, but I doubt it. I am on AIUK (the first link). The two other fora is rather unknown to me. But in general archers and even bow builders (as far as I know) doesn't know the mechanical properties of the woods they are using. Because they go by experience: If the limb is so and so thick, and...