Loc black brandt 4 inch baffle system

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Scott Nokes

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Hi everyone, I'm building the loc BBX 4 inch kit and those is my first with the baffle system. The instructions are to clear and the coupler the pressure gives go in I lined with the LocStiffy tone supplied because of the pressure build up. Ifs that the correct thing to do, I've attached a rough sketch what I did
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heada

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It wont hurt the baffle to use the stiffy tube but it shouldn't be needed. The pressure inside the baffle should be the same as anywhere else inside the body tube. I skipped the baffle on mine since I wont be using motor ejection on it ever. The only time I've used the stiffy coupler is in an av-bay.
 

Scott Nokes

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Ok thank you,
I also can't make out, should the forward tube have a centering ring, because in the instructions, it shows attaching the shock cord direct to the nose, but then it shows a centering ring with a eye bolt in the middle which was not in my kit as off it goes at the bar of the forward tube
 

Scott Nokes

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Ok thank you,
I also can't make out, should the forward tube have a centering ring, because in the instructions, it shows attaching the shock cord direct to the nose, but then it shows a centering ring with a eye bolt in the middle which was not in my kit as off it goes at the bar of the forward tube
 

heada

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The baffle in my 4" kit has the normal coupler, 2 bulk-head plates (1 with a hole for the eye bolt that goes forward, one without that goes aft) and the 2 short sections of tube. If you use the stiffy coupler it goes inside the normal coupler and between the 2 bulk-heads.

There are 3 centering rings in the kit, aft. mid and forward and all 3 should be glued to the motor mount tube. The forward ring has no slots for fins and has the hole for the eye bolt. If you don't install the baffle, you would attach the shock cord to the eye bolt in the forward ring. If you install the baffle, you would attach the shock cord to the baffle instead of the forward centering ring. In both configurations, the forward attachment point is the nosecone. In other words, the shock cord goes between the nosecone and the forward centering ring -or- the nosecone and the baffle.
 

Scott Nokes

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Thank you so much, I'm doing it correct then. One more quick question, instead of expoxying the body tube, I would like to screw the tubes together for ease of moving. How and what do I use to do this
 

heada

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That will depend on how you'd like to do that and there are almost as many ways to do it as there are rocket designs.

I use nylon M2 screws (sometimes 2-56 screws, depending on what I have more of at the time) as sheer pins between sections that I want to come apart like the nosecone and the aft section of body tube below the av-bay. For sections I want to stay together during flight but be removable like forward of the av-bay, I drill into a bulk head and epoxy in a short section of steel tubing. I then tap that tubing for M2 and use steel M2 screws. The ejection charge will sheer the nylon M2 screws and those joints will open up, The steel screws that are screwed into tapped steel tubing will not sheer.
 

Scott Nokes

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The baffle in my 4" kit has the normal coupler, 2 bulk-head plates (1 with a hole for the eye bolt that goes forward, one without that goes aft) and the 2 short sections of tube. If you use the stiffy coupler it goes inside the normal coupler and between the 2 bulk-heads.

There are 3 centering rings in the kit, aft. mid and forward and all 3 should be glued to the motor mount tube. The forward ring has no slots for fins and has the hole for the eye bolt. If you don't install the baffle, you would attach the shock cord to the eye bolt in the forward ring. If you install the baffle, you would attach the shock cord to the baffle instead of the forward centering ring. In both configurations, the forward attachment point is the nosecone. In other words, the shock cord goes between the nosecone and the forward centering ring -or- the nosecone and the baffle.


So what stops there parachute and shock cord sliding back or does it test on to of the baffle
 

heada

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In my configuration, I have a drogue between the motor mount and a central av-bay and the main between the av-bay and the nose cone. When the apogee event fires from the av-bay, the aft section comes off after sheering the nylon screws and the drogue deploys. Then at the selected altitude, the main event fires and the nose cone separates and pulls the main out. In both cases the parachutes are allowed to move forward or aft and the ejection charges are sized so that the parachute and shock cord are fully ejected but not so hard as to snap the shock cord tight.

For you, there would only be a main parachute and it could move as well. You would need to ensure the motor ejection had enough force to fully eject the parachute and shock cord.
 

Scott Nokes

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In my configuration, I have a drogue between the motor mount and a central av-bay and the main between the av-bay and the nose cone. When the apogee event fires from the av-bay, the aft section comes off after sheering the nylon screws and the drogue deploys. Then at the selected altitude, the main event fires and the nose cone separates and pulls the main out. In both cases the parachutes are allowed to move forward or aft and the ejection charges are sized so that the parachute and shock cord are fully ejected but not so hard as to snap the shock cord tight.

For you, there would only be a main parachute and it could move as well. You would need to ensure the motor ejection had enough force to fully eject the parachute and shock cord.


Ok, should I make a forward ring with a large home just to act as stop for the parachute and kevlar sliding back and forth to much
 

Scott Nokes

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So if I do dual deployment like yours, I would need too make a bulkhead to separate the sections, it's that correct
 

Scott Nokes

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Mmm, so between the baffle system in the booster and the nose cone, I have no more separation just straight through. Does the baffle system not get glued in
 

heada

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Aft tube with fins, coupler, 1st middle tube, baffle that acts as coupler and could be a break point, 2nd middle tube with the forward fins, coupler, forward tube and then nosecone. In your configuration the recovery gear is between the baffle and nosecone so only 2 tube lengths but the ejection from the motor will need to pressurize all the tubes, from the forward centering ring up through the baffle all the way to the nosecone.
 

Scott Nokes

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Thanks so much for your help, I appreciate it. The loc instructions make it sound to epoxy half the baffle into the booster tube
 

heada

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That would be the break point I listed above and if I were using the baffle, that's what I would do. It'd make it a zipperless design.
 

Scott Nokes

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Ok, so don't epoxy the baffle as described, maybe just use some of those plastic shear screws to join the tube, could you show me some pictures of this please
Could I put a plain centering ring in there coupler of the front tube and have a drogue cut there and the main in the compartment below which would be the center tube
 

cbrarick

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I'm always baffled by the use of baffles, to me it's unnecessary complexity.
However, to each his or her own.
Two words of advice: Ground Test
 

DragonRocketry

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This is how I am building a 4 in BBX. The booster has a coupler with a bulkhead and u bolt, this is where it will separate for the drogue. Above the small fins I have an electronics bay to control deployment. I do not use motor ejection.

bbx 4in.jpg
 

heada

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If you use the baffle, epoxy it into the aft body tubes but not the forward body tubes. Then use sheer pins to hold it together.

Since I'm not using the baffle and using an av-bay, my pictures won't help as much. I'll see if I can do some quick sketch to help explain.

And yes, ground test is a must.
 

Scott Nokes

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Mmm ,I don't know why or what, but I'm missing something here. If I glued the baffle in to the front of the body tube, I have the eye bolt but then the rocket it's open all the way to the nose cone. That's why I thought the shoulder be another centering ring somewhere along the length to create the two compartments
 

Scott Nokes

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I was wondering, the kit supplied one length of shock cord. 25ft. Does anyone know how loc expect me to use it between the booster and the drogue chute and then from the payload bay and it's parachute
 

DragonRocketry

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The drawing I posted is not a loc kit, just my design on how I am building one.
 

C.O.B.H.C.

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Here how I'll be setting my BBX I just ordered. I'll be using a longer motor tube as the stock one is too short, not using the baffle system, adding a 54mm Aeropack motor retainer, add a LOC av-bay, and glassing the airframe. The drogue tether will be 60 feet of 9/16" Blue Water Tubular Nylon, and the main tether will be 40 feet of 9/16" Blue Water Tubular Nylon. Main parachute is going to be either a Top Flight 90" X-Form or a Sky Angles Classic II 60".
 

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Scott Nokes

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Thank you everyone for all your help. Although I've already glued the baffle coupler in place, I've decided I won't use it and any motors I use, I will not put an ejection charge and use an ejection charge with an altimeter.
An I right in saying the avionics bat wolff be there central tube with the canard find and the payload is the front tube would I put my parachute in the front payload tube and the electronics nasty in the tube section below were the little canards are
 
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C.O.B.H.C.

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Thank you everyone for all your help. Although I've already glued the baffle coupler in place, I've decided I won't use it and any motors I use, I will not put an ejection charge and use an ejection charge with an altimeter.
An I right in saying the avionics bat wolff be there central tube with the canard find and the payload is the front tube would I put my parachute in the front payload tube and the electronics nasty in the tube section below were the little canards are
You would put the av-bay in the coupler above the canard fins. LOC Precision sells av-bay kits which is what I use on all my LOC Kits.
 
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