# Help with a backup...

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#### Justin Horne

##### Well-Known Member
All right. We've been working on a Hawk Talon 3 for a while now. Its got the fiberglass version of the PML CPR 3k. It can fit one Co-pilot altimeter.. Not being one to like having just one altimeter, my dad had me figure out a way to put a backup in. After all, its an expensive rocket, and lots of pricey stuff aboard, and we dont want to lose it due to an altimeter failure!

So, I figured that the only place to put it in was in the nosecone (has a payload bay in it) . This eliminates a barrometric altimeter, and the only accelerometer ones I found are VERY expensive.. I found the Perfectflite minitimer. I think this will work well, but i have yet another problem! I would have to run the ematch wire all the way to the drogue compartment, through the CPR, which I can't... To have the timer fire into the main bay, the time delay wouldnt work. if i set it to fire at apogee, the main deplys at apogee... bad.. if I time it so it fires at a lower altitude, in the event of the main electronics failing, this would deploy the main a few feet below the ground...

All help would be very much appreciated..Thanks..

#### n3tjm

##### Papa Elf
This is how I do my dual deploys. The paiyload section is the main, and the section above the motor is the drouge. That way the motor ejection can act as the back up for the drouge... but
a timer for the main... you will need to know how long it will take to get to your deployment alt...

My advice... get a G-WIZ Deluxe 800 or similar altimeter which uses accelleromet. $150 which is not bad... actually... I would use that as a main altimeter... and the cheaper one as backup (lie the$65 Transolve PK alt), but I guess that will not solve this problem...

food for thought...

#### Justin Horne

##### Well-Known Member
I agree with you. Im not that much of a fan of the co-pilot vs any other altimeter... Id rather use a G-wiz or an RRCs (just cheaper than co-pilot) but I can get the darn thing to physicly fit in the CPR system.. Right now we are looking at buying fiberglass tubing and making regualr altimeter bay..