How To Mount FireFly

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4 months 2 weeks ago #11880 by Poppie1
How To Mount FireFly was created by Poppie1
I just bought a FireFly altimeter for my WATER ROCKET.

My available (so-to-speak) Payload space is 4" diameter cylinder by about 7" long (more than enough space)

 How do I make a "holder" for the FireFly such that
I can glue the holder to the inside of the 'cylinder' ? ?

I know I have to make holes in the Payload area for atmospheric pressure.  I assume 4 holes at 0.101" diameter 

I hope to be at the October 28th Launch to try out the altimeter

Those of you that currently use the FireFly altimeter, if you have a moment, please stop by to see me and maybe show me how to use it and interpret the beeps....I have the manual, but someone right there to show me would be really appreciated. 
Thanks Dick

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4 months 2 weeks ago #11881 by hermanjc
Replied by hermanjc on topic How To Mount FireFly
I have also built and launched water rockets, and it's a lot of fun! If you haven't already, check out www.aircommandrockets.com

Their website (and their YouTube channel) are a fantastic resource for all things water rocket from beginner through to extreme advanced.

This link has a tutorial on a parachute deployment mechanism, but the structure for it would adjust be great for an electronics bay.
www.aircommandrockets.com/construction_7.htm

Good luck and hope this helps!

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4 months 2 weeks ago #11891 by hgreenblatt
Replied by hgreenblatt on topic How To Mount FireFly
The firefly is a nice little altimeter that most of the TARC teams use for the TARC competition .
I have seen them mounted in many different ways in many different parts of the rocket - the nose cone, most typically a standard payload section and even seen them mounted in the booster next to the engine (which I would definitely not recommend)! 

To mount them in the payload section, which it sounds like you have (4" dia x 7" long), I have seen them simply taped to the side of the payload bay (not recommended), but a design I like is to get a small section of BT20 body tube which is aprox 0.7" inner diameter (or something similar) maybe an inch and a half or so long and that gets glued to the inside of the payload bay so it does not interfere with the shoulder of the nose cone or coupler below. The top of the little inner tube should be easily accessible by removing the nose cone. Cut some balsa to fit the base of the inner tube and glue it in the bottom. Then cut another section of balsa (or a plastic nose cone or coupler plug will also work great) that can plug up the top. It needs to be tight enough so the altimeter can't fall or get bumped out. Then you can drill a pressure equalization hole thru the side of the payload bay and into the smaller Firefly holder tube. A single 3/32" dia hole should be fine. Just make sure it does not line up with any lugs or anything that would interfere with the airflow over the side of the rocket. Finally you can use some packing foam (or similar) on the top and bottom of the altimeter to sandwich it and keep it from moving around in the tube. Just don't smother it which might interfere with the barometric sensor. 

Let me know if you need more clarification or a picture or something. 

- H

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4 months 2 weeks ago #11892 by Poppie1
Replied by Poppie1 on topic How To Mount FireFly
WOW.....thank you for such a detailed reply. I just made this sketch.
Does it reflect the basic idea of your suggestion? 
Rich
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4 months 2 weeks ago #11894 by hgreenblatt
Replied by hgreenblatt on topic How To Mount FireFly
Yes - exactly.  You could also just drill a hole directly thru the body tube and into the inner tube, where you have your glue arrow. That would give you quicker air compensation. But I think your design should be fine. Anyone else care to weigh in?

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4 months 2 weeks ago #11898 by Poppie1
Replied by Poppie1 on topic How To Mount FireFly
Thanks for the confirmation and suggestion.
i'm on vacation now and will miss the this weekends launch.

I hope to make the Oct 28th launch and hope to have the firefly mounted.

Again, if those that use firefly altimiters could stop by on the 28th to say hi and take a look at my mounting for comments you may have, I'd appreciate it.

Could someone reply back with a PHOTO or two of what your BT20 altimeter looks like

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