CZ Brat
Well-Known Member
- Joined
- Jan 3, 2013
- Messages
- 611
- Reaction score
- 5
Hey all. This is my first scratch built Mid High power rocket and my first build thread. The NDRS-SC-4 stands for Neighborhood Dispute Resolution System Stealth, Conventional warhead 4. I am going for a Stealth look to this rocket. It is 4 x 32 and about 34 oz sans motor. It is 29mm MMT and being designed to fly on G to baby H. 3 grain max due to size.
Because it is a short fatty, a lot of nose weight will be needed. With 6 7 oz, it has a stability of .75 to .86 with the largest motor. Even with 6oz and an angle of attack of 15°, it will still have a stability above .5 according to OR.
I am using a Mad Cow 4:1 plastic NC, 4 Vaughn Brothers BT (Discount Rocketry), and 1/8 plywood laser cut fins, rings and NC bulkhead. My local trophy shop that I do business with had a laser cutter, and he offered to cut these out for me for free (cool to watch it cut). Though OR cant support it, I am adding ¼ triangular balsa strips to be fillets. This should increase the angular, stealthy look of the rocket.
Nose weight. So if I am not doing something new or experimenting, the build is boring. So I am going to cast the lead nose weight. I put the NC in the freezer, then oiled up the inside with canola, and poured melted candle wax inside it. The outside only got a little warm, and there was no warping or deformation. Once it soft-set, I froze it again. I then put the tip in simmering water a few seconds to release the wax impression. I mixed up a batch of plaster of Paris and poured into a tin can. I then placed the wax impression into it. Once set, I placed it into a 200°F oven upside down with a cup to catch the wax. The wax fell out in about 15-20 minutes. I then left it in the oven another 45 minutes or so to help dry out the plaster. I may bake it once more before casting the lead.
I tried to post pics but TRF is freezing up every time I try. I will get some soon
Because it is a short fatty, a lot of nose weight will be needed. With 6 7 oz, it has a stability of .75 to .86 with the largest motor. Even with 6oz and an angle of attack of 15°, it will still have a stability above .5 according to OR.
I am using a Mad Cow 4:1 plastic NC, 4 Vaughn Brothers BT (Discount Rocketry), and 1/8 plywood laser cut fins, rings and NC bulkhead. My local trophy shop that I do business with had a laser cutter, and he offered to cut these out for me for free (cool to watch it cut). Though OR cant support it, I am adding ¼ triangular balsa strips to be fillets. This should increase the angular, stealthy look of the rocket.
Nose weight. So if I am not doing something new or experimenting, the build is boring. So I am going to cast the lead nose weight. I put the NC in the freezer, then oiled up the inside with canola, and poured melted candle wax inside it. The outside only got a little warm, and there was no warping or deformation. Once it soft-set, I froze it again. I then put the tip in simmering water a few seconds to release the wax impression. I mixed up a batch of plaster of Paris and poured into a tin can. I then placed the wax impression into it. Once set, I placed it into a 200°F oven upside down with a cup to catch the wax. The wax fell out in about 15-20 minutes. I then left it in the oven another 45 minutes or so to help dry out the plaster. I may bake it once more before casting the lead.
I tried to post pics but TRF is freezing up every time I try. I will get some soon