So I was initially planning on building a small 54 to 54 two stage rocket while in the US for my internationnal semester. After ordering the propellent and single use EMKs from RCS, and cutting the grains, I realized that I wouldn't have enough time to complete the project. So I was left with a 5G EMK, a 3G EMK, a stick of PropX, and two stick of Slower White thunder.
I used part of the Slower White and the 3G EMK to make a moonburner motor and flew it on a very simple rocket to 4.2km.
Now I was left with a 5G 54mm EMK, and a few grains of PropX... After running a few OpenMotor sims, and some OpenRocket simulations, I found out that it could be a very spicy flight... Mach 3 would be reached at an altitude of around 1500ft, with a peak mach number of around 3.3. The maximum acceralation was expected to be around 150Gs.
The whole design takes advantage of the fact that the EMK has to be assembled and bonded. The design is basically as short as possible. Let's go over the different parts, starting at the tip.
The nosecone tip was machined and anodized by JLCPCB for the amazing price of $15 after a coupon, plus shipping. The tip is threaded M5 for the sled threaded rod and its base diameter is 22mm. The 6° half angle nosecone was layed up at FAR at around 11pm in the cold. The plug was 3d printed and covered in two condoms to act as a mold release. I used 6 layers of 3" soller composite light sleeves and US composite 635 laminating resin with the medium hardener. After curing, the nosecone was sanded smooth and I used a bit of bondo to fill a few defects. the resulting nosecone was an absolute unit. It weighed 67.5g after all the trimming. The nosecone contains the entire avbay: an Easymini and an opensource RDF beacon. All powered by two 1S 120mAh lipo batteries from Altus Metrum. The avbay sled was printed out of PETG. The "eyenut" used is from Mcmaster: 5621N12
Now you may have noticed that there's no straight section on the nosecone... The coupler part of the motor closure. This part was 3d printed in aluminum by 3DPnxt on CraftCloud. It includes a small loop for harness attachment. There's a cavity meant to be injected with epoxy to bond the closure to the casing. This is done using small 1/8" hole and once injected with DP460, they were plugged using carbon fiber pins. This part is around 120g. The 15in topflight chute and the shockcord is contained in this coupler.
Going down a bit and there's the fincan. This part was also 3d printed by the same company in aluminum. The airfoil is a double-wedge, tapered from root to tip, and hollowed and with chevrons to reduce weight. It also has an integrated tailcone and 4 holes for 3/32 carbon fiber pins. Additionally the fincan was RTV in place. I was a bit disapointed with the finish as I choosed a finish that required manual sanding, and let's just say that they went a bit too agressive with the sanding. I had to do a bit of filling and painting to make it look acceptable.
As you can probably see in the last picture, it's a big throat diameter. I won't go into the motor design but it's 5 grains of PropX and 2 grains of Blue Thunder...
Fast forward to December 2, at FAR...
I painted the rocket the night before for maximum mach rash, assembled the avbay and the recovery system. The next morning at 9am it was ready to go, and in the FAR 54mm tower, ready to go with a ematch boosted with PropX shavings as igniter.
Liftoff pictures by Julian Rice.
Here's the liftoff video taken by @Brainstormz123:
View attachment IMG_6325.mp4
During the flight the beacon was beeping happily. A few second after liftoff I started a stopwatch, anxiously waiting as it got closer to the simulated impact time of 70s. At around 75s the beacon was lost... Hopefully someone will find it burried in the desert by chance...
I used part of the Slower White and the 3G EMK to make a moonburner motor and flew it on a very simple rocket to 4.2km.
Now I was left with a 5G 54mm EMK, and a few grains of PropX... After running a few OpenMotor sims, and some OpenRocket simulations, I found out that it could be a very spicy flight... Mach 3 would be reached at an altitude of around 1500ft, with a peak mach number of around 3.3. The maximum acceralation was expected to be around 150Gs.
The whole design takes advantage of the fact that the EMK has to be assembled and bonded. The design is basically as short as possible. Let's go over the different parts, starting at the tip.
The nosecone tip was machined and anodized by JLCPCB for the amazing price of $15 after a coupon, plus shipping. The tip is threaded M5 for the sled threaded rod and its base diameter is 22mm. The 6° half angle nosecone was layed up at FAR at around 11pm in the cold. The plug was 3d printed and covered in two condoms to act as a mold release. I used 6 layers of 3" soller composite light sleeves and US composite 635 laminating resin with the medium hardener. After curing, the nosecone was sanded smooth and I used a bit of bondo to fill a few defects. the resulting nosecone was an absolute unit. It weighed 67.5g after all the trimming. The nosecone contains the entire avbay: an Easymini and an opensource RDF beacon. All powered by two 1S 120mAh lipo batteries from Altus Metrum. The avbay sled was printed out of PETG. The "eyenut" used is from Mcmaster: 5621N12
Now you may have noticed that there's no straight section on the nosecone... The coupler part of the motor closure. This part was 3d printed in aluminum by 3DPnxt on CraftCloud. It includes a small loop for harness attachment. There's a cavity meant to be injected with epoxy to bond the closure to the casing. This is done using small 1/8" hole and once injected with DP460, they were plugged using carbon fiber pins. This part is around 120g. The 15in topflight chute and the shockcord is contained in this coupler.
Going down a bit and there's the fincan. This part was also 3d printed by the same company in aluminum. The airfoil is a double-wedge, tapered from root to tip, and hollowed and with chevrons to reduce weight. It also has an integrated tailcone and 4 holes for 3/32 carbon fiber pins. Additionally the fincan was RTV in place. I was a bit disapointed with the finish as I choosed a finish that required manual sanding, and let's just say that they went a bit too agressive with the sanding. I had to do a bit of filling and painting to make it look acceptable.
As you can probably see in the last picture, it's a big throat diameter. I won't go into the motor design but it's 5 grains of PropX and 2 grains of Blue Thunder...
Fast forward to December 2, at FAR...
I painted the rocket the night before for maximum mach rash, assembled the avbay and the recovery system. The next morning at 9am it was ready to go, and in the FAR 54mm tower, ready to go with a ematch boosted with PropX shavings as igniter.
Liftoff pictures by Julian Rice.
Here's the liftoff video taken by @Brainstormz123:
View attachment IMG_6325.mp4
During the flight the beacon was beeping happily. A few second after liftoff I started a stopwatch, anxiously waiting as it got closer to the simulated impact time of 70s. At around 75s the beacon was lost... Hopefully someone will find it burried in the desert by chance...
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