Orion14ed
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- Jul 2, 2012
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Hey guys! I am super excited to show you this build, because I am quite happy with the results. I will do my best to make this thread as in depth as possible.
My dream rocket to build is the Madcow Super DX3, it seems like a blank canvas with massive size. I really was hoping that this rocket would be placed on sale during Black Friday, instead I found the 4" Patriot at a nice price. I placed my order and began to build. Below are the steps I took, recalled and recorded the best to my ability. I hope you enjoy the read, and confirm that the build was up to par for a certification flight.
Parts:
The Madcow Website lists these parts as what comes in the box:
High Power Rocket
Heavy Duty Plastic Nose Cone
1/4" Plywood Laser Cut Fins and Rings
Delrin Rail Buttons
Cut Vinyl Decal
Pre-slotted Airframe
9/16" Tubular Nylon Shock Cord
I also opted for the optional 36" parachute, with a 38mm Motor Mount.
Along with items above, I also purchased 2 quicklinks, I believe they are .25" (I will check later), some 15 min epoxy from US Composites, an extra set of centering rings, and some run of the mill 5 min epoxy.
Tools:
As for tools used, a dremel with proper attachments, table saw, miter saw, rulers, and a lathe were all needed, when each was used will be mentioned throughout the thread.
The Motor Mount:
I did some research to see what the lengths of 38mm motors were, and what I would be expecting to use in this rocket. I opted to cut the motor mount tube to 12". This cut was made with a miter saw. Due to how the saw cuts, sanding was needed to ensure that the tube still maintained the same shape as before. After the tube was cut, some simple meassuring yeilded where the centering rings needed to be placed. I intended to place the forward ring about a .25" behind the tip of the tube. The middle ring was placed in a position where the ring would line up with the already slotted fin slits, this would allow for epoxy to contact the forward end of the through the wall fins, and the middle ring. The aft ring was then to be placed on with the internal fillets completed. I intended to place the assembly in so that from the aft end of the body tube half of an inch of the motor tube would be exposed.
Mounting the Rings:
Before I epoxied any ring to the tube, I placed the eyebolt assembly into the forward ring. After making sure the eyebolt was in nice and tight, I took some 5 min epoxy and secured it in place. I did not follow the instructions recommendation for the eyebolt position, instead I installed the eyebolt with the opening like so:
This allows for easy removal of the shockcord assembly via a quicklink.
The first step was to sand down the location where the rings would be mounted to the motor mount tube. The are was sanded so that the coating on the tube was removed, allowing the ring to bond directly to the tube in a wood to paper bond. This adds a bit of security with the bond strength.
I work in my neighbor's carpenter shop, so he is always suggesting things to teach me and how I could do my projects better. He suggested making a 38mm hole in a square block of wood, and using this as a way to ensure the rings would be square when bonding to the tube. I did exactly this, and ended up with this set up:
This would allow me to place glue where the ring would rest, slide it into place, and then place glue on one side of the ring, wait for it to set, then glue the other side with the clamp removed.
The epoxy I purchased required a 4:1 ratio of hardener to resin. To make sure these amounts were as exact as possible, I used syringes to measure out the two parts. This work quite well, especially when it was a nice temperature outside because both the resin and the hardener became a lot more viscous. I then would mix the epoxy for a good 5-8 mins before I applied it to the desired location.I did this for the motor mount, in the steps described above, and was pleased with the result.
Mounting the Motor Mount:
As mentioned above, my goal was to have the motor mount positioned in such a way where the middle ring is placed just right in respect to the fins, and where the tube stuck .5" from the end of the body tube. I at one point had the math all figured out in a sheet of paper and intended of showing it here, but has since lost it. I may go back and post it at a later time. Rest assured, the measurements were made, and I was confident I would get the mounting position I would be pleased with.
The prep was much like mounting the rings to the motor mount: sanding down the bonding location. This was done, and I was ready to mount the motor mount.
I wanted to make sure I could bond the rings to the tube in two place: forward of the middle ring, and forward of the forward ring. To do this, epoxy was placed as best possible where the middle ring would sit, but to ensure it would bond in the strongest way possible, I slid the motor mount to such a position that the middle ring was just behind the forward end of the fin slit. At this point, I needed a way to get glue into the slit, let it move around, and then push the assembly to its final position. To accomplish this, I used a very large syringe to put glue into the fin slots, where once the ring was pushed into place the epoxy would bond the middle ring to the body tube.
I followed the same procedure for the forward ring, but stuck my arm inside the BT, and made sure to make a nice epoxy rim where the ring and BT met, this was the result:
I was super pleased with the epoxy distribution, and was shocked that the large syringe worked so well, I was almost certain the epoxy would not be friendly to the tool.
Mounting the Fins:
To mount the fins, my carpenter friend showed me how to make a nice guide. I then made one myself.
First two cuts were made that were .25" in depth into the wood piece with a table saw, each perpendicular to one another; this is where the fins would sit in the mount. Next, I used a lathe to make a circular divet the same depth as the initial cuts. This was because the fins were to be flush with the end of the BT. Next, a hole was cut in the middle with the lathe to allow for the motor mount to slide through.
This created a fantastically sturdy platform for the fins to be mounted with, but one that required special attention as to not bond the mount to the rocket itself. I explored using wax paper as a solution to prevent the guide from being epoxied to the rocket, but opted to just use extreme caution when epoxying instead.
Each fin, fin slot, and fin mount slot was numbered to ensure there wasn't any confusion when I went to mount them. I then mixed the epoxy, placed each fin in, applied pressure to the mount, and placed it on a flat surface. I then used some elastic bands to make sure the fins were being pressed against the BT, and waited the proper amount of time.
Removing the mount, the fins were on nice and straight, and I was very happy. They certainly run parallel to the body of the BT which is nice, meaning less of a roll on launch day.
Fin Fillets:
It was then time to add the fillets to the fins. Sanding was done to the base of the fin, where the epoxy would bond the BT and the fin. The BT was also sanded in the corresponding location.
To make sure each filet was as uniform as possible, I measured a .25" from the base of the fin up on the fin, and .25" from the base onto the BT. I then applied a straight piece of tape on the fin and the BT to allow for a clean looking fillet.
Epoxy was then mixed with Phenolic Microballoons. The consistency of peanut butter didn't seem that possible without adding a very large amount of filler, so I added a fair amount, and proceeded with the fillets. I let the epoxy sit there for about 3 mins after pouring it into place, then ran a Popsicle stick over it to round it out. After about 5-10 mins, I removed the tape. The result was always a straight line of epoxy.
I repeated these steps for each external fillet and was generally satisfied. Some fillets turned out larger in diameter than others, but nothing too extreme where I would be concerned about balance. These fillets are large, and very, very, very, strong. I have no concern about them holding up.
Internal Fillets:
Internal fillets were messy, and a lot less smaller than the external fillets, but what important was that they bonded each part to eachother, which they did.
Here is what they looked like, I'm not proud, but hey, who really is about the internal fillets:
My dream rocket to build is the Madcow Super DX3, it seems like a blank canvas with massive size. I really was hoping that this rocket would be placed on sale during Black Friday, instead I found the 4" Patriot at a nice price. I placed my order and began to build. Below are the steps I took, recalled and recorded the best to my ability. I hope you enjoy the read, and confirm that the build was up to par for a certification flight.
Parts:
The Madcow Website lists these parts as what comes in the box:
High Power Rocket
Heavy Duty Plastic Nose Cone
1/4" Plywood Laser Cut Fins and Rings
Delrin Rail Buttons
Cut Vinyl Decal
Pre-slotted Airframe
9/16" Tubular Nylon Shock Cord
I also opted for the optional 36" parachute, with a 38mm Motor Mount.
Along with items above, I also purchased 2 quicklinks, I believe they are .25" (I will check later), some 15 min epoxy from US Composites, an extra set of centering rings, and some run of the mill 5 min epoxy.
Tools:
As for tools used, a dremel with proper attachments, table saw, miter saw, rulers, and a lathe were all needed, when each was used will be mentioned throughout the thread.
The Motor Mount:
I did some research to see what the lengths of 38mm motors were, and what I would be expecting to use in this rocket. I opted to cut the motor mount tube to 12". This cut was made with a miter saw. Due to how the saw cuts, sanding was needed to ensure that the tube still maintained the same shape as before. After the tube was cut, some simple meassuring yeilded where the centering rings needed to be placed. I intended to place the forward ring about a .25" behind the tip of the tube. The middle ring was placed in a position where the ring would line up with the already slotted fin slits, this would allow for epoxy to contact the forward end of the through the wall fins, and the middle ring. The aft ring was then to be placed on with the internal fillets completed. I intended to place the assembly in so that from the aft end of the body tube half of an inch of the motor tube would be exposed.
Mounting the Rings:
Before I epoxied any ring to the tube, I placed the eyebolt assembly into the forward ring. After making sure the eyebolt was in nice and tight, I took some 5 min epoxy and secured it in place. I did not follow the instructions recommendation for the eyebolt position, instead I installed the eyebolt with the opening like so:
This allows for easy removal of the shockcord assembly via a quicklink.
The first step was to sand down the location where the rings would be mounted to the motor mount tube. The are was sanded so that the coating on the tube was removed, allowing the ring to bond directly to the tube in a wood to paper bond. This adds a bit of security with the bond strength.
I work in my neighbor's carpenter shop, so he is always suggesting things to teach me and how I could do my projects better. He suggested making a 38mm hole in a square block of wood, and using this as a way to ensure the rings would be square when bonding to the tube. I did exactly this, and ended up with this set up:
This would allow me to place glue where the ring would rest, slide it into place, and then place glue on one side of the ring, wait for it to set, then glue the other side with the clamp removed.
The epoxy I purchased required a 4:1 ratio of hardener to resin. To make sure these amounts were as exact as possible, I used syringes to measure out the two parts. This work quite well, especially when it was a nice temperature outside because both the resin and the hardener became a lot more viscous. I then would mix the epoxy for a good 5-8 mins before I applied it to the desired location.I did this for the motor mount, in the steps described above, and was pleased with the result.
Mounting the Motor Mount:
As mentioned above, my goal was to have the motor mount positioned in such a way where the middle ring is placed just right in respect to the fins, and where the tube stuck .5" from the end of the body tube. I at one point had the math all figured out in a sheet of paper and intended of showing it here, but has since lost it. I may go back and post it at a later time. Rest assured, the measurements were made, and I was confident I would get the mounting position I would be pleased with.
The prep was much like mounting the rings to the motor mount: sanding down the bonding location. This was done, and I was ready to mount the motor mount.
I wanted to make sure I could bond the rings to the tube in two place: forward of the middle ring, and forward of the forward ring. To do this, epoxy was placed as best possible where the middle ring would sit, but to ensure it would bond in the strongest way possible, I slid the motor mount to such a position that the middle ring was just behind the forward end of the fin slit. At this point, I needed a way to get glue into the slit, let it move around, and then push the assembly to its final position. To accomplish this, I used a very large syringe to put glue into the fin slots, where once the ring was pushed into place the epoxy would bond the middle ring to the body tube.
I followed the same procedure for the forward ring, but stuck my arm inside the BT, and made sure to make a nice epoxy rim where the ring and BT met, this was the result:
I was super pleased with the epoxy distribution, and was shocked that the large syringe worked so well, I was almost certain the epoxy would not be friendly to the tool.
Mounting the Fins:
To mount the fins, my carpenter friend showed me how to make a nice guide. I then made one myself.
First two cuts were made that were .25" in depth into the wood piece with a table saw, each perpendicular to one another; this is where the fins would sit in the mount. Next, I used a lathe to make a circular divet the same depth as the initial cuts. This was because the fins were to be flush with the end of the BT. Next, a hole was cut in the middle with the lathe to allow for the motor mount to slide through.
This created a fantastically sturdy platform for the fins to be mounted with, but one that required special attention as to not bond the mount to the rocket itself. I explored using wax paper as a solution to prevent the guide from being epoxied to the rocket, but opted to just use extreme caution when epoxying instead.
Each fin, fin slot, and fin mount slot was numbered to ensure there wasn't any confusion when I went to mount them. I then mixed the epoxy, placed each fin in, applied pressure to the mount, and placed it on a flat surface. I then used some elastic bands to make sure the fins were being pressed against the BT, and waited the proper amount of time.
Removing the mount, the fins were on nice and straight, and I was very happy. They certainly run parallel to the body of the BT which is nice, meaning less of a roll on launch day.
Fin Fillets:
It was then time to add the fillets to the fins. Sanding was done to the base of the fin, where the epoxy would bond the BT and the fin. The BT was also sanded in the corresponding location.
To make sure each filet was as uniform as possible, I measured a .25" from the base of the fin up on the fin, and .25" from the base onto the BT. I then applied a straight piece of tape on the fin and the BT to allow for a clean looking fillet.
Epoxy was then mixed with Phenolic Microballoons. The consistency of peanut butter didn't seem that possible without adding a very large amount of filler, so I added a fair amount, and proceeded with the fillets. I let the epoxy sit there for about 3 mins after pouring it into place, then ran a Popsicle stick over it to round it out. After about 5-10 mins, I removed the tape. The result was always a straight line of epoxy.
I repeated these steps for each external fillet and was generally satisfied. Some fillets turned out larger in diameter than others, but nothing too extreme where I would be concerned about balance. These fillets are large, and very, very, very, strong. I have no concern about them holding up.
Internal Fillets:
Internal fillets were messy, and a lot less smaller than the external fillets, but what important was that they bonded each part to eachother, which they did.
Here is what they looked like, I'm not proud, but hey, who really is about the internal fillets:
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