Hi guys

I got a couple of question relating to a project I want to work on:

• What's the effect of vibration on electronics components/PCB/design, in the environment of a little rocket, launch from a 35 liter Avalancher at 300psi, with a top speed of 300m/s. (temp is under -20 degree C up in a mountain)
  
• Are common components I get from usually distributor environment friendly? or any info relating to environment friendly components please.

Thanks guys, any info/links/related research etc. is appreciated.

 

As for viberation, most electronic components have no problem with viberation. However you can use mini suspensions (such as rubber pads etc.) with your PCB mounting to redudece viberation a little bit.
But, -20degree might cause problem. You have to study the components datasheets in order to determine the minimum working temperature for the components.

 

Most normal ICs have a "Mil Spec" equivalent. Those military (mil) specification parts are slightly higher priced, but made for the environment you talking about. Part numbers that start with 74, the mil spec starts with 54. Google for 'mil spec' plus the part you are using.

 

Most normal ICs have a "Mil Spec" equivalent. Those military (mil) specification parts are slightly higher priced, but made for the environment you talking about. Part numbers that start with 74, the mil spec starts with 54. Google for 'mil spec' plus the part you are using.

I am worried that the xtal oscillator will be killed by the acceleration at launch, should I be worried about that?

 

I don't have the experience to tell you about that. Maybe some one else will answer. Or a Google search will tell you.

 

I am worried that the xtal oscillator will be killed by the acceleration at launch, should I be worried about that?

Hmm if you are worried about that then maybe you can try using the internal clock or an external non crystal oscillator .
Or as mentioned above , try isolating your PCB with silicon/rubber pads

 

I suggest googling for some charts, something like "my rocket accelerometer data chart" might get some results.

Lots of hobby rocket people put accelerometers in their rockets and put their results on the internet. That should show you roughly what level of G forces to expect.

 

Haha, I once rigged up a model rocket engine as a home-brewed bottle rocket, with all sorts of cherry bombs and whatnot on top. The engine took off so fast that everything was left behind at the launch pad! And yes, the payload still lit.

 

Hmm if you are worried about that then maybe you can try using the internal clock or an external non crystal oscillator .
Or as mentioned above , try isolating your PCB with silicon/rubber pads

I am concerned that the internal clock won't have the accuracy I want. I am hoping to have +/- 10ms accuracy.

I am at my researching stage now, but when I actually test, I will definitely try isolating the PCB with silicon/rubber pads etc..

 

I suggest googling for some charts, something like "my rocket accelerometer data chart" might get some results.

Lots of hobby rocket people put accelerometers in their rockets and put their results on the internet. That should show you roughly what level of G forces to expect.

That's a good idea, that's what I have come up with from here:

And i digged a bit and found some info, and it lead me to think I may be able to estimate the acceleration:

The tail comes off at 44m/s, it's about 10-15m from launch, so can I estimate the acceleration is about:
when s= 10m:
S=(at^2)/2 => s=(V(t)*t)/2 => 10m=(44m/s * t )/2 => t =450mS
V(t)=at => 44m/s = a * 450ms => 97m/s^2
when s=15m: a ~=65m/s^2

Does it make sense?

If my estimation is somewhat reasonable, will 100m/s kill a xtal oscillator?

 

I don't think 10g is much of a concern, but take a look here or here.

 

I don't think 10g is much of a concern, but take a look here or here.

Thanks wayneh, I think I will need some time to understand the info you provide, but those are helpful, thanks a lot.