CTI H125 - Wrong Delay

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SpaceManMat
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CTI H125 - Wrong Delay

Postby SpaceManMat » Thu Jul 23, 2020 9:49 pm

I flew the Night Fury (caliber ISP) at QRS this month. Was great to get a flight in after being grounded.

Anyway, did all the usual stuff in Open Rocket and came up with a 9 second delay for a CTI 266H125-12 so drilled out 3 seconds using the delay adjustment tool. All looked, but apogee came and went.. and eventually the chute deployed. Thought to myself I must have done something wrong somewhere. My son came back with the rocket missing the nose cone, so we went for a walk to where I thought it deployed, giving a bit of allowance for the wind, found it probably 30m from where I thought it ought to be. It had snapped the plastic tab but otherwise no damage to the rocket.

Took everything back home and dumped the flight log (altimeter was doing logging only) and the simulated apogee was fine, 9 sec would have been perfect. The actual delay was about 14.6 seconds, so getting close to 5 seconds longer than it should of.

2020-07-12 Night Furry H215.png


I filed a mess report, the reload was dated Aug 20 2013. I am guessing they have shipped the wrong delay with the reload. Any one have any other thoughts about what could have gone wrong?
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing

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OverTheTop
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Re: CTI H125 - Wrong Delay

Postby OverTheTop » Fri Jul 24, 2020 12:20 pm

Did you perhaps get any grease on the internal face of the delay grain? I have heard that this can slow the delay grain down.
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SpaceManMat
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Re: CTI H125 - Wrong Delay

Postby SpaceManMat » Sat Jul 25, 2020 7:31 pm

OverTheTop wrote:Did you perhaps get any grease on the internal face of the delay grain? I have heard that this can slow the delay grain down.


I can’t entirely rule it out as it was quite difficult to get it in the case. However I can’t see how grease would have gotten into the drilled out hole. I could understand maybe a tiny film getting on the face, but it’s the time to burn the material from the bottom of the hole to the powder that determines the delay.
QRS: 124
AMRS: 32 L2 RSO
Highest Altitude: 13,647 feet
Fastest Flight: Mach 1.55
Largest Motor: CTI 1115J530 IM
Current Project: X Wing


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