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Old 11-02-2015, 02:42 PM
Roscoe1951 Roscoe1951 is offline
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Default Two-stage booster damage

I'm pretty new to this hobby and yesterday launched my first 2-stage rocket an Estes Express. I used a D12-0 in the booster and a C11-5 in the second stage. The rocket flew well, the separation was clean and the chute deployed. The only problem was that after separation the booster came straight down, nose first and augered into the ground about 30 feet from the launch pad. The front of the tube was chewed up, a fin broke loose, and the tube buckled just forward of the rear centering ring. Is this normal? Shouldn't the booster have tumbled to lessen the impact?
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Old 11-02-2015, 03:34 PM
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Doug Sams Doug Sams is offline
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Originally Posted by Roscoe1951
I'm pretty new to this hobby and yesterday launched my first 2-stage rocket an Estes Express. I used a D12-0 in the booster and a C11-5 in the second stage. The rocket flew well, the separation was clean and the chute deployed. The only problem was that after separation the booster came straight down, nose first and augered into the ground about 30 feet from the launch pad. The front of the tube was chewed up, a fin broke loose, and the tube buckled just forward of the rear centering ring. Is this normal? Shouldn't the booster have tumbled to lessen the impact?
To be clear, CC Express? I've never flown one of these (but have flown many, many BP stagers). Eye-balling the booster, it looks like it ought to tumble. The common causes for not tumbling are that there's too much weight forward in the booster stage, or the fins are mounted too far aft.

If you used an extra long coupler, that could have shifted the weight too far forward.

With many kits, the stock position of the booster fins can cause lawn darting, but this isn't one of the kits I associate with that. The fins don't look too far aft in the catalog pics I've seen.

Anyway, sorry to hear your booster got buggered, but, if you repair or replace it, consider keeping the coupler short and the fins forward.

Also, one other thought, sometimes the weight of the motor keeps the booster unstable and makes it tumble. If yours spit its motor, that may have left the booster stable and caused it to augur in . So try putting a dab of tape on the booster motor to help it stay friction-fit into the tube.

Doug

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Old 11-03-2015, 12:17 PM
Roscoe1951 Roscoe1951 is offline
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Hi Doug, thanks for your quick response. The rocket is the CC Express. I didn't use a coupler but taped together the 2 engines. The fins on the booster were mounted with the rear edge of the fin even with the rear of the booster's body tube, as per the instructions. I will need to rebuild the booster. Would it be better to mount the fins so that the leading edge of the fin is even with the front of the booster's body tube? Also, both engines remained in the 2 stages. Best regards, Mike
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Old 11-03-2015, 02:20 PM
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Doug Sams Doug Sams is offline
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Quote:
Originally Posted by Roscoe1951
Hi Doug, thanks for your quick response. The rocket is the CC Express. I didn't use a coupler but taped together the 2 engines. The fins on the booster were mounted with the rear edge of the fin even with the rear of the booster's body tube, as per the instructions. I will need to rebuild the booster. Would it be better to mount the fins so that the leading edge of the fin is even with the front of the booster's body tube? Also, both engines remained in the 2 stages. Best regards, Mike
Hi, Mike,

Not sure exactly where, but I would definitely move them forward. My first instinct is to position them about midway along the length of the outer booster tube. If you add a coupler, then move the fins about another 1/4" forward.

Doug

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Old 11-03-2015, 03:07 PM
samb samb is offline
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Quote:
Originally Posted by Roscoe1951
Hi Doug, thanks for your quick response. The rocket is the CC Express. I didn't use a coupler but taped together the 2 engines. The fins on the booster were mounted with the rear edge of the fin even with the rear of the booster's body tube, as per the instructions. I will need to rebuild the booster. Would it be better to mount the fins so that the leading edge of the fin is even with the front of the booster's body tube? Also, both engines remained in the 2 stages. Best regards, Mike


You could also try locating the booster fins using this old school method from the Estes TR-2 white paper. I'll bet it comes pretty close to Doug's "that looks about right" placement.

http://www2.estesrockets.com/pdf/28...ction_TR-TN.pdf
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Old 11-03-2015, 05:39 PM
Roscoe1951 Roscoe1951 is offline
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Thanks, I'll give it a try.
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Old 11-03-2015, 07:06 PM
samb samb is offline
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Just something to consider as you rebuild the booster. And just to be clear, Doug Sams is one of the best designers and modelers that I know. I'd match his calibrated eyeballs to any sim program no question.
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