First dual deploy rocket

I'm attempting a dual deploy rocket for my L2 certification. I chose a LOC Fantom EXL for my attempt since others have had success with it and it comes complete, or as complete as a kit can get. Had some questions though (I wrote to LOC, didn't get a response). Better to ask a dumb question than make a dumb mistake:

1. The coupler is significantly longer than the stiffy tube coupler (by 2.5"). The longer coupler doesn't really concern me, just means the wood end plates will be recessed 1" on each side; however, the instructions said to center the stiffy coupler within the coupler which allows for the end plates to extend 1/32" beyond each end for strength. So, do I need to trim the coupler by 2.125" or just leave as is?
2. The lugs that mount on the sled are too long for the stiffy tube coupler (lugs are 0.5" longer than the stiffy tube coupler). The obvious solution to me is trim each lug by 0.5" so they are flush with the top of the stiffy coupler and will wedge perfectly between the wood end plates. Is this how it should fit?
3. When measuring for my motor retainer, it says I need a minimum of 0.375". Problem is that the instructions say the centering ring is suppose to be 0.125". The slots are 0.5" from the end of the body tube and the centering rings are 0.25" thick. To me, cutting the fin slot 0.125" longer is the easiest approach since I don't have to modify the fin tab and raising the fins 0.125" towards the nose cone has minimal changes to margin of stability.

I have a list of other mods I am doing (tubular nylon instead of supplied shock cords, rail buttons instead of the supplied launch lugs, and a X-form parachute for my drogue), so I don't mind modifying my rockets. I appreciate the feedback.

Performance nut said:

I'm attempting a dual deploy rocket for my L2 certification. I chose a LOC Fantom EXL for my attempt since others have had success with it and it comes complete, or as complete as a kit can get. Had some questions though (I wrote to LOC, didn't get a response). Better to ask a dumb question than make a dumb mistake:

1. The coupler is significantly longer than the stiffy tube coupler (by 2.5"). The longer coupler doesn't really concern me, just means the wood end plates will be recessed 1" on each side; however, the instructions said to center the stiffy coupler within the coupler which allows for the end plates to extend 1/32" beyond each end for strength. So, do I need to trim the coupler by 2.125" or just leave as is?
2. The lugs that mount on the sled are too long for the stiffy tube coupler (lugs are 0.5" longer than the stiffy tube coupler). The obvious solution to me is trim each lug by 0.5" so they are flush with the top of the stiffy coupler and will wedge perfectly between the wood end plates. Is this how it should fit?
3. When measuring for my motor retainer, it says I need a minimum of 0.375". Problem is that the instructions say the centering ring is suppose to be 0.125". The slots are 0.5" from the end of the body tube and the centering rings are 0.25" thick. To me, cutting the fin slot 0.125" longer is the easiest approach since I don't have to modify the fin tab and raising the fins 0.125" towards the nose cone has minimal changes to margin of stability.

I have a list of other mods I am doing (tubular nylon instead of supplied shock cords, rail buttons instead of the supplied launch lugs, and a X-form parachute for my drogue), so I don't mind modifying my rockets. I appreciate the feedback.

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Measure the length of your stuffy tube, coupler, and sled tubes. I'll check them against mine and see where your parts are off at. I just built the Fantom last week, haven't done anything to the Av Bay except stick parts in there and screw together. Won't take anything to take apart and measure.

Davidtmp said:

Measure the length of your stuffy tube, coupler, and sled tubes. I'll check them against mine and see where your parts are off at. I just built the Fantom last week, haven't done anything to the Av Bay except stick parts in there and screw together. Won't take anything to take apart and measure.

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coupler: 8"
stiffy coupler: 5.5"
sled tubes: 6"

Performance nut said:

coupler: 8"
stiffy coupler: 5.5"
sled tubes: 6"

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My coupler tube is only 6". Everything fits together like it should. Seems like you may have gotten an extra 2" of coupler. Not sure if this is related to anything happening or not, I know you like to have the couplers twice the diameter, but not sure you'd want an av bay recessed like that either.

Davidtmp said:

My coupler tube is only 6". Everything fits together like it should. Seems like you may have gotten an extra 2" of coupler. Not sure if this is related to anything happening or not, I know you like to have the couplers twice the diameter, but not sure you'd want an av bay recessed like that either.

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Seems the downside is that it is "inconvenient" because I have to stick my hand further into the coupler to mount my sled and tighten everything up.

1. I built a LOC Fantom last year, and finally flew it last weekend. My av-bay bulkheads are flush with the ends of the coupler tube, the stiffy should only be shorter than your coupler tube enough for the bulkheads to sit flush. You must have been shipped the wrong tube. It happens..... I would not want my bulkheads recessed, the separation charges will exert force on the extended ends of the tubes and could cause bad problems. Not something to take a chance with.

2. Trim the tubes if they are too long.

3. I first attached an Aeropack centering ring to my motor tube along with the rear centering ring, that way I ensure the motor tube is properly mounted into the Aeropack and touching the rear centering ring at the same time. Once the JB Weld cures, I put on the front centering ring (loose, not attached yet) and then put the motor tube in the body tube. Then I tack in the fins with 5 or 30 minute epoxy (30 is stronger) and once all three fins have the epoxy set up I cut the tabs in back of the fins and slide the whole fin can out. Then I can apply decent internal fillets to the fin root/MMT joint, and also epoxy on the front centering ring. I use Aeropoxy 6209 structural epoxy for this. After the epoxy is cured, I apply a ring of epoxy in the body tube an inch or so behind where the front centering ring will sit, then I slide in the completed fin assembly. Then after that cures, I apply the fin fillets.

Good luck, great kit, it was my first deploy flight and it performed awesome on an I435 Blue Thunder. It reached 2983' in a hurry. Good thing I didn't blink or I would have missed it.

neond7 said:

3. I first attached an Aeropack centering ring to my motor tube along with the rear centering ring, that way I ensure the motor tube is properly mounted into the Aeropack and touching the rear centering ring at the same time. Once the JB Weld cures, I put on the front centering ring (loose, not attached yet) and then put the motor tube in the body tube. Then I tack in the fins with 5 or 30 minute epoxy (30 is stronger) and once all three fins have the epoxy set up I cut the tabs in back of the fins and slide the whole fin can out. Then I can apply decent internal fillets to the fin root/MMT joint, and also epoxy on the front centering ring. I use Aeropoxy 6209 structural epoxy for this. After the epoxy is cured, I apply a ring of epoxy in the body tube an inch or so behind where the front centering ring will sit, then I slide in the completed fin assembly. Then after that cures, I apply the fin fillets.

Good luck, great kit, it was my first deploy flight and it performed awesome on an I435 Blue Thunder. It reached 2983' in a hurry. Good thing I didn't blink or I would have missed it.

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So did you mount the Aeropack per instructions (0.375") or did you use less MMT to mount the retainer? I dont see how you can get the fins on in their design position without either trimming the body tube or trimming the fin tabs.

Performance nut said:

So did you mount the Aeropack per instructions (0.375") or did you use less MMT to mount the retainer? I dont see how you can get the fins on in their design position without either trimming the body tube or trimming the fin tabs.

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I trimed the fin tabs just a little bit off the rear to get that rear ring in a little farther, to give room for the aeropack to go on fully. I cut maybe 1/8" off and test fit. I removed the rear centering ring till after I did my internal fillets, then glued it in, then the Aeropack. No issues whatsoever, flew great on an H238 on Sunday.

Performance nut said:

So did you mount the Aeropack per instructions (0.375") or did you use less MMT to mount the retainer? I dont see how you can get the fins on in their design position without either trimming the body tube or trimming the fin tabs.

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You could move the centering rings up the motor tube. If the motor tube is too short to do this, I would just get another tube and save the current one for another build. Just what I'd do if I was in your shoes.

Hope this makes sense.

Davidtmp said:

I trimed the fin tabs just a little bit off the rear to get that rear ring in a little farther, to give room for the aeropack to go on fully. I cut maybe 1/8" off and test fit. I removed the rear centering ring till after I did my internal fillets, then glued it in, then the Aeropack. No issues whatsoever, flew great on an H238 on Sunday.

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This was similar to what I was planning. I figured the fins would hold the MMT center while I applied fillets, put a ring of epoxy just aft of the fin tabs, and then install the centering ring and retainer.

Only difference is I'm leaning more towards cutting the tube vs the fins. Either way I don't think will impact the rocket much, cutting tubes is easier for me than cutting wood. I have various hobby knives that should make cutting the tube easy, I don't have many wood working tools that are exact enough to cut the fin tab.

Good luck with your L2. If this is your first DD, do you have your FFFG black powder, or know where to get it? My first DD, the powder was hard to find initially for me. The best place might be at a launch. Are you planning on using shear pins on the nose cone? I would strongly recommend ground testing that 1. your booster section separates without blowing the nose cone, and 2. your nosecone charge then separates nosecone. I would recommend shear pins, but not everyone uses them. I didn't my first time, used too much powder, and blew the main and drogue at apogee. Had a bit of a walk! Best of luck.

Chris

FFFF powder should be easy to find out here, there are a lot of front load rifle guys out here. Spoke to some of the rocket guys out here about it, they said it isn't that hard to find.

As far as shear pins, haven't considered them. I'm new to DD, so I'm still learning what will be needed. So far I have the LOC e-bay, deployment charge tubes with wire (picked them up from Wildman), and swivels for the drogue and main. Adept just stopped selling the Adept22, which was my first choice altimeter. Considering the DDCS2 now. Any additional hardware, I haven't purchased and not knowledgable on their uses.

Performance nut said:

FFFF powder should be easy to find out here, there are a lot of front load rifle guys out here. Spoke to some of the rocket guys out here about it, they said it isn't that hard to find.

As far as shear pins, haven't considered them. I'm new to DD, so I'm still learning what will be needed. So far I have the LOC e-bay, deployment charge tubes with wire (picked them up from Wildman), and swivels for the drogue and main. Adept just stopped selling the Adept22, which was my first choice altimeter. Considering the DDCS2 now. Any additional hardware, I haven't purchased and not knowledgable on their uses.

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I built the LOC ebay for my LOC IV. I attached the payload tube (probably most likely for your main chute) with removable rivets. This allows for easy access to the bulkheads for preparing your charges. A lot of people use the charge tubes from Wildman. Be careful how you mount them and how much powder you put in them. Someone told me to just tape them sideways on my bulkhead. I did a ground test on my 4 inch LOC IV and it blew a hole right through the side. I would get some suggestions on how to use them in your rocket. I don't think I put too much charge in (1.8 g). Also, the LOC kits are pretty light. Be careful to not make your drogue to big, or it will act like a parachute and your rocket will drift aways. I use a MissileWorks RRC2 mini. An RRC3 is coming out in the next month that is all over this forum. I am going to get one. Best of luck.

Chris

4kids49 said:

I built the LOC ebay for my LOC IV. I attached the payload tube (probably most likely for your main chute) with removable rivets. This allows for easy access to the bulkheads for preparing your charges.

Chris

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Do you have any pics?