Yet another project

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Karl

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I want to get into paralel boosters on the sides of rockets so I've come up with a small design to add small stages on the side of a 3" rocket.
Heres the rocksim file but without the boosters.
It's a 4x 24mm cluster with 3x 18mm boosters in between each fin.
Karl
 

Karl

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A picture with one booster already attached.
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Karl

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A closeup of the booster. Thats aluminium foil on the top of the motor tube . The motor tube was cut on a angle to reduce as much drag as possible.
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Karl

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A closeup of the block of balsa & 7mm long peice of cocktail stick. A 3mm launch lug sits over the cocktail stick.
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Karl

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It would help if I posted the picture :rolleyes:
 

Karl

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The block of balsa.
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Karl

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The TTW fin tabs. The fins will be internal & outernal filleted.
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Karl

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My bad (again :()
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Karl

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Could someone please suggest a way of cutting the Centering Rings & the motor tubes holes in the middle?
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jerryb

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Originally posted by Karl
Could someone please suggest a way of cutting the Centering Rings & the motor tubes holes in the middle?
Karl
compass and hobby knife... thats the simpliest way do do it...

thats how I do mine

later
Jerryb
 

Karl

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She is nealy finished , and her weight is 19oz. I plan to fly her on Sunday on a mixture of 2x D12-0's and 2x E9-6's. I've done the math and all the motors togethor can lift upto 35oz. Im just wondering will she be stable after the D's have burnt out?
Thanks
Karl
 

jetra2

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Looks kewl. Clusters kick TOTAL butt!

You should be more than OK with that motor combo. Throw a couple of motors in the boosters if you have any doubts. C6's would be best.

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Karl

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Thanks! :cool:
Im planning on throwing some C6-0's in those boosters after her maiden voyage on either 4x D12-5's or E9-6's. Im just not sure how to ignite the boosters & the outboards at the same time.
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jetra2

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DMB Rocketry could make you a seven motor clip whip, or you could use a combonation of a 4 motor whip and a 3 motor whip. Of course, you'd use the 4 motor on the main motors and the 3 on the outboards. Just to give you a hint of what you can be expecting on liftoff, I've attached a picture of my most recent clustering endevour, 4 motors. I've don it before, but this is this rocket's most recent launch!

Mmm...smoke n' fire! :D

Jason
 

Karl

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Jetra, thats a awesome lift off pic! I've launched a 7x C6 cluster and that was awesome, apart from it spinning like crazy & totaling the rocket :( I like the thick smoke trails :D But I think its just going to go poof......SEEYA! It touches 2000ft on 2x D12-0's and 2x E9-6's! With those C's in the outboards and 4 E's shes gonna scream! Do you have a video of that flight Jetra2?
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jetra2

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I wish I had a vid! That was an awesome flight! It was a C6 and 3x A8-3, so it got back to 'normal' volume after the AMAZING liftoff, and then to top it all off, there was the A8's ejecting, making a starburst-like smoke cloud in the air, about 500 feet up! SWEET FLIGHT! It also landed about 60-70 yards away. Surprisingly close for such a powerful flight. (in LPR)

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vjp

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Originally posted by Karl
She is nealy finished , and her weight is 19oz. I plan to fly her on Sunday on a mixture of 2x D12-0's and 2x E9-6's.
...please tell me you're not really going to put -0's in a non-booster stage.
 

Karl

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Cool! Is that a scratch built rocket ? Did you use DBM's cluster cables to ignite your motors? And wat do you think would be bes wadding or a heatsheild?
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Karl

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Originally posted by vjp
...please tell me you're not really going to put -0's in a non-booster stage.
I was going to, just so I dont loose her on her first flight. :( Is this a good or bad idea?
Thanks
Karl
 

vjp

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-0's are only designed for one purpose, to ignite an upper stage. When the propellant burns through at the top, it sends hot chunks of burning debris upwards, which is what lights the upper stage. It also creates a pressure wave, which can eject a recovery system just like an ejection charge. So using a -0 in place of a regular motor will most likely pop the chutes just as your rocket is at its peak velocity. Not likely to be a good outcome.:(

If you're mixing different motor classes, use motors which will eject at about the same time. i.e., E9-6's and D12-5's. Oh and make sure the thrust distribution is axially symmetrical, i.e. put the D12's diagonally from each other and the E9's diagonally from each other. So you don't wind up with more thrust on one side of the rocket from the other.
 

vjp

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Sorry, an E9-6 will eject closer to a D12-7, not a D12-5.

The delay is from end of thrust; an E9 burns for about 3 seconds, vs. 1.65 seconds for a D12.

Likewise, E9-4's and D12-5's are a close match, as are C6-3's and B6-4's, C6-5's and B6-6's. C6's and D12's burn for about the same time, so matching delays work well for these two motor types.
 

Karl

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I was going to plug the D12-0's with epoxy. But keep them inside the rocket rather than them coming out. I want to get this baby back. A 3" rocket what hits 2000ft on a BP cluster of only 7 motors is pretty high if you ask me.
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vjp

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Originally posted by Karl
I was going to plug the D12-0's with epoxy. But keep them inside the rocket rather than them coming out. I want to get this baby back. A 3" rocket what hits 2000ft on a BP cluster of only 7 motors is pretty high if you ask me.
Karl
That should work too. Or find some D11-P's, a plugged motor that is just about identical to a D12.

FWIW, some RSO's might not like you flying with epoxy-plugged motors, so you might want to ask around discretely first.:D

But - why? Substituting -0 motors for ones with delays will make absolutely no difference to its top speed or altitude. So your reasoning behind using a -0 in place of a standard motor has me a little perplexed.
 

Karl

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Sorry about that. Im also wondering if the boosters will hold up on the side of the rocket , they are COATED with Araldite ( realy hard 2-part epoxy ) and they feel really solid. What type of guidence would you suggest, Rail or Rod? If it's a rod, what size?
Cheers
Karl
 

havoc821

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Youcan plug them with epoxy but make sure you put a LOT on there. I did the same thing and ended up exploding 2 of 3 outboards off the side of one of my vid cam rockets. Cool video though!:D
 

vjp

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Originally posted by Karl
Sorry about that. Im also wondering if the boosters will hold up on the side of the rocket , they are COATED with Araldite ( realy hard 2-part epoxy ) and they feel really solid. What type of guidence would you suggest, Rail or Rod? If it's a rod, what size?
Cheers
Karl
Plain yellow glue is fine on anything up to "F" and sometimes even beyond. How heavy will your rocket be? Up to a pound a 3/16" rod should be o.k., past that you ought to go 1/4".

BTW, on your CLUSTER.RKT design, I would put the forward launch lug a bit farther back on the BT. With the forward end about at the midpoint of the BT.
 

Karl

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This thing flew!!! :eek: And flew amazingly! I flew her on 4x E9-6's, didn't bother with the outboards because of a lack of Quickmatch. Chris from WRS made me a clip whip, wired her up and she was ready to go. Pressed the button, FUUUUUUUUUUUUFFFFFF, and she was gone! Way up to the best part of 2000ft, ejection was a bit late, I will try a -4 second delay next time. The 3.5ft 'chute deployed for perfect recovery. Landed in a neighbouring field.

I didn't think it would move that fast due to the weight but boy, she got up there, QUICK! Only a minor scorching to the bottom of each fin, and a small hole in the 'chute.
I loved the amount of smoke & fire, AWESOME! The 4x E's left a little present for the ground below :rolleyes: :D

If anyone has the parts to build one of these, BUILD ONE!! :D
Karl
 

Karl

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Chris took a video IIRC, and pics of me with the rocket. When I get hold of them I'll put them onto my FTP and give you guys the link :D
Karl
 
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