Over the summer, @Frosty_Burrito and I decided to build a rocket capable of reaching 100k ft. This initially started as a much tamer project, but eventually evolved into a full minimum diameter 2 stage. It can fit a CTI 98 6xl to a CTI 75 6xl and current sims using an N3800 to M840 have it going ~112k and Mach ~3. If we go above our mass budget, we can easily use a larger motor in the booster so that we are still reaching the 100k ft. goal. This isn't meant to be the most optimized build by any means, we just want to get to 100k without compromising on too many things (especially recovery). Before we even attempt the full flight, we will be doing multiple test flights on much smaller motors to make sure everything is working properly.
Here are some pictures of the progress so far:
The fins were cut out of 1/8" G10 on a water jet and then covered with 4 layers of 6K carbon from Soller on each side. One of the big parts of this project is learning to vacuum bag, so we used it as much as possible. Once cured, the fins were cut out then sanded back to shape on a belt sander.
For beveling, we made a jig with a table saw based on this video. It took some practice to get right, so the sustainer fins turned out much better than the booster fins, but it should still be alright. We'll probably use a router
based jig in the future though this one worked alright in the end.
The fins were then tacked on with ES6209 and a little CA, and external fillets were done with more ES6209 and colloidal silica.
Since the fins already have a good amount of carbon added to them, we aren't going crazy with tip to tip. We are adding two additional layers of carbon on each fin and going up to the bevel. The first layer extends roughly one inch past the fillets and is made of 6K carbon from Soller. The second layer extending to the bevel and is made of 3K carbon. Each of these was also vacuum bagged and they came out fairly nicely. When the layup is complete, we intend on coating the bevels as well as the leading and trailing edges of the sustainer fins with JB weld for heat resistance. Our other choice would be to use Cotronics like Jim Jarvis, but that seems a decent bit more expensive and has a short shelf life.
In terms of the interstage, we are planning on having the sustainer motor stick out the aft end of the rocket and slide into a tube in the transition. After reading the Aeropac 100k report, we assumed we would not be able to use a normal 75mm airframe as the fit was too loose, and this was confirmed once we got the parts in hand. To remedy this, we rolled a short carbon tube directly on a CTI 75mm casing. While there is still a little wiggle, it is a much better fit than a normal airframe, and is much easier to shim with some tape.
I've reached the image limit for this post, so ill be adding more of our progress in this thread soon.
Here are some pictures of the progress so far:
The fins were cut out of 1/8" G10 on a water jet and then covered with 4 layers of 6K carbon from Soller on each side. One of the big parts of this project is learning to vacuum bag, so we used it as much as possible. Once cured, the fins were cut out then sanded back to shape on a belt sander.
For beveling, we made a jig with a table saw based on this video. It took some practice to get right, so the sustainer fins turned out much better than the booster fins, but it should still be alright. We'll probably use a router
based jig in the future though this one worked alright in the end.
The fins were then tacked on with ES6209 and a little CA, and external fillets were done with more ES6209 and colloidal silica.
Since the fins already have a good amount of carbon added to them, we aren't going crazy with tip to tip. We are adding two additional layers of carbon on each fin and going up to the bevel. The first layer extends roughly one inch past the fillets and is made of 6K carbon from Soller. The second layer extending to the bevel and is made of 3K carbon. Each of these was also vacuum bagged and they came out fairly nicely. When the layup is complete, we intend on coating the bevels as well as the leading and trailing edges of the sustainer fins with JB weld for heat resistance. Our other choice would be to use Cotronics like Jim Jarvis, but that seems a decent bit more expensive and has a short shelf life.
In terms of the interstage, we are planning on having the sustainer motor stick out the aft end of the rocket and slide into a tube in the transition. After reading the Aeropac 100k report, we assumed we would not be able to use a normal 75mm airframe as the fit was too loose, and this was confirmed once we got the parts in hand. To remedy this, we rolled a short carbon tube directly on a CTI 75mm casing. While there is still a little wiggle, it is a much better fit than a normal airframe, and is much easier to shim with some tape.
I've reached the image limit for this post, so ill be adding more of our progress in this thread soon.
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