One Rocket

[ValeryOchkov]

I can not solve this task in Prime (with units) Help me please!

In Mathcad 15 - no problem (see the attach). We can add air resistance, g=f(h) etc

PS

One North Korean rocket

[AlanStevens]

It seems starightforward enough in Prime 2 - see attached. Perhaps I'm missing something?

Alan

[ValeryOchkov]

Thanks, Alan!

I have done it too by help the Mathcad 15 Mathcad Prime convertor.

But I cannot do it direct.

Questions (2 old and 2 new) on the picture:

[AlanStevens]

Valery Ochkov wrote:

Thanks, Alan!

I have done it too by help the Mathcad 15 Mathcad Prime convertor.

But I cannot do it direct.

I didn't use the converter (I still only use M15 F000, so the converter doesn't work), I did it direct without any problems. In answer to your red questions: I also get the mess of words on the side of the solve block; and the blue h of the h(t) in odesolve; and the messy looking marker label. By increasing the number of -plotting points it is easy enough to get rid of the velocity glitch near tend:

Alan

[ValeryOchkov]

Other solution (Euler Method?) this problem from http://festival.1september.ru/articles/103956/

[ValeryOchkov · Accepted solution]

This is similar to the use of alcohol - first bad, then good, then bad again:

[AlanStevens]

I'm somewhat lost as to where you are going with this Valery! Does this mean you are now able to program this problem succesfully in Prime (something you didn't manage earlier)?

Alan

[ValeryOchkov]

AlanStevens wrote:

I'm somewhat lost as to where you are going with this Valery!

I also

But one interesting problem...

For animation and for this group

http://communities.ptc.com/groups/dynamic-models-in-mathcad

too...

[ValeryOchkov]

One North Korean rocket

The first part of the rocket flight - is a virtual flight (h=0). The rocket is on the start platform and burns fuel (m.f) as long as its weight (m*g) becomes (10 9 8 7 6 5 4 3 2 1 Zero) equal its engine thrust (F)

[AlanStevens]

Valery Ochkov wrote:

O

The first part of the rocket flight - is a virtual flight (h=0). The rocket is on the start platform and burns fuel (m.f) as long as its weight (m*g) becomes (10 9 8 7 6 5 4 3 2 1 Zero) equal its engine thrust (F)

I don't think the calculation shows this. At the end of the calculated "virtual" flight there is a significant upward velocity! If the rocket stayed on the platform just burning fuel it would have a zero upward velocity at the point of take-off.

Alan

[ValeryOchkov]

Yes - no limit to improve calculation

Add h=g(h) and air resistance - with cloud functions!

[AlanStevens]

Can't say I'm a big fan of the "if" statements being used directly "in-line", within the solver. I think it is easier to understand if done as follows:

Alan

[ValeryOchkov]

The animation is here - http://communities.ptc.com/videos/3904