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Scrap Heap
#1
Thought I would share a project I am considering that uses some scrap material including remains of other rockets. The only thing I need are a couple centering rings. The idea was to come up with a single deploy 29mm rocket that can go a mile high yet stay under mach 1 since it is cardboard and plywood.

I settled in on a design that has 7.5 oz. of weight in the nose that moves the CG very far forward. In so doing, I can minimize fin size and let the CP move forward as well. At the same time, the CD is reduced to 0.42. Not bad for a 2.26" dia. rocket.

The added weight in the nose cone should also add stability so that a camera mounted in the payload bay would not shake as much. It would be horizontally aligned as opposed to pointing down.

It would use a 14" chute so it would come down pretty fast, and I think I would configure it so that the nose cone would hit the ground first so the airframe, which is more fragile could slow down a little before it hits the ground. Ground hit velocity of the nose cone would be about 30 mph. A plastic nose should survive that. The charge in the motor would deploy the chute. It would need maximum delay for both the I224 and the I243.

Structurally, a 3rd centering ring located at the forward end of the motor mount should strengthen the airframe by creating additional support from the motor tube. Someone had mentioned painting the bodytube with CA. I would be interested in knowing how this is done since that glue dries so fast. I need to do something since it will be going transonic for over a second.

It would have a small altimeter for measurement purposes only and would also have a tracker in it as well since it would probably disappear off the pad.

Curious to know what people think.

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Evan Brown
NAR# 92851
Level 2
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#2
I am thinking that rocket designed for a 30mph descent speed violates a safety code somewhere.  I would design for <20ft/s if you are going to fly where there are people, cars or planes on the ground Wink
John Derimiggio
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#3
20 ft./sec is 13 mph. Seems a little slow. I don't get warnings at 30 mph, but I could keep it closer to 20, which is 29 ft./sec.
Evan Brown
NAR# 92851
Level 2
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#4
Probably ok but 20 ft/s is the NAR recommended limit for safe recovery.  It is not mandated in the safety code but you will have to get it past the MARS Safety check person.  We had a fast descending 'light' rocket cause 5 figure property damage and are a little sensitive about such things.
John Derimiggio
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#5
I understand.
Evan Brown
NAR# 92851
Level 2
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#6
ebrown,
Just out of curiosity, what software are you using??

Thanks,
Ken Kressler
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#7
Open Rocket. It is a free download. I am a little less confident of the speed and altitude calculations, but everything else is pretty good.
Evan Brown
NAR# 92851
Level 2
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#8
there is also Rocksim from apogee, it has a lot of support but it is not free.
Bill Clune L2 | NAR#88583
MARS Club|SRC|METRA|MDRA - Forever
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#9
Cool I guess that I got to have the rocket sim from Apogee. Just one thing more do any of you guys have this Apogee's RockSim?? I wondered if this is true regarding to Apogee's RockSim crashes, do any of you ever had software crashes?? I don't want to wind up couple of gremlins in my laptop.

Thanks,
Ken Kressler
NAR#94955
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#10
I'm thinking of buying RocSim as I get into my L3 project...timing is still flexible on that. It has a lot more features that Open Rocket.
Evan Brown
NAR# 92851
Level 2
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