I55 Mellow, 9 sec delay?

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jrkennedy2

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Anyone know why the I55 Mellow (CTI) has only an 9 second delay grain? Is there just no room for more? My Madcow Areobee-Hi really does well on this one but ejects a bit early...

Thanks!
 
Anyone know why the I55 Mellow (CTI) has only an 9 second delay grain? Is there just no room for more? My Madcow Areobee-Hi really does well on this one but ejects a bit early...

Thanks!

You have to realize that different propellants may take an optimized delay formula also. There are only so many types that 'keep the fire' under the case pressures seen for that comp. One of the problems you have is the long burn syndrome which requires a slower burning delay to give you any time at all after burnout. Altho the I55 isn't listed as a long burn, the flame front propagation requires a different delay comp than say a Warp or Vmax. Like you, I'm caught between a rock and a hard spot with mellows not liking to lift a lot of mass, but needing a longer delay to optimize altitude. You may want to look into the smallest alt you can get with apogee deployment. My solution was an RRc2+ and lipo using just apogee deployment. Straight smoke and good chutes.
 
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Delay grains burn faster under pressure. The extra burn time of mellow motors probably means there is less delay grain left at burnout.
 
Long burn motors are the perfect excuse to get into electronics! Cram an RRC2 or SCF into that nose and enjoy the wonder that is apogee detection. Those two, in particular, are super easy to set up for this purpose. Simply wire your charge to the drogue terminals and launch, right out of the box.
 
Thank you all very much! Never considered pressure and it affecting the delay grain formula or at least burn profile. I can do an RRC2 or even a Quark. I was just being lazy as my dual deploy and other electronics style rigs takes a little more setup. I just get the giggles listening to that long burn on the Aerobee Hi flight after minimal setup time. I'm being lazy and just got caught...

:blush:
 
Why would you need longer than 9 second delay the motor has trouble getting off the pad. Upper stage min. dia. maybe a couple extra seconds.
 
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